Cold Hardiness of Different Apple Rootstock Clones

The purpose of this investigation was to report the effect of the extreme weather event of the past winter (2008) on different apple rootstock clones including B9, M9, MM106, M26 (exotic) and Azayesh (native) grown in different soil textures in Karaj region, Iran. Young plants obtained from rooted cuttings were grown individually in plastic pots (40 cm in diameter & 42 cm in height), filled with sand, manure fertilizer and different soil particles (1:1:1). Statistical analysis of data indicated significant differences between years for all of the studied parameters among rootstocks (except for leaf phosphorus content), different soil textures (except for leaf N, ca & chlorophyll content, SPAD value, leaf surface, height & trunk diameter) and the interactive effects of rootstock x soil texture (except for trunk diameter, leaf Ca & P content, leaf chlorophyll & SPAD value). Field observations on the effects of extreme air temperatures (-4.7 vs. -0.5°C) and different soil textures revealed that the studied rootstocks were different in their cold hardiness. Azayesh grown in a soil texture of silt 48%, sand 20%, clay 31% and lime 14% and M9 grown in silt 49.2%, sand 19.8%, clay 31% and lime 18% were the most tolerant rootstocks, respectively. © 2010 Friends Science Publishers