Ameliorative impact of salicylic acid on growth of Abelmoschus esculentus var. Clemson spineless under aluminium toxicity

Abstract

The objective of the present study was to protect the growth of Abelmoschus esculentus var. Clemson spineless (okro) using salicylic acid (SA) in soil subjected to aluminium (Al) toxicity and Al chelated with
-1 ethylenediaminetetraacetic acid (EDTA). Okro plants were grown in soil contaminated with Al (1.5g kg^-1 ) in the following combinations: Al, Al+SA, Al+EDTA, Al+SA+EDTA and a control (water). The growth parameters were studied over a period of ten weeks while the total sugar and total chlorophyll contents were determined at the 10^th week of growth. Al toxicity caused significant reductions (57-84%) in all growth parameters (plant height, fresh and dry shoot weight, fresh and dry root weight, leaf area, stem girth, fruit fresh and dry weight, fruit number) except the Net assimilation rate, Leaf area ratio and Relative growth rate. Treatment of stressed plants with SA improved the growth parameters by 17 - 165%, total soluble sugar by 140% and total chlorophyll by 22%. Plants subjected to chelated Al (EDTA + Al) exhibited much greater reductions in growth than those grown in Al only. Treatment of stressed plants with SA under chelated Al toxicity (Al + SA + EDTA) improved the Growth parameters by 18% - 150%, total sugar by 130% and total chlorophyll by 140% but the impact was less than that of non chelated Al (Al+SA). Al toxicity caused marked reductions in growth parameters, chlorophyll and sugar contents but chelating Al with EDTA resulted in much more decrease in these parameters. SA exhibited higher ameliorative capacity when plants were exposed to non chelated Al toxicity.

Key words: Al toxicity, EDTA, Salicylic acid, Growth, Chlorophyll.