| With global temperature increasing,warming has become one of the major climate factors that threats food crops.At present,environmental pollution caused by heavy metals is serious due to the improvement of industrialization.As a kind of poisonous metalloid element,arsenic widely exists in the environment and causes harm to human health by entering the body through the food chain.It is vital to study the effects of warming in different stages on the growth and nitrogen,phosphorus,and arsenic uptake of rice and wheat which can provide important information to reduce the damage of warming on the growth of food crops and improve the yield and quality of food crops.In this thesis,we take use of common rice and wheat varieties in Jiangsu province as the experimental material(Zhendao No.16 and Tairuifeng No.5 for rice,and Sumai No.13 and Ningmai No.188 for wheat).Then,pot experiments were carried out in the greenhouse.We perform daily and nighttime warming treatments for rice and wheat at the tillering,booting,heading,flowingand filling stages,in comparison with natural temperatures in whole growth period.The purpose of this study is to compare the effects of warming at different growth stages on photosynthetic indices and yields of rice and wheat,and to clarify the differences in nitrogen,phosphorus and arsenic uptake by rice and wheat.The main results obtained in this thesis are as follows:(1)For treatment without arsenic,SPAD value of leaves of rice and wheat showed big difference for warming in tillering stage.Compared with the control,warming at the tillering,booting,and flowering stage had great effect on photosynthesis of rice and wheat(p<0.05),while the intercellular CO2 concentration of wheat had no significant difference.However,under the arsenic treatment,there is no big difference in SPAD value of leaves of Tairuifeng No.5,and SPAD value of leaves of Zhendao No.16,Ningmai No.188 and Sumai No.13 had differences in warming during the tilllering stage.The effects of arsenic treatment on photosynthesis of rice and wheat depended on the period of warming.(2)For treatment without arsenic,warming during the different growth stages had great effect on the yield components of rice,and warming during booting and heading stage had the greatest impact on the yield of rice.For arsenic treatment,the setting rate of wheat had great difference during booting stage and heading stage.In addition to the difference in grain number of panicles of Zhendao No.16,there was no big difference among the other three test subjects while warming during the growth stage.Under different arsenic concentrations,compared with the control,warming at booting stage and heading stage had a significant effect on the plant height and biomass of rice.Warming at the tillering stage and the grain filling stage had a greater influence on the plant height and biomass of wheat.(3)In general,without arsenic treatment,the critical period of uptake of nitrogen,phosphorus and arsenic in rice and wheat is warming during the tillering,booting,and heading stage.The effect of warming on the accumulation of arsenic in wheat was not significant.With arsenic treatment,the effect of warming on uptake of various components of rice and wheat in the experiment depended on the period of warming. |
