Lodging Resistance in japonica Rice Varieties with Different Panicle Types

Abstract

The difference of lodging resistance for nine japonica rice varieties from northern China with different panicle types was studied. The results showed that lodged culms frequently bend at the second or third internodes,20 to 40 cm above the ground. The lodging index was significantly and positively correlated with the length of basal internodes and the culm length. Significantly positive correlations were also found between the fresh weight of culm from different internodes to the top,long or short external diameters,area of cross section and breaking resistance,bending moment. The panicle length significantly affected the bending moment of various internodes. Significantly positive correlations were also noted between the fresh weight of panicle,and breaking resistance,bending moment. The neck-panicle angle had no significant effect on the lodging index. For a certain variety,curved panicle doesn't mean poor lodging resistance. Lodging resistance of varieties varied with the region and variety,therefore,the index should not be evaluated only based on panicle type. In general,rice varieties with erect and semi-erect panicle from northern China had smaller lodging index and stronger lodging resistance than those with curved panicle. The reasons were as follows:firstly,the varieties with erect and semi-erect panicle were dwarf with short basal internodes,which increased their lodging resistance; secondly,for the varieties with erect panicle,lodging resistance of basal culm was strong; finally,with short and light panicles,the varieties with erect and semi-erect panicles had slight bending degree of panicle neck,which reduced the force to stalk. In addition,the relationship between ecological environment,characteristics of varieties,panicle type and lodging resistance were also discussed.