Yield and water use efficiency of potato grown under different irrigation and nitrogen levels in an arid region

Water and nitrogen supply in potato cropping systems is an essential factor for controlling production level especially in arid and semi-arid regions. Shortage water availability and escalating irrigation costs along with high prices of fertilizers have caused attention to adopt practices to improve water and N use efficiency. The present work was conducted to assess the interaction effect of different amounts of water (W) and nitrogen (N) applied through drip irrigation on potato production, water use efficiency (WUE), nitrogen use efficiency (NUE) and total N uptake in an arid region. Potato plants were subjected to four irrigation treatments, 100% (W1.0), 80% (W0.8), 60% (W0.6) and 40% (W0.4) of crop ET (evapotranspiration) and four N levels, 160 (N160), 220 (N220), 280 (N280) and 340 (N340) kg N ha−1. Plants grown under full irrigation supply resulted in the highest tuber yield and there were significant reductions in total yield and yield components when applying less amount of water. Tuber weight was more sensitive to water deficit than tuber number, where the decrease in potato yield in the deficit water treatments was mainly due to a decrease in tuber weight (R2 = 0.982). Except for tuber number per plant, application of N adversely affected yield and yield components, when N level applied above 280 kg N ha−1 at W0.6, and above 220 kg N ha−1 at W0.4, respectively. The WUE was improved by N supply, but its effect decreased as the irrigation level increased. The WUE at W1.0, which produced the highest tuber yield, was 146 kg ha−1 mm−1 with N340 but this increased to 195 kg ha−1 mm−1 at W0.4 with N220. The NUE was affected greatly by the applied N amount and increased as the N level was decreased. The highest NUE value 176 kg yield kg−1 N was obtained at W1.0 treatment with N160 but this decreased to 136 kg yield kg−1 N with N340. The uptake of N increased with increase in the level of N applied up to the highest level but the reverse was true for N recovery. These results suggested that potato in an arid climate region can be cultivated with acceptable yields while saving irrigation water and reducing nitrogen supply but it is essential to exploit the interaction effect between these two factors to maximize resource use efficiency.

► Potato tuber yield varied widely under different amounts of water and N applied through drip irrigation system.
► Water stress is a more yield limiting factor than N fertilizer for potato production.
► The decrease in potato yield in the deficit irrigation treatments was mainly due to a decrease in tuber weight.
► The yield reduction under severe water deficit was much more severe at high N levels.
► Water use efficiency was conditioned by N level, but its effect decreased as the irrigation water increased.