EFFECTS OF DEFICIT IRRIGATION LEVELS AND POTATO (Solanum tuberosum L.) VARIETIES ON YIELD, YIELD COMPONENTS, AND WATER PRODUCTIVITY AT HARAMAYA, ETHIOPIA

Abstract

The right irrigation water management in agriculture is adopted to have a significant impact on water savings from deficit irrigation. DI is one of the talented irrigation plans to maintain an acceptable yield in the situation of a water shortage and uses efficient tools to optimize water use efficiency. Deficit irrigation improves water productivity through the consumption of less water while producing a comparable yield to that of an unstressed crop. However, this requires identification of a suitable crop type, crop variety, sensitivity of the crop to deficit irrigation, and local environment. The potato (Solanum tuberosum L.) has a crucial role in ensuring food and nutrition security worldwide. In Ethiopia, potato holds a prominent position among root and tuber crops, being the most produced and consumed, followed by cassava, sweet potato, and yam, and significantly contributing to national food security, poverty alleviation, income generation, and job creation, particularly in regions like the central, eastern, northwestern, and southern parts of Ethiopia. This research was conducted to introduce the effects of deficiency irrigation levels and potato (Solanum tuberosum L.) varieties on yield, yield components, and water productivity. The field experiment was conducted at the Haramaya University experimental site during off-season 21 and aimed at investigating the effect of deficit irrigation levels on potato varieties yields, yield components, and water productivity. The experiment was carried out in a split-plot design with nine treatment combinations and three replications. The three treatments include potato varieties (Gudene, Tulema, and Bubu) as the main plot and three deficit irrigation levels (100%, 80%, and 60% of evapotranspiration of crop). Crop water requirement was estimated using actual daily climatic data. The results revealed that the main and interaction effects of levels and varieties exerted a significant effect on the plant growth, tuber yield, yield parameters, and water use efficiency of potatoes. The highest marketable tuber yield of 32 t/ha was obtained from Tulema with 100% crop water application, and the minimum tuber yield of 27.26 t/ha was recorded with 60% ETc with the Bubu variety, respectively. The highest water use efficiency (WUE) of 10.44 kg/s was obtained from Tulema with 60% ETc, while the lowest one was recorded (4.73 kg/s) from Gudene with 100% ETc. The maximum yield reduction (14.81%) was recorded with Bubu 60% ETc, followed by Bubu 80% ETc (13.56%), and the minimum yield reduction (0.22%) was from Tulema 80% ETc. Therefore, Tulema verity showed the best performance with minimum yield reduction, was the was the best water-saving variety, and gave a chance for an additional area of land to be irrigated with saved water. The financial analysis revealed that the 80% ETc application of water by using the Tulema variety gave the maximum net benefit (127853 ETB) with the highest MRR (132.18%) relative to water-saving additional hectares. Therefore, in an area where water resources are scarce, it could be concluded that the Tulema potato variety, by saving irrigation water with respect to the Gudene and Bubu potato varieties, can solve the problem of water shortage and would ensure the opportunity for further irrigation development in the study area and similar agro-ecology.