The Action of Sirmate (3,4-dichlorobenzyl Methylcarbamate) on Chloroplast Ribosomes of Triticum Vulgare L. Seedlings

The most striking response of light-grown wheat seedlings to sublethal doses (0.1 m) of the herbicide Sirmate (3,4-dichlorobenzyl methylcarbamate) was the formation of achlorophyllous leaves. This herbicide did not inhibit seed germination and the leaves emerged normally, except that they had a bleached appearance. After 9 days, these plants died, presumably of starvation due to depletionofendosperm reserves. Postemergent application of Sirmate directly on plants caused contact injury or necrosis but did not induce chlorosis of mature green leaves. The mechanism of Sirmate's herbicidal action is still unknown, although Herrett and Berthold (5) suggested that Sirmate inhibited chlorophyll synthesis in light-grown seedlings, whereas in dark-grown plants the carotenoid pigments were not affected, quantitatively or qualitatively, by the Sirmate treatment. In the present investigation, we examined the effect of Sirmate on chloroplast ultrastructure and on the ribosomal population of darkand light-grown wheat seedlings.