بررسی اثر سه عامل پس رسی، اسید جیبرلیک و حذف پوشینه بر جوانه زنی بذر بروموس (Bromus japonicus Thunb.)

Japanese brome (Bromus japonicus Thunb.) is one of the most important annual narrow leaf weeds in wheat fields of Sistan and Baluchistan province. It force about 2-22 percent of yield loss depend on density and wheat cultivar.One of the important goals of germination and emergence studies in weed science is prediction of the dormancy longevity and germination time in field conditions. Therefore, the aim of this study was to evaluate germination properties of seeds at different times after physiological examination under the effect of gibberellic acid.An experiment was carried out as factorial based on randomized complete block design in 2013 by two factors include: 1- period of after ripening in six levels (immediately after harvest, 2, 4, 6, 9 and 12 months after harvest) and 2- pre-treatment by gibberellic acid for 48 hours in four concentrates (0, 100, 200, 300 mg/lit). The effect of these factors was evaluated for two types of Japanese brome seeds; glumelle and non-glumelle. Samples placed into the incubator and temperature was kept on 20◦C in dark condition. Germination percentage, germination rate and mean germination time were recorded in every 48 hours.The results showed that the effect of all experimental factors on germination properties was significant (P <0.01). Removal of glumelle, increasing the concentration of gibberellic acid and keeping more time after harvesting significantly increased germination percentage.In glumelle seeds, it takes about 6 months to reach 50% of its maximum (63%) in the 12th month after harvest. Germination rate increased from 2.5% per day in glumelle seeds to 18% per day in non- glumelle seeds. The duration of seed storage had a significant effect on its germination rate, so that at 12 months after harvest, it was approximately 15 times higher than harvest time.This experiment showed that removing glumelle and keeping seeds of the Japanese for 2 months and more have the greatest contribution to reduce non-deep physiological dormancy of this weed. Therefore, these two processes, the removal of the seed shell in the seeds of wheat and maintenance for more than 2 months, increase seed germination of the bromus. In general, it can be concluded that seeds of Bromus seed in seed bank can have germination by presence of important germination factors including proper seed placement, temperature, humidity and oxygen. This is an important point about using some control techniques in the Bromus management Plans. As a result, using the method of creating a false seed bed, most of the seedlings could be controlled on the field