小麦秸秆还田后不同水稻品种对简化穗肥施用的响应及其成因OA北大核心CSTPCD

[Objective]The aim of this study was to explore and analyze the differences in yield,panicle differentiation and degeneration,soil microbial activity,and response of soil alkali-hydrolysable nitrogen to simplified panicle fertilization among different rice varieties under the condition of wheat straw return(SR).[Method]As test materials,two cultivars were selected,including late maturing medium japonica rice Nanjing 9108(NJ 9108)and indica rice Yangdao 6(YD6).Rice yield,spikelet differentiation,and degeneration were evaluated under the interactive conditions of SR and simplified panicle fertilization(0﹕0,no panicle fertilization;2﹕0,full application of spikelet-promoting fertilizer;1﹕1,equal application of spikelet-promoting and protecting fertilizers;0﹕2,full application of spikelet-protection fertilizer).The nutritional basis of rice spikelet differentiation and degeneration was analyzed in terms of nutrient release from straw decomposition,alterations in soil microbial communities and enzyme activity,and soil alkaline nitrogen content.[Result](1)After SR,the average yield of NJ 9108 and YD 6 increased by 4.2%and 3.2%,respectively.Under panicle fertilization treatments,the highest yield for NJ9108 and YD6 was achieved under the 2﹕0 and 1﹕1 treatment,respectively.After no wheat straw return treatment(NR),the yield of both varieties was highest under the 1﹕1 treatment.The yield trend of panicle fertilization treatments was consistent within the range of 180-360 kg N·hm-2.(2)After SR,the initial 0-30 days were a period of rapid decomposition,with the rapid release of carbon and nitrogen from the straw.At 30 days,the average number of bacteria,fungi,and actinomycetes in the soil increased by 179.2%,and the average activity of urease,acid phosphatase,and sucrase increased by 88.8%.During the period of 40 to 60 days,the straw's decomposition and carbon-nitrogen release rates diminished,and the number of microorganisms and enzyme activities decreased significantly.Decomposition and carbon-nitrogen release of straw essentially stalled between 60 and 90 days,while the number of microorganisms and enzyme activities decreased gradually.From 10 to 40 days after SR,the soil's alkali-hydrolysable nitrogen content decreased by an average of 4.8%,while it increased by an average of 5.2%between 50 and 90 days.(3)After SR,the increase in soil alkali-hydrolysable nitrogen caused an increase of 1.4%in the average number of spikelets differentiation,a decrease of 12.3%in the average number of spikelets degeneration,but an increase of 4.4%in the average number of surviving spikelets.Rice harvest increased primarily due to an increase in the number of spikelets per panicle(the number of surviving spikelets per panicle).After SR,the 2﹕0 treatment reduced the rate of spikelet degeneration in NJ9108 and YD6 relative to NR by 23.5%and 7.6%,respectively.The number of spikelet differentiation and degeneration of NJ9108 increased by 8.9 and 5.7 spikelets per panicle under the 2﹕0 treatment relative to the 1﹕1 treatment,whereas Yangdao 6 increased by 6.8 and 11.6 spikelets per panicle,respectively.As the increase in the number of spikelets differentiation was greater than the increase in the number of spikelets degeneration,NJ9108 had the highest number of surviving spikelets under the 2﹕0 treatment,while YD6 had the highest number under the 1﹕1 treatment.[Conclusion]Wheat straw return increased rice yield,with NJ 9108 achieving the highest yield under the full application of spikelet-promoting fertilizer and Yangdao 6 achieving the highest yield under the equal application of spikelet-promoting and protecting fertilizers.Those factors that contributed to the increase in yield were mainly due to a significant reduction in the rate and number of spikelets degeneration and an increase in the number of spikelets per panicle.The decrease in the rate of spikelets degeneration for NJ 9108 was greater than that for YD6,which was the main reason for the difference in their response to different panicle fertilization treatments in terms of the number of surviving spikelets.