EFFECT OF SHORT-TERM WATERLOGGING APPLIED AT VARIOUS GROWTH PHASES ONGROWTH, DEVELOPMENT AND YIELD IN VIGNA-UNGUICULATA

The effects of short-term waterlogging during the vegetative, reproduc tive and total growth phases were investigated in four cultivars of co wpea (Vigna unguiculata L. Walp) in relation to their controls in a po t experiment conducted at the University of the West Indies, St. Augus tine, in 1989. All cultivars were able to recover completely and produ ce near to normal yields, when waterlogging was confined to the vegeta tive period. Recovery growth was affected in cultivars waterlogged dur ing the total growth phase and the plants were significantly smaller ( P < 0 . 05) in vegetative dry matter (60-80% of the size of their resp ective controls) even at maturity. Recovery growth was affected, to a greater extent, in cultivars possessing a small mainstem:branch ratio. Yield development in the waterlogged plants was affected by accelerat ed leaf senescence and consequent reduction in the reproductive period . As a result, yields in all the cultivars tested were significantly s maller (P < 0 . 05) than their respective controls and varied between 54 and 60% of the controls. Plants waterlogged during the reproductive phase were not significantly different (P < 0 . 05) in vegetative dry matter from the controls, but showed root degeneration and accelerate d leaf senescence in all but one cultivar (Local Red). Yield reduction , however, was significant (P < 0 . 05) only in IT-83S-898. Possible c riteria for selecting plants tolerant to waterlogging are discussed.