Environmental physiology of the bananas (Musa spp.)

The bananas are thought to be particularly sensitive to changes in the environment. This review considers some historical and recent investigations into the response of the leaf, root and reproductive system to the environment. Monteith's analysis of the response of plants to intercepted radiation is appropriate for analyzing the productivity of bananas and plantains. The banana is sensitive to soil water deficits, and expanding tissues such as emerging leaves and growing fruit are among the first to be affected. As soil begins to dry, stomata close and leaves remain highly hydrated, probably through root pressure. Productivity is affected because of the early closure of stomata. We find the common belief that bananas use large amounts of water does not have a strong physiological basis. Improvements in water-use efficiency in irrigated plantations could come from a closer match between plant water use and the amount of water applied. We examine recent data on water-use efficiency of different banana cultivars and propose that agronomists, physiologists and breeders could quantify the amount of water available in each rain-fed environment and work towards directing more of that water through the plant. The banana is day neutral for floral induction, but photoperiods of less than 12 h are associated with a slowing in the rate of bunch initiation that is independent of temperature expressed as growing degree days. This may contribute to seasonal variations in banana flowering, even in more tropical environments with moderate temperatures.