Effect of seed tuber size and intra row spacing on yield and quality of potato (Solanum tuberosum L.) Varieties at nono benja, jimma zone

A field experiment was conducted at Nono Benja District from December 2013 to May 2014 under irrigation to assess the response of different sizes of seed tubers and intra row spacing on yield and quality of potato varieties. The treatments consisted of factorial combination of two varieties (Jalenie and Gudenie), five levels of tuber sizes (20-35, 36-50, 51-65,66-80 and 81-95g) and five levels of intra row spacing (20, 25, 30, 35 and 40 cm). The treatments were arranged in a split-split plot design with three replications. There were a significant interaction effect of varieties, intra row spacing and tuber sizes (P<0.05) on plant height, number of main stems per plant, average tuber weight, tuber number per plant, total tuber yield, marketable tuber yield, unmarketable tuber yield, large tuber mean yield, medium tuber mean yield, small tuber mean yield. Variety by tuber size and intra row spacing was also influenced dry matter content and tuber specific gravity.The interaction effects of intra row spacing and seed tuber size was significantly (P<0.05) influenced the number of days to emergence. The days to flowering was also significantly (P<0.05) influenced by interaction effect of variety and intra row spacing. The highest plant height (80.38 cm) was recorded with variety Gudenie using tuber size of 66-80 g and planted at intra row spacing of 35 cm. The highest (9.79) number of main stems was recorded with variety Jalenie using tuber size of 81-95 g and planted at intra row spacing of 40 cm.The highest total tuber yield (24.84 t/ha) was recorded from Jalenie variety with tuber size 66-80 g and planted at intra row spacing of 25 cm. The highest (10.18 t/ha) larger tubers was recorded with variety Gudenie using tuber size of 66-80 g and planted at 25 cm. Variety Jalenie with tuber size of 66-80 g and planted at 25 cm produced the highest (8.04 t/ha) medium sized tubers. The highest small tuber (8.59 t/ha) was recorded from both varieties with intra row spacing of 20 cm and tuber size 81-95 g. Variety Gudenie planted at intra row spacing of 40 cm gave higher (19.98%) dry matter content and variety Gudenie using tuber size of 66-80 g gave higher (20.61%) dry matter content. The higher (1.077) tuber specific gravity was obtained with variety Gudenie planted at intra row spacing of 35 and 40 cm and also the higher (1.074) tuber specific gravity was registered with variety Guidene using tuber size of 66-80 g and/or 81-95 g and planted at intra row spacing of 40 cm. Number of main stems (r = 0.15*), tuber number per plant (r = 0.63**), average tuber weight (r = 0.23**), marketable tuber yield (r =0.95**) and unmarketable tuber yield (r = 0.18*) was positively correlated with total tuber yield. Average tuber weight (r = 0.36**) positively associated with marketable tuber yield, small tuber (r =- 0.40**), medium tuber (r = 0.44*). Large tuber negatively associated with dry matter content (r = -0.39**) and tuber specific gravity (r = -0.34**). Smaller tuber was positively correlated with Dry matter content (r = 0.50**) and tuber specific gravity (r = 0.56**). Dry matter content positively associated with tuber specific gravity (r = 0.88**). Generally, the use of intra row spacing 25 cm and tuber size of 66-80 g are advisable for the production of higher tuber yield of variety Jalenie, and variety Gudenie suggested for quality potato production at Nono Benja area.