Compensation Of Rewatering After Water Stress At Young Panicle Formation Stage And Booting Stage In Rice

The test was carried out at Rice Research Institute of Sichuan Agricultural University in Sichuan Wenjiang between the year of 2007 and 2008.It was about compensation effect of rice(Oryza sativa L) growth,development and physiological and biochemical traits after rewater by different time and water stress treatments at booting stage and heading stage.We have established a water stress threshold in rice drought initially,after a systematic research and analysis.It has some arguments about the effects of morphology, physiology,biochemistry,production and physiological and biochemical characteristics and other indicators after rewater.The compensation of yield and its composer in certain times mad different water stress on rice have been explained.The results are as follows:1.Yield and its composition factors index were increased and higher than the control lever after rewatered in slight-short time treatment.The results get the degree of the compensation effect.In other treatments,the yield and other fators increased slowly and did not reach the control level.2.Through various degrees of water stress treatments before rewater on five hybrid rice varieties in Jointing booting stage,-25±5 kp degrees of water stress treatment reached to the largest compensation effect,and Gangyou 527 showed the best performance.The sequence as follows:Gangyou 527＞D Liangyou 363＞Xieyou 527＞Gangyou 188＞Shanyou 63.3.CK had the highest maximum tiller number and dry matter accumulation among all treatments;-25±5 kp treated for 7 d performed with the best of stem and sheath material and the conversion rate and output rate and maximum tillering.-50±5 kp treated for 7 d was the same level as control.But the output rate and the conversion rate and yield with its components on stem and sheath material of 14ds of treatment had not reached the control level,and there were significantly differences in different treatments.4.Leaf area had smaller increase format after rewater by water stress,and increased slowly; leaf area index increased faster than before,especially short-lasting mild stress treatment had the biggest increase rate in all treatments. 5.Photosynthetic rate,water potential,chlorophyll a/b,SPAD content were all reduced after water stress,all factors in14d water control treatments were lower than 7d treatments; -50±5 kp stress had larger decrease than the same time deal with treatment of -25±5 kp stress treatments.These factors of Mild short-duration treatments reached the maximum, much higher than the control level,reached super-compensation effect;all factors of -50±5 kp of 7d treatments improved after rewater,some factors have reached the control level, and in long lasting deal with stress in a slight improve after rewater,but did not reached the control level.6.Soluble sugar,SOD,POD,CAT,MDA activity had improved under water stress,but reduced after rewater in different degrees.Experimental results showed that SOD,CAT, MDA activity in 8ds after rewater dropped to the limit,while the POD in the first 12d after rewater to reduce to the minimum value.All factors as upwards were lower than the control treatment in -25±5 kp of 7ds treatments;in the first 4d,enzyme activities were reduced to the control level on -50±5 kp of 7ds treatments,reaching compensation;long lasting deal with stress,the enzyme activities of whether mild or severe water stress had also reached the control level,especially the mild stress treatment,but all of them increased rapidly in a short time and can not achieve the later effect.7.Root length turn to longer,but root dry weight can not reach the control level after rewater at booting stage,this suggested that the more severe stress the stronger effect on the root dry weight,and the root dry weight increased after rewater.Root dry weight growth rate in strong treatments were bigger than in mild stress.