COMPARATIVE PHYTOTOXICITY OF SOME BENZOXAZINOIDS ON THE EARLY GROWTH OF SELECTED WEEDS

Abstract

Benzoxazinoids (or hydroxamic acids), the naturally occurring secondary plant metabolites, mainly in
graminceous crops exhibit great structural diversity. The present study explored the phytotoxicity of five
selected benzoxazinoids viz. 2-benzoxazolinone (BOA), 3-Methyl-2-benzoxazolinone (Me-BOA), 2-H-1, 4-
benzoxazin-3(4H)-one (H-BOA), 6-Methoxy-2-benzoxazolinone (M-BOA) and 6-Hydroxy-2-benzoxazolinone
(Hy-BOA) on the early growth (in terms of root shoot length) of three weeds namely Cassia occidentalis L.,
Echinochloa crus-galli (L.) Beauv. and Phalaris minor Retz. The results clearly indicate the negative influence
of benzoxazinoids on weed growth. The effect in all cases was a function of concentration. In all test plants
maximum effect was observed with the treatment of Me-BOA and M-BOA, followed by Hy-BOA, H-BOA and
least incase of BOA. Seeds of E. crus-galli and P. minor were found to be more sensitive to benzoxazinoid
treatment as compared to C. occidentalis