Effect of fertilizer management on dry matter accumulation, yield and fertilizer use efficiency of rice cultivar 'Huayou-14'

Rice is one of the most important crops in China. The production of rice has dramatically increased over the last 50 years due to high input of chemical fertilizers. To control the unreasonable application of fertilizers (e.g., more chemical fertilizers, less organic manure or neglect of crop growth curve), we researched the effects of fertilizer application on dry matter accumulation and yield of rice in Shanghai. The objective of the study was to explore a scientific fertilization management for high yield and high fertilizer use efficiency cultivation of rice in Shanghai. To this end, two-year (2014-2015) field Lysimeter experiment was conducted at a typical paddy rice plot in a rural suburb of Shanghai, China. The 'Huayou-14' rice cultivar, which is widely cultivated in Shanghai, was used in the experiment. A total of four treatments were investigated, including no fertilizer treatment (CK) as the control, receiving neither chemical fertilizer nor manure; sole chemical fertilizer treatment (CT) of 300 kg(N)·hm^-2 urea, 60 kg(P₂O₅)·hm^-2 calcium superphosphate and 60 kg(K₂O)·hm^-2 potassium chloride applied according to the practice of local famers in the area; sole organic fertilizer treatment (OT) of poultry manure with total N at the same rate of 300 kg(N)·hm^-2; and chemical-organic fertilizers mixture (MT) of 80% urea and 20% organic manure based on 300 kg(N)·hm^-2. The dry matter accumulation characteristics, yield, fertilizer utilization rate and profitability were analyzed for different fertilization treatments. The effects of different fertilization treatments on dry matter accumulation of rice became significant from booting stage, which was higher in MT and CT than in OT and CK. Dry matter accumulation curves of 'Huayou-14' during growth stage were simulated by Logistic equation Y=W_m/(1+ae^-bt), in which t is the days after transplanting, Y is the dry matter accumulation, W_m is the ultimate amount of dry matter. The maximum dry matter accumulation rate under MT increased respectively by 0.17 kg·hm^-2·d^-1 and 0.19 kg·hm^-2·d^-1 compared with OT and CK, but no significant difference compared with CT. Photosynthate accumulation at grain filling stage contributed mainly to rice yield. The contribution rate of photosynthate accumulation at grain filling stage to yield under MT was 76.3%, which was 9.4% and 5.2% higher than that under OT and CK, but had no significant difference from that under CT. At harvest, rice yield increased respectively by 15.6% and 63.4% under MT compared with OT and CK. However, no significant difference was observed between MT and CT. Agronomic efficiency of fertilizer significantly improved under MT, which was respectively 9.7% and 53.7% higher than CT and OT. It was possible to improve yield by increasing dry matter accumulation and extending growth period. The combined application of chemical fertilizer and manure was effective for dry matter accumulation as it provided sufficient nutrient supply for growth and dry matter accumulation even after flowering. Thus, it was a useful strategy for improving rice yield, reducing chemical fertilizer input and avoiding excessive waste of resources.