Abstract: The main objective of this study was to optimize the irrigation requirements of a melon crop (Cucumis melo L.) cultivated in semi-arid climate conditions. The field experiment was conducted in four plots under different irrigation regimes. The effects of four water levels on melon crop were investigated during the growing season. The treatment designated as T1 (control treatment) received an irrigation rate of 75% of the cumulative class A pan evaporation applied through drip irrigation system. The treatments T2, T3 and T4 received 90, 80 and 70%, respectively, of the irrigation applied in treatment T1. The canopy temperature was monitored through an infrared thermometer and the soil moisture content with a neutron probe. Crop Water Stress Index (CWSI), Water-Use Efficiency (WUE) and melon yield were evaluated for all irrigation treatments. CWSI mean of 0.35 presented the maximum yield and can be used as a threshold value to start the irrigation in melon crop. The maximum total yield (30,380 kg ha-1) occurred with a WUE of 55.37 kg ha-1mm 1 in treatment T2, while the minimum total yield (23,895 kg ha-1) occurred with a WUE of 56.00 kg ha-1 mm 1 in treatment T4. The results indicated that a 30% reduction (treatments T4) in water total was sufficient to alter significantly the melon yield, though the WUE values was not significantly different (p<0.05). The linear regression between CWSI and melon yield was statistically significant (p<0.05) for all treatments and therefore can be used with reasonable accuracy for melon yield prediction, under the growing condition this experiment.
Bernardo Barbosa da Silva , Jose Alberto Ferreira , Tantravahi Venkata Ramana Rao and Vicente de Paulo Rodrigues da Silva , 2007. Crop Water Stress Index and Water-Use Efficiency for Melon (Cucumis melo L.) on Different Irrigation Regimes. Agricultural Journal, 2: 31-37.