Mina Farsi; Mohammad Reza Fatahi Moghadam; Zabihollah Zamani; Darab Hassani
Abstract
The experiment was carried out during 2015-2016, with the aim of investigating the effects of scion cultivar, rootstock age and hormonal treatments on the success of walnut minigrafting. Analysis of results showed that all studied factors were effective on graft-take and survival of minigrafted walnuts ...
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The experiment was carried out during 2015-2016, with the aim of investigating the effects of scion cultivar, rootstock age and hormonal treatments on the success of walnut minigrafting. Analysis of results showed that all studied factors were effective on graft-take and survival of minigrafted walnuts and other growth traits of the scions. The highest graft-take was observed on one-year-old rootstocks in hormonal treatments of 20 mg/L BA + 12.5 mg/L IBA for ‘Jamal’ and 80 mg/L BA + 50 mg/L IBA for ‘Chandler’. The highest survival rate was observed on one-year-old rootstocks in control treatment and the lowest was on two-year-old rootstocks in hormonal treatment of 80 mg/L BA + 50 mg/L IBA. The highest growth rate of scion belonged to the scions of ‘Jamal’ on one-year-old rootstocks in hormonal treatment of 20 mg/L BA + 12.5 mg/L IBA and the lowest was in scions of ‘Chandler’ on two-year-old rootstocks in hormonal treatments of 20 mg/L BA + 12.5 mg/L IBA and 80 mg/L BA + 50 mg/L IBA. In addition, diameter of the graft union on two-year-old rootstocks was more than on one-year-old ones. Histological studies showed that increase in the diameter of the graft unit on two-year-old rootstocks was due to dead and necrotic tissues at the upper parts of it which acted as a barrier against passage of water and minerals from the rootstock to the scion and reduced the growth of the scion on two-year-old rootstocks.
Mina Farsi; Mohammad Reza Fatahimoghadam; Zabihollah Zamani; Darab Hassani; Ahmad Ahmadi
Abstract
Compared to other techniques of propagation, grafting is the most successful and feasible technique for asexual propagation of walnut plants. There is little information about graft union formation in walnut. Therefore, the objective of this study was to evaluate histological events during graft union ...
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Compared to other techniques of propagation, grafting is the most successful and feasible technique for asexual propagation of walnut plants. There is little information about graft union formation in walnut. Therefore, the objective of this study was to evaluate histological events during graft union formation in Juglans regia L. cv. Chandler scions when minigrafted on the one-year-old seedlings. Cross and longitudinal sections of the graft union were taken for examining different stages of grafting process after 1, 14, 30, 60, 120, 180, 420 and 540 days of minigrafting. One day after grafting, brown necrotic layers were observed at the cut edges. The first callus cells were initiated from cambium layer of rootstock 14 days after grafting but there was weak connection between two parts. New vascular connections between rootstock and scion were observed 30 days after grafting . Vascular connections were increased in central parts of the graft union 60 days after grafting. In mid-summer (180 days after grafting), necrotic layer was almost disappeared in the central longitudinal sections but they were increased especially in the bark, callus and top parts of the graft union due to high temperature and low humidity. In 420 days after grafting, two parts were strongly connected by xylem vessels, but necrotic layer was still remained and observed in some parts. In 540 day after grafting which was coincided with the end of second growing season, two parts were tightly connected to each other and necrotic layer disappeared in most of cross and longitudinal sections.
