Effects Of Liming And Straw Return On The Grain Yield And Quality Of The High-quality Double Rice

The red paddy soil is one of the main soil types in double rice area in southern of China.It’s low soil fertility,especially soil acidification seriously limiting the improvement of rice yield and quality.Lime application and straw return are effective measures to alleviate soil acidification and improve soil fertility,respectively.But,at present,little is know about the interactive effects of liming and straw return onyield and quality of high-quality rice.We used high-quality rice Qiliangyou 2012 for early rice and Meixiangzhan 2 for late rice as the test varieties to conduct a field experiment includeing two factors（liming and straw return）on a typical acidic red paddy from 2019 to 2020.Four treatments were arranged in this experiment:（1）Control,without liming and straw;（2）Liming,without straw,and lime was applicated 2.0 t·ha^-1 only once after the late rice harvest in 2018;（3）100%straw return in every season without lime;（4）100%straw return combine with liming only once in 2018.The main results are as fallowing:1.lime application and straw return significantly increased the yield and aboveground biomass in early and late rice season.Among them,lime application average annual increased yield by 9.7%and 8.3%in early and late rice season,respectively,and straw return average annual increased by 14.4%·and 10.5%.Lime application significantly increased the effective panicle in late rice season.Straw return significantly increased the spikelets panicle in early and late rice season.Lime application and straw return significantly increased the aboveground nitrogen uptake.Lime application average annual increased nitrogen uptake by 9.1%and 12.4%·in early and late rice season,and straw return average annual increased by 20.6%·and 22.8%.There were no significant interactive effects between liming and straw return on the yield and its composition,and aboveground biomass and nitrogen uptake.2.Lime application significantly increased the head rice rate in early and late rice season.Straw return significantly increased the head rice rate in early and late rice in 2019,but significantly decreased the head rice rate in late rice season in 2020.There were positive interactive effects between liming and straw return on the head rice rate in early rice season in 2019 and late rice season in 2020.Liming increased head rice rate by 1.6%and 2.2%under straw return in early rice season in 2019 and late rice season in 2020,while increased by 3.7%and 4.9%under straw removel.Liming significantly reduced the chalky rice rate in early and late rice season in 2020.Straw return significantly reduced the chalky rice rate in early rice season in 2019 and late rice season in 2020.Lime application significantly reduced the chalkiness rice rate in early rice season in 2019.Straw return significantly reduced the chalkiness rice rate in early rice season in 2019 and late rice season in 2020.There were positive interative effects between liming and straw return on the chalkiness in late rice season in 2020.Liming reduced chalkiness by 43.8%under straw return in late rice season in 2020;while reduced by 15.3%under the straw removel.Both liming and straw return tended to increase the protein content in early and late rice season.Among them,straw return reached a significant level in the early rice season in 2020.Liming tended to reduce the amylose content in early and late rice season,and reached a significant level in the late rice season in 2020.Straw return significantly reduced the amylose content in early and late rice season.Both liming and straw return significantly increased the peak viscosity and breakdown viscosity,and decreased the setback viscosity in early and late rice season.3.Both liming and straw return significantly increased the Mg and Fe content of polished rice in early and late rice season.There were positive interative effects between liming and straw return on the Fe content of polished rice in early and late rice season in2019.Lime application increased Fe content of polished rice by 3.5%and 10.1%under the straw return in early and late rice season in 2019,while increased by 16.4%and 2.5%under the straw removel.Lime application significantly reduced the Cd and Ni content of polished rice in early and late rice season.Straw return significantly increased the Cd content of polished rice in early rice in 2019.There were positive interative effects between liming and straw return on the Cd content of polished rice in late rice season in2020.Lime application reduced Cd content of polished rice by 38.1%under the straw return in late rice season in 2020,while reduced by 4.2%under the straw removel.4.Lime application significantly increased the soil p H by 0.73 and 0.49 units at maturity in the late rice season in 2019 and 2020.Straw return significantly increased the content of soil organic matter,alkali-hydrolyzable N and available P and K.Lime application significantly increased the content of soil alkali-hydrolyzable N,but reduced the content of soil available P in 2019.There were positive interative effects between liming and straw return on the content of soil alkali-hydrolyzable N in 2019.Lime application increased the content of soil alkali-hydrolyzable N by 2.4%under the straw return in 2019,while increased by 26.9%under the straw removel.Straw return significantly increased the content of soil available Mg in early and late rice.Lime application significantly decreased the content of soil available Fe and Ni in early and late rice season.In conclusion,straw return combine with liming can alleviate soil acidification,enhance soil fertility and rice yield,while improving rice quality and reducing Cd and Ni content in rice.Therefore,straw return combine with liming is beneficial to achieve high quality and sustainable production of rice on acidified red soil paddy in south China.