Planting date, water availability and plant density effects on dry bean production (Phaseolus, vulgaris L.).
Hlanga, Nokuthula Cherry.
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Dry beans (Phaseolus vulgaris L.) form an important part of the agricultural system in southern Africa. Small scale farmers use the crop in crop rotation or intercropping with another staple crop, maize. Although commercial seeds are not retained for use from one season to another, small-scale farmers do keep grain seed for reasons of germplasm preservation and economic reasons. It is important to understand the effect of some of the major agronomic factors on seed quality and crop performance in a situation where farmers retain seed from one season to another without using special seed storage methods. The objective of this study was to determine the effect of planting date, water availability and plant density on dry bean growth and yield using seed lots from subsequent generations of three dry bean varieties (Mtata, Malelane and Gadra). Dry beans subsequent seed quality varied significantly (P<0.05) among varieties, with Mtata, Malelane and Gadra having varied responses when subjected to varied agronomic conditions. All of the seed quality test indices varied significantly (P<0.05) among seed varieties, plant density, and water availability. Seed germination, germination velocity index (GVI), and mean germination time (MGT) were higher under rain-fed relative to irrigated conditions. This showed that dry bean varieties could be produced under water-limited conditions and produce relatively good seed quality. Field growth parameters were highly influenced and varied among agronomic management practices (dry bean varieties, plant density, season, and water availability). The three dry bean varieties Mtata, Malelane and Gadra had varied responses when subjected to varied agronomic conditions. Growth and yield parameters differed significantly (P<0.05) with planting date and water availability. Planting date (season), and water regime had considerable impact on growth and yield parameters. The highlight of the study was that the agronomic management practices have an important influence on crop growth and yield of dry bean crop. Although seed quality was statistically similar for the initial and post-harvest seed lots. Crop performance was better in the summer early season (January to April) when compared with the late season (May to August). Therefore, this study recommends that seed can be retained from previous harvest without significant loss of quality; however, careful selection of planting date is necessary to get optimum crop performance.