中国生态农业学报(中英文)

2011, 19(5): . doi: 10.3724/SP.J.1011.2011.00000

Abstract(2060) PDF(1158)

Abstract:

2011, 19(5): 985-986. doi: 10.3724/SP.J.1011.2011.00985

Abstract(1657) PDF(1823)

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A review of agricultural water-saving research at Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences over the last 30 years

ZHANG Xi-Ying

2011, 19(5): 987-996. doi: 10.3724/SP.J.1011.2011.00987

Abstract(2333) PDF(1979)

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Farmland water-saving research was conducted since the establishment of Luancheng Agro-Ecosystem Experimental Station, Chinese Academy of Sciences (simplified as Luancheng Station). In 1980s, the research was concentrating on optimizing irrigation scheduling to reduce irrigation application for practical use. During that period, farmers usually irrigated winter wheat 7 to 10 times per season. By application an optimized irrigation scheduling, irrigation number was reduced to 5 per season without penalties to yield. In 1990s, the research was changed to fundamental studies of water movement in field. Water transfer and regulation mechanisms in soil-plant-atmosphere continuum were the research focuses during that period, resulting improved understanding of the principles and potential in water-saving. Extensive root sampling was carried out to study the pattern of root growth and soil water utilization. Root distribution down the soil profile was then modified to allow the crop to use soil water more efficiently. Evapotranspiration (ET) and soil evaporation were determined from long term data for different growing stages of winter wheat and summer maize to provide basis for crop-water relation studies. The results showed that seasonal soil water evaporation (measured by micro-lysimeters) accounted for 20%~30% of seasonal ET that reduced soil evaporation could contribute significantly to in-field water-saving. With the intensifying in water shortage in this area, research focuses for the last ten years were on physiological and ecological bases of deficit irrigation. The effects of water deficit on crop growth, water use, yield and water use efficiency (WUE) of winter wheat were studied. The results established that grain production could increase even though irrigation applications were reduced by using a Regulated Deficit Irrigation strategy. The contribution of cultivar improvement on grain production, crop water use and WUE of winter wheat from 1970s to the present time was studied and the results provided guideline for selecting better cultivars for yield and WUE. Combining the technologies and experience of the last 30 years, integrated water-saving models were developed and extended for sustainable groundwater use. In future, water-saving research will still be one of the important research topics at Luancheng Station. Interdisciplinary research that combines breeding, nutrient, cultivation and water will improve crop yield and resource use efficiency.

Nitrogen flux and its manipulation in the cropland ecosystem of the North China Plain

HU Chun-Sheng, DONG Wen-Xu, ZHANG Yu-Ming, CHENG Yi-Song, LI Xiao-Xin, YANG Li-Lin

2011, 19(5): 997-1003. doi: 10.3724/SP.J.1011.2011.00997

Abstract(2062) PDF(1743)

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The North China Plain (NCP) is one of the areas of intensive cereal production in China, producing large winter wheat and summer maize. A critical challenge facing the agro-production sector of the NCP, however, includes over-application of chemical fertilizers, excessive soil nutrient accumulation and declining nutrient use efficiency. This study investigated relationship between nitrogen (N) flux and crop nutrient uptake/loss processes under conventional fertilization at 400 kg(N)·hm^-2·a^-1 in the winter wheat/summer maize crop rotation system in the piedmont region of NCP. The management practices of the fields were adjusted on the basis of the characteristics of N output fluxes. The results showed that in the region, a total N input of 561~580 kg·hm^-2 and output of 468~494 kg·hm^-2 resulted in a N surplus of 86~93 kg·hm^-2 per year. Organic N load in the study area was 24~36 kg·hm^-2. N loss via ammonia volatilization and NO₃^--N leaching was 60 kg·hm^-2 and 47~84 kg·hm^-2 per year, respectively, collectively accounting for 30% of applied N fertilizer in the region. N loss via nitrification-denitrification was only 5.0~8.7 kg·hm^-2 per year, accounting for 1%~2% of applied N fertilizer. Ammonia volatilization and NO₃^--N leaching were the main modes of N loss, and therefore the main drivers of lower N fertilizer utilization rate in the study area. Appropriate management practices such as adjustments of the rates and time of N fertilization and irrigation were important for decreasing ammonia volatilization, NO₃^--N accumulation in deep soil profile and therefore the mitigation of NO₃^--N loss in the region. Amendments with wheat/corn straw changed the rates of N transformation and migration in the soil, which also resulted in low NH₃ loss and NO₃^--N leaching. Analysis of precision fertilization via NO₃^--N or hyper-spectra information feature also showed that the main indices of N loss were the amount of soil available nutrient and crop nutrient content. This laid the basis for efficient fertilizer application in the study area. Control-release fertilizer and precision fertilization techniques improved crop nutrient uptake, which in turn increased N use efficiency. An integrated fertilizer utilization technique for sustainable environmental and agricultural development in the piedmont region of NCP was possible.

Agro-ecosystems water cycles of the typical irrigated farmland in the North China Plain

SHEN Yan-Jun, LIU Chang-Ming

2011, 19(5): 1004-1010. doi: 10.3724/SP.J.1011.2011.01004

Abstract(1937) PDF(2056)

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This paper reviewed the research progresses on hydrological cycles and water transformation studies at Luancheng Agro-Ecosystem Experimental Station, Chinese Academy of Sciences (simplified as Luancheng Station) during the past 30 years. As a mostly achieved progress, the evapotranspiration (ET) and its partitioning over irrigated winter wheat-summer maize cropland, which is the most common cultivation pattern in North China Plain, are clarified through multi-years observations using weighing lysimeter, micrometeorological measurements, and isotopic analysis. The annual ET of the irrigated wheat-maize field can reach to 870 mm·a-1, which exceeds the annual precipitation by around 350 mm at an average level. This gap between annual ET and precipitation is bridged by groundwater pumpage. As a matter of long-term over exploitation, the groundwater over the North China Plain experienced rapid depletion and caused wide concerns on sustainability. The study at Luancheng Station suggests that the soil evaporation shares about 1/3 of the total water consumption and the evaporation depth can reach deep to 20 cm under land surface through a isotopic method. Moreover, wheat transpiration is mainly dependent on the soil moisture in the depth of 0~40 cm soil layer, which is largely shallower than the generally used "planing wetting depth", i.e. 100 cm. As for the deep percolation or drainage of the soil water and the vertical recharge rate of groundwater, there exists large range among different studies with different method, such as soil water balance modeling, rainfall-infiltration experiment, etc. It is urgently needed to go to the details of water cycles over different agricultural land uses and soil properties, and to address the spatial heterogeneities in evapotranspiration, infiltration, and soil water balancing, over the plain.

Enhancement of wheat distant hybridization germplasm

AN Diao-Guo, XU Hong-Xing, XU Yun-Feng

2011, 19(5): 1011-1019. doi: 10.3724/SP.J.1011.2011.01011

Abstract(1985) PDF(1292)

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The related species of Triticinae are important and valuable gene resources for molecular improvement of wheat (Triticum aestivum L.). These species have a number of distinct characteristics that common wheat varieties simply do not have. Through distant hybridization and chromosome engineering in the past years, a number of new germplasms, including wheat ("Xiaoyan 6")-rye ("German white") addition, substitution and translocation lines, have been developed and characterized. The sequential genome in situ hybridization (GISH) and multi-color fluorescence in situ hybridization (FISH), specific molecular markers, combining with disease resistance evaluation and nutrition, quality and yield identification had screened 10 kinds of new wide hybrid germplasms, including sterile lines. The screened germplasms were highly resistant to stripe rust, leaf rust and powdery mildew. Some hybrid germplasms were also of high quality, enriched Zn and Fe, high nutrient efficiency and desirable agronomic traits. These traits made the germplasms new and valuable for effective wheat breeding. Also 414 new EST (expressed sequence tag) markers specific to rye genome and 31 new markers specific to rye chromosome arms had been developed. These molecular markers could be used in marker-assisted selection breeding or to rapidly detect corresponding rye chromosomes or chromosome segments introgressed into wheat background. The identification and mapping of new resistant genes derived from wheat relatives were ongoing. Some new advanced lines of wheat-rye and wheat-Agropyron cristatum were being developed for release as new cultivars.

Demonstration practices and effects of new agro-technologies developed at Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences over the last 30 years

HU Chun-Sheng, ZENG Jiang-Hai, WANG Shao-Ren

2011, 19(5): 1020-1024. doi: 10.3724/SP.J.1011.2011.01020

Abstract(2075) PDF(2125)

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This paper summarized regional demonstration practices and effects of new agro-technologies developed at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences (or Luancheng Station for short) over the last 30 years. In 1978, Luancheng County was selected as one of three comprehensive experimental bases for national agricultural modernization. New technologies for greenhouse facility, rural renewable energy, straw mulching and model cultivation of winter wheat were initially imported or developed in Luancheng and extended to North China in early 1980s. The peri-urban agriculture model combined with farming, livestock, fruit and vegetable production was developed and demonstrated in the mid 1980s. The resource-saving agriculture model focused on water saving was developed and disseminated in the region in the early 1990s. The urban agriculture model with characteristic information technology and sightseeing agriculture was developed and demonstrated in the early 21 century. Luancheng Station has developed agricultural models/technologies suitable for regional agricultural modernization that adequately serve the local farmers. In the 1970s, the station launched experiments for agricultural modernization practices in China. It had led agro-technological innovations/modernization and established regional agricultural modernization models at different agricultural development stages which promoted the development of agricultural modernization in China.

Analysis of published research papers based on experimental data from Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences

LI Rong-E, FENG Xue-Zan

2011, 19(5): 1025-1031. doi: 10.3724/SP.J.1011.2011.01025

Abstract(2079) PDF(1761)

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Bibliometeric analysis tools combined with CNKI and ISI Web of Knowledge literature databases were used to identify published research papers on experimental data from the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences for 1981~2010. The search and analysis yielded 1 151 published papers, of which 920 were in Chinese and 231 in English. For 1981~2010, the number of published papers increased with time. Prior to 2001, papers were mainly published in Chinese. The number of papers published in English increased at an annual rate of 22.4% after 2001. Number of papers published in Chinese peaked in 2005. The authors' institutions were mainly in Hebei Province, Beijing City and Shandong Province. Most of the international coauthors were in Japan and the United States. Wheat, maize, water use efficiency, yield and soil moisture were the most frequent key words, indicating that water use by wheat and maize was the most commonly research fields at the station. The published papers were largely funded by the National Science and Technology Programs and Chinese Academy of Sciences Programs. Some of the papers were, however, funded by the Science and Technology Programs of the local governments. A relatively small number of the papers were funded by international cooperations. The publishing journals mainly included the Chinese Journal of Eco-Agriculture; Agricultural Research in Arid Areas; Acta Agriculturae Boreali-Sinica; Hydrological Processes; Agricultural Water Management; Plant, Soil and Environment; and Irrigation Science. On the average, each of the published papers was cited 5.6 times for 1981~2010. A total of 6 papers were cited more than 100 times and 34 papers cited more than 50 times.

Analysis of field water consumption, its pattern, impact and driving factors

SUN Hong-Yong, ZHANG Xi-Ying, CHEN Su-Ying, SHAO Li-Wei, WANG Yan-Zhe, DONG Bo-Fei

2011, 19(5): 1032-1038. doi: 10.3724/SP.J.1011.2011.01032

Abstract(3919) PDF(3218)

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Agricultural water use accounts for about 70% of total water consumption in the North China Plain (NCP). So, the researches on field water consumption and its pattern, impact and driving factors critical for developing agricultural water-saving practices and also learning water transfer mechanisms in soil-plant-atmosphere continum (SPAC) are very important. This paper reviewed the proceedings in field water cycle and water-saving research in the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences since its establishment. Long-term site-specific experiments on irrigation schemes since 1985, straw mulching schemes since 1986, tillage schemes since 2002, large weighing lysimeter data streams since 1995, and other agro-experiments have been conducted at the station. Water balance methods and large weighting lysimeter data were used to estimate evapotranspiration (ET) in the station. Soil evaporation (E) was measured using the micro-lysimeter method. The results showed that water consumption during winter wheat and summer maize cropping periods was similar, averaging 430 mm per cropping season. The trend in water consumption increased with increasing irrigation of winter wheat, which had increased on the average from 283 to 493 mm. The coefficient of variation in ET was negatively correlated with irrigation, and was mainly driven by precipitation difference. The ratio of E to ET for winter wheat and summer maize was 1/3, and also similar for the tow crops. This implied that limiting E was a critical water-saving factor in the region. Field experiments at Luancheng station in recent 20 years showed that straw mulching significantly reduced E, to somewhere in the neighborhood of 40~50 mm. Wheat and maize straw mulching reduced E by 58.0% and 40.4% in summer maize and winter wheat fields, respectively. Despite the fact that differences in E existed for different field tillage practices,zero-tillage, as compared with traditional tillage, significantly reduced E. The irrigation, tillage and planning schemes as well as canopy characteristics affected crop water consumption and agricultural water-saving in the region. The above findings laid the basis for theoretical and technical developments of agricultural water-saving practices in NCP.

Effects of climate change and agricultural technology improvement on evapotranspiration and crop yield

CHEN Su-Ying, ZHANG Xi-Ying, SHAO Li-Wei, SUN Hong-Yong

2011, 19(5): 1039-1047. doi: 10.3724/SP.J.1011.2011.01039

Abstract(2312) PDF(2352)

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Along with the development of farm mechanization, improved production conditions, varietal breeding and favorable climatic changes, crop yields have drastically increased across the globe. Despite this achievement, however, evapotranspiration has not continued to increase with increasing crop yields. To that end, meteorological data for 1955~2007 at Shijiazhuang Meteorological Station were analyzed for changes in seasonal climatic factors that affected winter wheat and summer maize. Long-term (1992~2009) irrigation experiments at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences (or Luancheng Station in short) were also used to study the effects of climate change on evapotranspiration and yield of winter wheat and summer maize. The studies showed that the use of farm machinery in Hebei Province increased by 7.3 times in 2007 over that in 1983. Mechanization rate of cultivation, planting and harvesting was 59.65%, indicating that farm mechanization in Hebei Province had entered the intermediate stage by 2007. Summer maize yield increased by 2.08% per year, and with winter wheat straw mulching, saved about 14 mm of water. For the period 1955~2007, climatic factors during winter wheat and summer maize seasons had also changed. The average sunshine duration, relative humidity, wind speed, daily temperature range had significantly dropped during the growing seasons of two crops. Minimum temperature, average temperature and accumulated temperature had increased significantly. Although the trends of change in climatic factors had not significantly affected evapotranspiration (ET₀), water demand for the two crops increased due to decreasing rainfall. Long-term irrigation experiments showed that winter wheat and summer maize yields greatly increased due to improvements in production conditions, varietal breeding and climate change. In recent years, however, evapotranspiration had been relatively stabilized due to the extensive application of improved water-saving technologies.

Characteristics and effects of climate warming on winter wheat/summer maize cropping system in recent 50 years in the piedmont of Mount Taihang

QI Yong-Qing, SUN Hong-Yong, SHEN Yan-Jun

2011, 19(5): 1048-1053. doi: 10.3724/SP.J.1011.2011.01048

Abstract(1986) PDF(1781)

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Climate warming and its impact on cropping systems constitute a major aspect of agricultural development research in countering climate change. While the North China Plain (NCP) is one of the most important crop production bases of China, the piedmont regions of Mount Taihang are the most productive zones in the plain. Winter wheat and summer maize constitute the basic cropping system in NCP. In such a tight double-copping system, heat condition is the main factor that controls both sowing and harvesting dates of the crops. This paper established a case study on temperature and agricultural heat resources data for the last 50 years in Shijiazhuang, a typical area of the piedmont regions of Mount Taihang, to discuss the characteristics of climate warming and the related impacts on winter wheat/summer maize cropping system in the piedmont regions of Mount Taihang. For the last 50 years, an obvious warming trend at 0.35 ℃·10a^-1 was noted in the studied area. The trends in climate warming at the seasonal cycle were unequal, while a sharp increase (0.51 ℃·10a^-1) in winter and a more moderate increase (0.20 ℃·10a^-1) in summer. Climate warming in the studied area caused an increase in effective accumulated temperature (AT). In the last 2 decades, annual >10 ℃ AT increased obviously compared with the period of 1961~1990. The increased heat accumulation in recent years resulted in about 10~20 days extension of the suitable growing season. That favored crop growth and higher potential grain productivity. The sharp and unbalanced seasonal warming patterns resulting from regional climate warming distinctly impacted winter wheat/summer maize cropping system in the studied area. The emergence and seedling stages of winter wheat were temperature sensitive periods, and the suitable >0 ℃ AT was about 500~600 ℃ before overwintering stage. After 1990, the >0 ℃ AT in wheat season increased by 10% and the warmer seedling stage in turn decreased the safety level of overwintering stage. For that reason, wheat seeding date had been postponed to adapt to climate warming. Due to the higher heat resources and longer growing seasons, total >10 ℃ AT in maize season increased beyond 2 900 ℃. This was sufficient for mid-late maturity maize varieties in the piedmont regions of Mount Taihang.

Water balance and yield-increasing efficiency of irrigation of winter wheat under different irrigation schemes

PEI Hong-Wei, SUN Hong-Yong, SHEN Yan-Jun, LIU Chang-Ming

2011, 19(5): 1054-1059. doi: 10.3724/SP.J.1011.2011.01054

Abstract(1704) PDF(1367)

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Water is the most important limiting factor of wheat-maize double cropping system's production in the North China Plain (NCP). Water-saving agriculture is critical for social stability and sustainable economic development. To elevate irrigation efficiency in NCP, field experiments were conducted during three growing seasons of winter wheat at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences. Five irrigation schemes were designed in winter wheat seasons in the study area. The irrigation schemes included rainfed scheme (A) with no irrigation throughout the growing season, well irrigation scheme (B) with 100% field-capacity irrigation at all the stages, recovery water-stress irrigation scheme (C) with no irrigation at recovering stage and 80% field-capacity irrigation at all other growth stages, jointing-heading water-stress irrigation scheme (D) with no irrigation at jointing-heading stage and 80% field-capacity irrigation at all other stages, and then grain-filling water-stress irrigation scheme (E) with no irrigation at grain-filling stage and 80% field-capacity irrigation at all other stages. All the treatments had 3~4 replicates and irrigation was only done when moisture in the 0~100 cm soil depth was less than 65% of field capacity. The field irrigation experiments were conducted from October 2007 through June 2010. The results showed that evapotranspiration (ET) for treatments A, B, C, D and E were 251±58 mm, 482±48 mm, 352±44 mm, 388±22 mm and 324±53 mm, respectively. The volume of irrigation was positively related to yield in all the treatments. Yields for treatments A, B, C, D and E were 2 950±635 kg·hm^-2, 5 994±994 kg·hm^-2, 5 163±885 kg·hm^-2, 5 047±1 180 kg·hm^-2 and 5 249±975 kg·hm^-2, respectively. Irrigation efficiency varied from year to year in relation to precipitation trend. The effect of water on yield was therefore significantly different for the three years. In wet years, irrigation efficiency was 1.9 kg·m^-3, it was 0.4 kg·m^-3 in dry years and 1.6 kg·m^-3 in normal years.

Preliminary research on isotopic composition of water vapor in irrigated fields

ZHANG Yu-Cui, CAI Ying-Zhe, Stephen Parkes, Matthew F. McCabe, YANG Fan, WANG Qian, SHEN Yan-Jun

2011, 19(5): 1060-1066. doi: 10.3724/SP.J.1011.2011.01060

Abstract(1703) PDF(1618)

Abstract:
Improvements in water use efficient and limited groundwater consumption are important for water sustainable resource development. Atmospheric water vapor exchange sufficiently indicates water consumption in irrigated agro-ecosystems. This paper clarified the changes in water vapor isotopic composition with height and time of the day or longer periods. The relationship between the quantity and isotopic composition of evapotranspiration vapor was also determined. The chamber method (which was based on high frequency and real-time water vapor stable isotope analyzer) was used to measure isotopic composition of water vapor at different heights and times of the day/period. Using water vapor flux of crop land measured with Eddy Covariance method, the relationship between isotopic composition and evapotranspiration was also determined. Based on the different time scales, the results showed that water vapor isotopic composition at the ecosystem boundary layers continuously fluctuated during several days. The daily changes were stable with smaller fluctuations at hourly time-scale. There was a steady enrichment in daily changes in isotopic composition under atmospheric background. No obvious trend of change was noted in isotopic composition of the day. With no direct and rapid canopy effect, isotopic composition under atmospheric background was stable at hourly time-scale. There was also an obvious enrichment of chamber isotopic composition of evapotranspiration. Isotopic compositions of evaporation and transpiration were similar for midnight and clearly dissimilar during early morning and noon. Due to isotopic fractionation, isotopic composition of evapotranspiration water was heavier than the vapor at 2 m height. A good linear correlation was noted between the quantity and isotopic composition of evapotranspiration with correlation coefficient of 0.87 and regression equation of y = 53.21x-115.06. The study typified the vitality of evapotranspiration research via the isotope method.

Comparative advantages of Large Aperture Scintillometer and Eddy Covariance instrument for measuring evapotranspiration in irrigated farmlands

YANG Fan, QI Yong-Qing, ZHANG Yu-Cui, Bridget R. Scanlon, SHEN Yan-Jun

2011, 19(5): 1067-1071. doi: 10.3724/SP.J.1011.2011.01067

Abstract(2357) PDF(1945)

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Evapotranspiration (ET), a critical element of surface energy balance, plays an important role in the exchange of energy, mass and momentum in the soil-plant-atmosphere continuum. Large Aperture Scintillometer (LAS) is recent emerging instrument put on the ground to observe surface fluxes across pixel dimensions. This study validated the reliability of LAS observations with observation data from Eddy Covariance (EC) instruments. EC is the officially recognized and commonly used ET equipment in the Chinese Ecosystem Research Network (CERN). Heat flux was measured in summer maize fields via both LAS and EC at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences in August 2010 and compared. The results showed a significant consistency in both daily and monthly changes in heat flux measurements by LAS and EC. ET obtained from LAS was almost consistent with that from EC (R²=0.800 4) at the monthly scale. However, some differences existed in the daily change probably due to the effects of underlying principles, environment conditions and measurement scale. The study suggested that surface water and heat flux data collected via LAS was reliable and applicable in verifying estimated ET via remote sensing.

Interactions between evolution of farming systems and environment for agricultural production in the Huang-Huai-Hai Plain during the historic period

LIN Zhong-Hui, MO Xing-Guo

2011, 19(5): 1072-1079. doi: 10.3724/SP.J.1011.2011.01072

Abstract(1721) PDF(1449)

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Agricultural development in a certain geographical region is closely related to its natural resource base and development level of socio-economy and technology. The effects of agricultural production on the environment is changing with the evolution of farming systems. Based on a literature analysis, the interactions between the development of farming systems and the environment for agricultural production in the Huang-Huai-Hai Plain during the historic period were discussed. Agricultural development of North China Plain during the historic period was closely related to the channel stability of the lower reach of Yellow River. Before Song Dynasty, the low level of agricultural production in the Hebei Plain compared to the Huang-Huai-Hai Plain was the results of the channel shifts of the Yellow River in the Hebei Plain coupled with the destruction of war. After Song Dynasty, agricultural development of the Huang-Huai-Hai Plain was suffering from the Yellow River in a long period of time. Before modern agricultural science and technology was transferred into the North China Plain, farming systems was mainly constrained by the natural environment, but a slight improvement. The effects of development of farming systems on the environment were mainly the removal of natural vegetation because of artificial plants, the destruction of natural vegetation in mountain area due to the need of timber, the blockage of river downstream, the disappearance of lake, the poor drainage and the area increasing of saline land. Therefore, the worsening environment led to the low level of agricultural production in the North China Plain in a long historic period.

An overview of root hydraulic lift in root-soil systems

SHAO Li-Wei, SUN Hong-Yong, CHEN Su-Ying, ZHANG Xi-Ying

2011, 19(5): 1080-1085. doi: 10.3724/SP.J.1011.2011.01080

Abstract(4004) PDF(2791)

Abstract:
Root-soil system may be considered as a subsystem of the soil-plant-atmosphere continuum (SPAC). Synchronously, dynamic mechanisms in root-soil systems improve water and nutrient supply in the brother SPAC system. Plant root hydraulic lift is a process of root-soil systems that optimizes the homogeneous distribution and use of soil water. This phenomenon is a normal in plant root systems. Plant hydraulic lift processes make it easy to the most use of soil water and to facilitate soil nutrient utilization. Systemic optimization explains the mechanism of root hydraulic lift, which occurrence is restricted by environmental conditions and other inevitable factors. Root hydraulic lift water volume is a non-negligible element of plant growth, which provides a larger portion of water needed for transpiration. Hydraulic lift is not only a transpiration factor, but also a physiological and ecological element of plants. Applied root hydraulic lift research has the potential to improve agricultural development and ecological restoration in draught regions.

Effects of deficit irrigation on physio-ecological indices of winter wheat

SUN Hong-Yong, ZHANG Xi-Ying, CHEN Su-Ying, SHAO Li-Wei, WANG Yan-Zhe, LIU Ke-Tong

2011, 19(5): 1086-1090. doi: 10.3724/SP.J.1011.2011.01086

Abstract(1774) PDF(1738)

Abstract:
Water shortage is the main limitation to agricultural productivity in the North China Plain — a main grain production base in China. It has therefore been a major research task to develop an agricultural production practice that uses limited fresh water resources in the region. Deficit irrigation is a new irrigation scheme that optimally uses water resources while maintaining high economic yield. This paper reviewed the effects of deficit irrigation on physio-ecological indices of winter wheat at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences. Field plot irrigation experiments had shown that different levels of deficit irrigation at different growth stages of winter wheat affected root size and distribution in the soil profile, canopy structure, biomass growth, grain yield, and water use efficiency. The experiments showed that different levels of deficit irrigation facilitated leaf stomata adjustment which in turn affected the photosynthetic products and distributions of dry matter. The highest grain yield was obtained under optimal deficit irrigations at the different growth stages. This implied that the levels of deficit irrigation were different at different growth stages of winter wheat. The deficit sensitivity index was highest at jointing stage, when was not suitable time for deficit irrigation. In other words, deficit irrigation at other growth stages like the recovering and grain-filling stages little affected grain yield and therefore resulted in high water use efficiency. Based on the above results, an optimal irrigation scheme was developed in relation to the trend in precipitation leveling the region — i.e., 1, 2 and 3 times of irrigation at about 60~70 mm every time in wet years, normal years and dry years, respectively. The optimal irrigation scheme had been widely used in the North China Plain region.

Effect of plant film-forming anti-transpirant on transpiration efficiency of winter wheat flag-leaf

SHI Chang-Hai, KONG Shao-Hua, ZHAI Hong-Mei, YANG Jing, LI Dong-Xiao, LIU Meng-Yu

2011, 19(5): 1091-1095. doi: 10.3724/SP.J.1011.2011.01091

Abstract(1850) PDF(1662)

Abstract:
Restraining crop transpiration is critical for improving water use efficiency under scarce water resource conditions. Plant film-forming anti-transpirant (PFA) significantly limits plant water consumption, which in turn increases water use efficiency. However, PFA is rarely applied in winter wheat cultivation. We studied the effects of PFA on water stress physiology and senescence of flag leaf of winter wheat "Kn 9204" under different irrigations. The wheat was irrigated 0, 1, 2 or 3 times (respectively denoted as I0, I1, I2 and I3) during the entire period of growth. The results suggested that transpiration rates decreased, photosynthetic rates remained unaffected and transpiration efficiency increased under spray PFA treatment. Flag-leaf water retention under spray treatment was higher than that of CK. Excised-leaf water loss rate under spray treatment was lower by 10.3%, 10.3%, 12.8% and 16.9% under I0, I1, I2 and I3 irrigation treatments, respectively, than that of CK with increasing flag-leaf relative water content and water potential.Under 1, 2 or 3 times of irrigation, wheat superoxide dismutaseon (SOD) and catalase (CAT) activities dropped. Under zero irrigation, however, SOD and CAT activities exceeded that of CK. The rate of change (rate of curve) in malonyldiadehyde content under different treatments ranked as follows: I1+CK (10.59) > I1+PFA (6.99) > I2+CK (5.05) > I2+PFA (3.66) > I3+CK (2.36) > I3+PFA (1.56). This suggested that spray PFA slowed down flag-leaf senescence as it maintained a water condition that restrained active oxygen (AO) production, ensured AO normal scavenging and sustained integrated cell membrane. Hence the high photosynthetic rate coupled with low transpiration rate induced high water use efficiency. Physiologically, this increased water use efficiency under spay PFA treatment. On the basis the results, it was concluded that PFA reduced flag-leaf transpiration and eased dry/hot-wind stress in winter wheat. Despite these findings, it was recommended to continue active research into the effects of spay PFA treatment on winter wheat production.

Analysis of water use efficiency of different winter wheat cultivars under different irrigation schemes on the basis of yield

DONG Bao-Di, SHI Chang-Hai, QIAO Yun-Zhou, YANG Jing, ZHAI Hong-Mei, LI Dong-Xiao, LIU Meng-Yu

2011, 19(5): 1096-1103. doi: 10.3724/SP.J.1011.2011.01096

Abstract(1844) PDF(1569)

Abstract:
Five drought tolerant winter wheat cultivars were used to evaluate the differences in the effects of harvest index (HI) and biomass water use efficiency (WUE_bm) on grain yield water use efficiency (WUE_y) under different irrigation schemes. The wheat cultivars included dryland cultivars of "Xifeng 20" and "Jinmai 47", dry/wetland cultivar of "Shijiazhuang 8", and wetland cultivars of "Shi 4185" and "Kenong 9204". The results showed significant differences in WUE_y and its changing trends among different drought tolerant wheat cultivars. Dryland cultivars had significantly lower WUE_y than wetland and wet/dryland cultivars, with the highest WUE_y difference of 42.01%. Average water consumption of the drought tolerant wheat cultivars was 343~350 mm. No significant difference was noted in the amount of water consumption among different cultivars. This suggested that although dryland cultivars were drought tolerant, it did not limit the rate of water consumption. It also suggested that the main factor of WUE_y was WUE_bm and HI. Dryland cultivars had significantly lower HI than wetland and wet/dryland cultivars, with the highest HI difference of 25.91%. Significant positive correlations were noted between HI and WUE_y, and between WUE_bm and WUE_y. The correlation between plant height and HI was negative (R² = 0.574). Under no irrigation, no obvious difference was noted in WUE_bm among different cultivars. Dryland cultivars had lower HI than the other cultivars. The difference in WUE_y among different cultivars was driven by the differences in HI. Under supplemental irrigation conditions, however, wetland and wet/dryland cultivars had higher WUE_bm and HI than dryland cultivars. The differences in WUE_y came mainly from interactive effects of HI and WUE_bm. The results suggested that different drought-tolerant wheat cultivars had responded differently to the same condition and therefore had different adaptation strategies to environmental conditions. Dryland cultivars enhanced WUE_bm which in turn led to higher WUE_y in extreme drought conditions. Wetland and wet/dryland cultivars, on the other hand, enhanced HI and WUE_bm to yield higher WUE_y under supplemental irrigation conditions.

Water use efficiency of winter wheat in ridge cultured wheat||spinach-tomato cropping system

QIAO Yun-Zhou, RUAN Fen, DONG Bao-Di, SHI Chang-Hai, ZHAI Hong-Mei, LIU Meng-Yu

2011, 19(5): 1104-1108. doi: 10.3724/SP.J.1011.2011.01104

Abstract(1856) PDF(1444)

Abstract:
Ridge planting and intercropping of winter wheat (Triticum aestivum L.) are important cropping systems in the North China Plain (NCP), in which there exists an acute shortage of water resources especially for crop production. This study analyzed water use efficiency (WUE) of winter wheat in wheat||spinach-tomato cropping system using both traditional and ridge cultivation as the control practices. Traditional cultivated spinach (Spinacia oleracea L.) and tomato (Lycopersicon esculentum Miller) system was the control cropping practice for the spinach||tomato intercropping system. The results showed that wheat grain yield under ridge planting and intercropping was 11% less than under traditional cultivation (401 kg·667m^-2). The reduction in grain yield was attributed to low tiller number as ridge-edge effect was not fully exploited. Tiller numbers of ridge-planted ridge-intercropped wheat were 13.2% and 8.2% less than traditional cultivated wheat system. Row tiller number was much less in either ridge-planted or ridge-intercropped systems than in traditional cultivation system. Comparisons among the three cropping systems suggested that traditional wheat cropping had the highest WUE (1.039 kg·667m^-2·mm^-1), and that intercropping had the lowest WUE (0.868 kg 667m^-2·mm^-1). Ridge cultivation had a smaller WUE (0.944 kg·666.7m^-2·mm^-1) than traditional cultivation system because between- ridge water was not fully utilized. Yield of spinach was, however, not affected by wheat. Yields of intercropped and traditional cultivation spinach systems were 826 kg·667m^-2 and 851 kg·667m^-2, respectively, with a difference not statistically significant. However, tomato growth was greatly hampered under the intercropping system. Stem diameter and biomass per plant under intercropped tomato was respectively 27% and 37% less than that under traditional cultivation system. This suggested that after spinach harvest, tomato transplanting should be postponed as long as possible so as to shorten crop symbiosis and make the cropping system more manageable. It was therefore concluded that wheat||spinach-tomato cropping system facilitated di-season vegetable and food production, provided that the wheat and vegetable cultivars were properly selected and cultivated.

Soil nitrate leaching and control methods in the piedmont of North China Plain

LI Xiao-Xin, MA Hong-Bin, HU Chun-Sheng, ZHANG Gui-Jie

2011, 19(5): 1109-1114. doi: 10.3724/SP.J.1011.2011.01109

Abstract(1967) PDF(1732)

Abstract:
Soil core and soil water samples were collected in a long-term field experiments to study soil nitrate nitrogen (NO₃^--N) accumulation and leaching in winter wheat/summer maize double-cropping system under different agricultural management practices in the North China Plain (NCP). The results showed that NO₃^--N accumulation in the soil profile and NO₃^--N leaching through the root zone increased with increasing N fertilizer application (P<0.05). Application of P and K fertilizers improved the grain yield and harvested more N in grains. P and K inputs increased the amounts of harvested N in grains by 123 kg·hm^-2·a^-1 and 31 kg·hm^-2·a^-1, respectively. Based on the experiment, the amount of irrigation also affected NO₃^--N accumulation and distribution in the soil profile. The amounts of accumulated NO₃^--N in the 0~400 cm soil profile significantly decreased with increasing irrigation frequency. Arid irrigation treatment (i.e., no irrigation and one irrigation during winter wheat and summer maize seasons, respectively) produced 1 698 kg(N)·hm^-2 of accumulated NO₃^--N in the 0~400 cm soil profile. This was significantly higher (P < 0.05) than those of deficient irrigation (i.e., 2~3 irrigations during winter wheat season, irrigation when needed during summer maize season) and sufficient irrigation (i.e., 4~5 irrigations during winter wheat season, irrigation when needed during summer maize season) with accumulated NO₃^--N in the 0~400 cm soil profile of 1 148 kg(N)·hm^-2 and 961 kg(N)·hm^-2, respectively. Compared with deficient and sufficient irrigation treatments, accumulated NO₃^--N in the 100~200 cm soil layer was higher than in the other soil layers under arid irrigation treatment. From 2003~2005, increases in NO₃^--N in the 0~400 cm soil profile were different among different irrigation treatments. The amounts of fertilizer N left in the soil under arid irrigation, deficient irrigation and sufficient irrigation were 23%, 22% and 47%, respectively. No-tillage decreased grain yield, changed soil water movement and increased water storage in deep soils, which in turn increased the risk of NO₃^--N leaching. Based on the results, 200 kg·hm^-2·a^-1 N input with less irrigation and balanced fertilization were the most effective mode that protected groundwater from nitrate pollution in NCP.

Ammonia volatilization and control mechanisms in the piedmont of North China Plain

DONG Wen-Xu, WU Dian-Ming, HU Chun-Sheng, ZHANG Yu-Ming, YANG Pei-Pei, WANG Ying

2011, 19(5): 1115-1121. doi: 10.3724/SP.J.1011.2011.01115

Abstract(2200) PDF(1598)

Abstract:
As an important mode of nitrogen (N) loss, ammonia volatilization in farmlands causes air pollution and water eutrophication. Increased N application dose should be accompanied with reduced ammonia volatilization to improve N fertilizer efficiency. This could lay a strong theoretical basis for optimal fertilizer use. To that end, a double-layer-sponge-trapping method was used to measure ammonia volatilization following the application of different N fertilizers in the growing season of wheat-maize double cropping system and in an incubation experiment with different soil moistures or amended with wheat or corn straw. The experiments were conducted at the Luancheng Agro-Ecosystem Experimental Station (LAES) of Chinese Academy of Sciences from October 2002 through June 2004. Urea N fertilizer was applied at the rates of 200, 400 and 600 kg(N)·hm^-2·a^-1, respectively, and with no N fertilizer as the control. The study showed that ammonia volatilization was significantly affected by the fertilization dose and time, soil moisture and irrigation mode. For winter wheat, ammonia volatilization occurred immediately after N fertilizer application．It gradually increased, apparently reaching the maximum in the first 1~5 days after fertilization. Ammonia volatilization was high during summer maize growing season, increased sharply after (N fertilizer) dressing, and hit the highest rate on the 1st day after fertilization. N loss via accumulated ammonia volatilization was 0.66~35.00 kg(N)·hm^-2·d^-1, accounting for 0.09%~14.90% of the applied fertilizer. Ammonia volatilization largely occurred in summer maize season, accounting for 80% of N loss in the double cropping system. The high ammonia volatilization in the summer maize season was due mainly to the high temperature and overland broadcast mode of fertilization. Irrigation reduced ammonia volatilization. The earlier the irrigation after fertilization was conducted, the less was ammonia volatilization. Ammonia volatilization also increased with lower initial water content. Amendment with wheat or maize straw increased the rate of urea hydrolysis in loam soils, triggering peak NH₃ loss to occur one day earlier and much lower than non-amended urea. With urea alone, cumulative NH₃ loss was 7.2%~9.7% of applied urea. When urea was amended with wheat or maize straw, cumulative NH₃ loss was only 1.1%~2.1% or 2.2%~7.2% of applied urea, respectively. Thus the characteristics of ammonia loss were dependent on the modes of application of urea and soil moisture conditions.

Soil greenhouse gas emission in winter wheat/summer maize rotation ecosystem as affected by nitrogen fertilization in the Piedmont Plain of Mount Taihang, China

WANG Yu-Ying, HU Chun-Sheng

2011, 19(5): 1122-1128. doi: 10.3724/SP.J.1011.2011.01122

Abstract(2169) PDF(1667)

Abstract:
The effect of soil nutrient augmentation via nitrogen deposition or fertilization on the processes of storing, releasing and re-absorbing of methane (CH₄) carbon dioxide (CO₂) and nitrous oxide (N₂O) greenhouse gases (GHG) in soil ecosystems are poorly understood. This study described an original field experiment for measuring soil GHG flux at nitrogen application rates of N0 [0 kg(N)·hm^-2], N200 [200 kg(N)·hm^-2], N400 [400 kg(N)·hm^-2]and N600 [600 kg(N)·hm^-2] in winter wheat/summer maize double cropping system in the Piedmont Plains of Mount Taihang. CH₄, CO₂ and N₂O emissions from soils under the winter wheat/summer maize rotation system were measured from July 2008 through June 2010 using the static transparent chamber and gas chromatography technique. The results showed that soils under winter wheat/summer maize ecosystems served as CH₄ sink, and CO₂ and N₂O sources. With increasing nitrogen application, CH₄ absorption rate decreased and CO₂ and N₂O flux rates increased. In winter wheat season, CH₄ absorption rate under N0 treatment was significantly higher than under other nitrogen treatments. Both CO₂ and N₂O emission flux rates under N600 treatment were significantly higher (P<0.05) than under N0 treatment. Nitrogen fertilization and irrigation sharply induced CO₂ and N₂O peak flux emissions and decreased CH₄ peak absorption. Rising soil temperature, precipitation or alternating wet/dry weather increased soil N₂O and CO₂ emission flux rates. Negative N₂O flux rates were observed under low temperature and high evaporation conditions in N0 application treatments in winter. CH₄ emission accumulation for 2008~2009 under N0, N200, N400 and N600 treatments was -1.42, -0.75, -0.82 and -0.92 kg·hm^-2·a^-1, respectively. For 2009~2010, it was -2.60, -1.47, -1.35 and -1.76 kg·hm^-2·a^-1, respectively. CO₂ emission accumulation for 2008~2009 under N0, N200, N400 and N600 treatments was 15 598, 19 346, 21 456 and 29 013 kg·hm^-2·a^-1, respectively. For 2009~2010, it was 10 318, 11 474, 13 984 and 20 639 kg·hm^-2·a^-1, respectively. Then N₂O emission accumulation for 2008~2009 under N0, N200, N400 and N600 treatments was 1.05, 2.16, 5.27 and 6.98 kg·hm^-2·a^-1, respectively. Also for 2009~2010, it was 1.49, 2.31, 4.42 and 5.81 kg·hm^-2·a^-1, respectively.

Enzymological regulation of soil nutrient cycle in the piedmont region of North China Plain

QIN Shu-Ping, HU Chun-Sheng, ZHANG Yu-Ming, WANG Yu-Ying, DONG Wen-Xu, LI Xiao-Xin

2011, 19(5): 1129-1133. doi: 10.3724/SP.J.1011.2011.01129

Abstract(2021) PDF(1750)

Abstract:
Soil enzymes are the biochemical catalysts of soil nutrient cycle. Research efforts on enzymological mechanisms of soil nutrient cycle are vital in evaluating the state of soil nutrients in the piedmont region of North China Plain (NCP). The objectives of the study were to investigate: i) the distributions of soil enzyme activity in the soil profile and ii) the correlations between soil enzyme activity and nutrient content of different particle-size fractions. The soils were collected from long-term field experimental plots at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences. The distributions of soil urease and alkaline phosphatase activities in the 0~10 cm, 10~20 cm, 20~30 cm and 30~40 cm soil layers were analyzed. Then the collected soil samples were grouped into coarse sand (2 000~200 μm), fine sand (200~63 μm), silt (63~2 μm) and clay (2~0.1 μm) fractions using low-energy sonication. Next the correlations among soil enzyme activities and soil nutrients contents were determined for the coarse sand, fine sand, silt and clay fractions. The results showed that the activities of soil urease and alkaline phosphatase decreased with increasing soil depth and increased with decreasing particle size. Enzyme activities were significantly correlated with soil nutrient content in coarse and fine sand fractions, but not so much correlated in the silt and clay fractions. These results suggested that soil enzyme activities were important driving factors of soil nutrient cycle. The enzymes in coarse and fine sand fractions promoted in situ catalytic activities and contributed greatly to soil nutrient cycle. On the contrary, enzymes in the silt and clay fractions inhibited in situ catalytic activities via soil mineral absorption, limiting their contribution rate to soil nutrient cycle.

Effect of conservation tillage on soil quality in the piedmont plain of Mount Taihang

DU Zhang-Liu, GAO Wei-Da, CHEN Su-Ying, HU Chun-Sheng, REN Tu-Sheng

2011, 19(5): 1134-1142. doi: 10.3724/SP.J.1011.2011.01134

Abstract(3789) PDF(3487)

Abstract:
Conservation tillage is a viable option for sustainable agricultural development in the North China Plain. Yet few studies exist on the influences of conservation tillage practices on soil quality. The objective of this study was to investigate soil quality changes as related to the shift from moldboard plow to conservation tillage practices based on a long-term field experiment. The experiment was started in 2001 and included four winter wheat tillage treatments — moldboard plow without corn residue (CK), moldboard plow with corn residue (CT), rotary tillage with corn residue (RT), and no tillage with corn residue (NT). In 2007, the soil organic carbon (SOC) content, bulk density (ρ_b), water stable aggregate, water retention curve, soil saturated hydraulic conductivity (K_s) and soil microbial biomass C and N were measured after winter wheat harvesting. Soil samples were also collected in 2008 and analyzed for SOC, ρ_b and earthworm count. The results indicated no significant (P > 0.05) differences in stored SOC among the treatments. However, conservation tillage showed SOC stratification in the soil profile. This was indicated by higher SOC stratification ratios (SR) of 1.74~2.04 for RT and NT, and 1.37~1.45 for CK and CT. Earthworm abundance and microbial biomass C and N also increased under RT and NT treatments. Application of NT significantly (P < 0.05) increased soil ρ_b in the upper 0~20 cm soil layer, and also improved soil aggregate stability (measured by mean weight diameter). Whereas CT and CK treatments significantly increased the proportions of fissures (> 500 μm) and transmission pores (500~50 μm), NT treatment increased storage pores (50~0.5 μm) in the 0~5 cm soil layer. Tillage management increased soil K_s, field water capacity and plant available water content. The S index suggested that shift from conventional tillage to conservation tillage improved soil quality in the piedmont region of Mount Taihang.

Change in farmland soil fertility and nutrient management strategy in the piedmont of Mount Taihang, North China Plain

ZHANG Yu-Ming, HU Chun-Sheng, MAO Ren-Zhao, ZHANG Jia-Bao, DONG Wen-Xu, LI Li-Feng

2011, 19(5): 1143-1150. doi: 10.3724/SP.J.1011.2011.01143

Abstract(1969) PDF(1840)

Abstract:
The trend, degree and mechanism of change in soil nutrient/fertility in farmlands of Luancheng, Hebei Province was analyzed using soil survey data for 2008, 2000 and 1979, from which a sustainable strategy for agricultural nutrient resource management was put forward. The results indicated a significant change in soil fertility for 1979 through 2008. There was a significant increase (P<0.01) in soil organic matter, Olsen-P, available K, and especially in available N. Average available N increased from 56.7 mg·kg^-1 in 1979 to 80.0 mg·kg^-1 in 2000, and to 109.1 mg·kg^-1 in 2008. This represented an annual increment of 1.1 mg·kg^-1 and 3.6 mg·kg^-1 in 1979~2000 and 2000~2008, respectively. Available N increased by 1.9% and 4.5% annually for 1979~2000 and 2000~2008 and with a total corresponding increase of 41.1% and 36.4%, respectively. The rate of increase in 2000~2008 was higher than in 1979~2000. Soil organic matter content increased from 11.6 g·kg^-1 in 1979 to 11.6 g·kg^-1 in 2008, which represented an annual increment of 0.24 g·kg^-1. Soil organic matter increased by 2.1% annually and by 62.1% in total for 1979~2008. Soil Olsen-P content increased from 17.5 mg·kg^-1 to 24.7 mg·kg^-1 in the 30-year period, represented a total increase of 41.1%. It was then evident that no shortage existed in soil potassium due to the calcareous nature of soils in North China coupled with occasional potassium fertilizer application in the past century. This resulted in a decrease in available K from 140.6 mg·kg^-1 to 111.4 mg·kg^-1 in 1979~2000, representing 20.8% decrease over the period. Available K increased to 149.5 mg·kg^-1 in 2008 as a result of incorporating straw into the soil and increasing potassium fertilizer application in the current century. Soil fertility in the farmlands of Luancheng was high with a high potential for agricultural production. While the key to nutrient management in the region lied with nitrogen, the overall objective of nutrient management was sustainable high crop yield and sound environment. While nitrogen management should include real-time soil nutrient deficiency diagnosis and dosage, phosphorus and potassium management should based on constant soil nutrient monitoring and conservative phosphorus/potassium application. Fertilizer management practices that incorporate straw into the soil and combine the application of organic and inorganic fertilizers should be implemented in the study area.

Estimation of regional evapotranspiration over the Hebei Plain using geostationary satellite data

SHU Yun-Qiao, LI Hong-Jun, LEI Yu-Ping

2011, 19(5): 1151-1156. doi: 10.3724/SP.J.1011.2011.01151

Abstract(3248) PDF(2249)

Abstract:
Fengyun-2C (FY-2C) is the first Chinese operational geostationary meteorological satellite with one visible and four infrared channels of optical imaging radiometer. Image acquisition temporal frequencies of FY-2C are 1 h and 30 min for dry and rainy seasons, respectively. This allows for mapping diurnal variations in land surface temperature (Ts) at a relatively high temporal scale. Data from FY-2C satellite were applied in combination with Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products to assess regional evapotranspiration (ET) over the Hebei Plain. The approach was based on the improved triangle method, where the temperature-vegetation index space included thermal inertia. As the method requires information on temperature change, the emergence of geostationary meteorological satellite data capable of determining land Ts at high temporal scale had made it possible to estimate daily Ts change from optimal observations. Two thermal infrared channels (IR1: 10.3~11.3 μm and IR2: 11.5~12.5 μm) from FY-2C were used to estimate Ts via a split window algorithm originally proposed for the MSG-SEVIRI sensor. As it compared reasonably well with observations of Ts, the FY-2C high temporal resolution data were exploited to determine morning rise in Ts. The chosen time windows were 8:00 and 12:00 local time. Combined with 16-day composite MODIS vegetation indices product (MOD13) at a spatial resolution of 5 km and Ts difference (ΔTs) from FY-2C, evaporative fraction (EF) was interpolated in ΔTs-NDVI triangular-shaped scatter space based on the improved triangle method. Using energy balance, regional daily actual ET was eventually derived from the EF and available energy estimated from MODIS surface albedo products MCD43. Spatial variations in the estimated surface variables (Ts, EF and ET) corresponded well to land cover patterns and farmland management practices. Estimates based on this method were validated with field observations from Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences in Hebei Province (37o53′N, 114o41′E). The estimated ET and EF also compared well with lysimeter data collected for the period from June 2005 to September 2007, with RMSE of 0.92 mm for ET and 0.14 for EF and corresponding R² of 0.74 and 0.55. Of particular interest was the high temporal frequency of FY-2C acquired images, increasing the likelihood of acquiring cloud-free images with the potential for plotting estimated daily ET maps. The study demonstrated that FY-2C was highly valuable in water resources and agricultural management applications in China.

Monitoring soil moisture by apparent thermal inertia method

YANG Shu-Cong, SHEN Yan-Jun, GUO Ying, KONDOH Akihiko

2011, 19(5): 1157-1161. doi: 10.3724/SP.J.1011.2011.01157

Abstract(1857) PDF(1756)

Abstract:
Soil moisture is one of the most important indices for agricultural drought monitoring and water resources management. Remote sensing is a critical technology for monitoring spatial and temporal variations in soil water content. The thermal inertia method, which is a thermal infra red (IR) technology, has demonstrated advantages in monitoring soil water condition. Among the several models for computing soil thermal inertia by remote sensing, ascertaining the conditions for monitoring soil water content by thermal inertia remains a major obstacle. This paper proposed an improved model for calculating Apparent Thermal Inertia (ATI). In the first step, a new soil ATI model with improved algorithms for simulating net radiation was developed. Then a strict control ground experiment was conducted to test the proposed model. A total of 10 experimental plots with different vegetation covers and soil water contents were set up at the Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences. The vegetation covers were fully representative by NDVI (normalized difference vegetation index). The actual measured land surface temperature, NDVI, albedo, soil water content, solar radiation and long-wave atmospheric radiation were used to compute ATI under different land cover and soil water conditions. Then correlation and regression analyses were finally done to relate ATI and soil water content. The results indicated that the proposed thermal inertia model reliably monitored the soil water condition, especially in low vegetation cover areas. For low vegetation cover (NDVI < 0.35), the coefficient of determination between ATI and soil volumetric water content was > 0.7. The proposed thermal inertia method was invalid for NDVI > 0.35 and the corresponding coefficient of determination was < 0.2. NDVI that was the equivalent of 0.35 could be critical for determining the applicability of the proposed model in monitoring soil water conditions. This was because temperature dynamics (the most critical criteria for calculating ATI) for bare and vegetated lands were different. However, the proposed model was not only simple, but it carries distinct physical meaning and easy-to-use interfaces. The experiment suggested that the model was applicable in reliably monitoring soil water conditions.

Soil moisture monitoring in agricultural lands via active-passive microwave remote sensing

GUO Ying, SHEN Yan-Jun, ZHAO Chao

2011, 19(5): 1162-1167. doi: DOI:10.3724/SP.J.1011.year_id].01162

Abstract(2010) PDF(1953)

Abstract:
Soil moisture is a critical element for monitoring crop growth and drought in agricultural lands. Microwave remote sensing is a reliable mode of retrieving soil moisture in real time and under all weather and physiographic conditions. Retrieving soil moisture via combined active and passive microwave remote sensing has the advantage of high spatial resolution and real-time measurement at regional scale. Although it has practical significance for agricultural lands, this technique has largely been previously applied in retrieving soil moisture under natural vegetation. Here, the technique was used to retrieve soil moisture in agricultural lands. The TRMM Microwave Imager (TMI) emissivities at different soil moisture and surface roughness conditions were simulated using the Advanced Integral Equation Model (AIEM). After emissivity sensitivity analysis of soil moisture and roughness, a soil moisture inversion model for bare surfaces via passive microwave remote sensing was established based on the parameterized microwave radiation model (Qp model). The inversion algorithm for vegetated surface was established using the microwave radiation transfer model (ω-τ model). Then a soil moisture variation inversion algorithm that combines active and passive microwave remote sensing (using TRMM Microwave Imager and Precipitation Radar data) was developed based on the Simple Scattering Model (SSM) and Geometry Optical Model (GOM). The daily soil moisture variations in agricultural lands between 30o~38oN and 110o~120oE was estimated for January through April of 2008. The retrieved daily soil moisture variations were compared with interpolated daily precipitation variations at the grid which is located at 34.45oN and 119.25oE in the croplands of Lianyungang, Jiangsu Province. The study showed that microwave remote sensing was practicable in monitoring and managing soil moisture in agricultural lands.

Diagnosis of the state of N in wheat via digital image processing technique

ZHANG Li-Zhou, HOU Xiao-Yu, ZHANG Yu-Ming, LI Hong-Jun, CHENG Yi-Song, HU Chun-Sheng

2011, 19(5): 1168-1174. doi: 10.3724/SP.J.1011.2011.01168

Abstract(1721) PDF(1409)

Abstract:
This study used digital image acquisition via digital camera and analysis method in combination with rapid soil and plant N test to diagnose the state of N in wheat crops and recommend N fertilization modes in wheat fields. The relationship between color parameters and N nutrient indices was analyzed and the possibility of using digital image analysis method to diagnose the state of plant N evaluated. Then a standard method for digital image acquisition and application in plant N diagnosis was established. The best mode for diagnosing the state of plant N via digital image analysis method was also determined. The study further established a N diagnosis index system and an equation for recommending N application. The result indicated that digital image processing technique was usable in detecting the N state in winter wheat. The best angle between digital camera and wheat canopy in the field was 30°~60°. Significant correlations were noted among color parameters and N application rate, SPAD, plant nitrate content, plant total N content and nitrate contents in the 0~90 cm soil depth at wheat jointing and booting stages. Compared with other plant canopy color parameters, normalized greenness intensity (NGI), calculated as G/(R+G+B), was much better as it produced better correlations with plant total N, SPAD, nitrate content and soil nitrate content at jointing stage. While NGI was the best diagnosis index, jointing was the key diagnosis stage of the state of N in winter wheat crops.

Evaluation of cropland productivity in the Hebei Plain via graded multi-year MODIS-NDVI data

WANG Rui, LI Hong-Jun, LEI Yu-Ping?

2011, 19(5): 1175-1181. doi: 10.3724/SP.J.1011.2011.01175

Abstract(1775) PDF(1866)

Abstract:
Moderate resolution imaging spectroradiometer sensor (MODIS) provides high-temporal, medium-spatial resolution science-quality global land cover data. Calculated normalized differential vegetation index (NDVI) from MODIS data is widely used for crop growth monitoring and yield forecasting. However, variations of NDVI values in the same season of each year lead to uncertainties and biases in forecasting cropland productivity. This study presented a method for evaluating cropland productivity and indirect monitoring of soil quality, using annual NDVI calculated from multi-year MODIS data in the Hebei Plain. Calibrated Landsat data with high spatial resolution were used to process geometric registration of the MODIS data. This was used to determine the exact region with continuous winter wheat cultivation for many years in the plain. Mean NDVI of winter wheat cultivated area from reviving to maturity stage was calculated for 2000~2008 and ranked into different levels in order to analyze for spatial variations in farmland productivity. The study showed that while high productivity croplands were mainly located in the piedmont of Mount Taihang, medium or low productivity croplands were in the central and eastern regions of the plain. Longitudinal change in NDVI was not regular, indicating that the method used was not affected by latitude difference. The distribution pattern was driven by variations in local land use types and cropland quality management. The study also analyzed the causes of biases in the coefficient of variation for the 9-year NDVI data. The analysis showed that the coefficient of variation was relatively high during the reviving and maturity stages of winter wheat, with also spatial differences. Combined geo-spatial and NDVI analysis was used to map cropland productivity at county level. The map showed spatial differences in productivity with huge potential croplands where low/medium productivity was located at. The study therefore laid the theory basis for land control and cropland quality management in Hebei Province, which could be vital for improving cropland quality at county level.

Changes and driving forces of land use/cover and landscape patterns in Beijing-Tianjin-Hebei region

HU Qiao-Li, QI Yong-Qing, HU Yin-Cui, ZHANG Yu-Cui, WU Cheng-Ben, ZHANG Guang-Lu, SHEN Yan-Jun

2011, 19(5): 1182-1189. doi: 10.3724/SP.J.1011.2011.01182

Abstract(1793) PDF(1128)

Abstract:
Conversion matrix of land use/cover, landscape fragmentation index (LFI) and landscape diversification index (LDI) were used to quantitatively and qualitatively analyze changes in land use/cover (LUC) and landscape pattern (LP) for 1990~2000 in Beijing-Tianjin-Hebei (BTH) region and their driving forces. Two typical sample belts were used in the study. The results showed that changes in LUC and LP were significant especially in the residential areas of Beijing, Tianjin and Shijiazhuang cities. The application of component and correlation analyses on socio-economic statistical data showed that LUC and LP changes in the region were mainly driven by socio-economic, agro-production and transportation factors. Terrain and policy effects on the changes in LUC and LP were also analyzed and discussed. Complex terrains hindered human disturbances in the west/north mountain areas. Compared with mountainous areas therefore, the plains had more profound changes in LUC and LP in the study area. On the other hand, ecological policies such as conversion of croplands into forests and grasslands along with land development and consolidation constituted critical modes of LUC and LP changes in mountainous regions. Comprehensive analysis on the driving forces of LUC and LP changes in the region showed that socio-economic factors were more important in the metropolises and that agro-production conditions dominated in traditional agricultural areas. The analysis and especially that of temp-spatial analysis provided a useful dimension to land resources management and protection in the BTH study area.

Operation and demonstration of precision planting in Luancheng County

CHENG Yi-Song, HU Chun-Sheng, ZHANG Yu-Ming, LEI Yu-Ping, LI Hong-Jun, LI Xiao-Xin, CHEN Su-Ying

2011, 19(5): 1190-1198. doi: 10.3724/SP.J.1011.2011.01190

Abstract(1780) PDF(1110)

Abstract:
The Piedmont Plain of Mount Taihang is a typical high-yield agro-region in the North China Plain (NCP) with a relatively strong intensive agricultural activity. It is therefore one of the most important grain-production bases in China. With rapid agricultural and socio-economic development, severe water shortages due to groundwater over-exploitation and increasing agricultural non-point source pollution due to intensive application agro-chemicals/fertilizers gravely threaten sustainable agricultural development in the region. Precision agriculture is therefore an inevitable choice of direction for future agricultural development in the region. The agricultural production in China is characterized as peasant household unit production, so, it is critical to experiment and explore precise planting at county level. Luancheng County, Hebei Province was chosen as a demonstration area, where precision agriculture technology demonstration and operational implementation were designed. The observation network in the county established by GPS precise positioning had a spatial resolution of 1 km × 1 km with an effective sample area containing 288 points. The resolution of sample points in the core demonstration area was further reduced to 20 m × 20 m. At the county and demonstration area scales, agricultural research and basic data analysis that sufficiently reflected spatial variability were conducted. Optimized management network and consulting platform assembly were used to enhance fertilization at county level and to establish regional characteristics of water-saving cropping patterns in the region. Two demonstration modes (i.e., field and greenhouse semi-intelligent control and variable water-saving irrigation systems) provided sufficient economic and environmental benefits of crop cultivation in the region. These modes were recommended for the promotion of accurate wheat cultivation intelligent systems as part of the broader development of regional precision agriculture demonstration models. Hence precision agriculture technology research and demonstration in Luancheng County had provided a technological demonstration model, which was a useful practice for the full implementation future precision agriculture models in the region.

Screening and evaluating low nitrogen tolerant wheat genotype at seedling stage

ZHAO Hua-Tian, WANG Rui-Fang, XU Yun-Feng, AN Diao-Guo

2011, 19(5): 1199-1204. doi: 10.3724/SP.J.1011.2011.01199

Abstract(1710) PDF(1728)

Abstract:
Nitrogen tops the list of crop macro elements essential for plant growth and development. Several studies have shown that under low nitrogen conditions, crop species/genotypes vary widely in nitrogen uptake ability and utilization efficiency. Planting wheat cultivars with high nitrogen efficiency is the fundamental way to raise nitrogen utilization efficiency; and exploiting nitrogen tolerant wheat germplasm resources is the basic of breeding wheat varieties with high nitrogen efficiency. To this end, 30 advanced distant hybridization lines of wheat and wheatgrass, one T1BL·1RS translocation line of distant hybridization of "Xiaoyan 6" and "Germany white" (rye), two recombinant inbred lines of "Xiaoyan54 × Jing411" and 13 commercial wheat varieties, were screened and evaluated for low nitrogen tolerant genotypes in hydroponic culture at seedling stage. Analysis of variance showed significant to very significant differences in 13 nitrogen efficiency related traits between two nitrogen treatments and among genotypes. Principal component analysis showed that the first three principal components had an accumulative contribution rate of at least 81.2%, implying that they contained most of the information to reflect the overall trait resources. The proportions of relative shoot/plant nitrogen uptake, root/shoot ratio, shoot dry weight, plant dry weight, shoot nitrogen utilization efficiency and root nitrogen content of the three principal components were significantly high. A comprehensive evaluation suggested that 08B41 had the highest score (1.60) for the best nitrogen tolerant wheat line in the 32 distant wheat hybridization lines. Then "Kn9204" had the highest score (2.10) for the best nitrogen tolerant wheat variety in the 13 commercial wheat varieties. Clustering analysis showed that the 46 wheat genotypes were broadly categorized into 3 groups (low nitrogen tolerant type, medium nitrogen tolerant type and low nitrogen sensitive type with 15, 22 and 9 genotypes, respectively). 9 advanced distant hybridization lines (08B41, XJ19-1, 08B8, 08B10, 08B13, 08B25, WR9603, 08B2, 08B5) and 6 commercial wheat varieties ("Kn9204", "Han7086", "Henong827", "Shimai18", "Shi4185", "Shixin733") were noted to have low nitrogen tolerance. These low nitrogen tolerant genotypes were utilizable in breeding N-efficient wheat varieties. The study also discussed the roles of wheat related species in improving the genetic makeup of N-efficient wheat varieties.

Identification of germplasm with enriched micronutrients of wild emmer and progeny of wild emmer × common wheat

XU Yun-Feng, XU Hong-Xing, AN Diao-Guo

2011, 19(5): 1205-1209. doi: 10.3724/SP.J.1011.2011.01205

Abstract(1807) PDF(1893)

Abstract:
Malnutrition caused by low concentrations or deficiencies of especially zinc (Zn) and iron (Fe) bio-micronutrients in human food affects a large proportion of the world population. Bio-fortification via conventional breeding or modern transgenic approaches improves bio-available essential mineral contents in edible portions of crops. This is regarded as an economically sustainable strategy for mitigating micronutrient malnutrition. Wheat (Triticum aestivum L.) is a vital cereal crop that accounts for ≈30% of total human cereal consumption in the world. Improving Zn, Fe and protein contents in wheat grain augments human nutrition, which especially alleviates micronutrient malnutrition in people who live on cereals. Wild emmer wheat (T. turgidum ssp. dicoccoides) is a critical potential donor of grain micronutrients, proteins and other desirable traits of common wheat. This study reported the screening of wild emmer accessions and their derivatives with common wheat for enriched grain Zn, Fe and protein concentrations. The study analyzed the relationships among grain Zn, Fe and protein concentrations, grain yield and yield traits, presenting a unique opportunity for wheat bio-fortification breeding. In this study, 32 accessions (derived from crossing wild emmer versus common wheat) and 4 lines of wild emmer were examined for grain Zn, Fe and protein contents. The progenies of wild emmer × common wheat exhibited not only high genetic diversity, but also enhanced grain Zn, Fe and protein contents. Principal component and correlation analyses showed that grain Zn, Fe and protein contents were positively correlated, suggesting that the three traits were combinable and could be simultaneously enhanced. Compared with common wheat alone, 3 lines of wild emmer wheat, and 14 wild emmer × common wheat accessions were identified as rich sources of grain Zn, Fe and protein. The results indicated that introgression of alien genes from wild emmer wheat to common wheat significantly improved grain Zn, Fe and protein contents in common wheat. Five accessions with improved micronutrient and protein contents, high grain yield and desirable agronomic traits were directly usable in wheat bio-fortification breeding.

Resistance of Chinese wheat landraces and relatives at seedling stage to powdery mildew

XU Hong-Xing, XU Yun-Feng, GENG Li-Ge, AN Diao-Guo

2011, 19(5): 1210-1214. doi: 10.3724/SP.J.1011.2011.01210

Abstract(1830) PDF(1819)

Abstract:
Powdery mildew is a major wheat (Triticum aestivum L.) foliar disease caused by Blumeria graminis f. sp tritici (Bgt). The deployment of resistance resources including genes/alleles has been critical in controlling powdery mildew of wheat foliar disease. In wheat cultivation, powdery mildew (Pm) resistant genes most commonly used at the present belong to the race-specific resistance genes with high resistance levels. However, the extensive use of these resistance genes have frequently changed the pathogen population and rapidly induced new virulent strains of the pathogen. It has therefore been a long-term objective to identify effective new Pm resistance genes from the vast wheat germplasm resources. To identify resources that are effectively resistant to powdery mildew, 258 wheat landraces along with 42 wheat relatives were evaluated with E09 isolate of prevalent Chinese Bgt at seedling stage. The results showed that 5 of the 258 wheat landraces and 20 of the 42 wheat relatives were immune, nearly immune or highly resistant to E09. The above 25 wheat germplasms challenged with additional 5 different Chinese Bgt isolates (the E03, E05, E18, E20 and E23 isolates) to postulated the unknown Pm resistance genes/alleles. Comparison to the 28 known Pm resistance genes showed that the Pm resistant genes of the 25 wheat germplasms were completely different from the known 21 Pm resistance genes, Pm1a,Pm2, Pm3a, Pm3b, Pm3c, Pm3d, Pm3e, Pm3f, Pm4a, Pm4b, Pm4c, Pm5a, Pm6, Pm7, Pm8, Pm9, Pm17, Pm19, Pm24, Pm28 and Pm33. It was, however, not very distinguishable from Pm1c, Pm1e, Pm12, Pm13, Pm16, Pm20 and Pm21 resistance genes. The 25 wheat germplasms could carry new Pm resistance genes, whose sources were not only different from the others, but also carried 7 Pm resistance genes. This study explored effective new resistance resources of Chinese wheat landraces and their relatives which laid the basis for in-depth exploration and effective use of novel powdery mildew resistance genes. Despite this finding, more Bgt isolates would still need to be challenged to further confirm this result.

Development of "Kn199" new winter wheat variety and its cultivation in China

ZHANG Wei, WANG Jing, JI Jun, WANG Zhi-Guo, AN Diao-Guo, ZHANG Xiang-Qi, ZHANG Ai-Min, LI Jun-Ming

2011, 19(5): 1215-1219. doi: 10.3724/SP.J.1011.2011.01215

Abstract(1843) PDF(1194)

Abstract:
Secale cereal and Thinopyrum elongatum have been successfully applied in wheat genetic improvement in North China. By crossing "Kn9204" (a 1RS/1BL translocated and derivative of wheat-Thinopyrum ponticum partial amphiploid) with "Shi4185", a new variety (named "Kn199") with a high and stable grain output had been developed and approved by the National Crop Variety Approval Committee (NCVAC) in 2006. "Kn199" was an early-maturing variety, with compact plant form, 75~80 cm plant height, spindle spike and short awn. Its grain filing time was short. The grains were plumping with 40~42 g of 1000-grain weight. The yield "Kn199" was significantly higher than that of the control variety "Shi4185". Because of developed root system, and higher root activity at later growth stage, "Kn199" could absorb water and nutrient more efficiently even those in deep soil. The cultivation showed that the variety was adaptable to a large range of environments and resistant to adversity with a stably high yield. The release of "Kn199" had seen a rapid propagate of the wheat variety. "Kn199" had now become one of the major varieties in the northern region of the Huang-Huai Winter Wheat Production Base, including southern and central Hebei, Shandong, northern Henan and southern Shanxi.

Analysis of high and stable yield characteristics of "Kn199" winter wheat cultivar

ZHAO Hui, ZHANG Wei, WANG Jing, JI Jun, WANG Zhi-Guo, LI Jun-Ming

2011, 19(5): 1220-1228. doi: 10.3724/SP.J.1011.2011.01220

Abstract(2093) PDF(1626)

Abstract:
"Kn199" winter wheat cultivar is 1RS/1BL translocation line and derivative of octoploid synthetic Triticum aestivum and Elytrigia elongata species. It has excellent frost hardiness, winter survival, drought tolerance, hot/dry wind resistance, onsite adaptability and yield stability. Its robust root system facilitates high water absorption and nutrient uptake at the depth of soils especially under drought stress conditions. In this study, nitrogen and phosphorus use efficiency (NUE, PUE) of "Kn199" under reduced and optimum nutrient supplies were investigated in relation to yield potential under limited irrigation conditions. A field experiment was set up in 2008 where wheat yield traits such as pre-winter tiller number, post greening plant number, filling spike number were investigated. Wheat plant tissues were also taken at different growth stages and the 1000-grain weight, per spike grain, per plant spike, yield index and sterile spikelet measured after harvest. The results showed that "Kn199" accumulated more dry matter with a greater distribution in kernels than the other genotypes under both low [120 kg(N)·hm^-2] and normal [180 kg(N)·hm^-2] nitrogen inputs. Partial factor productivity of applied N (PFP_N) in the nitrogen-saving trial was 54.4 kg·kg^-1 for "Kn199", yielding 6 532.5 kg·hm^-2 under 120 kg·hm^-2 N supply. It was 40.6 kg·kg^-1, yielding 7 312.5 kg·hm^-2 under 180 kg·hm^-2 N supply. Under lower phosphorous input of 60 kg(P₂O₅)·hm^-2 in long-term nurseries, "Kn199" exhibited the most desirable PUE attributes such as high tillering capacity, spike formation and harvest population. With sufficient soil water prior to winter, one or two times of irrigation in spring was enough for "Kn199" to yield 7 500 kg·hm^-2 in North Huang-Huai winter wheat cultivation region. Under the adverse and severe climatic conditions such as extreme frosts, droughts and hot winds, "Kn199" cultivation benefits stable grain yield and food security in the region.

Path analysis of summer maize agronomic traits and yield in the Huang-Huai-Hai Plain

WANG Min, XU Ping, LIU Xin-Jiang, ZHANG Zheng-Bin, YANG Yin-Fu

2011, 19(5): 1229-1236. doi: 10.3724/SP.J.1011.2011.01229

Abstract(1678) PDF(1571)

Abstract:
The increasing water shortage in the agricultural sector in the Huang-Huai-Hai Plain (3HP) necessitates the selection and growing of more summer maize varieties with high yield and water use efficiency (WUE). A total of 11 hybrid maize varieties (commonly grown in the 3HP) were selected and planted in a random design and water-saving condition. The crops were irrigated only once at seeding stage. The agronomic traits, WUE and yield of the crops were analyzed via path coefficient and principal component analysis. The results showed that the yields of "Huafeng 8", "Liyu 18", "Jundan 20" and "Jiyu 3" exceeded 10 000 kg·hm^-2 with WUE greater than 3.0 kg·m^-3. This set of crops belonged to high WUE and super-high-yield type hybrid maize variety. Yields of "Yuanshen 213" and "Zhongke 11" were greater than 9 000 kg·hm^-2 with WUE of at least 2.7 kg·m^-3, this set of crops belonged to high WUE and high-yield type hybrid maize variety. The yields of "Jundan 18", "Denghai 662", "Jinong 1" and "Denghaichaoji" were higher than 8 000 kg·hm^-2 with WUE of 2.3~2.7 kg·m^-3, and which belonged to the stable-yield type hybrid maize variety. Principal component analysis showed that "Jiyu 3", "Liyu 18", "Huafeng 8" and "Jundan 20" were excellent varieties in terms of drought-resistance, water-saving and high-yield traits, and should therefore be widely cultivated in the study area of 3HP. Also based on path analysis, the comprehensive effects of 7 main agronomic traits on yield ranked as follows: core weight > 100-grain weight > row kernel number > bald point length > kernel length > ear length > ear row number. Whereas core weight, row kernel number and 100-grain weight had the most positive direct effect on yield, bald era length had the most negative effect on yield. The results of this study laid the basis for the selection and promotion of maize varieties with good traits for drought-resistance, water-saving and high-yield in the 3HP region.

2011 Vol. 19, No. 5