Department of Horticulture, Faculty of Agriculture, Shahed University, Tehran, Iran
There is minimal information about the effect of heavy metals such as lead and copper on pollen grains and pollen tubes of fruit trees. Fruit set of these plants are affected by different environmental, biological, physical and chemical factors. If one of these factors be abnormal, pollination, fertilization and fruit set and orchard yield will decrease. In polluted cities, this phenomenon is affected by the stresses of heavy metals. Almond is one of the most important nut fruits of Iran. Pollen germination and tube growth are the main basic factors of fruit set in almond. In this study, the effects of heavy metals, copper and lead, on pollen germination and tube growth of five almond cultivars included Azar, Mamaei, Shahroud 21, Shahroud 18 and Shokofeh, were studied in vitro. The results showed that both traits were affected significantly by different levels of metals and cultivars. Increasing the concentrations of heavy metals resulted in a decrease in pollen germination and tube growth of all cultivars. In the concentrations, 250 ppm pollen germination and tube growth neared to zero in the most cultivars. Lead showed the highest toxicity on pollen germination and tube growth. However, Shahrodi 21 and Shahrodi 18 cultivars showed the highest sensitivity to copper and lead among the cultivars.