Growth and yield response of cassava varieties ( <i>Manihot esculenta</i> Crantz) to nitrogen fertilization across contrasting agroecology in Southern Ethiopia

Abstract

Abstract Cassava ( Manihot esculenta Crantz) plays a crucial role in mitigating food problems; however, its productivity is affected by low soil fertility, especially nitrogen deficiency, which is a major constraint to crop growth and yield. The study aimed to evaluate the effects of nitrogen fertilizer and cassava varieties on the agro‐morphological traits and root yield across different locations. The experiment was conducted at Hawassa, Belela, and Bilate in Sidama and South Ethiopia during the 2022 and 2023 growing seasons. The treatment consisted of four cassava varieties (Hawassa 04, Qulle, Chichu, and Kello) and three levels of nitrogen fertilizer (0, 50, and 100 kg N ha −1 ). The experiment was arranged in a Randomized Complete Block Design with a 4 × 3 factorial arrangement and three replications at each location. Results showed significant improvements in growth traits and root yield parameters due to nitrogen application and varietal difference. Among the tested varieties, Chichu consistently produced the higher yield across locations. The application of 100 kg ha −1 nitrogen at the Bilate location produced the greatest root yield of Chichu by 90.61% increment over unfertilized plot of Qulle. For Hawassa and Belela, Chichu with 50 and 100 kg ha −1 N applications can be recommended for cassava yield, respectively. The observed variation among varieties and locations highlights the genetic differences and the influence of environmental conditions on cassava performance. Higher nitrogen rates likely enhanced vegetative growth, leading to increased storage root development. Optimizing these factors, farmers can improve productivity and contribute to food security.