Efficacy of Guava (Psidium guajava) Mulch Allelopathy in Controlling Tomato (Solanum lycopersicum) Weeds

Abstract

Tomato (Solanum lycopersicum) is one of the most important vegetable crop whose production involves the use of synthetic herbicides with detrimental impact on biodiversity. Allelopathy effectively controls horticultural crop weeds. Different plant parts (flowers, leaves, stems, bark, roots) have allelopathic activity that varies over a growing season when used as mulch.  Mulching is a horticultural technique that protects the roots of plants from heat and cold by use of mulch to cover the soil surface around plants. Tomato production in Kakamega County is below 2% and weeds are ranked high among the yield reducing factors. This study assessed the allelopathic effect of guava leaves mulch type (18.0 cm thick) as a management tool for weed control in tomato crops and no mulch as control treatment with three most popular determinate tomato varieties. The mulch treatments were arranged as factorial in a Randomized Complete Block Design (RCBD) to minimize non–experimental bias. Tomato variety sub-treatments were replicated three times in the experimental plots at Masinde Muliro University of Science and Technology (0⁰17¹N, 34⁰45¹E). The field project was conducted during the short rains and long rains season of 2016-2017. Data obtained was subjected to analysis of variance (ANOVA) using SAS software, version 9.3 at p<0.05 confidence level. Least Significance Difference (LSD) was used to separate the means. Weed density incidence was significantly highest in control plots up to 100% and lowest in mulched plots (13.41%). Allelopathic control of weeds sustains global food and nutrition security for future generations.