Growth and Yield of Determinate and Indeterminate Soybeans in Mozambique.

Soybean is relatively a new crop in Mozambique but recent domestic and regional demand for soy-based products has stimulated interest in production by smallholder farmers. Domestic demand for soybean grain from the poultry and livestock industry alone is estimated at 50,000 tons/year. Despite this demand, current production nationwide is estimated at 15,000 tons/year due in part to limited access to improved varieties and information on better crop and soil management practices. The main objectives of this study are to identify high-yielding soybean genotypes adapted to the various agro-ecological zones of Mozambique and to determine the optimum planting date for the selected genotypes. Field experiments were conducted on clay loam soils at several locations in 2007-2010 using several genotypes developed in Nigeria by IITA. For the planting date trials, seeds were planted at various locations on four different dates at 14-day intervals beginning in December. Fifteen promising genotypes were selected from more than 400 genotypes screened for further evaluation. The growing period for all genotypes is longer than that observed in Nigeria due to the relatively low temperatures in Mozambique. Some genotypes did not complete seed-filling when planted after the second week of January. In addition, the plants were bigger and taller, and also produced more foliage at sites with cool and high rainfall. Yields consistently decreased across locations when planting delayed. For example, yields in 2008/09 for the site with relatively high rainfall on average ranged from 2700-4700 kg/ha when planted in the second week of December compared with 580-2260kg/ha for those planted in the last week of January. The relatively early-maturing genotypes fitted well into the cropping systems of all agro-ecologies compared with the late-maturing genotypes. At all locations, early planting between the first and third week of December was the best time to plant soybean.