Investigation frost damage and selecting tolerance olive cultivars and genotypes.

The basic requirements of olive development program are identification and introduction of compatible cultivars with different climates especially with hight risk region of cold winter. Low temperature and frost damage is the main restriction factor for olive growing. This research was conducted to investigation frost damage and selecting tolerance olive cultivars in provinces of Qazvin, Zanjan, Golestan, Semnan, Kerman, Qom. In January 2007; above mentioned provinces received a severe fast hitting freeze which brought temperatures down lower than-23 C° in Qom and -13 C° in Golestan,was bring about severely damage on olive orchards, especially in new planted and young orchards. Frost damage was little in old olive orchards. The result of frost damage was decreased in yield of next year. This research was evaluated the scope of damage to rate of leaves shedding and leaves color, injured textures under skin and vessels, annual and perennial shoots, trunk, root and yields, dry mater of one year old shoots, bark splitting in shoots and trunk, emergence of new leaves in next year, content of protein and carbohydrate in leaves of resistance and sensitive cultivars. The result of Zanjan province indicated that cultivars Grossane, Dan and Khodairy hadn't any symptoms of frost damage. These cultivars took the cold resistance degree. The symptom of frost damage on cultivars Amygdalolia, Abu-satel, Mission and Kornicabra was leaf necrosing and decoloration in leaves of shoot tips, so they categorized in related cold resistance. Frost damage caused one year old branches with length 10-20 cm died back in cultivars Verdial de Jaine, Mavi, Arbequina, Roghani and Loques. These cultivars grouped in relative sensitive to cold. Frost cased to split bark of young branches 20-30 cm and in Koroneiki and Cipressino the length of bark split was more than 50 cm. These cultivars categorized in sensitive to cold. In Qazvin province selected two regions in the of Tarom-e-sofla county. The first region was altitude 300-350m and second region was located with altitude 1000m above of sea level. The result showed cultivar Charchangi is cold tolerance. In these regions frost damage mainly was on shoot tips and buds. In Golestan province results indicate that cultivars and genotypes had significant deference in frost resistance. The local genotypes Ilam malekshahi, Lemeski and Ilam nargeseh are less sensitive to frost damage. Koroneiki, Mazanilla, Balaidi, Frantoio, Kalamata, Leccino and Ascollano are the most frost-susceptible cultivars and cultivars Zard, Roghani, Grossane, Hashem abad and Valanolia had moderate resistance. In Qom province with attention to cold duration and severity so that were lower than olive tolerance limitation to cold, the majority of olive trees dried and cut from ground surface, and only roots hadn't injure. In the young tree (one & two year) even roots destroyed and in the next year didn't rescue. Among studied cultivars, Zard, Roghani and Fadak78 cultivars didn't injured, so that just young foliage injured partially. Ascolana cultivar had high tolerance to freezing related to other foreign cultivars. The result showed that Iranian cultivars had higher tolerance to freezing. The effects of irrigation and fertigation completely was clear on increasing cold resistance of olive trees in Astan-e- Qods orchards in Semnan province. In some parts of this orchard trees that hadn't suitable irrigation and nutrition frost damaged the foliage. The cultivar of Abusatel indicates good resistance to frost and produced flower and fruit for next year. The frost damage in Kerman Province with -10 C° majority was on one and two year olds shoots.