Phosphorus Accumulation,Utilization And Translocation Characteristics In Rice Under Saline-alkaline Stress

In this study,saline-alkaline stress tolerance was screened in seed germination stage for 40 rice varieties,and then 10 rice varieties of them were screened in growth period.Dry weight and phosphorus(P)accumulations and translocations of 4 typical varieties(saline-alkaline-tolerant Dongdao-4 and C hangbai-9 vs saline-alkaline-sensitive Tongyu-315 and C hangbai-25)were also preliminarily investigated.Finally,two rice varieties(Dongdao-4 vs C hangbai-9)were chosen to analyze rice growth,dry weight and P accumulation,utilization and translocation with light(p H 8.27,ESP 9.7%)and severe(p H 9.09,ESP 21.56%)saline-alkaline soils and P applications(P0,P50,P100,P150,P200).Main results were showed as follows:The saline-alkaline tolerance was dynamic with the rice development and significantly different among varieties.Dongdao-4 and C hangbai-9 maintained tolerant ability in the whole growth stage,while Tongyu-315 was tolerant in seed germination but sensitive in the whole growth period,and Changbai-25 was sensitive consistently.It was found that significant positive correlations existed in grain P content and plant dry weight,while grain weight and P content both showed significant negative correlations with plant N a+/K+.Saline-alkaline stress greatly reduced rice dry weight and P accumulation,1000-grain weight and seed-setting rate,and increased Na+/K+ ratio.The lighter damages were found in tolerant rice varieties.The difference of dry weight and P translocation was obvious.The contribution of dry weight translocation was less than 20%.While the P translocation contributed more than 60%.Rice varieties showed significantly different dry weight and P translocation in saline-alkaline soils.Light saline-alkaline stress greatly reduced plant dry weight and P accumulations but improved their translocation,translocation efficiency and contribution to grain parts.The dry weight translocations of Dongdao-4 and C hangbai-9 changed less,but the P dry weight translocation of these two varieties changed significantly,and it was contrary to Tongyu-315 and C hangbai-25.Severe saline-alkaline stress partly reduced seed-setting rate and dry weight and P translocation,while increased stem dry matter and P acquisition efficiency,which were less effected in Dongdao-4.Moreover,Dongdao-4 owned greatly higher P acquisition efficiency than that of Tongyu-315 in rice maturity.In addition,the responses and the optimal P levels were also different among varieties and saline-alkaline conditions.Higher available P in light saline-alkaline soil made it possible for rice varieties to assimilate relative higher biomasses,yields and P even with non P application.For the greatest grain yield,Dongdao-4 had the optimal P application in 150 kg ha-1 and 200 kg ha-1 in light and severe saline-alkaline soils,respectively.And that Tongyu-315 had the optimal P application in 100 kg ha-1 in two soil types.Thus,the saline-alkaline-tolerant rice variety was more sensitive to P application,especially in severe stress condition with greatly reduced Na+/K+ ratio and increased biomass and P assimilation and translocation of plant.While the saline-alkaline-sensitive rice variety was more insensitive to P application with consistently higher Na+/K+ ratio and then suffered more serious damages from severe saline-alkaline stresses.Thus,the varieties and soil conditions should be all considered in identifying the optimal P application in agricultural production.