EFFECTS OF FURROW IRRIGATION METHODS AND INTERVALS ON TUBER YIELD RELATED AND QUALITY OF POTATO (Solanum tuberosum L.) GENOTYPES AT HARAMAYA, EASTERN ETHIOPIA

Abstract

Potato is an important cash and food security crop in mid and highlands areas of eastern Ethiopia. However, the yield of the crop is constrained by many factors including improper application of irrigation amount and intervals. The field experiment was conducted at Haramaya University (Raare) research station during 2020 cropping season to assess the effects of furrow irrigation methods and intervals on tuber yield and quality of potato genotypes and to estimate water productivity and optimum irrigation amount for potato production. The treatments consisted of two potato genotypes (Bubu and CIP-392781.1), two furrow irrigation methods (fixed and alternate), and three irrigation intervals (six, eight and ten days) arranged factorially in a randomized complete block design with three replications. Phenological, growth, tuber yield and yield related parameters, tuber quality and water productivity were collected. The result revealed that the main or interaction effects of genotype, furrow irrigation methods and intervals significantly (P<0.05) affected most of the measured traits. Both varieties had resulted in higher marketable tuber number per hill under alternate furrow than fixed irrigation method and at higher rates of irrigation interval. On the other hand, the highest average tuber weight (158.03 g) was registered from genotype CIP-392781.1 with fixed furrow irrigation method at six day irrigation interval. Bubu under fixed and alternate furrow irrigation methods and CIP-392781.1 under fixed furrow irrigation method had resulted in significantly higher marketable tuber yield in the range of 33.85 to 35.78 t ha-1. On the other hand, higher tuber dry matter content (21.97%) and tuber specific gravity (1.10 g cm-3) were observed under increased rates of irrigation interval for genotype CIP-392781.1. Alternate furrow irrigation method at eight days interval had resulted in the highest water productivity (13.20 kg/m3) for genotype Bubu while it is the lowest (8.70 kg/m3) for genotype CIP-392781.1 at six irrigation intervals with the same irrigation method. Moreover, 17.6% of irrigation water saved under alternate furrow irrigation methods at eight days interval could irrigate additional area of 0.25 ha to compensate reduced tuber yield as a result of deficit irrigation. For instance, applying alternate furrow irrigation method increased additional tuber yield of 8.77 ton that can earn additional returns to potato producers as compared to fixed furrow irrigation method. This suggests that for maximizing tuber yield under non-water stress scenario irrigation water could be used in fixed furrow irrigation method. However, under limited irrigation water scenario and high cost of irrigation water, irrigation could be applied in alternate furrow methodat six days interval to minimize water loss, maximize water productivity, and improving tuber yield in the study area and similar agro-ecology.