ISHS Acta Horticulturae 490: II International Symposium on Banana: I International Symposium on Banana in the Subtropics
ECOPHYSIOLOGY OF BANANAS: THE GENERATION AND FUNCTIONING OF THE LEAF CANOPY |
| Author: | D.W. Turner |
| Keywords: | Musa, leaves, leaf gas exchange, leaf area index, productivity, light, water, roots |
| DOI: | 10.17660/ActaHortic.1998.490.21 |
| Abstract:
This review focuses on the generation, and some aspects of the functioning, of the banana leaf system. The leaf system is the source of primary productivity in the banana and its size and functioning varies considerably in the subtropics. The rate of appearance of new leaves is a measure of development in bananas and plantains and is governed by temperature and plant ontogeny. Environmental and edaphic factors and plant ontogeny affect leaf size and a quantitative description of their responses is required. Leaf area index can be used as a management tool but we need to distinguish between physiological and agronomic approaches to its use. Productivity in bananas is governed by 'source' and 'sink' components of the plant system. Source components include intercepted radiation, and radiation use efficiency. Sink components include estimates of sink size, such as harvest index and the number of bunches present, and sink activity expressed as a temperature coefficient. At the individual leaf level recent work has demonstrated the non-saturating light response curve for net photosynthesis of individual leaves. This means that banana leaf canopies will be sensitive to shading. Banana leaves are very hydrated tissues that resist drying by rapidly closing their stomata. Leaf tearing reduces productivity independently of the effects of wind speed and the stomata on shredded leaves partially close so that the temperature of torn and untorn leaves remains quite similar. Experiments on root restriction and partial drying of the root system demonstrate the direct link between root function and stomatal conductance. These interactions have significance for planting dates, densities, root health and water management regimes. | |
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