Hamed Hasanzadeh; Abdolhossin Mohammadi; Ebrahim Zakerifard; Maryam Mohammadi
Abstract
In order to evaluate the effect of different irrigation regimes on yield and yield components of 4 onion cultivars in a warm and humid climate, an experiment was performed as split plot design in RCBD with 4 replications. Main plots consisted of 4 irrigation regimes (irrigation after I1=35±3, ...
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In order to evaluate the effect of different irrigation regimes on yield and yield components of 4 onion cultivars in a warm and humid climate, an experiment was performed as split plot design in RCBD with 4 replications. Main plots consisted of 4 irrigation regimes (irrigation after I1=35±3, I2=50±3, I3=65±3 and I4=80±3, mm evaporation from class A pan) and sub-plots consisted of 4 onion cultivars (‘White Grano’, ‘Admiral’, ‘Primavera’ and ‘Mineroa’). Seeds were sown in nursery and, after 2 months, transplants were planted in the field at 10×30 cm spacing. After bulb growth stopped and onion neck dried up, leaf number, plant height, bulb length, number of layers, dry matter, yield, and water use efficiency (WUE) were measured. Results showed that there was no significant difference between irrigation treatments in bulb length, layers number and dry mater. However, yield decreased by irrigation intervals up to 65 mm evaporation from class A pan, but it increased significantly in irrigation interval of 80 mm evaporation. Vegetative growth increased by reduction of irrigation interval. The highest WUE was observed in ‘Withe Grano’ and ‘Primavera’ cultivars in 80 mm evaporation treatment (5.528 and 5.381 kg/m3) and the least was in ‘Primavera’ cultivar in 35 mm evaporation treatment (1.858 kg/m3). WUE increased by reduction of irrigation in all cultivars. For ‘White Grano’, ‘Admiral’ and ‘Primavera’ cultivars recommended irrigation intervals is 19 days in January, 20 days in February , 15 days in March, and 12 days in April, based on 80 mm evaporation treatment. In the case of ‘Mineroa’ cultivar, considering no significant difference between the highest irrigation treatments with 65 mm evaporation treatment, it is recommended that irrigation intervals be 15 days in January, 17 days in February , 12 days in March, and 10 days in April. Under the condition of this study, White Grano cultivar, followed by Admiral, performed higher than the other cultivars, especially with respect to WUE and yield. Therefore, they are recommended for planting in the region.