Interaction between Irrigation and Nitrogen Levels and Their Effect on Yield, Quality, and Water Use Efficiency of Potato under Drip Irrigation System
DOI:
https://doi.org/10.65420/sjphrt.v2i3.162Keywords:
Potato, drip irrigation, nitrogen fertilization, water use efficiency, tuber quality, sustainable resource water managementAbstract
A field experiment was conducted during the growing season in Al-Maraziq, Janzour, Libya, to evaluate the interactive effects of three drip irrigation levels (100%, 70%, and 40% of field capacity) and five nitrogen rates (0, 120, 210, 300, and 390 kg N ha) on potato (Solanum tuberosum L., cv. Spunta) yield, tuber quality, and water use efficiency (WUE). A split-plot design with three replications was adopted. Results indicated that moderate irrigation (70% FC) achieved the highest WUE (96 kg mm ha), representing a 10.4% improvement over full irrigation. Nitrogen rate of 300 kg N ha (N3) produced the maximum WUE (97 kg mm ha), reflecting a 49% increase compared with the control treatment. Crop evapotranspiration (ETc) increased progressively with irrigation and nitrogen levels, reaching a maximum of 320.30 mm under I1N3 and a minimum of 143.82 mm under I3N0, confirming the strong interaction between vegetative growth intensity and water consumption. Total tuber yield was highest under full irrigation (28.59 t ha). Yield declined by 12.4% under 70% irrigation and by 36.9% under 40% irrigation. Regarding nitrogen fertilization, maximum yield was recorded at 300 kg N ha (27.10 t ha), followed by a decline at 390 kg N ha, indicating diminishing returns at excessive N supply. Moderate nitrogen application (210 kg N ha) resulted in superior tuber quality parameters: dry matter (20.27%), specific gravity (1.087), and starch content (15.23%). Excess nitrogen reduced quality due to prolonged vegetative growth and delayed physiological maturity, which limited carbohydrate translocation to tubers. The study concludes that 70% irrigation combined with 300 kg N ha optimizes water productivity, while full irrigation with 210-300 kg N ha maximizes economic yield. These findings emphasize the importance of integrated irrigation-nitrogen management strategies for sustainable potato production under semi-arid conditions.
