[Evaluation of the effects of cobalt-60 gamma radiation on budding of Triticum aestivum seeds]

Previous studies have reported a significant difference between the effects of low and high dose rate gamma rays. The goal of current study was to determine the dose for enhancing the rate of budding of Triticum aestivum cv Arvand seeds. 5355 seeds with similar phenotype were provided and exposed to gamma rays produced by a CO-60 machine installed in Tabriz Imam Khomeyni Hospital [Theraton-1000, Field Size=10x10cm, SSD=80cm and Dose Rate=155cGy/min]. Then, seeds were exposed in 6 groups [one control group and 5 groups with daily doses of 0, 100, 250, 500 and 750 cGy respectively for 9 days]. 75 seeds from each group were daily counted, sterilized and then transferred to petry dishes. Budding seeds were daily counted and coleoptile length, number of roots and length of roots were measured for each seed in each petry dish after 5 days. Statistical analysis was performed using MSTATC in Random Complete Blocks Design. Our data showed that the optimum dose for maximum budding was 500 cGy per 4 days. Also, we observed that using 500cGy in 4 days was useful for geographical places with short-time growth seasons. Regarding our results, we recommend using 250 cGy per 4 days that is more economical than 500cGy per 4 days. Meanwhile, all examined doses showed a significant decrease in the number of budding seeds after 7[th] day. This can be due to the destructive effects of gamma rays on the budding seeds. We hope our findings help farmers produce crops with high yields

Different sites of photodamage in chilling-sensitive (sorghum) and chilling-resistant (barley and wheat) plants.

The electron transport chain was affected to varying degrees by high light intensity at low temperature in different crop plants. The PS II was found to be the sensitive site while PS I showed very little change in its activity. Photoinhibition affected the oxidizing side of PS II in all three plants. However, the site of inhibition was different in chilling-sensitive and chilling-resistant plants. In sorghum, the water splitting reaction was damaged while in barley and wheat the damage occurred in the reaction centre itself. It appears that photoinhibition may affect different sites within the PS II in chilling-resistant and sensitive plants.