Effects of elevation variations on main agronomic traits and yield of Brassica juncea var. crassicaulis Chen ＆ Yang

【Objective】By analyzing the effects of elevation variations on the main agronomic traits and yield of Brassica juncea var. crassicaulis Chen ＆ Yang（tuber mustard）, the present paper aimed to provide a theoretical basis for selecting the optimal planting area of tuber mustard variety in the Western Sichuan Plateau. 【Method】The study selected tuber mustard variety Jintian No. 3 as research material, employing variation analysis to study the differences of its main agronomic traits and yield traits at different elevations（1510, 2081, 2579 and 2936 m）. The methods of correlation analysis, stepwise regression analysis and path analysis were employed to study the relationships among elevations, agronomic traits and yield traits of tuber mustard. 【Result】At different elevations, the coefficient of variation of various traits of tuber mustard ranged from 4.88% to 33.51%. Among agronomic traits,edible stem diameter had the highest coefficient of variation, while among yield traits,gross weight per plant had the highest coefficient of variation. Plant height and edible stem length generally decreased with elevation increasing, and there were extremely significant negative correlation with elevation（P＜0.01, the same below）. Edible stem diameter, peel thickness, gross weight per plant, net weight per plant and yield per plot generally increased initially and then decreased with elevation increasing, and there were extremely significant positive correlation with elevation. Yield per plot was significantly（P＜0.05） or extremely significantly positively correlated with edible stem diameter, peel thickness, gross weight per plant and net weight per plant. The results of stepwise regression analysis indicated that yield of tuber mustard was primarily influenced by elevation, edible stem diameter, stem internode length and gross weight per plant, with a determination coefficient of 0.993. Path analysis showed that the direct path coefficients of 4 independent variables on yield per plot were ranked as follows: elevation（0.484）＞gross weight per plant（0.421）＞edible stem diameter（0.338）＞stem internode length（0.180）, and the indirect path coefficients were ranked as follows: edible stem diameter（0.495）＞gross weight per plant（0.479）＞elevation（0.450）＞stem internode length（0.127）. 【Conclusion】In order to achieve a higher yield of tuber mustard variety Jintian No. 3 in the Western Sichuan Plateau, it is necessary to focus on the selection of elevation, edible stem diameter and gross weight per plant, while also taking stem internode length into account. The yield of tuber mustard variety Jintian No. 3 reaches the highest at the elevation of 2579 m, where the planting scale can be moderately expanded.