Effects Of Different Transplanting Modes And Densities On Rice Yield And Quality Under Rice-duck Integrated Farming

The technology of rice-duck integrated farming has many advantages,such as weeding,insect control,fertilizer cultivation,muddy water cultivation,promoting rice plant development,and significant comprehensive economic benefits.Previous studies on rice-duck integrated farming mainly focused on the comparison with conventional cultivation,or under a single mode and density of transplanting However,the effect of the interaction between machine planting mode and density on rice-duck integrated farming is not clear yet The experiment was conducted in Test Base of Jiangyan in 2018-2019?Under the rice-duck integrated farming,two varieties of conventional japonica rice Nanjing 9108 and indica japonica hybrid rice Yongyou 2640 were used,and two kinds of seeding-transplanting modes,carpet seedling and pot seedling,and five kinds of seeding-transplanting densities were set respectively.The effects of different machine transplanting methods and densities on rice yield and its formation were studied.The test shows that:(1)In yield,pot seedling transplanting increased the spikes per 667m2,seed setting rate and 1000-grain weight of Nanjing 9108,and increased the spikes per 667m2 and grains number of Yongyou 2640.In the aspect of yield formation,pot seedling increased leaf area index and tiller number of Nanjing 9108.Therefore,the yield and formation of rice transplanting by pot seedling machine is better than that by carpet seedling machine.Under the mode of carpet seedling transplanting,with the increase of density,the number of tillers per mu of rice increased,the leaf area index increased,and the SPAD difference was not significant;Nanjing 9108's number of spikes per 667m2 increased,grains number decreased,seed setting rate increased,1000-grains weight increased,and the final yield increased;Yongyou 2640's number of spikes per 667m2 increased first and then decreases,grains number per panicle decreased,1000-grains weight increased,and the seed setting increased first and the final output increases first and then decreases.Under the mode of pot seedling transplanting,with the increase of density,there was no significant difference in SPAD,leaf area index and tiller number per 667m2 of rice increased;Nanjing 9108's number of spikes per 667m2 increased,grains number decreased,difference of 1000-grain weight was not significant,number of spikes per 667m2 increased first and then decreased,the final yield increased first and then decreased;Yongyou 2640's number of spikes per 667m2 increased,grains number per panicle decreased,the seed setting rate increased,and the difference of 1000-grain weight was not significant,the final yield increases first and then decreases.Therefore,carpet seeding transplanting can choose 2.22×104/667m2 of planting density,while the pot seedling transplanting can choose 1.68×104/667m2 of planting density.(2)In quality,among different transplanting methods,the milling quality of rice in bowl seedling transplanting is still higher than that in carpet seedling transplanting,which has no significant effect on the precision and roughness,but the head milled rice rate of the two varieties has been improved.In the aspect of appearance quality,the chalkiness rate and chalkiness degree of rice transplanting by bowl seedling machine were higher than that by carpet seedling machine,which was not good for appearance quality of rice.In terms of nutrition and cooking quality,the protein content of potted seedlings is higher than that of carpet seedlings,and the amylose content of potted seedlings is lower than that of carpet seedlings;the mechanical insertion mode has little effect on the gel consistency;the taste value is related to the variety,and the mechanical insertion mode still has no effect on it.Therefore,higher rice quality can be obtained by transplanting seedlings in a bowl without considering the appearance quality.With the increase of density,in the aspect of milling quality,the changes of roughness and precision are not significant,but the head milled rice rate decrease;in the aspect of appearance quality,chalkiness and chalkiness rate increase.In terms of nutritional quality,there were differences among varieties.With the increase of density,the protein content of rice decreased.The amylose content of Nanjing 9108 increased at first and then decreased,while the amylose content of Yongyou 2640 decreased.The gel consistency of Nanjing 9108 increased,but the gel consistency of Yongyou 2640 decreased.In terms of eating quality,with the increase of density,the eating value of Nanjing 9108 did not change significantly,while that of Yongyou 2640 became better.Therefore,high-density transplanting can obtain rice with better taste,but high-density transplanting can reduce the milling quality,appearance quality and nutritional quality of rice,and different densities can be selected according to the needs.(3)Among different transplanting methods,the nitrogen accumulation of pot seedling transplanting is better than that of carpet seedling transplanting.The nitrogen content rate,nitrogen absorption amount,nitrogen absorption amount and absorption ratio of pot seedling transplanting are better than that of carpet seedling transplanting in different periods.Therefore,pot seedling transplanting can still be selected.With the increase of density,the nitrogen absorption and nitrogen content of each period showed an overall upward trend.High density planting is beneficial to the nitrogen accumulation of rice.In combination with the yield,the mechanical planting density of 2.22 X 104/667m2 can be selected for conventional japonica rice,1.85×104/66m2 for indica japonica hybrid rice,and 1.68×104/667m2for pot seedling.