Plant density studies with banana (cv. Williams) in a subtropical climate. I. Vegetative morphology, phenology and plantation microclimate

Abstract

SummaryThe influence of plantation age and plant density on pseudostem size, canopy cover and vegetative growth characteristics of banana cv. Williams was investigated over four cropping cycles at Burgershall Research Station, in the subtropical Eastern Transvaal. Densities were 1000, 1250, 1666 and 2222 plants ha−1. Over all densities, pseudostem height, lamina area, numbers of functional leaves at flowering and LAI increased with plantation age up to the second ratoon (R2). This increase in canopy cover caused vegetative and total cycle intervals to be extended progressively from plant crop to R3. Within cycles, higher density had little effect on plant height or lamina length, but induced thinner plants with significantly narrower leaves than at low density. Peak ratoon LAI at flowering almost doubled between 1000 and 2222 plants ha−1. At 1000 plants ha−1, four cropping cycles were completed in the same period as three cycles at 2222 plants ha−1. Annual leaf emergence rate was significantly reduced by up to five leaves with an increase in plant density from 1000 to 2222 plants ha−1, which was also accompanied by a 3–4°C reduction in pseudostem temperature. Up to six more leaves per plant were produced at 2222 plants ha−1 and only 14% of the available radiation was transmitted through the primary canopy compared with 30% at 1000 plants ha−1. Crop cycle interval is an important component of annual yield at different densities.