Responses of Dry Matter Production and Distribution in Rice (Oryza sativa L.) to Ozone and High Nitrogen Supply

Abstract

An ozone free-air control enrichment(O3-FACE) experiment was conducted in 2011 to study the effects of O3 and high nitrogen(N) supply on dry matter production and distribution of rice.Two cultivars,Shanyou 63(SY63,three-line hybrid indica cultivar) and Yangdao 6(YD6,inbred indica cultivar),were investigated.The results showed:(1) Elevated O3 concentration significantly reduced the biomass of stems and foliages in the mid-filling stage by 30.20%,21.95% for SY63 and 21.71%,11.12% for YD6,respectively,due to the significant decrease of the net photosynthetic rate.O3 exposure also significantly reduced the yield,the biomass of roots and panicles in the harvesting stage by 45.75%,48.62%,37.15% for SY63,and 28.91%,35.22%,28.01% for YD6,respectively.Increasing N supply could mitigate O3-induced reduction of the net photosynthetic rate,the dry matter and yield,where the yield and biomass of stems,foliages,roots and panicles were changed by elevated O3only by-26.88%,-13.52%,-5.84%,-26.33%,-16.19% for SY63,and-12.68%,-16.26%,+5.19%,-14.55%,-20.22% for YD6,respectively;(2) In SY63 and YD6 exposed to O3,the root-shoot ratio and root dry matter distribution in whole plant decreased significantly,and the ratio of foliage dry matter distribution increased significantly,but there was no significant effect on the ratio of stem or panicle dry matter distribution.High N supply could increase the ratio of root or foliage dry matter and the root-shoot ratio at O3-FACE treatments;(3) O3 exposure could reduce N accumulation of SY63 and YD6,which would show upward trends after high N treatments.These results implied that increasing N supply could mitigate O3-induced changes in dry matter production and distribution of SY63 and YD6.