Abstract
Pre-planting mulching of moist soils with black and transparent (solarization) polyethylene films for six weeks raised soil temperatures 3- 11°Cover uncovered control soil and reduced populations of Macrophomina phaseolina (Tassi) Goid. 62-100%, Pythium spp. 67-88% and Gram-positive bacteria 64-99% after treatment of two soil types in southwestern Mexico. Solarization reduced weed populations 97-100% and black film mulching 76-99% one week after film removal. Although charcoal rot (M. phaseolina) was not controlled by mulching on the indicator crop of sesame (Sesamum indicum L.), seed pod yield was increased up to 97% and dry seed up to 72% over control soil after mulching. Black film mulching was as effective as solarization for increasing yield of sesame. Post-planting mulching with black film increased growth of woody perennial Mexican lime (Citrus aurantifolia (Christm.) Swingle) seedlings up to four-fold. No effect was found on mango (Mangifera indica L.); and growth of herbaceous perennials, papaya (Carica papaya L.) and banana (Musa cv.), was hindered by the film mulches. A ten-fold reduction in dry-season irrigation requirement sometimes was achieved using the post-planting film mulches, even when no growth increases were obtained.
