Effects of Rice Straw Combined with Inorganic Fertilizer on Grain Filling and Yield of Common Buckwheat

This study aims to clarify the effect of rice straw combined with inorganic fertilizer on the grain-filling characteristics and yield formation of common buckwheat (Fagopyrum esculentum Moench) and provide a scientific basis for straw fertilizer utilization and the scientific fertilization of common buckwheat in Guizhou Province.Common buckwheat 'Fengtian1' was field-grown and treated with no straw and no fertilization (CK), no straw with normal fertilizer (SF), full straw with 20% reduction in conventional fertilization (SH), full straw with 40% reduction in conventional fertilization (SM), full straw with 80% reduction inconventional fertilization (SL), and full straw with no fertilization (HT). The results showed that the initial growth power (R-0), maximum and average grain-filling rate, and starch synthase activity of the superior grains were higher than those of the inferior grains. Compared with CK, the treatments with straw and inorganic fertilizers remarkably increased the contents of available nitrogen, available potassium, available phosphorus, and organic matter in the rhizosphere of common buckwheat. SH and SF treatments remarkablyimproved the fertilizer contribution rate and fertilizer agronomic utilization rate, promoted root growth, and enhanced the starch branching enzyme and soluble starch synthase activities of superior and inferior grains. Compared with CK, SH treatment considerably increased the number of grains per plant, grain weight per plant, 100-grain weight, and final yield. Thus, straw combined with inorganic fertilizers, particularlythe SH treatment, should be recommended as an agronomic method for promoting grain filling and increasing the yield of common buckwheat.