Abstract:

This study aims at expounding the effects of combined application of chemical fertilizer, organic fertilizer and microbial fertilizer on photosynthetic performance, biomass distribution and yield of soybean in the semi-arid region of the Loess Plateau. ‘Fendou 78’ was taken as the research object, and 6 treatments were adopted, including chemical fertilizer proportion application (N, NPK and 2NPK), chemical-organic combined application (NPK-O), chemical-microbial combined application (NPK-B) and the control. The association mechanism between leaf photosynthetic physiology and organs biomass accumulation, and between the distribution law and yield formation was analyzed. The results showed that: (1) SPAD, photosynthetic rate and transpiration rate were increased by 1.8%-5.3% at the flowering stage under 2NPK, NPK-O and NPK-B; water use efficiency of leaves was improved by 8.8%-19.3%; (2) stem and leaves biomass were significantly increased by 19.9%-46.3% under NPK、NPK-O and NPK-B; (3) NPK, 2NPK and NPK-B effectively regulated the biomass transformation between soybean pods and grains, the grain/pod rate and harvested index were obviously increased by 11.9% and 19.6%, respectively; (4) the yield of soybean was increased by 34.0% averagely under the optimized fertilizer application, the average growth rate of NPK-O was 41.3%, and the average growth rate of NPK-B was 36.8%. In conclusion, organic fertilizer and microbial fertilizer combined with chemical fertilizer application could optimize soil water and nutrients status, effectively regulate the photosynthetic performance and biomass distribution of soybean, and guarantee the sustainable increase of soybean yield.

Key words: dry-land soybean, fertilizer distribution, physiological regulation of photosynthesis, biomass distribution, grain yield formation