Abstract:

【Objective】 In rice breeding, improvement of lodging resistance has been a main aspect for high-yield and excellent-qualities. This study investigated the lodging resistance of erect panicle Japonica rice in northern China. It would be beneficial to improve ment of lodging resistance of Northern japonica rice and realization of high-yield and excellent-quality in rice. 【Method】 Thirty days after heading, the lodging resistance of every elongating internodes of erect panicle type rice (EPT) and curved panicle type rice (CPT) were studied by using 12 japonica rice cultivars as materials and T-test as statistical analysis method. Furthermore, to demonstrate the reason why erect panicle type japonica rice has better lodging resistance than curved panicle type japonica rice, the correlations between the breaking resistance of the culm and its characteristics of physics and mechanics were studied. 【Result】 The results revealed that there was no significant difference in bending moment of the 1st, 2nd, 3rd and 4th internodes between erect panicle type rice and curved panicle type rice (CPT). But EPT had greater breaking resistance of the 1st, 2nd and 3rd internode than CPT. So that the lodging index of the 1st, 2nd and 3rd internodes of EPT was lower than that of CPT. The correlations between the breaking resistance of culm and its morphological traits, anatomical features, chemical components were further studied. There were many reasons for the breaking resistance of 1st, 2nd and 3rd internodes of EPT increased. Firstly, EPT had thicker culm wall and larger culm wall area than EPT. Secondly, the mumber of vascular bundles, the area of vascular bundles, the area of phloem and the area of xylem of EPT were lager than those of CPT. Thirdly, EPT had higher cellulose content in comparison with CPT. 【Conclusion】 In selection of lodging resistant cultivars, one should consider those characterized with thicker culm wall , larger culm wall area, better vascular bundle characters with high cellulose content in their stems. In northern of China, breeding erect-panicle cultivars would be an effective way to improve lodging resistance of japonica rice

Key words: japonica rice')">japonica rice, lodging resistance, erect panicle, curved panicle, culm tissue characteristics, culm configuration, chemical components of culms