Influence of directional photosynthetic radiation on panicle health, malformation dynamics and morphological traits in mango (Mangifera indica L.) varieties

Abstract

Mango panicle malformation is a major constraint affecting productivity, yet its interaction with microclimatic factors such as directional radiation remains inadequately understood. The present study was conducted to evaluate the influence of incident photosynthetic radiation from different canopy directions on panicle health, malformation and associated morphological traits in five mango varieties (Dushehari, Langra, Amrapali, Fazli and Sunderja) under field conditions. The experiment was laid out in an asymmetrical factorial randomized block design with three replications, considering varieties and four directional exposures (north, south, east and west). The results revealed significant variation among varieties, directions and their interaction for all studied traits. Among the varieties, Langra exhibited superior performance with the highest number of healthy panicles and the lowest malformation percentage, whereas Sunderja and Fazli showed greater susceptibility to malformation. Directional influence was pronounced, with the south-facing canopy producing maximum healthy panicles and minimum malformation, while the north direction recorded the highest malformation incidence. Total panicle number was primarily governed by varietal potential, whereas panicle health and malformation were strongly influenced by radiation environment. Morphological traits further indicated that healthy panicle length was highest in Dushehari, while malformed panicles exhibited greater elongation in Amrapali and Sunderja, suggesting altered growth behaviour under stress conditions. Correlation and multivariate analyses demonstrated a strong positive association between healthy and total panicles, and a negative relationship between healthy panicles and malformation percentage, highlighting the detrimental effect of malformation on productivity. The findings emphasize that both genetic factors and directional radiation play a crucial role in regulating panicle development in mango. Selection of tolerant varieties such as Langra, combined with favourable canopy orientation, can serve as an effective strategy to minimize malformation and enhance productivity under varying environmental conditions.