Drought response of a tropical legume (Pachyrhizus erosus L.): Physio-biochemical adjustments at seedling stage

Abstract

Introducing crops higher in protein contents than indigenous tubers is one of the ways of combating malnutrition in Nigeria. Pachyrhizus erosus tuber contains high protein in addition to its agronomical advantage as a legume crop. Soil water deficit is one of the most critical stresses negatively impacting global food production through its adverse effects on plant growth. The objective of this study was to evaluate the effect of water deficit on P. erosus seedlings. Through the investigation of morphological and physio-biochemical parameters, this study explores the effects of three levels of soil water deficits (25, 50 and 75% of field capacity representing: Slight, moderate and severe water deficit respectively) on P. erosus at the seedling stage.Results indicated that severe and moderate water deficit reduced the Leaf Relative Water Content (LRWC), Leaf area and increase in the relative growth rate of P. erosus seedlings which suggests the adoption of an effective drought adaptive strategy by the plant. Water deficits had no notable effect on proline synthesis but increased Malondialdehyde contents. Severe and moderate water deficit impaired the photosynthetic apparatus of P. erosus particularly at the later phase of seedling developments, which was as a result of the reduction in LRWC and area of a leaf of P. erosus. Conclusion: Despite the negative effects of soil water deficit, P. erosus maintained tolerance through a resilient antioxidant mechanism, reduction of LRWC and growth parameters. This will make it survive the seasonal drought period experienced yearly.