Effects of Time of Earthing up and Varieties on Growth, Yield and Quality of Potato (Solanum tuberosum L.) in Southern Zone of Tigray, Northern

Abstract

Potato is the fourth largest food crop globally, following rice, wheat, and maize. In Ethiopia, it serves as both a food and cash crop, playing a vital role in improving the livelihoods of smallholder farmers, especially in the highlands. However, productivity remains low due to factors such as limited knowledge on optimal agronomic practice particularly time of earthing up and the use of low yielding varieties. This study evaluated the effects of time earthing up time and varieties on growth, yield and quality of potato. The experiment was conducted under irrigation from February to June 2024 in Southern Tigray, Northern Ethiopia, using a Randomized Complete Block Design (RCBD) with factorial combinations and three replications. Treatments included four time of earthing up (Control, 15, 30, and 45 days after complete emergence) and three varieties (Local/Tebeb, Gudenie, and Belete). Results showed that the time of earthing up and varieties, and also their interaction effects had showed significantly influenced (P < 0.05) on growth, yield and quality parameters. Earthing up at 15 days after complete emergence was recorded the tallest plants (81.02 cm), the highest average tuber weight (52.62 g), number of large size (22.59), specific gravity (1.220) and dry matter content (24.40%), lowest number of unmarketable (4.4) and number of greening tubers (1.669) compared to the control (no earthing) and late earthing up. Gudenie recorded the highest number of stem (10.750), plant height (79.20cm), number of large size tuber (18.06), weight of large size tuber (1136.8 g), dry matter content (22.86%) and the lowest number of unmarketable tuber (2.683) that compered to local (Tebeb) varieties. The combination of Gudenie variety with 15 days earthing up was obtained highest total tuber number (33.80), total tuber yield (31.90 t/ha) and marketable yield (31.11 t/ha), whereas the lowest marketable yield (10.89) and total tuber yield (14.05) was from the combination of local (Tebeb) with no earthing up. Correlation analysis revealed strong positive relationships between average tuber weight and both marketable (r=0.791) and total tuber yield (r=0.84), whereas greening negatively affected on yield performance. Economic evaluation demonstrated that the Gudenie variety, when earthed up at 15 days after complete emergence, achieved maximum profitability, with a net benefit of 1,185,496 ETB/ha and a marginal rate of return of 1,520%. These findings suggested that the combination of Gudenie with 15 days earthing up was recommended for potato production in the study area and similar agroecological zones. However, further research across multiple locations, seasons, and years was necessary to validate and generalize these recommendations.