Organic Mulches and Weeding Frequencies Effect on Weed, Growth, Yield and Yield Component of Onion (Allium cepa L.) at the district of Mekelle, Tigray, Ethiopia.

Abstract

Onion (Allium cepa L.) is produced for home consumption and as income sources for many smallscale farmers and commercial growers in Tigray. However, the yield of the crop is not as high as the crop potential due to biotic and abiotic constraints among those weed competition is the major. Therefore, an experiment was conducted from January to June 2024 during the irrigation season with the objective of evaluating the effects of organic mulches and weeding frequencies on weed, growth, yield and yield components of onion. The experiment was laid out in a randomized complete block design (RCBD) with 3 replications. The factors include three organic mulching (No mulching, Grass mulch and Wheat straw mulch) and 4 weeding frequencies (No weeding, single weeded, twice weeded and thrice weeded) made a total of 12 treatments. Results indicated that the highest marketable bulb yield (40.49 t ha-1), highest total bulb yield (41.5 t ha-1), longest plant height (63.8 cm), highest number of leaves per plant (20), longest leaf length (38.4 cm), highest average bulb weight (119.2 g), widest bulb diameter (7.1 cm), longest bulb length (6.4 cm), highest weed control efficiency (75.93 %) and highest weed control index (73.04%), was found in treatment (T8) combination of grass mulch and thrice weeded. The most frequent, abundant and dominant weeds were found to be Galinsoga parviflora cav. and Bidens pilosa L., with a frequency value of (100 % and 88.9 %,), abundance (20.1 and 12.3) and dominance (30.3% and 18.6%), respectively. The partial budget analysis of marketable bulb yield revealed that the highest marginal rate of return was obtained from (grass mulch combined with thrice weeded) with a percentage of marginal rate of return of (281.8%). The experiment was done for only one season at a single location and therefore it needs to be repeated over season and locations to make a conclusive recommendation.