GROWTH RESPONSES OF ABELMOSCHUS ESCULENTUS (L.) MOENCH UNDER STRESSES OF DROUGHT AND MELOIDOGYNE INCOGNITA INFECTION

Abstract

Growth and agricultural production of crops including, Abelmoschus esculentus (okra), a staple and nutritious vegetable cultivated and consumed in sub-Saharan Africa, is threatened and constrained by abiotic and biotic stresses caused by global climate change. While individual stressors cause devastating impacts to agricultural production, the possible combination of different multiple stresses (either jointly or sequentially), could pose a greater threat to global food production and food security. This study aimed at exploring morphological responses of okra plants cv. ‘Meya’ subjected to individual, sequential and concurrent stresses of drought and Meloidogyne incognita a causative agent of root-knot disease. Results showed both stresses significantly reduced growth and yield components of plants. Individual drought stressed plants significantly reduced growth compared to plants stressed with only nematode infection. Varied morphological differences were observed between plants stressed in sequence and those that received both stresses concomitantly. Plants subjected to dehydration stress prior to nematode infection coped better with the stress combination in comparison to plants that were challenged with nematode infection before dehydration stress and concurrent drought-nematode stress. This okra cultivar was either highly or moderately resistant to nematode infection by moderate formation and establishment of galls and egg masses. Survival mechanisms of this cultivar under both stresses could be primarily linked to its water-use efficiency as well as several cascades of changes in signal transduction pathways.