Cytological Effects of Pesticides

The effects of 2, 4, 5-tichlorophenol, 2, 4, 5-T, 2, 4-D, and 2, 4-dichlorophenol were studied on the meiosis, pollen viability and yield of Vicia faba plants. Two types of treatments were conducted: spray, and seed-soak-treatments. Plants were sprayed at two developmental stages when they were 15, and 35 days old. Spraying plants when they were 35 days old with the experimental agents effected a relatively higher percentage of abnormal PMCs than that induced when the plants were 15 days old. Soaking of seeds in the experimental agents before planting resulted in the lowest percentage of abnormal PMCs in comparison with the spray treatments. The most dominent types of abnormalities were: stickiness, lagging chromosomes, and chromosome fragmentation. Spraying plants when they were 35 days old with 2, 4, 5-T was the only treatment which effected a significant percentage of sterile pollen grains. Spraying plants when they were 15 days old was found to be the most effective treatment, where nearly all the used chemicals showed a significant effect either in the 1st or in the 2nd generation. All the used agents had no harmful effect on the yield, and their effect diminished in the 3rd generation.