| Abstract | Water and nutrient are central factors in the growth and production of any crop, but at the same time their availability, efficiency and cost involved for their use are the real constraint faced today. The application of water and nutrient through conventional methods instigating loss to water and pollution to surface and ground water through runoff and leaching. It is very evident to optimize their use through new efficient irrigation application technology with well-prepared irrigation and nutrient schedules especially study area Punjab Pakistan where water scarcity is a huge threat to the future of agriculture. Potato production in Pakistan play a very important role in agriculture production and fulfilling the food requirement for increasing population. This study emphases on assessing the impact of irrigation and fertigation schedule on fresh tuber yield(t/ha) of potato using DSSAT-SUBSTOR-potato model. The model was calibrated and validated with experimental fresh tuber yield (t/ha) data for cultivar SL 5-2 from 2014-2015 and 2016-2017 obtained from Potato Research Institute Sahiwal Punjab Pakistan. The model performed good with percentage error value of within ± 15 %, R2 = 0.8663 and RMSE= 2.28. The model was then fed with daily irrigation scheduling strategies IS1, IS2, IS3, IS4 and IS5 which represent daily irrigation schedule, daily adjusted irrigation schedule (according to tuber initiation and development stage) of potato, two-day, three-day and five-day cumulative irrigation. The irrigation strategies IS1, IS2, IS3, IS4 and IS5 with three split fertigation treatments showed mean percentage increase in fresh tuber yield (t/ha) as 5.5%, 11.55%, 18.6%, 25.6% and 0% from observed fresh tuber yield (t/ha) respectively. The irrigation strategies IS1, IS2, IS3, IS4 and IS5 with fertigation schedule with eight splits showed mean percentage increase in fresh tuber yield (t/ha) as 14.05%, 23.6%, 29.9%, 30% and 4.75% from observed fresh tuber yield (t/ha) respectively. The change of sowing date to one week earlier 28th October for five irrigation strategies IS1, IS2, IS3, IS4 and IS5 with fertigation schedule resulted in -14.09%, -0.72%, 4.18%, -2.2% and -27.87% change in fresh tuber yield(t/ha). The change of sowing date to one week later to 11th November for five irrigation strategies IS1, IS2, IS3, IS4 and IS5 with fertigation schedule resulted in 28.19%, 32.54%, 46.62%, 35.49% and 39.74% change in fresh tuber yield(t/ha), respectively. The IS3 is showing maximum percentage change of 46.62 % in fresh tuber yield (t/ha) with 312 mm of irrigation water than observed for study area and cultivar. The further delay of sowing date to 18th and 25th November resulted similar decrease in fresh tuber yield. Therefore, based on these findings adoption of irrigation scheduling strategy IS3,cumulative two-day irrigation with fertigation schedule (eight splits) and change in sowing date to 11th November could be helpful to increase fresh tuber yield (t/ha) for SL 5-2 potato cultivar and study area. |