Effect of bulb size and bulb cutting on growth and yield of onion (allium cepa l.) in two ecological zones of Ghana

Abstract

Two field experiments were carried out at Asante-Mampong and Hohoe research fields to assess the effect of bulb sizes and bulb cutting on growth and yield of onion (Allium cepa L.) using Bawku Red Onion. The experimental design used was Randomized Complete Block Design (RCBD) with nine (9) treatments and three (3) replications. The treatments were: Control (Bawku onion seed), SB (small bulb, 20-40 mm), BB (large bulb, 40-60 mm), 1/5 SB (small bulb, cutting at 20 %), 1/4 SB (small bulb, cutting at 25 %), 1/2 SB (small bulb, cutting at 50 %), 1/5 BB (large bulb cutting at 20 %), 1/4 BB (large bulb, cutting at 25 %) and 1/2 BB (large bulb, cutting at 50 %). Data were analysed using Genstat (11th Edition). The results show that the highest percentage of crop establishment (100%) was recorded from BB and 1/4 BB and the lowest percent of crop establishment (55.37%) was recorded from 1/5 BB at Mampong while at Hohoe 1/5 BB (97.94 %) observed the highest crop establishment and 1/4 BB recorded the lowest at 52.60 %. No significant difference was observed between onion seed and 1/2 at Mampong. 1/2 SB recorded highest number of leaves (5.74) and 1/5 SB (3.54) as the lowest at Mampong while at Hohoe 1/5 SB and 1/5 BB recorded highest number of leaves (5.44) and 1/4 SB (3.54) recorded lowest. No significant difference was observed between onion seed, SB, 1/4 BB and 1/2 BB at Mampong and between onion seed, SB and 1/2 SB at Hohoe. At Mampong, BB obtained the highest leaf height at 37.49 cm and 1/5 SB at 15.69 cm as the lowest. At Hohoe, 1/5 SB recorded the highest leaf height of 31.92 cm and 1/4 SB giving the lowest leaf height of 12.99 cm. No significant difference was observed between onion seed and 1/2 SB at Mampong and between onion seed and BB at Hohoe. The biggest neck diameter was observed by 1/2SB and BB at 1.415 cm and 1.31 cm in both experiments at Mampong and Hohoe respectively at 60 DAP while the smallest neck diameters (0.85 cm) were observed in both 1/5 SB and 1/5 BB at University of Education,Winneba http://ir.uew.edu.gh xiv Mampong and in Hohoe 1/4 SB (0.78 cm) recorded the lowest. No significant difference was observed between onion seed, SB, 1/4 BB and 1/2 BB at Mampong and between Onion seed, SB, 1/5 SB, 1/4 SB, 1/2 SB and 1/4 BB at Hohoe. highest plant height was recorded by BB (41.38 cm) while 1/5 SB (17.95 cm) recorded the lowest at Mampong. At Hohoe, 1/5 SB recorded the highest height (34.45 cm) and 1/4 SB the lowest (16.92 cm). Onion seed and BB observed no significant difference. The highest fresh bulb weight (72.95 g) was recorded by BB and the least (34.32 g) by 1/5 BB at Mampong. At Hohoe, the highest fresh bulb weight (65.20 g) was produced by 1/5 SB and the least fresh bulb weight (25.54 g) was produced by 1/4 BB. No significant difference was observed between Onion seed and 1/4 BB at Mampong. At Mampong experiment, SB had the highest bulb diameter (5.42 cm) and the least (3.12 cm) bulb diameter was from 1/5 BB. At Hohoe, 1/5 SB had highest bulb diameter (5.16 cm) and the least bulb diameter (2.16 cm) was from 1/4 BB. No significant difference was observed between Onion seed and BB and between 1/5 SB, 1/2 SB and 1/4 BB at Mampong. At Mampong, the highest bulb yield of 3.65 t/ha was recorded from BB and the least bulb yield of 1.72 t/ha was from 1/5 BB while in Hohoe 1/5 SB (3.28 t/ha) recorded the highest bulb yield and least was from 1/4 (1.27). Based on the study it is therefore recommend that farmers use BB (40 – 60 mm) as planting materials, to obtain high bulb yield