ISHS Acta Horticulturae 662: VII International Symposium on Temperate Zone Fruits in the Tropics and Subtropics
THE BEHAVIOUR OF SOME APPLE ROOTSTOCKS IN RELATION TO THE CHILLING REQUIREMENT |
| Author: | G.A. Finetto |
| Keywords: | rootstock, scion, chilling requirement, one-year-old shoot, spur |
| Abstract:
Most of the temperate fruit trees need the utilisation of rootstock and scion combination for overcoming several constrains and improve the quality and quantity of the produce. In the tropical and subtropical zone some experiences have indicated that the utilisation of local material as rootstock for temperate fruit species could improve the suitability of these species. However few authors have studied the influence of the rootstocks on chilling requirement of scion buds. In order to improve the knowledge on this field from 1993 up to 1996 one high chilling apple cultivar Golden Delicious planted in 1985 on three rootstocks (M 27, M IX and M 26) was studied. Thirty samples of one-year-old twigs and shoots with spurs were taken from the three rootstock/cultivar combination starting from 1st October up to 31st March. The material was collected weekly and kept with their bases in water and in growth chamber for 20 days at 21°C. Apical and lateral burst buds were both counted and evaluated as to percentage of the total (%BB) and as to bud development stage (b.d.s.). The outdoor temperature during the winters were recorded and Richardson formula was tested. The three rootstocks gave different responses to overcome dormancy. M IX appears the earliest followed by M 27 and M 26 during the three years. To explain the results it is necessary to recall that the cytokinins, as growth regulators, are the responsible of the bud break. The roots of M IX could produce more cytokinins than the other rootstocks tested. Another explanation could be related to the anatomic of the scion grafted on this rootstock. In this case M IX induces a reduction of the vessel dimension in the scion. Thus the buds in the scion should receive an amount of cytokinins that is more concentrated than the other rootstocks. | |
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