STUDY ON THE COMBINED EFFECT OF NPSB FERTILIZER RATES AND VARIETIES ON GROWTH, YIELD AND YIELD COMPONENTS OF GARLIC (Allium sativum L.) IN GUMMER DISTRICT OF GURAGE ZONE, ETHIOPIA

Abstract

Garlic (Allium sativum L.) is one of the major horticultural crops known worldwide with respect to its production and economic value. It is also the main bulb crop produced in Ethiopia, including the southern region. However, farmers are producing garlic from locally available varieties without or with low rates of fertilizer input which results in low yield. Therefore, this experiment was conducted to evaluate the response of garlic varieties to different rates of NPSB. Three improved garlic varieties (Kuriftu, HL and Tseday) and one local cultivar (‘Tuma”) and four levels of NPSB fertilizer rates (0, 144, 244, 344 kg NPSB ha ˡ ) were used. The experiment was arranged in a 4 X 4 factorial experiment under a Randomized Complete Block Design (RCBD) with three replications. Plant height (cm) and leaf number were significantly influenced by the interaction effect of varieties and NPSB fertilizer except leaf length (cm) that was significantly influenced only by the main effect of variety and NPSB. All yield and yield related traits were significantly influenced by the interaction effect of varieties and NPSB fertilizer rates except days to 50% emergence and bulb weight (g) that were significantly influenced only by the main effect of variety and NPSB. The highest total bulb yield was obtained from variety Kuriftu (8.81 t ha ˡ ) at the NPSB rate of 244 kg ha ˡ , and the lowest recorded from the local cultivar (5.52 t ha ˡ ) without NPSB (0 kg) fertilizer application. The maximum plant height (74.17cm) was recorded from variety HL at 244 kg/ha NPSB and the highest number of garlic leaves (10.33) were obtained from variety Kuriftu that received the highest NPSB rate of 344 kg/ha. The longest leaf was recorded from variety Tsedey (34.875cm) which was followed by variety Kuriftu (34.154cm) and HL (32.596cm). The highest statistically significant bulb weight was recorded equally from variety Kuriftu, Tsedey and HL 43.42g, 42.77g and 41.92g respectively. Marketable bulb yield was very highly significant (P<0.001) and positively correlated with leaf number (r =0.68***), bulb weight (r =0.64***), bulb diameter (r =0.72***), and highly significant (P<0.01) and positively correlated with plant height (r =0.41**) and leaf length (r =0.46**). The cost benefit analysis indicated that variety Kuriftu with the application rate of 244 kg NPSB ha ˡ gave the maximum MRR (1974.3%).