Differential Response of Two Soybean Cultivars to Paraquat
نویسندگان
چکیده
The soybean cultivars “ K w angkyo” and “H o o d ” are differentially sensitive to the bipyridylium herbicide paraquat (l,r-d im ethy l-4 ,4 '-b ipyrid in ium ion). This was confirm ed by visible injury observations, m easurem ents o f desiccation levels and chlorophyll conten t, and tracings o f chlorophyll fluorescence induction o f fully expanded first trifoliate leaves o f these two culti vars after exposure to a wide range o f paraq u a t concentrations. The m argin o f this intraspecif ic differential tolerance to paraquat was narrow and the ratio o f the pa raq u a t concentrations causing 50% injury to the to lerant K wangkyo and to the susceptible H ood soybean (approxi m ate tolerance factor) was found to be 10. P araquat a t 1 |im or higher inhibited rapidly the C 0 2 fixation capacity o f leaf mesophyll cells, isolated enzym atically from bo th cultivars. Thus, the tolerance o f Kwangkyo soybean to paraqua t does not appear to result from any differ ences at the site o f paraquat action in chloroplast m em branes. A t early time periods (30 min to 2 h) after treatm ent with 100 jim o f paraquat, chlorophyll fluorescence induction was com pletely suppressed in first trifoliate leaves o f H ood, bu t not in those o f K w angkyo soybean. At longer time periods (= 3 h), paraqua t suppressed chlorophyll fluorescence induction similarly in leaves o f both soybean cultivars. These results suggest tha t reduced m obility o r a delayed release o f paraquat in the mesophyll cells o f K w angkyo m ay be involved in the observed to ler ance o f this soybean cultivar to this herbicide.
منابع مشابه
Comparative Effects of Paraquat on Antioxidant Components and Scavenging Enzymes in Kwangkyo and Hood Soybean
The effect o f paraq u a t on hydroxyl radical production , glutathione and ascorbate content, and glutathione reductase and superoxide dism utase activities was assayed in the to lerant “K w angkyo” and the susceptible “ H o o d ” cultivars o f soybean [Glycine max (L.) Merr.]. Seed lings o f both cultivars a t the fully expanded first trifoliate leaf stage were treated with paraquat at 0, 1,...
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