Water shortage is a serious problem to restrict the sustainable agricultural development in the North China Plain (NCP). Conservation of water and improvement of WUE has become an important way to solve the water crisis and achieve the sustainable agricultural water use. Winter wheat is the major crop in NCP, during its growing season; rainfall is far less than the crop water requirement. Irrigation is essential for high yield of this corp. Irrigation water use of winter wheat accounts for more than 60% of all irrigation to agriculture in the NCP. Therefore, it is important to reduce irrigation water use by winter wheat to conserve water in NCP. Border irrigation is the major irrigation method for winter wheat in NCP. Then it is important to study the methods to reduce irrigation water use under border irrigation to winter wheat in NCP.This research concentrated on two ways to reduce irrigation water use. One method was to reduce irrigation water per application by using interval border irrigation method, which was alternately one plot was irrigated and one plot was not irrigated. The non-irrigated plot would use the lateral infiltrated water from the next irrigated plot. By this way the total irrigation water use per application was reduced and the wetted soil surface was also reduced that decreased soil evaporation. The second method was regulated deficit irrigation scheduling to reduce numbers of irrigation application. During some growing stages that were not sensitive to water stress, irrigation was omitted and moderate water stress improved the biomass remobilization to grains. The results were improved water use efficiency and grain production, at the same time water use and irrigation water use were both reduced. This study investigated the effects of interval border irrigation and different irrigation scheduling on performance of winter wheat to provide reference for optimized irrigation management in this area. The main investigated program is soil water content, the yield and the WUE, the root of winter wheat, dry matter, leaf area index, photogyology and the Stamata contuctance. The main results are: 1）The effects on yield and WUE of winter wheat under border irrigationResults showed that the yield of winter wheat reduced while the width of no-irrigate plot in fixed border irrigation increasing. The yield of 2m, 1.5m and1m width plot in fixed interval-border irrigation which are irrigated two times was reduced 5.47%, 4.92% and 1.83% compared with the CK, and the yield fixed interval-border irrigation which are irrigated one time is reduced 3.9%, 1.39% and 0.96%, the alternate border irrigation was reduced 6.03% compared with the CK, and yield of the CK which was irrigaeted two times is less than which irrigated one time 0.97%. But the total irrigation water use was reduced by one-third to one-second, so the WUE of 2m,1.5m and1m width plot in fixed interval-border irrigation which are irrigated two times was increased 24.47%,55.27% and 33.42% , and the yield fixed interval-border irrigation which are irrigated one time is increased 9.69%,18.49% and 24.05%. The results suggested that for interval border irrigation the width of 2m-1m plots was the most efficient irrigation method. The different irrigated deal results the soil water content different in fixed interval border irrigation, so the length of root of winter wheat is changed, it is good to the weight of thrount of gain when reduce the root in surface soil. The stomata contuctance is increasing while the distance form the irrigated plot is longer because of the iateral infiltration. Small stomata contuctance in order to reduce the ET, but reduce the photogyologriphy in same time, so the dry matter accumulation of border irrigation is less than CK. The results suggested that for interval border irrigation the width of 2m-1m plots was the most efficient irrigation method. 2）the effects on yield and WUE of winter wheat under deficient irrigationYield of winter wheat was quadric related to numbers of irrigation application. Moderate irrigation application achieved the highest yield and frequent irrigation reduced yield. Irrigation once produced the highest grain production and higher WUE among the six treatments. The total seasonal water consumption was reduced by 40.7% compared with the most frequently irrigated treatments (five irrigation applications).Moderate irrigation is good for grain yield of winter wheat; Irrigation twice produced the highest dry matter and leaf area index. The daily "lunch break” phenomenon of stomata conductance was not obvious for all the treatments except for the rain-fed. The diurnal peak value for photosynthetic rate of flag leaf under one and two irrigation treatments occurred late than that for other treatments. The results showed that optimized irrigation could stop the “lunch break” and be favorable for grain production. The results suggest that in plenty rainfall year once irrigated is the moderate irrigation application.
Zero-evaporation pot experiments during the seedlings stage and the whole life history were conducted on Luancheng Agri-ecology Station of Chinese Academy of Sciences between October, 2006 and June, 2007.4 representative winter wheat varieties with different ecotype were selected to study the differences of physiological water consumption and transpiration ratio among the varieties and the effect of water and fertilizer factors on the physiological water consumption correlation traits of winter wheat under different water and fertilizer treatments. Conclusions form the experiments were listed as the followings: 1. Physiological water consumption and biomass under different treatments were more associated with the traits of the varieties themselves. 2. For the differences among the varieties under the same treatment, physiological water consumption and transpiration ratio traits can be tested quickly during the short time of seedlings stage to represent the trend of those during the whole life history. It can shorten the research period. But the response of the varieties during seedlings stage and the whole life history to different treatments differed.3. The variety in irrigated and dry land and the variety in dry land with poor soil were divided to the type of higher transpiration ratio, the variety in irrigated land with rich soil was divided to the midst one, and the variety in dry land with rich soil was divided to lower one.4. According to the analysis of the traits, Shijiazhuang 8, the variety in irrigated and dry land, behaved best in economy yield and WUE for yield, so it is of more worth to popularize Shijiazhuang8 in agricultural production. 5. Water stress increased transpiration ratio. Physiological water consumption and dry matter increased during the experiment of seedlings stage under water stress, but those reduced during the experiment of the whole life history.6. Adding fertilizer increased transpiration ratio, and its promoting effect increased with the grade of water stress. Adding fertilizer during the experiment of seedlings stage reduced physiological, which increased during the experiment of the whole life history. Adding fertilizer reduced WUE for yield, but the differences was not significant.
Ecological problems in North China Plain becoming increasingly prominent have become a major limiting factor of sustainable development of agriculture. Accurate crop growth and yields simulation is important to sustain agricultural development and make decision by agricultural department. In this study, Regional Crop Growth Model (RCGM) for spatial estimating of crop yields was developed by combining GIS technology, spatial database and crop growth simulation model. On the basis of crop growth process and soil water balance of SUCROS, a site-specific crop growth module is developed on VB6 platform. A personal geodatabase for RCGM is established to manage spatial data such as crop data, soil texture, and land-use and attribute data such as meteorological data and statistical data. RCGM is integrated by GIS and site-specific crop growth module on VB6 platform and ArcGIS Engine components. The experimental data during 2000-2003 at Luancheng Agricultural Experimental Station CAS are used for model calibration at site scale, and 2002-2003 data of Luancheng County are used for model verification at the county scale. Yields simulation results are aggregated to villages so that they can be compared with yields statistics available from agricultural department. The villages of relative error at 10-30% account for 59.89% of 177 villages in Luancheng County, with the average relative error of 20.51%. RCGM is applied to monitor winter wheat yields during 2007-2008 in Hebei Plain, and results show that winter wheat yields are influenced mainly by weather, soil and winter wheat ecological zone. Regional Crop Growth Model was applicable at regional scale.
The temporal and spatial variability of N2O concentration and N2O fluxes in soil profiles under different N treatments were studied in an irrigated winter wheat and summer maize rotation field in the North China Plain. The relationship between N2O concentration and the influential factors was analyzed. The estimated models about N2O concentration,soil temperature and soil moisture was built using correlaton analysis linear regression method. N2O emission，the amount of increased N2O-N and it’s integated GWPs contribution and the percentage of applied N in different soil depth under different N treatments were estimated.The results as follows:1) Significant spatial variation and temporal variation of the nitrous oxide amount were found in the soil. N2O peaks occurred after high rainfall or irrigation. The highest concentration of N2O were found in August in Summer when the temperature was higher and water was sufficient. Generally，the order of the peak of N2O concentration in the soil profile as follows:30cm<60cm<90cm<150cm<200cm<250cm<300cm. When the peaks of N2O emission occurred after heavy rainfall or irrigation，the order could be described as：90-200cm＞250-300cm≌30-60cm.N2O concentration was relatively high below the 30cm in the soil profile. Under N0 treatment(no applied N), the maximum N2O concentration value was 5617.2ppbv and the average was 948.5ppbv, while the largest value under fertilized treatment was 42041.9ppbv and the average was 1839.4ppbv. Both the control(N0) and fertilized treatments had the same Patterns.2）The estimate models about N2O concentration, soil temperature and soil moisture have been built using linear regression method.3）Under different trearments the seasonal patterns of N2O concentration in the same depth were similar. The N2O concentration in summer-maize was higher than those in winter-wheat. The peaks of N2O concentration occurred 3-15 days after fertilization and the amount of the peaks increased with the increased nitrogen rates. The difference of N2O concentration under different N treatments was significant.4）The N2O losses increased with the increased N rate. N2O flux were abuout 0.23 、0.43，0.53，0.52 kg•ha-1 per year under N0, N200, N400, N600, respectively. N2O flux in the soil profle in winter-wheat were: 0.16,0.29,0.35,0.41 kg•ha-1, which were higher than those in summer-maize (0.07,0.14,0.17,0.11 kg •ha-1). The N2O flux in wheat-maize rotation field under traditional agricultural management (applied 400kg N ha-1) in this studied area was about 0.53 kg N ha-1, account for 0.132% of applied N. The amount of increased N2O-N and it’s average integated GWPs contributions was estimated as 0.0154m-2 in different soil depths under different N treatments .
Water scarcity is a serious problem that restricts agricultural development in the North China Plain (NCP). Conserving water and reducing crop water use are key factors for sustainable agricultural development in this region. This study examined the possibility of using biological measures to reduce crop water use and enhance crop drought resistance. The measures included defoliation, hydraulic lift and application of silicon. The hypothesises in the three measures were that defoliation could reduce the size of canopy to reduce transpiration, hydraulic lift by deep root system to release water in the dry top soil layer during night could relocate soil moisture for efficiently soil water utilization, and application silicon could reduce leaf transpiration rate and improve crop drought resistance. Field and pot experiments were carried out at Luancheng Station of Agro-ecological System in NCP during 2006-08 to test those hypothesises.1. The effects of defoliation1.1 Responses of winter wheat to defoliationField and pot experiments were conducted to investigate the effects of defoliation on crop performance and the possibility of defoliation on improving crop drought resistance and reducing water use during 2006-2008, two growing seasons of winter wheat（Triticum aestivum L）in North China Plain. Four intensities of defoliation (0%, 30%, 60% and 90%) were imposed to winter wheat either at heading or at anthesis under deficit condition, and two levels of defoliation (0% and 90%) at anthesis under three levels of soil water regimes were carried out in field. Additional pot experiments with four levels of defoliation under two water regimes were arranged. Results showed that 90% defoliation (only flag leaf kept) at both defoliation timing significantly reduced grain production. Under wet condition the reduction was over 20%, while under dry condition the reduction was about 12%. Yield reduction was greater for defoliation at heading than that at anthesis, and it was mainly caused by the reduction in kernel weight. 30% defoliation (top three leaves kept) slightly increased grain yield and 60% defoliation (top two leaves kept) slightly reduced grain production. Root length density in the top soil profile was significantly reduced by 90% defoliation at anthesis under wet condition, but it was increased under dry condition. Dry matter remobilization to grains under 60% and 30% defoliation was increased that resulted relative higher harvest index. Photosynthetic rate of the remained leaves after defoliation was enhanced under all soil moisture condition. Though defoliation reduced seasonal water use (ET), yield reduction was much greater than that the reduction in ET under intensive defoliation, resulting lower water use efficiency (WUE). Mild and moderate defoliation slightly decreased ET and WUE was similar with the non-defoliated treatment. The results showed that to conserve soil moisture by removing leaves might not be economic. Under the condition of this study, WUE of winter wheat was not improved by defoliation, and defoliation could not be used as a measure of water-saving. But in very dry condition the reduction in ET by defoliation might help the crop last longer.1.2 Responses of maize to defoliationField experiments were conducted to investigate the effects of defoliation on water use and grain yield of maize. Three defoliation intensities and two time of defoliation under two water regimes were conducted during 2007-2008, two seasons of maize. The results showed that defoliation of maize significantly affected grain yield, with 17-39% yield reduction under 60% defoliation.of the leaves along the stem from bottom to up. Howevere, 30% defoliation slightly increased grain yield. The same to winter wheat, defoliation in drought conditions and after silking was benefit to buffering grain yield decrease caused by defoliated leaves, compared with in moisture conditions and before tasselling. Different defoliation intensity affected WUE of maize, 30% defoliation increased WUE by 9%, and 60% defoliation decreased WUE by 20%. Photosynthetic rate of saved leaves after defoliation was enhanced and dry matter remobilization of 30% defoliation was increased, which was benefit to grain yield of 30% defoliation. Defoliation decreased ET, but 60% defoliation resulted in much more yield reduction than that of ET. Detasselling together with the top three leaves after pollination significantly increased grain yield and WUE of maize. This measure increased grain yield by 7.5-13% and WUE by 21-24% compared with CK. The reason behind this result might be the improvement in light distribution in the canopy after removing the tasselling and the top leaves. Maize is a light sensitive crop. With high density maize canopy is generally bigger. The radiation condition in the middle parts of the canopy was not very good, where the leaves near the cob were. The results from leaf photosynthetic rate along the stem showed the highest leaf photosynthetic rate occurred at the leaves near the cob. Then detasselling and removing several top leaves improved the light condition and photosynthetic rate of the most important leaves of maize. 2. The effects of silicon application on leaf transpiration and WUE Field and pot experiment were conducted to investigate the effects of silicon application on water use and crop yield under dry and wet conditions to winter wheat and maize. Field experiment included four treatments: wet and dry conditions with and without silicon application, respectively, for both crops. Pot experiment included eight treatments: wet, light deficit, moderate deficit and severe deficit with and without silicon application for maize. Field results showed that yield of winter wheat was increased by 4% and WUE by 18.3% by application of silicate fertilization under dry condition. Maize yield was improved by 5.6-14.4% and WUE by 10-30% under dry condition, and it was 2.8-9.9% and 2.4-3.4% under wet condition, respectively. Results from pot experiment showed that the effects of silicon application varied with soil moisture on maize. Compared with no silicate fertilization, silicate fertilization affected maize growth and WUE more significantly under light and moderate water deficit conditions than other treatments. Silicate fertilization increased root dry weight by 8-49% and shoot dry weight by 12-48% under three water regimes, except for severe deficit condition. WUE was improved by 25-40% under light and moderate water deficit condition by application of silicon. Silicon application increased special leaf weight of winter wheat, decreased water loss rate of excised-leaf and increased root weight of summer maize. Therefore, silicate fertilization of winter wheat and summer maize may increase soil silicon concentration, promoted silicon assimilation and deposit in plants, then decreased no-stomatal transpirations, improved stomatal conductance and photosynthesis with no much transpiration, and advanced water use and grain yield formation. 3. The effects of hydraulic lift on soil moisture and crop growthField experiments were conducted to test the effects of root “hydraulic lift” on top soil moisture and its effect on nearby crops. Five legumes: alfalfa, tall fescue, smooth bromgrass, alfalfa, red clover and hairy vetch were grown in different plots with four replicates. After one year growth, the roots of the legumes were cut at one side of the plots down to 40 cm and the roots at the opposite side were intact. Spinach was grown for about one month along both sides of the plots in the spring when rainfall was small and top soil was dry. After the harvest of spinach, maize was planted in the same way as the spinach. Another test involved the intercropping of maize and wheat with alfalfa. The results showed that some of the legumes such as tall fescue and smooth bromgrass had a big root system, with total root length over 20km.m-2, and higher root length density in the deep soil profile. Then it was possible for the root extracting the stored soil moisture in the deep soil profile to release it in the dry topper soil layer during the night. TDR results showed that moisture of the topper soil layer near the legumes with intact roots was slightly improved. Thermographic images also showed that the canopy temperature of the spinach near the legumes with intact roots was lower than that along the side with cut roots. With the improvement in water statues, biomass of spinach and maize were improved by 16-30% and 6-32%, respectively. The effects of different legumes were different. The performance of alfalfa was better than other legumes. The effects of those legumes on nearby crop growth might be not only related to soil moisture, but also to soil fertilization. The P content of spinach and maize in shoot near the legumes with intact root was greater than that in other places. The root of legume crops could remobilizating soil P that benefited crop growth. The intercropping test showed that yield and WUE of maize was improved by 18.8% and 31.4% when grown together with alfalfa. However, because the repulsion effects between legume roots with wheat roots and disadvantageous light competition between leaves, the intercropping of wheat with alfalfa reduced wheat yield and WUE by 9.3% and 6.1% correspondingly.The results from this study showed that it was possible to regulate soil water distribution along soil profile by hydraulic lift, reduce canopy size and transpiration by moderate defoliation and reduce leaf water loss rate by application Si. Those measures could improve crop drought resistance and water use efficiency. Biological water saving measures could be further studied and used as water-saving measures in water shortage areas.
A recombined inbred (RIL) population of 186 lines, which was generated from the cross between two elite Chinese common wheat varieties Xiaoyan54 and Jing411，was used to study the change pattern of seedling transpiration efficiency and its related traits，grain yield and related physiological and agronomic traits, and to dissect the quantitative inheritance of them. QTL analyses were performed using the software of Win QTL Cart V2.5 based on the composite interval mapping approach. The results were as the following:1. Pot experiment was conducted under 2 level of water supply (CK: enough water supply, drought : 60% water of CK) at seedling stage. The results showed that the change pattern of transpiration efficiency , root dry weight, shoot dry weight, biomass and water consumption was conformed to normal distribution，which is quantitative characters. 34 additive QTLs were detected on chromosomes 1D、2A、2D、4D、5B、5D、7Aand 7B , each could account for 4.8%～16.64% of the phenotypic variance respectively, in which 8 additive QTLs were major ones( accounted for more than 10% of the phenotypic variance).2. Field experiment was conducted under rain-fed condition. The results showed that the change pattern of grain yield and related physiological and agronomic traits was conformed to normal distribution which is quantitative characters. 41 additive QTLs were detected ,each could account for 5.71%～27.14% of the phenotypic variance respectively. Among them, 27 additive QTLs were major ones，each could account for more than 10% of the phenotypic variance respectively.3. 4 QTLs for seedling transpiration efficiency from pot experiment and 1 QTLs for leaf WUE from field experiment was located on chromosomes 5B, and both enhanced alleles might come from Xiaoyan 54, which is consistent with the higher drought resistance of Xiaoyan54.4. QTLs distributed in regional trends, showing a multi-effect or close due to the knock-on effect, high correlation traits have some common QTLs. Section wmc329.3-CFA21582 on chromosome 1D was detected for seedling shoot dry weight(07), biomass (07,08) and water consumption (07,08) under two soil moisture; Section ms614.1-CFD56.1 on chromosome 2D was detected for stem dry weight, harvest index, plant height (jointing stage, heading-flowering period , grain-filling stage and harvest period), chlorophyll-content and leaf water potential; Section CFA2170-ms155 on chromosome 3A was detected for inefficient spikelet number, leaf area, leaf dry weight; Section ms212-CFD29 on chromosome 5d was detected for grain yield, spike weight and leaf WUE. These common QTLs indicate the internal relations at molecular level.
Soil salinization and water deficiency are the major abiotic factors that restrict crop production. Both of salt and drought stress may decrease the soil water potential which results in the difficulty of water absorption by plants and cell dehydration even death. Despite some of the similarities between water and salt stress in their effects on plant growth, surprisingly, few attempts have been made to evaluate the combined effects of water and salt stress on plants. The winter wheat, growing in salt affected soils of North China, is usually facing on both of salt and water stress. Especially in spring due to high evaporation and low rainfall, the salt and drought stresses greatly affect seedling growth of winter whea. Therefore, it is necessary to investigate the combined effects of salt and drought stresses on growth of winter aheat and its physiological aspects for the better production of winter wheat in salt and drougt affected areas.Two winter wheat (Triticum aestivum) cultivars, Cang-6001 which is salt tolerant and Shijiazhuang-8 which is drought tolerant, were selected in this research. The objective of the present study was to investigate whether the salt can modify the response of winter wheat to drought stress and illustrate some physiological mechanisms involved in this response. A hydroponic experiment and pot culture were carried out in this study. In hydroponic experiment, PEG-6000 and NaCl was used to stimulate drought stress and salt stress separately. Nine treatments with three replicates were employed including three levels of salt treatments (0, 25mmol•L-1, 50 mmol•L-1) and three levels of PEG-6000 treatments (0, 8.3%, and 12.6%). The growth, organic solute accumulation, Lipid peroxidation, and ions were analyzed. In pot culture, four levels of soil salinity (0‰，3‰，5‰，7‰) combined with three levels of soil moisture (75%～85%， 55%～65% and 35%～45% of filed capacity) were designed. There were three replicates in pot culture experiment, and the growth parameters and osmolytes were analyzed. The main results are as follows: 1. Plant growth was increased by addition of proper salt under drought stress condition, while it was inhibited more by addition high salt. At 12.6% of PEG 6000 solution, adding 25 mmol•L-1NaCl increased the accumulated dry weight and plant water content by 36.1% and 9.4% separately compared with No-NaCl PEG treatments. Under 55%～65% of field capacity condition, the grain weight of cang-6001 and Shijiazhuang-8 per plant was increased by 18.6% and 12.9% at 3‰ of soil salinity level, compared with that of no salt stress control, separately, while it was decreased great at 5‰ soil salinity level.2. The seedling Na+ content was increased by addition of proper salt in 8.3% or 12.6% PEG 6000 solutions, while it was declined by high salinity. The seedling Na+ contents were increased 2.5 and 3.8 times in the combined treatment of 25 mmol•L-1 NaCl and 8.3% or 12.6% PEG, compared with single PEG treatments. Proper Na+ level in plants may play the role as osmotic substance to reduce the osmotic potential of cell and increase the ability to absorb water from environment. 3. Under drought stress, adding proper amount of salt increased leaf soluble sugar content. It was increased significantly by addition of 25 mmol•L-1 NaCl in 12.6% PEG solution compared with that of no NaCl PEG treatment, and by addition of 3‰ NaCl under 55%～65% of field capacity compared with that of no NaCl treatment (p<0.05).4. Leaf MDA content was decreased by addition of proper amount of salt under drought stress condition. The MDA content in leaves was decreased by 25.9% in the treatment of 12.6% PEG combined with 25 mmol•L-1NaCl,compared with that of no NaCl treatment. It indicates that moderate salinity may eliminate active oxygen production in plant. 5. The analysis of correlation among Na+, soluble sugar and MDA content in leaves showed that the increased Na+ may increase the accumulation of soluble sugars, and the accumulation of soluble sugars may reduce the content of MDA.