COLD-HARDINESS EVALUATION OF PERSIAN WALNUT BY THERMAL ANALYSIS AND FREEZING TECHNIQUE

In this work, cold hardiness of one-year-old shoots of 4 walnut cultivars (‘Serr’, ‘Pedro’, ‘Hartley’ and ‘Lara’) and 4 promising genotypes (‘Z₆₃’, ‘Z₅₃’, ‘Z₃₀’ and ‘Z₆₇’) were examined by computer-assisted thermal analysis (TA) and freezing test during November and December, 2007. In the TA method thermoelectric modules (TEM) were used to determine the exotherms that are produced when water or tissue freezes.
The freezing treatment consisted of decreasing temperature at 2°C h^-1 and the TEM signal was recorded by the computer at 6 s intervals, and downloaded directly to an excel spreadsheet.
In each cultivar, low and high temperature exotherms of the shoots were recorded by this system.
In the second method, shoot segments were wrapped in moistened cheese cloth and placed in test tubes and were submerged in a prolonged temperature bath treatment and cooled at a rate of 2°C h^-1 and subjected to freezing temperatures -5, -10, -15, -20, -25 and -30°C and held for 16h at each temperature.
The shoot segments were then visually evaluated for damage.
Based on our results, the cultivars and promising genotypes were classified into hardy, semi- hardy and non-hardy groups. ‘Lara’, ‘Pedro’ and ‘Serr’ were the hardiest and ‘Hartley’ was the least hardy among all cultivars and promising genotypes tested.

VI International Walnut Symposium

A.A. Aslamarz, K. Vahdati, M. Rahemi, D. Hassani

frost, injury, supercooling, Juglans

https://doi.org/10.17660/ActaHortic.2010.861.35