Effects Of Warming On The Growth And Cadmium Uptake Of Rice Under Cadmium Pollution

With the increasing global warming and soil heavy metal pollution,the combined effects of soil cadmium pollution and temperature on rice yield,physiology and quality should pay more attention.This study uses climatic cabinate and 8 common rice varieties of ricec in Jiangsu(Wuyunjing 21,Nanjing 46,Liandao 99,Nanjing 9108,Wuyunjing 30,Xinliangyou 6,Nei 5you 8015,Y Liangyou 5867)to analyze the effects of temperature increase on germination and seedling growth of rice under cadmium stress by using hydroponic experiments.At the same time,two varieties(Wuyunjing 30 and Xinliangyou 6)were selected for pot experiments to explore the changes in temperature on rice growth,physiology and cadmium absorption under different cadmium contaminated soil.The main findings obtained in this study are as follows:(1)The effect of increasing temperature on germination rate under low-concentration cadmium treatment was different among varieties;increasing temperature under high-concentration cadmium treatment significantly increased the germination rate of Xinliangyou6(P<0.05)during rice germination and seedling growth.Increasing the temperature under cadmium treatment increased the seed vigor index,bud length and root length of rice.The influence of seedling on seedlings was different between varieties,which could reduce the fresh weight of rice root and aggravated the toxic effect of cadmium on root.(2)The moderate temperature increase the photosynthetic rate of Wuyunjing 30 under cadmium stress increased.Under cadmium treatment,the high temperature decreasedthe Fv/Fm value of Wuyunjing30 significantly(P<0.05).The temperature increase under cadmium treatment increased the rice ABS/RC,TRo/RC,ETo/RC and DIo/RC.Moderate increase in temperature can increase the antioxidant enzyme activity of Wuyunjing 30 under low cadmium treatment.The excessively high temperature reduces the enzyme activity.Xinliangyou6 significantly inhibited SOD and CAT activities under high temperature under cadmium treatment(P<0.05).Antioxidant enzyme activities did not completely follow the changes of MDA,and the sensitivities of different enzymes to cadmium and temperature weredifferent.(3)Increasing the temperature under cadmium treatment reduced the dry matter mass in each part,and increasing temperature under high cadmium treatment significantly inhibited root dry weight and grain weight(P<0.05).The increase in soil temperature under cadmium treatment significantly reduced the number of full grains and seed setting rate of the two varieties of rice(P<0.05).The temperature did not change the order of cadmium accumulation in various parts of rice,and it was still root>stem and leaf>grain.Increasing temperature under cadmium treatment promoted cadmium content in various parts of rice,the degree of increase in cadmium content in different parts of different rice varieties under temperature changes is different.The increase of temperature will promote the accumulation of cadmium content in rice,and the increase of cadmium content in grain will affect the cadmium safety of rice.Changes in temperature have complicated the response of rice to adversity under cadmium pollution.As global temperature rises,the accumulation of cadmium in rice grains is gradually strengthened,which affects cadmium safety in rice.It is of practical significance to select climate-stable rice for planting on cadmium-contaminated soil.