Diallel analysis of heterosis and combining ability for chlorophyll content across growth stages in okra [Abelmoschus esculentus (L.) Moench]
Year: 2026
Type: article
Abstract: Chlorophyll content governs photosynthetic efficiency and is increasingly recognised as a nutritionally relevant trait in okra yet its genetic architecture has received little attention relative to yield and fruit-quality traits. To address these 9 genetically diverse okra parents were crossed in a full 9 × 9 diallel excluding self-crosses, producing 36 direct F1 hybrids and their 36 reciprocals. Along with the parents and 3 commercial checks these were evaluated in a randomized block design with 2 replications during the spring summer season. Leaf chlorophyll content was recorded with a SPAD 502 Plus at 30, 60, 90 and 100 days after sowing and the resulting data were used to estimate heterosis and combining ability. Analysis of variance revealed significant treatment differences at 30 and 100 days after sowing and highly significant F1 versus reciprocal mean squares at every stage pointing to a significant reciprocal effect, indicating a possible maternal or other parent of origin contribution to chlorophyll expression. Partitioning of hybrid variance by Griffing's diallel model showed that general combining ability mean squares consistently exceeded specific combining ability mean squares establishing the predominance of additive gene action which was most pronounced at the seedling stage and progressively decreases as the crop matured. This confirmed that additive gene action dominates the inheritance of this trait and it dominates most heavily at the seedling stage gradually due to non-additive gene effects as the crop matures. Two parents OL-3 and OL-8 stood out as the best general combiners through the vegetative to flowering period while Okra line-2 emerged as the outstanding combiner for chlorophyll retention at full maturity. Among the 72 hybrids tested OL-3 × OL-5 recorded the highest chlorophyll content at maturity backed by the strongest positive specific combining ability effect and standard heterosis of 58.5 to 87.4 percent over the commercial checks. The reciprocal cross OL-6 × OL-1 also produced a significant positive specific combining ability effect further highlighting the importance of maternal inheritance. These findings indicate that recurrent selection exploiting additive variance combined with hybrid development using OL-3, OL-8 and OL-2 as base parents and OL-3 × OL-5 as a promising hybrid combination offers a practical route to improving chlorophyll content and by extension the photosynthetic and nutritional quality of okra.
Institution: University of Horticultural Sciences Bagalkote
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W7204163755