RESPONSES OF POTATO (Solanum tuberosum .L) CROP YIELD TO SOIL MOISTURE STRESS CONDITIONS AT DIFFERENT GROWTH STAGES: THE CASE STUDY AT WO

Abstract

Potato (Solanum tuberosum L.) is produced in Central Rift Valley of Ethiopia as one of the staple food and the production and productivity is limited by the scarcity of water. A field experiment was conducted to study the influence of soil moisture stress on different growth stages of potato with the objectives of identifying crop growth stages sensitive to soil moisture stress, to investigate the relative yield response factor of Potato under different treatments, to determine the irrigation water requirement at each treatments and to investigate the water use efficiency under different treatments. The experiment was conducted on sandy loam soil at Wondo Genet in SNNPRs of central rift valley, southern, Ethiopia during the 2017/18 cropping season. The experimental design was randomized complete block design with three replications seven treatments including the control treatment were devised to represent some possible combinations of water application. The result showed that soil moisture stress occurred at different growth stage had a significance (p<0.05) effect on plant height, number of tuber per plant, tuber length, tuber diameter, tuber fresh weight, and total tuber yield of Potato. The highest plant height (92.67 cm and 85.16 cm), number of tuber per plant (11.33) ,tuber length (7.7cm), tuber diameter (5.73 and 5.53 cm), tuber fresh weight (756.67 and 735.67 g), and total tuber yield (29.16 and 28.36 t /ha) were obtained from T1and T5 respectively; while the lowest plant height (47.43 cm), number of tuber per plant (4.33 and 3.66 cm), tuber length(2.86 cm), tuber diameter (2.36 cm), tuber fresh weight (216.67 g), and total tuber yield (10.2 t /ha) were recorded from T3, T4 and T6, T4, T6, T3 and T6 respectively. Most of the parameters (dependent variable) that are plant height, tuber number per plant, tuber length, tuber diameter and total tuber yield showed significant yield reduction in their values as moisture stress increased at different growth stages. Growth parameters were slightly affected by moisture stress when the stress was imposed during the initial and late season growth stages but they were not significant. Initial and Midseason growth stage of potato tuber was the most critical stage (causes 65% yield loss) for soil moisture stress followed by development stage (49% yield reduction). The highest water use efficiency was obtained from T5 (7.26 kg/m3 ) and the lowest one were from T3 (3.93 kg/m3 ). Missing irrigation at the late season growth stage (T5) affects potato tuber insignificantly. This study has shown in order to avoid high yield reduction; The variety should not be stressed consecutively at initial and midseason growth stages well established