Effect of variety and earthing-up frequency on growth, yield and quality of potato (Solanum tuberosum L.) At bure, north western Ethiopia

Potato (Solanum tuberosum L.) is one of the most important vegetable tuber crops produced in Ethiopia. Yield and productivity of the crop has been far below the world average owing to several factors including lack of high yielding varieties and inappropriate agronomic practices observed in most farmers’ fields. Thus, a 3x5 factorial experiment arranged in Randomized Complete Block Design (RCBD) with three replications was conducted at Bure Woreda, western Zone of Gojjam from December 2010 to April 2011 to assess the effect of variety and earthing-up frequency on growth, yield and quality of potato. Three different varieties (Belete, Zengena and Gera) and five earthing-up frequencies (no earthing-up, one time, two times, three times and four times earthing-up) were used in the experiment. The results revealed that varieties and earthing-up frequency significantly (P<0.05) affected total tuber number per plant. The maximum total tuber number per plant (15.82) was recorded by Zengena variety and three times earthing-up frequency (15.58),while the lowest tuber number per plant (11.46) was recorded by Gera variety and, from plants grown without earthing-up (11.13). Significantly the highest total tuber yield and the maximum tuber yield per ha (38.32 and 34.05 t/ha) were recorded by variety Belete and three times earthing-up frequency, respectively, while the lowest (24.43 and 30.07 t/ha) was recorded by Gera variety and no earthing-up, respectively. Significantly maximum marketable tuber number (8.9 and 10.5/plant) was obtained by Belete variety and three times earthing-up frequency, respectively. Variety and earthing-up frequency also showed significant effect on marketable yield per ha. The maximum marketable yield (27.27 and 27.23 t/ha) was recorded by Belete variety and three times earthing-up frequency, respectively. The maximum unmarketable yield (11.06 t/ha) was recorded by Belete variety and no earthing-up (10.72 t/ha), while the lowest unmarketable yield (4.39 t/ha) was recorded by Gera variety and four times earthing up frequency (6.03 t/ha). Total yield per hectare was highly significantly and positively correlated with marketable yield per hectare (r=0.86**), total tuber number per hectare (r=0. 57**) and number of marketable tuber per ha (r=0.39**). Significantly (P<0.05) the highest leaf area index (3.17) was recorded by Belete variety, while the lowest (2.30) was obtained from Gera variety. Similarly, leaf area index was highly significantly and positively correlated with tuber yield per ha (r=0.71**), total tuber number per hectare (r=0.46**), and marketable yield per ha (r=0.51**). The result of this study verified that growth, yield and quality of potato are influenced by variety and earthing up frequency. It can be concluded that Belete variety and three times earthing-up frequency produced higher total yield and marketable yield per hectare than other varieties and earthingup frequencies. Thus, variety Belete and three times earthing-up frequency after complete plant emergence can be used at the study area, for the better marketable yield and quality potato production. Since the experiment was conducted for one season and in one location, further research, involving different varieties, growing seasons and location, may be suggested to come up with conclusive result.