Study On Physiological Mechanisms Of Lodging Resistance And Evaluating Method In Rice

Lodging had impact on the yield and qulity of rice.Breeding for dwarfness enhanced the ability for lodging resistance and economical coefficient.But the biological yield wasn't changed much.The breakthrough must happen in the biological yield,if the yield was enhanced,when the yield achieved a certain level.One of important ways for increasing biology yield was increasing plant height,but it brought the danger of lodging. The factors except plant height become important research content.Stalk physical property is the major factor which effected the ability for lodging resistance,the stalk's mechanica lstrength is the most important index for breedings election.This ceperiment selected fifty-one varieties(line) which we use widely.The breaking resistance of the stem base, internode length,thickness,the base of the stem dry weight and culm dry weight,etc.were investigated.And then,the relevant traits of correlation analysis and path analysis,and cluster analysis of lodging index,the difference among varieties in lodging resistance were carried out,established initially lodging evaluation system of rice.The result indicated:The basal internode moment and the length of the first basal internodes had positive effects on the lodging index,but the dry weight of basal internodes,break moment and culm morphology index had negative effects on the lodging index.The results showed that break moment of basal culms was a good parameter for quantifying the culms intensity. The base of 10 cm dry weight,thickness and the number of vascular bundle have more positive effects on breaking moment;while the length of first and second internode,bending moments have greater negative effects on breaking momentAccording to determination coefficients.between the stem characters and lodging index,their decisive degree for lodging index were as follow:the decision coefficient from breaking moment,the moment-section,plant height,the dry weigh of basal internode per 10 cm,single stems dry weight,bending stress,the number of small vascular bundle,the number of big vascular bundle,the high barycenter,the length of the first base elongated internode,section modulus,marrow area,culm morphology index,the length of the second base elongated internode to lodging index were 26.16%,16.13%,13.65%,9.75%, 8.86%,7.57%,7.07%,6.38%,6.19%,5.89%,5.80%,3.8%,3.64%,0.12%,so a broken moment the decision of the largest extent,the length of the second base elongated internode of the minimum level of the decision;the common decision coefficient between plant height and culm morphology index for the lodging was the greatest degree of co-decision,reached 9.76 percent.This can be used as rice lodging a preliminary evaluated methods.According to the difference of lodging index,the varities studied could be classified into three types by systematic cluster:high resistance type,middle type and lodging type. Results showed that high resistance type have an advantage over other types. Lodging-resistance properties were studied on three type.The results indicated that for high resistance type,break moment of basal culms was greater;the basal internods accumulated more mass and more vascular bundles.The total number of the bundle was significantly and positively correlated with the number of secondary branches and thousand-grain weight;the great vascular bundles was significantly and positively correlated with the number of secondary branches and thousand-grain weight,was nagtively correalated with number of productive ear;the number of small bundle was significantly and positvely correlated with the number of the first and second branches and the number of grain in one ear,so more vascular not only increased grain and grain weight,but al played an important role in lodging-resistance of rice.In this study,the variety with the shorter base internodes,high accumulation of base dry matter and more base vascular bundle had stronger broken moment and was not easy in lodging,it can screen the variety with shorter base internodes,high accumulation of base dry matter and more base vascular bundle to improve the lodging of rice.So the contradiction between lodging-resistance and plant-height could be hamonized air a level of higher standard.