Interactive Effects of Genotype and Nitrogen on the Phenology and Yield Determination of Okra [Abelmoschus esculentus (L.)]

Limited studies have been conducted to assess key yield-determining processes and their inter-relationships in okra under both nitrogen (N) poor as well as optimum growing environments on a set of contrasting genotypes. Therefore, in this study, we analyze the yield formation in two diverse genotypes of okra (Sabz Pari SP' and Arka Anamika AA') across seven contrasting N environments (0-300kgha(-1)) and to determine effects of genetic (G), environmental (E) and their interaction (GxE) on a set of traits relevant to vegetative growth, onset of reproductive cycle, pod characteristics, and yield. The effects of G, E, and GxE were significant for majority of traits. Ranking of genotypes changed across the environments for most of the traits indicating a cross-over type GxE interactions. Majority of traits showed differential response to varied N availability. Mean values of plant height, canopy diameter, leaves plant(-1), leaf area plant(-1), stem girth, internodes plant(-1), length of internode, pod length, pod diameter, and pod yield enhanced with rising N (50-300kgha(-1)). However, pod fresh weight and number of pods plant(-1) declined with N availability above 150kgha(-1). The onset of first flowering delayed with decline in N availability and vice versa. Late maturing genotype AA indicated a better yield potential across N environments by producing 50.96% more yield over early maturing genotype SP. There existed significant inter-relationships among most of the traits. Four traits including leaf area plant(-1), pod diameter, pod fresh weight and number of pods plant(-1) explained most of the variance (97.4%) in pod yield. It was concluded that gain in these parameters may lead to an increase in pod yield. Our approach could be useful in developing an indirect selection criterion for yield improvement in okra and could provide a theoretical framework for breeding programmes in developing an ideal genotype.