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A field experiment comparing different irrigation frequencies and soil matric potential thresholds on potato evapotranspiration (ET), yield (Y) and water-use efficiency (WUE) was carried out in a loam soil. The experiment included five treatments for soil matric potential: F1 (-15 kPa), F2 (-25 kPa), F3 (-35 kPa), F4 (-45 kPa) and F5 (-55 kPa) and six treatments for irrigation frequency: N1 (once every day), N2 (once every 2 days), N3 (once every 3 days), N4 (once every 4 days), N6 (once every 6 days) and N8 (once every 8 days). Results indicate that both soil matric potential and drip irrigation frequency influenced potato ET,Yand WUE. Potato ET increased as irrigation frequency and soil matric potential increased. Comparing soil water potential, the highest ET was 63.4 mm (32.1%) more than the lowest value. Based on irrigation frequency treatments, the highest ET was 36.7 mm (19.2%) more than the lowest value. PotatoYand WUE were also found to increase as irrigation frequency increased. PotatoYincreased with an increase in soil water potential then started to decrease. The highestYand WUE values were achieved with a soil matric potential threshold of -25 kPa and an irrigation frequency of once a day. [ABSTRACT FROM AUTHOR]

Abstract: This study was conducted to determine the optimum irrigation water amounts for muskmelon (Cucumis melo L.) in plastic greenhouse. The irrigation water amounts were determined based on the percentage of field water capacity. On the same basis of irrigation start-point of 60% (the percent to comparing to the field water capacity), there were four different irrigation water levels 100% (T100), 90% (T90), 80% (T80) and 70% (T70) as the four different treatments. The results showed that plant growth, fruit production and quality were significantly affected under different irrigation water amounts. Plant height and stem diameter decreased as well as fruit yield from treatment T100 to T70. Fruit quality was the best in the T90 treatment. The irrigation water use efficiency (IWUE) values found in this experiment showed that the lower the amount of irrigation water applied, the higher the irrigation water use efficiency obtained. Hence, based on the quality and quantity of muskmelon yield, the regime for 90% of field water capacity is the suitable soil irrigation treatment (T90) which can save irrigation water and improve the quality of fruit. Combined the crop yield, quality and pan evaporation inside greenhouse, obtained Kcp=1.00 values can be recommended for the most appropriate irrigation scheduling, irrigation water amount is better between T100 and T90. Therefore, applying water by drip irrigation in relation to the amount of water evaporated from a standard 0.2m diameter pan is a convenient, simple, easy, and low cost method inside a plastic greenhouse. [Copyright &y& Elsevier]