Evaluation of row spacing and mulching on weed control, growth and yield of green pepper in Busia County, Kenya
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Green pepper (Capsicum annuum) is one of the most important and remunerative vegetable crops. Row spacing and mulching are important factors that influence water use, weed suppression, growth, quality, and yield of vegetables. Due to increased pressure on land, climate change and increased demand for vegetables, there is need for deployment of optimal agronomical practices that will ensure enough food production. This study was undertaken to determine the optimum spacing and mulching for higher yields of green pepper in Kenya. The experiment was conducted during the long rainy season of 2015 (March-August) and validated during the short rainy season of 2015 (September-December) at Alupe sub-station of the Kenya Agricultural and Livestock Research Organization (KALRO). It was laid out in a randomized complete block design with factorial arrangement and treatments replicated three times. Two varieties of capsicum were used, California Wonder and Yolo Wonder under three spacings (50 × 40 cm, 40 × 40 cm, and 30 × 40 cm) and three types of mulches (black polythene mulch, transparent polythene mulch and straw mulch) while bare soil was used as the control. Data was collected on seedling vigor, plant height, number of leaves/plant, number of branches/plant, number of flowers/plant, stem girth, weed species/plot, weed vigor/plot, weeds fresh weight, weeds dry weight, fruit mass/plot, seed number/fruit, fruit length, fruit diameter, fruit number/plant and fruit number/plot. The collected data was subjected to Analysis of variance using SAS statistical software and where significant differences were observed means were separated using LSD at P≤0.05. Both green pepper varieties responded similarly to the treatment with mulching types showing significant (P≤0.05) differences in most of the growth, weed control and yield parameters. The black polythene mulch was the best mulch material in weed suppression by allowing the lowest weed biomass (207 g/m2) and number of weed species (<3) while the control plot had a mean of 1629 g/m2 of fresh weed biomass and an average of 8 weed species per m2. The effect of different plastic mulches on fruit mass per plant was significant at P≤0.05 where the black plastic polythene mulch had the heaviest fruits during the short rains (924.5 g/plant) and during the long rains season (649.8 g/plant). The transparent polythene mulch led to most vigorous plant growth during the early stages while the straw mulch had the greatest vigor in later stages. All the mulch materials were superior in suppressing the weeds compared to the bare soil in all the sampling stages. The row spacing exhibited significant influence on most parameters except the number of branches per plant, fruit fresh weight, fruit mass, fresh weed biomass and average weed dry weight. The number of weed species were highest in the widest row spacing with a mean of 5 different species per 1 m2 quadrat while the other treatments had lower than 4 species. A maximum of 1878 g/ m2 of fresh weed biomass was observed under the widest row spacing of 50×40 cm during the short rains season while only 1269 g/m2 being observed on the 30×40 cm row spacing at 4 weeks after transplanting (4 WAT). The plant spacing had significant variation in all the growth and yield components except for fruit length. In both seasons, the number of branches per plant, stem girth and number of fruits per plant significantly increased with increasing plant spacing but the plant height, number of leaves per plant, fruit breadth and yield per plant significantly increased with the decreasing plant spacing. Therefore mulching is an appropriate technology to increase the green pepper production in Kenya and even under the tropical conditions.