3. Results and discussion
3.1. Crop water use and seed yield
The irrigation number, amount, and crop ETa and seed yield
for each treatment are listed in Table 4. During the growing season,
treatments with 7-, 14-, and 21-day intervals were irrigated
12, 6, and 4 times, respectively. The amount of irrigation varied
with irrigation intervals and levels. The total amount of irrigation
changed from 33 to 555mmin 2013 and from 42 to 506mmin 2014.
Total rainfalls during the growing season of pumpkin were 59.2
and 83.6mm in 2013 and 2014, respectively. The rainfall during
the growing season of 2013 and 2014 were similar to the historical
average for the region.
Seasonal evapotranspiration changed between 194.2 and
660.2mm in 2013 and between 208.6 and 629.6mm in 2014
(Table 4). The highest evapotranspiration was calculated with 7-
day irrigation interval at full irrigation (I100) in both the years. The
low ETa values were obtained in S21 treatments in both the years.
It was the main reason to expose S21 treatments to the maximum
water-stressed condition. Especially, in all S21 treatments except
for S21I100, the available soil moisture was near to the wilting point
before the irrigation due to the long irrigation interval. A decrease
in root zone moisture status reduces the magnitude of soil water
flux with a concomitant decline in ETa (Hillel, 1998).
The seed yield of pumpkin in the growing period in 2014 was
lower than that in 2013. This may be attributed to the differences
in the climatic conditions. Also, the low seed yield in 2014 might