Assessing Effect of Different Irrigation Intervals and Planting Methods on Onion Yield

This study was carried out to investigate the effects of different irrigation regimes and planting methods on yield, yield components, morphological traits, and storage characteristics of a local onion cultivar, namely, Goli Ghesse. The experiment was conducted as a factorial split plot design with RCBD arrangement in four replications and for three years at Kheirabad Research Station. Irrigation intervals were allocated to the main plots and planting methods were studied in the sub plots. Irrigations were initiated after 40, 70, 100 and 130 mm cumulative evaporation in treatment E1, E2, E3 and E4, respectively. Two planting methods consisting of direct seeding and transplanting were used in this experiment. Seasonal and combined analysis of variance was done and means were compared using Duncan's multiples rang tests. Combined analysis showed that there was significant difference at 5% confidence level among treatments. Assessing effect of different irrigation intervals on average yield revealed that bulb yield in direct planting was 45.54 t/ha, which was 0.6 t/ha more than transplanting method, but this was not significant. Also, results showed that the highest bulb yield (60.8 t/ha) was obtained from E1. In comparison, treatments E2 to E4 had 48.88, 40.23, and 32.21 t/ha bulb yield and were in statistical groups of b, c, and d, respectively. But, cultivation method had no significant effect on yield at 5% probability level. .Effect of planting method on water use efficiency was significant at 5% level and the highest amount was obtained from transplanting method with 10.295 kg onion bulb/m³. Thus, irrigation interval after 70 mm evaporation from Class A pan and transplanting are recommended for Zanjan and other regions with similar climate and soil conditions.