The experiment was conducted at the research field of Irrigation and Water Management Division (IWM), Bangladesh Agricultural Research Institute (BARI), Gazipur during the rabi season of 2016-2017 and 2017-2018. BARI Hybrid Mistikumra -1 was used as the pumpkin variety. Seven irrigation treatments were used for the experiment, where each treatment was replicated four times following randomized complete block design (RCBD). The treatments were as follows:
T1 = Full irrigation (100% of FC) at 10-days interval
T2 = Full irrigation (100% of FC) at 15-days interval
T3 = Deficit irrigation (75% of FC) at 10-days interval
T4 = Deficit irrigation (75% of FC) at 15-days interval
T5 = Deficit irrigation (50% of FC) at 10-days interval
T6 = Deficit irrigation (50% of FC) at 15-days interval
T7 = Drip irrigation at 3-days interval
* 2t/ha of straw mulch will be used for all treatments.
**For T1 to T6, irrigations were applied using the ring basin method.
The soil type of the experimental field was sandy-loam, with a field capacity of 29% and a bulk density of 1.5 g/cc. The weather of the experimental site during the crop growing season was dry, where the maximum temperature was recorded in April and the minimum temperature was in January in both years. The average relative humidity was recorded highest in the month of December and gradually decreased afterward. Total rainfall of 113.4 mm and 81.8 mm were recorded during the crop season of 2016-2017 and 2017-2018, respectively. A summary of the weather information of the experimental location
Land preparation was done by using the tractor, power tiller, etc. Fertilizers were applied at the rate of N75, P36, K60, S21, Zn2, B1.4 kg/ha, and cowdung 5.0 t/ha. All fertilizers except nitrogen were applied in a pit, 7 days before planting and mixed thoroughly with the soil. N was applied around the plant as side-dressing at 15, 35, 55, and 75 days after planting under moist soil conditions and mixed thoroughly with the soil for better utilization. Seeds were sown on 21 November 2016 (Year 1) and 19 November 2017 (Year 2), respectively on seedbed to produce seedlings. Seedlings were transplanted in experimental plots on 6 December 2016 (Year 1) and 8 December 2017 (Year 2), respectively at a rate of 1 seedling/pit. Each treatment contains 4 plants and the unit plot size was 4m × 4m. Pit dimension was 60cm × 60cm × 60cm with a spacing of 2.5 m between two plants. Common irrigation of 15L was applied from seedling to proper plant establishment. After one month of transplanting, every treatment was mulched by using a paddy straw @2.0 t/ha. Sex feromen traps were placed in the field to control fruit fly infestation. Pruning was done continuously up to 8 to 10 nodes on the main branch. To control disease infection and insect infestation Otistin @20g/20L of water, Admire @4ml/15L of water and secure @30g/30L of water was sprayed. Weeding was done according to necessary. The soil moisture was monitored in each plot by using the gravimetric method at 30 cm intervals down to 60 cm. The amount of applied water was measured by the time-volume technique. Soil moisture was collected before sowing, before irrigation and after harvest. Irrigation water was applied by the ring basin method to bring the soil moisture up to field capacity considering the effective root zone depth of 60cm. In the case of drip irrigation (T7), two drippers were installed per plant and dripper emission was assumed to be uniform. A 400L water tank was installed between two treatments and irrigated according to the design. Pumpkin fruit was harvested between 15 March to 17 April in Year 1 and 18 March to 20 April in Year 2.
Seasonal water use (SWU) was calculated by adding applied water, effective rainfall (ER), and soil water contribution (SWC). Water productivity (WP) was calculated as the ratio of fruit yield and water use (SWU). Data on the number of fresh and damaged fruit, number of fruit per plant, unit fruit weight, yield per plant, and fruit yield was recorded. All the data were analyzed statistically by using R software and mean separation was done Duncan multiple range test at 5% level of significance. Financial analysis was done by considering the water-limiting situation (Ali et al. 2007; English 1990). Total cost was calculated by adding total operating cost, interest on operating cost, and land-use cost.