Viable pollen grains and eggs are necessary for processes of pollination, fertilization, and embryo formation for seed production. Various staining techniques were used to estimate pollen viability in herbicide treated plants. Effect of metsulfuron-methyl (۲-[in(۴-methoxy-۶-methyl-l,۳,۵-triazine-۲-yl) amino] carbonyl] amino] siilfonyl] benzoic acid) on pollen grain viability of dyers woad (Isatis tinctoria h.) inflorescence was investigated. Pollen grains of these plants were treated with ۳,۵,۸,۱۲ g a.i./ha metsulfuron in mid-anthesis stages. The treated plants were harvested in ۱,۳,۵,۷,۹ and ۱۲ day intervals after treatment and compared with control plants. Aniline blue in lactophenol (acid) and acetocarmine in glycerin (basic) were used for staining herbicide treated pollen grains. Full staining of dyers woad pollen grains significantly declined as herbicide application rates increased. Postponing the time of harvest through intervals of several days after treatment decreased the pollen grain stainability, irrespective of herbicide rate. With similar staining trends among pollen grains with the acidic and basic techniques, a significant difference in stainahility rate of the pollen grains was observed, with lower staining rates with aniline blue in lactophenol versus acetociirmine in glycerin. The rate of pollen grain stainability of herbicide treated weeds gave an adequate estimation of viability and fertility of pollen grains. As the percentage of pollen grain stainahility decreased, the efficacy of metsulfuron increased and vice versa. Use of various acidic and basic stains to estimate pollen viability can be an adequate procedure to determine the treated herbicide efficacy.

Pollen grain, Mcisulfuron, Staining technique, Aniline blue, Acetocarmine