Effect of Irrigation Regimes on Yield and Quality of Grapes (Vitis vinifera L.) cv. ‘Makutopora red’ in Dodoma Tanzania

Abstract

Application of water to vines at a lower amount than the crop water requirement has shown to improve grape quality in some grapevine cultivars depending on the drought resistance and tolerance of the cultivars. In order to know the amount of water that can be lowered it is necessary to know the exact amount of water that is required by the plant. The daily transpiration (ET_b) of mature Vitis vinifera L. cv. ‘Makutupora red’ grown in Dodoma-Tanzania for wine production during two growing seasons (2014 and 2015) was measured by compensation heat pulse method. Average daily transpiration was found to be 4.46 liters per plant in 2015 and 4.54 liters per plant in 2014.  Water lost through evaporation (ET_e) was also determined on daily basis by using soil moisture probes (DFM Software Solution). The average daily evaporation found to be 0.46 liters per plant in 2015 and 0.42 liters per plant in 2014. After the determination of crop water requirement, the vines were subjected to different irrigation regimes in order to study their effects on grape yield and quality. Three different drip irrigation methods conversional drip irrigation (CDI), partial rootzone drying ( PRD) and root zone deficit rationing (RDR) together with four levels of water at 100% of crop evapotranspiration (ET_c),  63.5% of ET_c,  56.3% of  ET_c and  48.9% of ET_c were interacted in order to determine a combination that would give good grape yield and quality. The results showed that a decrease in the amount of water applied to the vines caused an improvement in grape quality and a decrease in grape yield. Conventional drip irrigation CDI was observed to be the best option for optimum grape yield and high grape quality at 63.5% of crop evapotranspiration. Conventional deficit irrigation at 56.3% of crop evapotranspiration was found to be a good option for very high quality grapes but with a decrease in grape yield.

Key words: Grape yield, grape quality, deficit irrigation.