Research On Effects Of Flooding Stress At Tillering Stage On Rice Morphology,physiology,yield And Quality

Flood disaster is one of the main natural disasters in the middle and lower reaches of the Yangtze River and its south.The effects of flooding stress on morphology,physiology,yield and quality of rice were studied in order to find the critical value of the depth and time of waterlogging at tillering stage of rice,determine the drainage standard of farmland,and promote the sustainable development of agriculture.In this experiment,Yangjing 4227 was selected as the test variety.The effects of flooding at tillering stage on morphology,physiology,yield,yield components and quality of rice were studied with the combination of 1/2(submerged waist),2/3(submerged neck)and 1/1(fully submerged)of plant height and 1,3,5,7 and 9 D of flooding duration.The main conclusions are as follows:In terms of morphology and physiology,with the increase of submergence depth,the plant height(measured after 2 days of restoring growth after submergence)of 1-day flooding treatment decreased,while the plant height of 3 days,5 days,7 days and 9 days flooding treatment increased gradually compared with the control.At full heading stage,the plant height,panicle length and internode length of 1-day flooding treatment had no significant difference or increase compared with the control,while those of 3 days,5 days,7 days and 9 days flooding treatment were higher than those of the control.The control showed a gradual downward trend.The SPAD value,net photosynthetic rate,intercellular CO2 concentration,injury flow rate and amino acid content in bleeding fluid of rice plants after anthesis decreased or significantly decreased with the deepening of flooding degree compared with the control.With the increase of flooding depth,the contents of nitrogen,phosphorus,iron,manganese and zinc in rice plants increased first and then decreased with the prolongation of flooding time,and at 3 or 5 days,the contents of nitrogen,phosphorus,iron,manganese and zinc in rice plants increased first and then decreased with the prolongation of flooding time.Peak value appeared,while copper content decreased first and then increased.Peak value appeared at 5d,while potassium and magnesium decreased gradually with the prolongation of flooding time.Root characteristics and root absorptive capacity of rice underground parts showed a gradual decline trend except for the phenomena of no significant difference or increase in the treatment of 1D flooding compared with the control,except for the treatment of 3d,5d,7d and 9D flooding.In terms of yield and rice quality,with the increase of flooding depth,the number of panicles,grains per panicle and seed setting rate in flooding 1 day treatment were higher than those in control,while the yield and yield components in flooding 3,5,7 and 9 days treatment showed a downward or significant downward trend;the rice roughness,milled rice rate,head milled rice rate,length-width ratio,chalky grain rate and amylose content of flooded 3,5,7 and 9 days were not significantly different from those of the control,while the chalkiness,reduction value and protein content of flooded 15 3 and 5 days and peak viscosity,hot slurry viscosity,final viscosity and gelatinization temperature of flooded 1,3 and 5 days were significantly improved compared with the control.For example,other rice quality indicators showed a downward or significant downward trend with the prolongation of flooding time.With the deepening of flooding degree,the processing quality of rice had little effect,but the appearance,cooking and nutritional quality of rice improved after a short time of flooding treatmentThe correlation analysis showed that the net photosynthetic rate of flag leaf of rice plant was positively correlated with magnesium content of rice plant(r=0.866**);root bleeding flow was positively correlated with total root uptake area(r=0.663**),amino acid content in root bleeding fluid was positively correlated with nitrogen content of rice plant(r=0.821**);total root length,total root surface area and root volume were positively correlated with yield.Guan(r=0.613*,0.669*and 0.691*),leaf net photosynthetic rate and SPAD value were positively correlated with yield(r=0.815**and 0.863**),plant yield and effective panicle number were positively correlated with plant nitrogen content(r=0.777**and 0.762**),and iron content was positively correlated with plant iron content(r=0.662*and 0.601*).Rice protein content was positively correlated with total root uptake area and rice yield(r=0.662*and 0.601*).There was a significant positive correlation between plant nitrogen content(r=0.641*and 0.732**).If the yield of submerged rice is reduced by less than 10%,without affecting the processing quality of rice and improving the appearance,nutrition and cooking quality of rice,the criteria for rainwater storage in rice fields at tillering stage are put forward:submerged waist(1/2),submerged neck(2/3)and full submerged(1/1).The duration of field rainwater storage can last for 1-3 days.