Simultaneous Selection of Oil Yield and Other Agronomic Characteristics in Winter Rapeseed Hybrids

Rapeseed is one of the most important oilseed plants in the world. Therefore, the selection of high-yielding genotypes is especially important in this plant. Production of high yielding hybrid cultivars is the main objectives of breeding programs in rapeseed. Also, study on relationships between yield and other agronomic traits will improve the efficiency of a breeding program with appropriate selection criteria. Therefore, the objectives of this research were to the selection of new rapeseed hybrids and to find interrelationships among traits.

In this research, 21 rapeseed hybrids (yielded crossing between 3 restorers with 7 cytoplasmic male sterile lines) along with four cultivars Okapi, Ahmadi, Nima and, Nafis were evaluated in a randomized complete block design with three replications in Seed and Plant Improvement Institute (SPII), Karaj during the 2018–2020 growing seasons. The phonological, morphological characteristics and yield and its components including days to flowering starting, days to end of flowering, flowering period, days to physiological maturity, plant height, number of lateral branches, number of pods per plant, number of seeds per pod, and head, thousand seed weight, oil content, seed yield, and oil yield were measured. In this study, the selection index of ideal genotype (SIIG) and factor analysis were used to select rapeseed genotypes and study the relationships between the traits.

Based on the SIIG index, the genotypes G15, G3, G10, G5, G22, G8, G4, and G25 with the highest SIIG values (0.706, 0.680, 0.667, 0.665, 0.647, 0.641, 0.610, and 0.607 respectively) were the superior genotypes. On the other hand, G23, G18, G1, G24, G21, G7, and G13 genotypes with the least amount of SIIG value (0.219, 0.315, 0.334, 0.383, 0.397, 0.398, and 0.402 respectively) were the weakest genotypes for most studied traits. The genotypes G15, G5, G22, G3, and G10 with high SIIG values as well as higher oil yield that total averages were recognized as superior genotypes from the point of yield and other agronomic traits. Also, the results of factor analysis indicated a positive relationship between thousand seed weight with seed yield and oil yield.

Generally, the results indicated that the genotypes of G15, G5, G22, G3, and G10 were recognized as superior genotypes from the point of oil yield and other agronomic traits. Also, the trait of thousand seed weight could be used as a suitable criterion in selecting for increased yield in rapeseed breeding programs.