Document Type : Full Paper
Ph. D. Cadidate and , Faculty of Agriculture, University of Zanjan, Zanjan, Iran
Associate Professor, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
Associate Professor, Temperate Fruits Research Center, Horticultural Sciences Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Associate Professor, Gorgan University of Agricultural and Natural Resources, Gorgan, Iran
The physiological and biochemical traits of 12-year-old olive trees cvs. Zard and Direh were studied in response to thermal fluctuations during growing seasons in Tarom region (Zanjan province, NW of Iran) for two successive years 2017-2018. The experiment was carried out as split plots in time based on complete randomized block design (cultivar as main plot and time as sub-treatment). The sampling and data recording were performed during four different time including; May, July, August and September correspond to the 28, 45, 44 and 36 °C, respectively. The results showed that the photosynthesis rate of cv. Direh during stressful high temperature conditions at July, and in compare to May decreased two times more than cv. Zard. Cultivar Zard, in spite of its high photosynthesis rate, showed lower amount of cumulative shoot growth and dry weight, which was mainly due to the large amount of fruit yield efficiency in this cultivar. The proline accumulation in leaf tissue of ‘Direh’ failed to play a constructive role in developing higher heat stress tolerance in this cultivar. The soluble carbohydrates concentration in ‘Zard’ was higher than ‘Direh’ during all period of study. In general, cv. Zard had more tolerance to increased heat stress during growth season.