Effects Of Slow-release Fertilizer On Source-sink Conversion Of Rice In Alternate Wet-dry Rice Fields

AWD and slow-release fertilizer could regulate the source-sink conversion effect of rice,thus affecting rice yield and quality.In order to explore the regulation effect of slow-release fertilizer on source-sink conversion effect of rice in AWD rice fields,and to clarify the relationship between source-sink conversion and yield and quality.In this study,two irrigation modes（flood irrigation CF and AWD）were used.In the secondary area,four replicates were set with different nitrogen management methods（no N0 treatment,conventional N1,the slow release fertilizer N2）,and one of the replicates was used as the damage area,Rice plant height,tillering,dry matter,nitrogen uptake,soil ammonium and nitrate nitrogen,filling parameters,yield and quality were measured and analyzed.The main results are as follows:（1）AWD and slow release fertilizer had significant effects on rice growth.There was no significant difference in tiller number between the two irrigation modes,but the application of N2 reduced the number of ineffective tillers.The number of ineffective tillers in N1 increased by 2.33-23.51 plants/m^-2compared with that in N2,and the final tiller number in N2treatment was 2.63%higher than that in N1 treatment at the end of rice growth.AWD increased by 11.2%（at grain filling stage）and 11.06%（at the end of growth stage）,and N2increased by 14.01%（root）,6.51%（leaf）,7.49%（stem）and 12.86%（panicle）than N1 in dry matter accumulation at grain filling stage.Compared with N1,dry matter accumulation at the end of growth increased by 15.05（stem）and 20.55%（panicle）.（2）AWD and slow-release fertilizer promoted the accumulation and transport of nitrogen sources in rice.AWD increased leaf nitrogen uptake by 28.05%compared with CF at grain filling stage,root nitrogen uptake by 4.91%compared with CF at growth stage,and nitrogen uptake by 31.51%（root）,19.74%（leaf）,28.49%（stem）and 35.92%（panicle）in N2 treatment compared with N1 at grain filling stage.At the end of growth stage,nitrogen uptake by N2increased by 45.8%（leaf）,20.8%（stem）and 25.69%（panicle）compared with N1,and promoted the continuous growth of root morphology,ensuring sufficient nutrient transport and making the nutrient uptake in the shoot of rice stable,contributing to the rice yield.（3）The two irrigation modes on the change of soil nitrogen sink,there is no obvious difference,After jointing and booting stage,the change of soil ammonium and nitrate nitrogen in N2 treatment is relatively slow,and it is always lower than that in N1 treatment until the filling stage begins to exceed N1 treatment,mainly because N1 has been basically consumed from N1 to filling stage,and N2 will according to the required for rice and release of nitrogen,Play a"strong source to promote the storage capacity"role.Compared with CF treatment,AWD reduced water consumption by 18.74%（2019）and 14.57%（2020）,and increased water production efficiency by 14.47%in 2019,while the difference was not significant in 2020 due to climate reasons.There was no significant difference in water consumption and water production efficiency.（4）AWD and slow-release fertilizer had significant effects on sink-source transformation and rice quality.AWD and N2 treatments promoted dry matter and nitrogen transport from source to sink by increasing rice"source"supply,and affected the formation process of grain sink,that is,increased initial growth potential and maximum filling rate of rice.AWD significantly increased protein content,amylose content and chalkiness grain percentage of rice,while N2 significantly decreased protein content,chalkiness grain percentage and chalkiness degree of rice,thus compensating for the deficiency of AWD on appearance quality.（5）Through the comprehensive analysis of source-sink transformation relationship and quality of rice,it was shown that the more"source"accumulation,except the amount of nitrogen absorbed by leaves,had a greater impact on rice yield at the filling stage.Therefore,the nitrogen content in leaves should not accumulate too much,which was not easy to improve the yield continuously,and also easy to lead to the extravagant waste of nitrogen.The"source"of rice plays an important role in the process of grain formation,and the effect of"source"on 1000-grain weight is negatively correlated,indicating that the more the accumulation and transport of"source"in rice,the more unfavorable the accumulation of1000-grain weight.There was a significant positive correlation between initial growth potential,maximum filling rate and effective panicle number,which was beneficial to increase rice yield.Through principal component analysis,accumulation and leaf and stem of rice"source"of nitrogen transport,improves the initial growth potential of the grain-filling,maximum grouting rate and effective panicle number,ensure the rice grains formed in the process of nutrient supply,played a"storage capacity"expanding effect,and reduce the grain formation in the content of protein,rate(chalky rice percentage and chalk white degree,In addition,the percentage of whole rice and amylose content were increased,and the appearance,processing and cooking quality of rice were improved.In conclusion,AWD can reduce water consumption and improve water production efficiency of rice,while slow-release fertilizer can provide nitrogen according to plant needs in AWD rice fields,improve accumulation and transshipment of"source"in late growth stage of rice,increase sink capacity,and ensure stable rice yield and improve appearance,processing and cooking quality.This study provided theoretical and technical basis for improving nitrogen use efficiency of AWD irrigated rice field and realizing sustainable development of rice field production.