Nutritional And Agronomic Mechanism For High Yield And High Efficiency Production Of Winter Wheat Under Low Nutrient Input Condition In Dryland Area

The overuse of fertilizers has led to both high production costs and great risks of environmental pollution. The sustainable development of agriculture cannot be achieved without fertilization nowadays, therefore, rational application of fertilizer in agriculture and increase fertilizer use efficiency will be crucial. Using the different responses of genotypes to nutrient to carry out breeding is the most economical and effective way to achieve high yield and high nutrient efficiency. In order to understand the nutritional and agronomic mechanism for high yield and high efficiency production of winter wheat under low nutrient input condition in dryland area, nine winter wheat varieties were planted in a field where no fertilizer applied for six years. The main objective of this thesis was to study the effects of fertilizer input levels on the winter wheat yield responses, to analyze differences of accumulation and translocation of dry matter and nutrients, and to evaluate nutrient efficiency. The main results were as follows:1. Yield, dry matter, spike number, and kernel number per spike of different varieties had diverse responses to the level of fertilizer input under dryland condition. High-yielding varieties were characterized with high levels of dry matter, spike number, and kernel number per spike, and their sensitive responses to fertilizer rates contributed remarkablely to higher yields when more fertilizer was applied.2. With the increase of fertilizer rate, total accumulation of dry matter, the post-anthesis dry matter accumulation of different yielding cultivars increased, on the contrast, dry matter translocation, remobilization efficiency and contribution of remobilization to grain yield of winter wheat decreased. The dry matter increments of high-yielding varieties were bigger than the low-yield ones, showing a stronger response to the input of fertilizer rate. In addition, high-yielding varieties were characterized with high post-anthesis dry matter accumulation resulting from high SPAD and high photosynthetic rate of their functional leaves (flag leaves) during the grain filling stage while there was no obvious advantage for their dry matter translocation, remobilization efficiency and contribution of remobilization to grain yield.3. The N translocation rate and post-anthesis P accumulation of different yielding cultivars increased with the raise of fertilizer rate. P translocation rate decreased at first and then increased during the grain filling stage, while N and P translocation efficiency and the contribution of N and P translocation to grain showed a downtrend. High-yielding varieties were characterized with high post-anthesis N and P accumulation, and low levels of K loss resulting from high ability of saving translocated K in grain, their N and P translocation, remobilization efficiency, and contribution of N and P remobilization to grain yield were all greater than the low-yield ones, but there was no obvious advantage for their pre-anthesis K accumulation and K translocation.4. With the increase of fertilizer rate, N and P uptake in shoot and grain of different yielding cultivars increased, and the increments were greater in high-yielding varieties than the low-yield ones, showing a stronger response to the input of fertilizer for high-yielding cultivars. However, N and P harvest index was not affected by the fertilization treatments. Compared with the low-yielding cultivars, the high-yielding ones were greater by 222% and 49% for N recovery efficiency and N partial factor productivity, while 766% and 49% for P recovery efficiency and P partial factor productivity, respectively, at the low fertilizer input rate. Partial factor productivity of different yielding cultivars were significantly decreased by high fertilizer input rate.