Differential Drought Tolerance Revealed by Morpho-Physiological Indices in Some in Vitro Micro-Propagated Malus domestica Borkh. Rootstocks

This is the authors' abstract. We don't add key points for this paper.

Apple (Malus domestica Borkh.) is commercially propagated using the rootstock and scion system. Different rootstocks have various effects on the characteristics of the apple varieties. Drought stress is an important environmental stress that impacts crop growth and physiology. This study aimed to optimize the micropropagation and rooting medium of four commercially important apple rootstocks including ‘MM.106’, ‘MM.111’, and ‘Golab Semirom’ apple varieties and the ‘Esfahan’ quince cultivar, as well as to investigate their morpho-physiological response to induced drought stress. Modified MS medium containing N6-benzyladenine (BA) at the concentration of 0, 0.25, 0.5, 0.75 and 1 mg/L was used for micropropagation. The highest proliferation rate for all rootstocks was observed at 1 mg/L BA. Rooting was carried out in modified 1/2MS and LS medium containing 0, 1, 2 and 3 mg/L of indole-3-butyric acid (IBA). The best rooting rate of ‘MM.106’ was observed in LS containing 1 mg/L of IBA, and for ‘MM.111’ in 1/2MS medium containing of 3 mg/L of IBA. Rooted seedlings were transferred to soilless medium and drought stress was induced by irrigation water volume at four levels including control, mild, moderate and severe stress. Measured morpho-physiological indices showed that the best morphological performance and the highest amount of chlorophyll a, b, total chlorophyll, and carotenoid contents were seen in the control treatment, while the highest proline content was seen under severe stress. In general, ‘MM.111’ and ‘MM.106’ rootstocks can be recommended for cultivation under moderate and severe drought stress conditions, respectively.