Lorvlie Gay, Marie Claudette Georges, Jean VilioRomélus and Ludger Jean Simon*
College of Agriculture and Environmental Sciences, American University of the Caribbean (AUC)
Pierre Toussaint Campus, Route Nationale No. 2, Charpentier, Les Cayes, Haiti.
Key words.Cleome viscosa, Cyperusrotundus, Digitariasanguinalis, bulb yield, plant height.
Abstract. Onion is an important vegetable crop in Haiti. A field experiment was conducted at Ducis, South Haiti, during the 2015- 2016 vegetable season to study the effect of locally available mulching materials on bulb yield and quality of onion. Yellow Granex onion alaçatı escort seedlings were field transplanted on January 9, 2016 in a randomized complete block design of four treatments (unmulched onion, cassia leaf mulch, vetiver root mulch, and wood shaving mulch) and four replications. The variables measured were onion plant height and number of leaves per plant at bulb initiation, density of the dominant weeds (Cleome viscosa, Cyperusrotundus, and Digitariasanguinalis) at 35 and 51 days after transplanting (DAT), bulb yield, bulb rot, and thick neck at harvesting (92 DAT).
Pearson correlation, analysis of variance and least significant difference tests were performed at 5% alpha error. Onion plant height ranged from 49.45 cm for cassia leaf mulch to 57.75 cm for vetiver root mulch (p=0.0042). No significant difference was detected between vetiver root mulch and wood shaving mulch. Neither was there significant difference between cassia leaf mulch and unmulched onion. The average number of leaves per plant ranged from 5.25 for cassia leaf mulch to 5.85 for vetiver root mulch, without significant differences between treatments (p=0.4696). No significant buca escort weed density differences were detected at 35 DAT for C. viscosa and C. rotundus.In contrast, D. sanguinalisdensity was higher for unmulched onion (70 plants m-2) than the other treatments (p=0.0018), without significant differences between cassia leaf mulch (7 plants m-2), vetiver root mulch (3 plants m-2) and wood shaving mulch (0 plant m-2). At 51 DAT, significant weed density differences were detected for all three dominant weed species. C. rotundus density was lower for wood shaving mulch compared to cassia leaf mulch and unmulched onion (p=0.0193), without significant difference with vetiver root mulch. D. sanguinalis density was highest (47 plants m-2) for unmulched onion (p=0.0009), without significant differences between cassia leaf mulch (16 plants m-2), wood shaving mulch (4 plants m-2) and vetiver root mulch (4 plants m-2). Likewise, C. viscosa densityat 51 DAT was highest (22 plants m-2) for unmulched onion (p=0.0149), without significant differences between cassia leaf mulch (4 plants m-2), wood shaving mulch (2 plants m-2) and vetiver root mulch (2 plants m-2). Total bulb yield ranged from 21.88 t ha-1 for cassia leaf mulch to 34.47 t ha-2 for wood shaving mulch (p=0.0025). There was no significant total yield difference between vetiver root mulch (27.50 t ha-1) and unmulched onion (29.02 t ha-1).When the onion bulbs were graded into small (diameter less than 5 cm), medium (diameter of 5- 7.5 cm) and large (diameter greater than 7.5 cm), significant differences were detected between mulch treatments. Cassia leaf mulch resulted into the highest small bulb yield (p=0.0262), without significant differences between vetiver root mulch, wood shaving mulch and unmulched onion.Yield for medium bulbs ranged from 14.82 tha-1 for cassia leaf mulch to 27.06 t ha-1 for woodshaving mulch (p=0.0038). Medium bulb yield for vetiver root mulch and unmulched onion were respectively 20.09 t ha-1 and 24.55 t ha-1, without significant difference between the two treatments. The large bulb yields ranged from 0.0 t ha-1 for cassia leaf mulch to 3.04 t ha-1 for wood shaving mulch (p=0.0441). No significant difference was detected between wood shaving mulch and vetiver root mulch. Neither was detected significant difference between cassia leaf mulch and unmulched onion. Vetiver root mulch resulted into the highest percentage (3.28%) of bulb rots (p=0.0292). No significant bulb rot differences were detected between wood shaving mulch (1.89%), cassia leaf mulch (1.19%) and unmulched onion (1.48%). No significant thick neck differences were detected between treatments (p=0.2280), ranging from 0.44% for unmulched onion to 1.05% cassia leaf mulch.Total bulb yield was directly correlated to number of medium bulbs (r=0.81,p=0.0002) and number of large bulbs (r=0.50, p=0.0460)harvested, and indirectly correlated to density of C. rotundus at 51 DAT (r=-0.51, p=0.0444) and number of small bulbs harvested (r=-0.88, p<0.0001). The results of this experiment show that wood shavings and vetiver roots can be effectively used as mulching materials to control weeds, promote vigorous plant growth and increase bulb yields in onion.
*Corresponding author
ljeansimon@auc.edu.ht
