Evapotranspiration, crop coefficient and seed yield of drip irrigated pumpkin under semi-arid conditions

•Crop coefficient, yield and yield components of confectionary pumpkin grown under field conditions were investigated.•The effect of irrigation interval was significant on seed yield and the yield parameters.•The average crop coefficients across the years, for the stages of initial, crop development, mid-season, and last season were 0.56, 0.72, 0.95, and 0.65, respectively.

Pumpkin (Cucurbita pepo L.) is one of the most important plants in Turkey. A 2-year experiment (2013-2014) was conducted in the Konya Plain of Turkey in order to investigate the response of confectionary pumpkin to irrigation intervals. The experiment was laid out in a randomized block design consisting of three irrigation intervals (I7: 7-day, I14: 14-day, I21: 21-day) with three replications each. Actual evapotranspiration (ETa) of irrigation treatments varied from 521.2 to 660.2 mm in 2013 and from 493.6 to 629.6 mm in 2014. On an average, the ETa rate was 4.71 mm day−1 under I7 and declined by 8% and 21% under I14 and I21, respectively. Crop coefficients (Kc) varied similar to ETa among the different growing stages, i.e., from a mean of 0.56 at the initial stage to 0.95 at mid-season. The mean Kc was estimated to be 0.74 for the whole season. Irrigation intervals were found to significantly affect the seed yield and the quality of pumpkin in 2013 as well as 2014. No statistically significant differences (P ≤ 0.05) were found between the I7 and I14 treatments in both the years although the I7 treatment was observed to produce the highest seed yield (1275 kg ha−1). Hence, in terms of water savings, the irrigation interval could be extended to 14 days without a significant decrease in the seed yield in case of arid and semi-arid areas such as the Konya Plain.