Phytotoxic effect of 2-benzoxazolinone (BOA) against some vegetable crops.

Benzoxazolin-2(3H)-one (BOA) is a well known allelochemical that is being explored for its herbicidal activity. However, not much is known about its effect on crop plants. The present study investigated the effect of BOA on germination and early growth of four vegetable crops viz. Pisum sativum L., Raphanus sativus L., Brassica oleracea L. var. botrytis and Brassica oleracea L. var. capitata. At 1000 microM, germination of P. sativum, R. sativus and B. oleracea var. botrytis was reduced by more than 50%, whereas that of B. oleracea var. capitata was completely suppressed. Further, BOA reduced the root and shoot length of the test plants by approximately 40-82% and approximately 55-85%, respectively. In general, the effect was more pronounced on the root (approximately 82% in B. oleracea var. botrytis) than on the shoot growth (approximately 73% B. oleracea var, botrytis). 2-Benzoxazolinone significantly enhanced the contents of proteins (by 6-28%) and carbohydrates (by 61-189%) in B. oleracea var. capitata and decreased the activities of related enzymes like proteases (by 13-36%), alpha-amylases (19-60%) and beta-amylase (25-70%). The observed decline in the activities of hydrolytic enzymes amylases suggest that BOA interferes with the vital metabolic processes in the germinating seedlings leading to growth reduction. The study reveals that BOA interferes with the germination and early seedling growth of vegetable crops and induces biochemical alterations.