THE EFFECT OF IRRIGATION SYSTEMS AND DEFICIT IRRIGATION LEVELS ON PRODUCTIVITY AND WATER USE EFFICIENCY OF TOMATO CROP UNDER SANA'A BASIN CONDITIONS

Sana'a basin is located between latitude 16.8° and 17.4° northern and longitude 40° and 44° eastern; the elevation above the sea level is 2200m. Its climate is semi-arid, where its average rainfall is 235 mm/year. The total area of Sana'a basin is 320000 hectares and the cultivated area is estimated as 107000 hectares. The annual water consumption of agricultural irrigation in Sana'a basin is estimated as 180 million cubic meters, which withdraw from the conserved ground water through more than 6000 wells, whereas the shortage percentage of ground water recharge from the rainfall is 400%, which causes decreasing in the ground water level about 6 meter/year.  The actual water requirements of irrigated crops are 70 million cubic meters, that means the traditional irrigation efficiency in Sana'a basin is not exceed 40%.  The aim of this research is to increase the productivity and water use efficiency under Sana'a basin conditions. The research was studied the effect of different irrigation systems (drip-in, drip-on, furrow + hydrosol polymer, and furrow) and water supply levels (50, 75, and 100%  deficit irrigation from actual requirement) on the productivity, water use, and water use efficiency of tomato crop under Sana'a basin conditions in Yemen. The study took place at the college of agriculture in experiment farm of university Sana'a on crop tomato. The experiment was designed according to split plot design. The statistical data analysis and formulating prediction equations for studied properties was done using computer program (SAS). The results of research are indicated – as sample: The effect of different irrigation systems was significant (p < 0.01) on the productivity, water use and water use efficiency of tomato. The highest productivity of tomato is found to be 31443.3kg/ha for furrow irrigation system with hydrosol polymer, whereas the lowest is found to be 24113.3kg/ha. While the lowest water use is found to be 397.16mm for drip-in irrigation system, whereas the highest is found to be 595.75mm for furrow irrigation system. While the highest water use efficiency is found to be 6.52 kg/m³ water for drip-on irrigation system, whereas the lowest is found to be 4.22 kg/m³ water for furrow irrigation system. The effect of water supply levels (deficit irrigation levels) was significant (p < 0.01) on the productivity, water use and water use efficiency of tomato. The highest productivity of tomato is found to be 30644.2kg/ha for 100% water supply level, whereas the lowest is found to be 21724.2kg/ha for 50% water supply level. While the lowest water use is found to be 330.98mm for 50% water supply level, whereas the highest is found to be 661.94mm for 100% water supply level. While the highest water use efficiency is found to be 6.77 kg/m³ water for 50% water supply level, whereas the lowest is found to be 4.76 kg/m³ water for 100% water supply level. The effect of interaction between irrigation systems and water supply levels were significant (p < 0.01) on water use, while the other studied properties were not significant. The lowest water use is found to be 264.78mm for drip-in irrigation system at 50% water supply level, whereas the highest is found to be 795mm for furrow irrigation system at 100% water supply level. The highest productivity is found to be 37667kg/ha for furrow irrigation system with hydrosol polymer at 100% water supply level, whereas the lowest is found to be 19887kg/ha for furrow irrigation system at 50% water supply level. The highest water use efficiency is found to be 7.78 kg/m³ water for drip-on irrigation system at 100% water supply level, whereas the lowest is found to be 3.43 kg/m³ water for furrow irrigation system at 100% water supply level.