# Enhancing yield and oil content in oilseed rape hybrids: Insights from line × tester and SIIG approaches

## TL;DR

This study identifies high-yield oilseed rape hybrids using genetic analysis and a selection index to improve oil production and agronomic traits.

## Contribution

The study combines line × tester and SIIG methods to identify superior oilseed rape hybrids with high oil and seed yield.

## Key findings

- Hybrids T1 × L5, T1 × L6, and T3 × L1 showed the highest specific combining ability for seed yield.
- T3 × L1, T1 × L5, T1 × L3, and T2 × L3 were identified as high-oil-yielding hybrids with good agronomic traits.
- Phenological traits were mainly controlled by additive effects, while agronomic and qualitative traits were influenced by non-additive gene effects.

## Abstract

The production of high‐oil‐yielding hybrid varieties is a primary objective in oilseed rape (Brassica napus L.) breeding programs. Biometric genetic experiments such as line × tester provide valuable insights into the genetic structure of traits associated with high oil yield.

In this study, 21 winter hybrids of oilseed rape were evaluated, which were generated by crossing three restorers with seven CMS lines. The experiment was conducted using a line × tester experiment based on a completely randomized block design. Phenological, agronomic, yield, and oil yield components were assessed in this study. The ideal genotype selection index (SIIG) methodology was also employed to identify superior hybrids based on all studied traits simultaneously.

Significant differences were observed between the obtained hybrids and the check cultivars. Heritability analysis revealed that phenological traits were primarily controlled by additive effects, while agronomic and qualitative traits were mainly influenced by non‐additive gene effects. Both broad‐sense and narrow‐sense heritability exhibited a wide range, underscoring the importance of genetic variance. Notably, the hybrids T1 × L5, T1 × L6, and T3 × L1 showed significant specific combining ability values of 394.74, 541.73, and 1236.79, respectively, making them the top specific combinations for increasing seed yield. Based on the SIIG index, hybrids T3 × L1, T1 × L5, T1 × L3, and T2 × L3 emerged as high‐oil‐yielding hybrids with desirable agronomic traits.

The identified superior hybrids by line × tester and SIIG approaches hold promise for the development of high‐yielding oilseed rape cultivars with desirable agronomic traits in oilseed rape breeding programs.

Line 1 and Tester 2 exhibited the highest positive GCA values for seed yield and oil yield, respectively.Crosses T1 × L6 and T3 × L1 demonstrated the highest significant positive SCA values for seed yield and oil yield, respectively.T1 × L5 (G5), T1 × L6 (G6), and T3 × L1 (G15) were detected as top‐specific combinations for increasing seed yield.T3 × L1 (G15), T1 × L5 (G5), T1 × L3 (G3), and T2 × L3 (G10) emerged as high‐oil‐yielding hybrids with desirable agronomic traits based on the SIIG approach.

Line 1 and Tester 2 exhibited the highest positive GCA values for seed yield and oil yield, respectively.

Crosses T1 × L6 and T3 × L1 demonstrated the highest significant positive SCA values for seed yield and oil yield, respectively.

T1 × L5 (G5), T1 × L6 (G6), and T3 × L1 (G15) were detected as top‐specific combinations for increasing seed yield.

T3 × L1 (G15), T1 × L5 (G5), T1 × L3 (G3), and T2 × L3 (G10) emerged as high‐oil‐yielding hybrids with desirable agronomic traits based on the SIIG approach.