关键词: 白菜型冬油菜, 农艺性状, 演变规律, 通径分析, 主成分分析

Abstract:

【Objective】 Based on the experimental results from 2006 to 2022 of 81 winter turnip rape varieties across eight representative ecological zones (extremely arid, arid, and semi-arid regions) including Jiuquan, Zhangye, Wuwei, Lanzhou, Qingyang, Pingliang, Tianshui, and Longxi. The objective was to investigate the evolution of agronomic traits, to offer insights for breeding research and the cultivation of winter rapeseed in northern China. 【Method】 The tested varieties were classified into strong cold tolerant and moderately cold tolerant. The major agronomic traits were subjected to genetic gain analysis, correlation analysis, path analysis, and principal component analysis. The results illustrate, significant enhancements in the agronomic characteristics of northern winter rapeseed over the 17-year period.【Result】 For the strong cold tolerant varieties, plant height, branching position, number of branches, number of siliques per plant, and yield per plant showed a gradual increase, with an average annual increase of 0.87%, 1.07%, 0.0837%, 6.09%, and 0.0281%, respectively. The number of siliques and 1000-grain weight showed a downward trend, with average annual decrease of 0.0289% and 0.012%, respectively. For moderately cold tolerant variety, plant height, branching position, number of branches, number of siliques per plant, and yield per plant also increased, with average annual increase of 2.18%, 2.19%, 1.27%, 0.117%, and 0.0776%, respectively. The number of branches and 1000-grain weight decreased, with average annual decrease of 0.109% and 0.00702%, respectively. Correlation analysis showed a highly significant positive correlation between yield per plant and the number of siliques per plant. Path analysis of agronomic traits and yield per plant revealed that for the strong cold tolerant varieties, the number of siliques per plant (0.961) contributed most to seed yield per plant, followed by the seeds per silique (0.365). The largest contribution of cold tolerant varieties to the yield per plant was the branch position (1.173), followed by the number of siliques per plant (0.544). Path analysis of yield per plant and climatic factors showed that strong cold tolerant varieties were greatly affected by accumulated temperature of 10 °C, while cold-resistant varieties were greatly affected by negative accumulated temperature of 0 °C. Principal component analysis (PCA) screened out three principal components with a cumulative contribution rate of 78.617% of the overall variance, among which the number of siliques per plant, branch position, and 1000-grain weight were the main factors causing the differences among these varieties.【Conclusion】 Substantial advancements have been achieved in the genetic enhancement breeding of agronomic characteristics of winter rapeseed in northern China. The yield per plant has been steadily increasing. The plant type has also been greatly improved. The number of siliques per plant was the main factor to increase the yield of Brassica rapa L.. The adaptability of strong cold tolerant varieties to the external environment surpasses that of moderately cold tolerant varieties.

Key words: Brassica rapa L., agronomic traits, law of evolution, path analysis, principal component analysis