Water use and nutritional water productivity of taro (colocasia esculenta L. Schott ) Landraces.

Abstract

Taro (Colocasia esculenta) is a vital drought tolerant crop with the ability to produce corms of high nutritional quality, but it still occupies low levels of utilisation and research in South Africa. Information on crop agronomy, management practices and water use has been limited and not available to farmers. The study aimed at determining the response of taro landraces to water availability under controlled environment conditions in a growth chamber. Further, the crop response to dryland conditions during the 2018 and 2019 growing seasons was observed. Under field conditions, the experimental factors were planting date and fertiliser level. The eddo type taro landraces were all collected from rural areas of KwaZulu-Natal. For controlled environment facility (CEF), the experimental design was arranged as a randomized complete block design (RCBD) and replicated three times, with three factors: temperature(~33/18°/C day/night; 60–80% RH), water regimes (30% and 100% of crop water requirement (ETa) and taro landrace. For field trials, a factorial design in randomized complete block design (RCBD) with three replications was conducted. Three experimental factors were examined namely; planting dates (October, November and December), three organic fertilisers (0, 160 and 320 N kg per hectare) and two taro landraces MG and PI. The CEF results revealed that better relative growth and development were associated with better corm starch content and this occurred more at 100% compared with 30% ETa. However, water use efficiency (WUE) and nutritional water productivity were found to be higher in response to 30% ETa compared with 100% ETa. The results of the field trial indicated that planting date and fertilisation have a significant effect on crop establishment, growth parameters, actual yield and yield parameters, mineral, starch, and moisture content. The yield parameters were decreased by delaying planting but increased by organic fertiliser. The corm mineral content increased by organic fertiliser application, but the starch content was decreased. It is concluded that taro growth and corm size will increase in response to water and nutrient availability, but the nutritional value of the corm may be compromised.