Abstract:

The paper aims to analyze the main factors affecting the yield of Brassica napus with different maturity stages under climatic conditions in Chengdu, and provide a theoretical basis for resistance breeding of B. napus. Correlation analysis, path analysis and principal component analysis were used to analyze the relationship between the agronomic traits, the stem breaking resistance, the incidence of Sclerotinia sclerotiorum and the yield of B. napus. The yield of early-maturing rape varieties was significantly and positively correlated with the number of effective siliquae per plant, the number of seeds per siliquae, and the breaking resistance of the middle and upper part of the stem. The yield of mid-maturing rape varieties was significantly and positively correlated with the plant height, the first branch height, the number of effective siliquae per plant, the breaking resistance of the lower part of the stem, and the breaking resistance of the lower and middle part of the stem. The greatest direct path coefficient of yield was the number of effective siliquae per plant in both early-maturing rape varieties and mid-maturing rape varieties. The greatest indirect comprehensive effect on yield were the number of seeds per siliquae in early-maturing rape varieties and the breaking resistance of the lower part of the stem in mid-maturing rape varieties, respectively. The principal component analysis showed that the 15 agronomic traits were divided into four major categories in early-maturing rape varieties and three major categories in mid-maturing rape varieties. For early-maturing rape varieties, they were lodging resistance traits, plant type traits, yield components traits and disease resistance traits. For mid-maturing rape varieties, they were yield components traits, plant type traits and lodging resistance traits. Under the natural climatic conditions of Sichuan Province, in the breeding of early-maturing and mid-maturing rape varieties, the selection of plant type, lodging resistance traits and disease resistance should be strengthened while ensuring the yield components traits.

Key words: Brassica napus, stem breaking resistance, agronomic traits, yield, correlation analysis, path analysis