RESPONSE OF TWO SLENDER LEAF (CROTALARIA SPP) SPECIES TO WATERING REGIMES

Abstract

Slender leaf is an indigenous vegetable in Kenya. Two main species of slender leaf are Crotalaria brevidens and Crotalaria ochroleuca. Despite their healthy benefits they contain alkaloids and oxalates which in high amounts, are toxic to human. They bind calcium in the body leading to kidney stones. It is necessary to define the best watering regime so as to use water efficiently, since climate change threatens water sustainability. Two pot experiments were conducted between January and December 2014 in a tunnel in JKUAT to evaluate the effects of watering regime on the growth and yield of two slender leaf species and on their alkaloid and oxalate content at two growth stages (vegetative and reproductive). The treatments were the two species and 4 watering regimes (40%, 60%, 80% and 100% of 1500ml). Agronomic data (leaf number, height, girth, flowers and branch number) was collected on tagged plants weekly and subjected to analyses of variance. Alkaloid and oxalates content in the harvested leaves were gravimetrically determined. There was a significant interaction (p≤0.05) between the water regime and variety with respect to leaf number and branches. Watering regime had a significant (p≤0.05) effect on alkaloid content in the two varieties. Water deficit (40%) reduces yield and increases alkaloids and oxalates concentration which increases with plant age. Oxalates and alkaloids are significantly more in C. brevidens than C. ochroleuca. Recommended water regime is 60% after 3 days. C.ochroleuca can be consumed at both stages while C. brevidens at vegetative stage.

Key words: Slender leaf, Crotalaria brevidens, Crotalaria ochroleuca watering regime, alkaloid, oxalates