7. Sources of Pod Yield Losses in Groundnut in the Northern Savanna Zone of Ghana

Abstract

Groundnut (Arachis hypogaea L.) has gained prominence as a food and cash crop due to its increasing importance, both in the domestic and export markets. Its products, such as oil and cake, are for both domestic and industrial uses. However, farm level yields in Ghana have remained as low as 800 kg/ha compared to developed countries of more than 3,000 kg/ha. Variation in the yield of the groundnut crop has been found to be a genetic trait influenced by environment or the interaction of both. In order to identify the sources responsible for these low yields on farmers’ fields, and to be able to advise them to increase their yields, a field experiment was conducted in 2007 and 2008 on a savanna soil at Nyankpala, involving three groundnut varieties, in a split-plot design replicated four times. The varieties (Chinese, Manipinta and Nkatie-Sari) were the main factor and three harvesting stages (at maturity of each variety, 1 week after and 2 weeks after the first harvest) were the sub-plots. Pod yields were between 2,500 kg/ha and 3,100 kg/ha for the three varieties in both years at physiological maturity, which were higher than yields from the subsequent harvest dates. The decline in pod yield when harvesting was delayed beyond physiological maturity was attributed to insect infestation of the pods, sprouting of the nuts in the soil and difficulties in harvesting, resulting in most of the nuts either not harvested or physically damaged. The Chinese variety had more sprouted nuts as well as nuts left not harvested in the soil probably due to its spreading nature compared to Manipinta and Nkatie-Sari, which can be described as the bunch types. Nkatie-Sari significantly gave the highest pod yield at each stage of harvest than the other varieties. It is advisable that farmers plant improved varieties, making sure they harvest at physiological maturity, before the onset of the dry season, in order to obtain optimum pod yields of the groundnut.