Resistance of apple-tree varieties on dwarf rootstock and inserts under heat shock conditions

Abstract

Purpose.To study the parameters of water regime in apple-tree varieties grown on dwarf rootstock 62-396 and inserts 62-396 and 3-17-38 during the vegetation period in relation to their heat tolerance. Methods.Field investigations, statistical evaluation, analytical approach.Results.A high level of water content ranging from 71.5 to 73.1% was determined in the leaves of apple-tree varieties at the beginning of vegetation.An average level of water content (from 62.8 to 65.5%) in leaves of studied apple-tree scion-rootstock combinations was recorded during the period of the intensive growth of shoots and formation of ovaries and fruits (June–August). There was no significant difference between varieties as for water content in leaves. Analysis of variance revealed the significant reliable difference as for water content in leaves between dwarf rootstock and inserts at p < 0.05. It was determined that on average for the period of two years ‘Yablochny Spas’ variety lost less water than ‘Orlinka’ after the heat shock. At the same time, the maximum water-holding ability was revealed in the varieties on the dwarf rootstock 62-396. Conclusions. During analysis of variance, the substantial reliable intervarietal differences were recorded for the water content at 5% and 1%-level of significance.The mutual influence between varieties, dwarf rootstock and inserts for water loss after the heat shock at p < 0.05 and 0.01 was reliably confirmed. After the impact of high temperature stress (+50 °C) and water saturation, the studied apple-tree scion-rootstock combinations were able to restore water content at a high level. Scion-rootstock combinations ‘Yablochny Spas’ and ‘Orlinka’ on the dwarf rootstock 62-396 were specified as those that had the highest heat tolerance potential.