The Resource Use Efficiencies And Trade Off Among Spring Wheat Cultivars With Different Drought Resistance

Plant resources efficient utilization and trade-off strategy is one of the hot topics in the field of plant ecology and agricultural ecology. Water, nitrogen and light energy are the essential resources for plant growth, the relationship between environmental supply level and plant acquisition ability and utilization efficiency, the response of plant canopy-root structure and biomass allocation to water and nitrogen levels should be further studied. Three spring wheat cultivars with different drought resistance as experimental materials in this research, setting different water and nitrogen supply levels, to explore the responses of spring wheat canopy-root structure and functions, biomass accumulated and allocation to water and nitrogen levels, analysis of nitrogen, water and light use efficiency and trade-off relationship with cultivars. The main results obtained are as follows:(1)Phenotypic plastictity of three spring wheat cultivars(canopy height, specific leaf area, leaf inclination angle, root length, root tip number, root mean diameter, root volume, root surface area, root projected area) were significantly different. Specific leaf area, leaf inclination angle, soble sugar, soble protein, proline and canopy nitrogen content were significantly different in the canopy vertical level. Drought resistant cultivars Heshangtou and Xihan No.2 were bigger in root system and higher in canopy height, higher in leaf osmotic adjustment substances, lower in transpiration rate, absorption and maintain ability of soil water and nitrogen were strong. Non-drought resistant cultivar Ningchun No.4 characterized with compact plant type, canopy nitrogen vertical distribution gradient was obviously, light resource capture and utiliztion ability was strong, bring much more photosynthetic electron assigned to photochemical reaction direction, net photosynthetic rate was high. When increased irrigation and appropriate nitrogen application(Heshangtou and Xihan No.2 in the application of nitrogen 150kg·hm-2, Ningchun No.4 in the application of nitrogen 225kg·hm-2), can changed the wheat canopy and root structure and function, promoted light interception and improved absorption ability of water and nitrogen.(2)Reproductive allocation, grain yield, irrigation water use efficiency and yield component fantors(effecyive spike number, grain number per spike, 1000-kernel weight) of Ningchun No.4 were significantly highter than drought resistant cultivars. Biomass yield and each organic biomass accumulation of Xihan No.2 were biggest, and light use efficiency was highest. Biomass water use efficiency of Heshangtou was highest. Drought resistance cultivars Heshangtou and Xihan No.2 were low sensitivity to soil moisture and high sensitivity to soil nitrogen, No-drought resistance cultivar Ningchun No.4 instesd. Increased irrigation the biomass water use efficiency of no drought resistance cultivars were obviously deceeased, and increased nitrogen levels was promoted contribution rate to nitrogen biomass dry matter production efficiency and grain nitrogen of drought resistance cultivars. Water supply increased, and biomass water use efficiency of three cultivars were significantly decreased. Nitrogen use efficiency(nitrogen dry matter production efficiency, nitrogen harvest index, nitrogen agronomic use efficiency, nitrogen partial production productivity) were significantly decreased with plant nitrogen acquistion quantity increased, when nitrogen increased.(3)Significantly negative correlation among nitrogen dry matter production efficiency to light use efficiency and biomass water use efficiency, and light use efficiency was significantly positively correlated with biomass water use efficiency. Therefore, there were clear trade-offs among nitrogen dry matter production efficiency to light use efficiency and biomass water use efficiency.This study investigates resource use efficiencies and their responses to water and nitrogen levels in wheat with different drought resistant, to provide a scientific basis for better understanding of trade-off relationship among light, water and nitrogen use efficienciea. It is clear to know the irrigation and nitrogen levels to promot resource use efficiency in different drought resistant cultivars, and has an important practical guiding significance for the agricultural resource efficient utilization of oasis irrigation area.