Abstract

Grape is a major fruit crop which occupies 33% of the total area of fruit cultivation in Yemen. Grape vines are cultivated under both irrigated and rainfed production systems. The irrigation practices in grape orchards are traditional with low efficiency due to high losses of water. In order to obtain rapid and reliable results, the comparison of five equations for calculation of evapotranspiration and obtaining the Kc values by utilizing actual evapotranspiration of grape became necessary. Crop water requirement of grape trees in Sawan, Bani Hushaish District in Sana'a Governorate was studied and two methods of irrigation were investigated for two years (2005-2006). The investigated irrigation methods were: bubbler (localized) irrigation and basin irrigation. Results indicated the significant superiority of bubbler irrigation over the basin irrigation. The actual water requirements reached 601 and 736 mm water depth respectively with application efficiency reaching 82.6% and 69.8% respectively. The irrigation water productivity of the bubbler irrigation was significant (3.8 kg/m3) while it was less under basin irrigation (1.8 kg/m3). Results indicated that the average crop coefficient throughout the growing season ranged from 0.42 in the case of using Ivanov equation and 0.75 in the case of Hargreaves. In addition to standard FAO Penman-Monteith equation, the Hargreaves and Blaney-Criddle are the best equations that can be used in determination of crop water requirements and irrigation scheduling of grapes. It was also observed that the highest crop coefficient was recorded in the months of May and June in all treatments.

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