The late-season period in the humid tropics is characterized by drought and the production of crops such as tomato (Lycopersicon esculentum L.), okra (Abelmoschus esculentum), pepper (Capsicum spp.) and leafy vegetables depends upon the utilization of stored soil water. The efficient use of stored soil moisture ensures maximum plant adaptation and yield stability. The growth, development and yield of tomato grown on mulched and unmulched hand-hoed, raised beds and ridged sandy loam soil during the late cropping seasons of 1994, 1995 and 1996 in Akure, Nigeria was investigated. Hand-hoeing reduced soil temperature and conserved more soil moisture than ridging or the raised bed while grass mulch improved soil temperature and soil moisture regime compared with bare ground. Root biomass and root/shoot ratio increased in the order ridging, raised bed and hand-hoeing while shoot biomass, leaf area/plant and percentage fruit set decreased in the order raised bed, ridging and hand-hoeing. Number of fruit and fruit yield/plant produced by raised beds were significantly higher than those produced by ridging and hand-hoeing. Mulch ameliorated the hydrothermal regime of the soil, improved the vegetative and flowering performance and significantly increased the fruit yield of tomato over bare ground.

SUMMARYIncreasing plant density in maize from 8 to 32 plants/m2, without irrigation, had little effect on the time of ear primordia differentiation but delayed the time of silking (by up to 16 days), reduced the potential grain sites available for pollination and the number of grains pollinated, and increased grain abortion during the grain fill period. In cv LG11 sufficient fertile ears were retained to maintain grain yield throughout the wide range in density, whereas yield fell in Anjou 210 due to barrenness after silking, which was the major factor responsible for the intolerance of this variety to high density. However, in a variety such as Anjou 210, which has a tendency to barrenness under stress, the grain content of the end product would not be affected at the plant densities normally used for maize silage.

The growth and yield of late-season tomato was studied at Akure, Nigeria, from 1995 to 1998. In each year, treatments were 0 (bare ground) or 12 kg/ha grass mulch applied to tomatoes at densities of 1·9, 2·8, 3·7 and 5·6 plants/m2 in a factorial combination. Increase in plant density and mulching reduced soil temperature at 5 cm depth while only the latter enhanced soil moisture at 10 cm depth throughout tomato growth. The improved soil hydrothermal regime resulted in earlier onset of flowering, 50% flowering date and date of first harvest respectively and shorter fruit harvest duration in tomato grown on either bare ground or at increased plant density.Although increased plant density reduced shoot dry weight per plant at final harvest, both root length per plant and root dry weight per plant were enhanced. Fruit yield/ha increased as plant density increased although yield of the individual plants and their components were significantly reduced. Because of compensation at higher plant population densities, it is economical to grow late-season tomato at 5·6 plants/m2. Mulching enhanced growth and yield of tomato compared to bare ground and the result emphasizes the need for early and rapid growth of late-season tomato before the onset of terminal drought.