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.
Amin Hassankhah; Kourosh Vahdati; Majid Rahemi; Darab Hassani; Saadat Sarikhani Khorami
Abstract
Walnut production is limited by late-spring frost in many countries. The current research was carried out to evaluate chilling and heat requirement of catkin and terminal buds break on six selected superior walnut genotypes and cultivars (‘C-25’, ‘88-1’, ‘88-2’, ‘Chandler’, ...
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Walnut production is limited by late-spring frost in many countries. The current research was carried out to evaluate chilling and heat requirement of catkin and terminal buds break on six selected superior walnut genotypes and cultivars (‘C-25’, ‘88-1’, ‘88-2’, ‘Chandler’, ‘Jamal’ and ‘Damavand’). The Utah and accumulation growing degree hours (GDH) models were applied to determine the chilling and heat requirements under field and greenhouse conditions, respectively. ‘Damavand’ cultivar (650 CU) and ‘C-25’ genotype (650-800 CU) had the lowest chilling requirement for terminal bud break. ‘Jamal’ cultivar and ‘C-25’ genotypes had the lowest chilling requirement to break the dormancy of catkins (650–800 CU). ‘Chandler’ cultivar and ‘88-1’ and ‘88-2’ genotypes as late-leafing genotypes/cultivars had the highest chilling and heat requirements to break dormancy of terminal buds (800-1100 CU and 11832-12648 GDH) and catkin (800-950 CU and 11484-12180 GDH). In conclusion, late-leafing genotypes/cultivars had the higher heat requirement than early-leafing genotypes/cultivars. Based on the results, a linear and significant relation was observed between chilling requirement and heat accumulation. Therefore, heat accumulation of buds and catkins was reduced by increase in the amount of chilling requirement. Furthermore, the result revealed that heat accumulation is more important than chilling requirements to estimate walnut budbreak date. The GDH of catkins and terminal buds was decreased with increase in the average temperature during heat accumulation.
