Evaluation of Five Varieties of Onion (Allium cepa L.) In Two Different Savannah Ecozones in Ghana

Abstract

Two separate field experiments were conducted at Sogakope (Tordome), in the South-Tongu District of the Volta Region and at the University of Ghana Research farm, Legon, in the Greater Accra Region from August, 2017 to March, 2018. The aim of this study was to evaluate the yield performance of four introduced varieties of onion namely, Dayo, Trophy, Red-Creole, and Orient against the commonly grown variety ‘Bawku-Red’ under two different ecozones in Ghana. The experimental design used was a randomized complete block design (RCBD) with five (5) treatments and four (4) replications. The varieties represented the treatments. The data collected was subjected to analysis of variance (ANOVA) using GenStat 9th Edition Software. Means which differed significantly were compared using the Fisher’s Protected Least Significance Difference (LSD) at probability level of 5% of significance (P=0.05). Correlations analysis were done to determine the associations among parameters. The results showed that variety “Orient” performed better than the other varieties followed by “Trophy” in terms of vegetative growth, reproductive growth, bulb quality and bulb yield than “Bawku-red” in both locations. For vegetative growth, the highest number of leaves were recorded in “Orient” (7.0) and “Trophy” (7.0) at 8 WAT. Highest plant height were also registered in “Red-creole” (46.4 mm) and “Orient” (60.1 mm) at Sogakope, and Legon respectively. The biggest plant stem was obtained both in “Orient” (13.59 mm) and (12.40 mm) at Sogakope and Legon respectively. For reproductive parameters, the longest bulb length was obtained in “Trophy” (52.3 mm) followed by “Red-creole” (49.6 mm). “Trophy” plants yielded bulbs having significantly thicker necks (13.09 mm) compared to plants from all the other cultivars. The highest average bulb weight was obtained from “Orient” at both sites followed by “Trophy” at Legon. The biggest marketable bulb weight was registered by “Orient” (533 g) followed by “Red-creole” (441 g). For bulb quality, “Bawku-red” presented a dark maroon color, “Orient” presented maroon color and “Trophy” presented regatta color, while “Dayo” and “Red-creole” both presented the same mulberry colour. In terms of bulb form, “Bawku-red”, “Red-creole” and “Orient” produced thick flat bulbs, while “Dayo” and “Trophy” produced globe bulbs. At 4 week after harvesting, “Orient” (12.85) was significantly higher than the rest of varieties in terms of sugar content followed by “Bawku-red” (12.02) at Sogakope. While at Legon, “Bawku-red” (14.93) contained more sugar than the other varieties followed by “Orient” (13.20). The varieties “Orient”, “Red-creole” and “Bawku-red” had long shelf life compared to “Trophy” and “Dayo” which had short average shelf life. For bulb yield, “Orient” gave the highest yield of (8.22 t/ha) at Sogakope and (7.19 t/ha) at Legon followed by “Trophy” (8.1 t/ha) at Sogakope and (6.05 t/ha) at Legon. Total bulb yield, had positive and highly significant correlation with average bulb weight (1.00**), bulb weight (1.00**) and bulb diameter (0.82**) at Sogakope. It also had significant positive association with bulb length (0.50*). At Legon, bulb yield had a strong significant positive association with bulb length (1.00**), bulb neck (0.94**), bulb weight (0.60**), bulb firmness (1.00**) and plant height (0.59** and 0.63**). Variety Orient may therefore be recommended as an additional variety for planting in the Southern sector of Ghana.