The experiment detected the chill hour requirements of 6 female and 8 male
varieties of Pistachio (Pictacia vera L.) cultivated in Aleppo, Idleb, Hama and
Dar’a in Syria needed to break down their bud dormancy. Studied cuttings left
at 2°C in cool
chamber for 650, 750, 850, 950, 1050 and 1150 hours were placed
into growth chamber offering temperature, moisture and brightness similar to
those available in nature during the period of blooming flowers. Statistical
analysis distinguished clearly between the chill requirements of the female and
the male varieties, where the males needed lower cold hours. Also, the female
varieties showed differences among them in their chill requirements due to
genetic resources which were affected by their geographical areas and
attitudes. The period in the growth chamber needed to reach a proper
blooming ranged between 32 days in the case of Ashoury variety cultivated in
Dar’a with 1150 chill hours and 54 days with Nab Aljamal variety existed in
Hama and Idleb with 650 chill hours. Meanwhile, in the male varieties this
figure was between 22 days for male 2 cultivated in Idleb (1150 chill hour) and
43 days for Male E in Dar’a (650 chill hours). The cluster configuration
between the males and females varieties was sorted by putting them in two
relative distant sub-clusters. The females varieties were distributed sorted into
sub-groups as well, insuring the similarity among the ones belong. In addition,
The males varieties were distributed into two types depending on their earliness
blooming time (early: Hama1, Hama2, Idleb1, Idleb2 – late: A jellin, E Jellin,
Aleppo1, Aleppo2). The results could be useful for the decisions of what
varieties to be grown in certain places depending on natural chill hours
available there.
