Low yields and yield instability due to the use of old land races were limiting sweet potato production by resource-poor farmers in the zone. The Experiment was conducted at Bore Agricultural Research Center during 2018 and 2019 summer cropping season at Adola sub station and on-farm with the objective of identifying the cultivars, which could have wide or specific adaptations, and to select and recommend adaptable, frost and disease tolerant and high yielding orange type sweet potato cultivars for midlands of Guji Zone. To this effect four (Kaboli, Naspot 12, Naspot 13, Kaboli and local) improved orange varieties of sweet potato, Ipomoea batatas L., based on their yield and disease resistance performance were tested in RCBD with three replications with the spacing of 100cm*30cm between rows and plants, respectively. A widely cultivated variety (Local) was included as check. The combined analysis of variance across locations showed significant variation among genotypes and locations interaction for the number of roots, root weight, marketable yield, unmarketable yield and total storage root yield (t/ha). Based on this, the maximum mean value of root number per plot (21.33, 36.66 and 21.33) was recorded from Naspot-13, Naspot-12 and Naspot-13 variety at Dufa, Boke and Gobicha sites, respectively. However the minimum (16.00, 19.33 and 16.00) mean value of root number was recorded from Local Variety across locations. The maximum fresh root weight (670.33g and 444g) was recorded for Kabode and NASPOT-13 Variety over locations. On the other hand, the lowest fresh root weight (447.33, 437.33g and 296.33g) was recorded by Kaboli variety at all locations. The highest mean value of total root yield (65.09 t ha-1 and 59.88 t ha-1) was recorded by Naspot-13 at Dufa and Gobicha locations in 2018 and 2019 cropping seasons. While Naspot-12 gave maximum (55.16 t ha-1) total root yield at Boke location. However Kaboli gave the least (43.09, 27.19 and 37.69 t ha-1) total root yield over locations and years. Therefore Naspot 13 and Naspot-12 sweet potato varieties were more adaptable, disease tolerant and high yielder and should be promoted to farmers of the study areas for optimum production.

The experiment was conducted at Bore Agricultural Research Center on station for three consecutive years' main cropping seasons with the aim to adjust planting date and fertilizer rate for Irish Potato production. Four level of fertilizer rate (0, 61.5, 82, and 114 kg Nitrogen and 0, 69, 92, and 115kg P ha-1 and planting date Immediately rain season (T1), 7days after rain (T2), 15days after rain (T3), 3 weeks later (T4). The treatments were arranged in RCBD in factorial arrangement with 3 replications. Tubers were planted on plot size of 4 m x 5m at spacing of 1m between plot, 1.5m b/n block, 70 cm between rows and 30cm between plants. The variety used in this experiment was Gudane. Based on the combined analysis of variance treatments over three consecutive years indicated that interaction effect of Planting Date and Different Fertilizer Rate significantly (P<0.001) affected Days to 50% emergency, maturity, plant height, stem number, number of tubers, and fresh tuber yield. However, parameters days to flowering and average tuber weight are non-significant (P<0.05) difference between each treatment means. The combined effect of immediate planting date (T1) with control (no nutrient) treatment (R1) recorded shortest (9.55 days) to emergency and early days to maturity (104.22days). And also regarding plant height the maximum (74.28 cm) plant height was recorded for treatment planted at first planting date with combined nutrient application of 114 kg N* 115 kg P. The interaction effect of immediate planting date with 82 kg N*92 kg P 2 O 5 shows significant (P<0.05) maximum (9.1) stem number of potato. The maximum number of tubers (9.88, 9.66 and 9.44) was observed when tubers were planted at first week and applied with 82 kg N+92 kg P; 114kg N+115 kg P and second week with 82 kg N+92 kg P of fertilizer rates respectively. The highest Total tubers yield (41821 kg ha-1 and 41395 kg ha-1) were obtained from T 1 R 3 (Immediate planting with combined nutrient of 82 kg N* 92 kg P 2 O 5) and T 2 R 3 (Immediate planting with combined nutrient of 82 kg N* 92 kg P 2 O 5) respectively.