Advances in lentil production through heterosis: Evaluating generations and breeding systems

Heterosis is defined as increased performance of the F 1 hybrid relative to its parents. In the current study, a cohort of populations and parents were created to evaluate and understand heterosis across generations (i.e., F 1 to F 3 ) in lentil, a self-pollinated annual diploid (2n = 2× = 14) crop species. Lentil plants were evaluated for heterotic traits in terms of plant height, biomass fresh weight, seed number, yield per plant and 100 grain weight. A total of 47 selected lentil genotypes were cross hybridized to generate 72 F 1 hybrids. The F 1 hybrids from the top five crosses exhibited between 31%–62% heterosis for seed number with reference to the better parent. The five best performing heterotic crosses were selected with a negative control for evaluation at the subsequent F 2 generation and only the tails of the distribution taken forward to be assessed in the F 3 generation as a sub selection. Overall, heterosis decreases across the subsequent generations for all traits studied. However, some individual genotypes were identified at the F 2 and sub-selected F 3 generations with higher levels of heterosis than the best F 1 mean value (hybrid mimics). The phenotypic data for the selected F 2 and sub selected F 3 hybrids were analysed, and the study suggested that 100 grain weight was the biggest driver of yield followed by seed number. A genetic diversity analysis of all the F 1 parents failed to correlate genetic distance and divergence among parents with heterotic F 1 ’s. Therefore, genetic distance was not a key factor to determine heterosis in lentil. The study highlights the challenges associated with different breeding systems for heterosis (i.e., F 1 hybrid-based breeding systems and/or via hybrid mimics) but demonstrates the potential significant gains that could be achieved in lentil productivity.