Study On The Response Of Rice Yield And Rice Quality To Flooding Stress

China is a country prone to natural disasters,and flooding is one of the most serious agricultural disasters in China.The effects of flooding stress on morphological and physiological,carbon and nitrogen metabolites,nutritional characteristics,yield and rice quality of rice were studied to find the critical values of flooding depth and flooding time during the tillering stage of rice,to determine the drainage standard of farmland and to promote sustainable agricultural development.In this experiment,South Japonica 9108 was selected as the test variety,and treatment combinations of inundation depth of 1/2(inundation waist),2/3(inundation neck)and 1/1(full inundation)of plant height and inundation time of 1d,3d,5d and 7d were set respectively,while the control(CK)was managed with conventional alternate wet and dry water conservation.Main study findings:In terms of morphophysiology,the longest root length and root volume of each inundation treatment tended to decrease compared to the control as the inundation depth increased;the number of adventitious roots in the 1d and 3d inundation treatments tended to increase and then decrease compared to the control;the root diameter in the 1d inundation treatment tended to increase compared to the control.The SPAD values and stem dynamics of the rice plants after flowering showed a decreasing or significant decrease with increasing inundation compared to the control;with increasing inundation depth,the above-ground nitrogen content of the rice plants in the treatments of 3d,5d and 7d inundation showed a decreasing and then increasing trend.The above-ground phosphorus content of rice under different inundation depths showed a decreasing trend with increasing inundation time.In terms of carbon and nitrogen metabolites,the protein content of rice showed a trend of decreasing and then increasing with increasing flooding depth,with the lowest value occurring at 3d of flooding.The soluble content of rice under the 1d flooding treatment was significantly lower than that of the control,while the soluble content of rice under the 5d and 7d flooding treatments was significantly higher than that of the control.With increasing flooding time,the rice sucrose content of rice plants under different flooding depths showed a decreasing trend followed by an increasing trend.In terms of yield and rice quality,the number of spikes and yield of the 1/1-1d treatment were significantly higher than the control level,while the number of grains per spike,set percentage and thousand grain weight were not significantly different compared to the control,while the remaining treatments showed a decreasing or significantly decreasing trend in yield and yield components.The percentage of whole rice concentrate increased compared to the control,except for the treatment in the 1/1(fully flooded)condition.The chalkiness and chalkiness of rice tended to increase,then decrease and then increase with increasing flooding time.The peak viscosity,hot slurry viscosity,disintegration value and final viscosity of rice in the 1d,3d,5d and 7d treatments tended to decrease or significantly decrease with increasing flooding depth compared to the control.With increasing flooding depth,the abatement values of the 1d,3d and 5d treatments tended to increase or significantly increase compared to the control;with increasing flooding time,the straight-chain starch content of rice tended to increase and then decrease,and the decrease became greater with increasing flooding depth;with increasing flooding degree,the processing quality of rice was not significantly affected,while the appearance,cooking and nutritional quality of rice after short flooding treatments had The appearance,cooking and nutritional quality of the rice improved to a certain extent after a short period of flooding.Correlation analysis showed that the percentage of whole refined rice was significantly or highly significantly positively correlated with rice protein,soluble sugars and total starch(r=0.636*to 0.745**)after the tiller stage of South Japonica 9108 was stressed by flooding.Chalkiness showed a significant negative correlation with rice protein,soluble sugars and total starch(r=-0.498*to-0.697*).Chalkiness showed a significant negative correlation with rice protein and total starch(r=-0.569*to-0.592*).Straight-chain starch showed a highly significant negative correlation with rice protein and total starch(r=-0.786**to-0.891**)and a highly significant positive correlation with soluble sugars(r=0.725**).If the yield reduction of rice under flooding treatment is controlled within 10%,there is no significant effect on the processing quality of rice and the appearance,nutrition and cooking quality of rice are improved to some extent.In this study,the upper limit of rainwater storage in paddy fields at the tillering stage was proposed:flooded waist(1/2),flooded neck(2/3)and fully flooded(1/1),and the length of rain storage in the field could last from 1 to 3d.