Optimizing nitrogen fertilizer rates for selected hot pepper varieties (Capsicum annuum L.) under dryland conditions in Asaita, Afar Region, Ethiopia

The northeastern Ethiopian (Afar Awash basin, including the Asiata district) soils are deficient in macronutrients like Nitrogen and affected by ongoing alkaline problems. At the same time, it is characterized by high salinity and low nitrogen tolerance. These have effect on growth, yield, and NUE of Solanaceae in general, and hot pepper in particular. However, studies on the effects of variety and inorganic nitrogen fertilizer rates on the growth, yield, and NUE of green pods of hot Pepper are scant in the study area. Therefore, a field experiment was conducted to determine the optimal nitrogen fertilizer rate that maximizes fruit yield and nitrogen use efficiency of selected hot Pepper ( Capsicum annuum L.) varieties under irrigated dryland conditions in Asaita district during the 2021/22 cropping season. The treatments consisted of four hot pepper varieties (Marko Fana, Melka Awaze, Melka Shola, and Irta Ale F1) and four nitrogen fertilizer rates (0, 23, 46, and 69 kg ha ^− 1 ). They were laid out in a 4x4 factorial arrangement in a randomized complete block design with three replications. The ANOVA result show that Pod length, pod diameter and 50% days of flowering were highly significantly (P < 0.001) affected by interaction effect variety and nitrogenous fertilizer rate; plant height, number of pod per plant and total pod yield were highly significantly (P < 0.001) affected by main effect of nitrogen fertilizer rates whereas marketable pod yield per plot and nitrogen use efficiency were highly significantly (P < 0.001) affected by main effect of variety. On the other hand, the number of branches per plant and the unmarketable green pod yield per plot are considered. Above-ground biomass and harvesting index were found to be statistically non-significant due to the main and interaction effects of variety and nitrogen fertilizer rates. The Maximum total green pod yield (8.30 kg/plot) and NUE (9.40 g g ^− 1 ) were obtained with the height application rate of nitrogenous fertilizer ha ^− 1 and the Irta Ale F1 variety, respectively. Therefore, the improved green pod yield and nitrogen use efficiency achieved through the application of nitrogenous fertilizer and the use of the Irta Ale F1 variety are important for ensuring sustainable hot pepper production and productivity.