Effects of rootstock type on morphological and biochemical markers related to salinity tolerance in almond cultivar Shahrood-12

The use of unsuitable water for irrigation of agricultural land and the formation of salt soils is a serious threat to agriculture. Salinity stress can affect the morphological and biochemical properties of plants. Several studies have shown that the tolerance threshold for most of the stone fruits, including almond, is low in salinity stress, so that in salinity of 2.8, 4.1 and 7 dS/m, respectively, 25, 50 and 100 percent of its yield decreases. In almond, as with other fruit trees, the choice of tolerant rootstock and scions is a very suitable strategy to reduce the effects of salinity, especially in the arid areas. The aim of this study was to investigate the morphological and biochemical characteristics of several rootstock and scions in comparison with the without rootstocks to find the most tolerance rootstock and scions combination in comparison with the without rootstocks to salinity stress.

In this research, the effects of salinity stress on the biochemical properties of almond (Shahrood 12) grafted on some of the prnnus rootstocks (Bitter Almond, Tetra, GF677 and GN15) and non-grafted rootstocks under salt stress. Experiment was carried out in a factorial experiment based on a completely randomized design with two factors of 8 rootstocks and scion compositions and non-grafted rootstocks and 5 levels of salinity were performed in three replications.

The results showed that increasing the salinity level from zero to eight dS.m-1, the studied morphological traits also increased to their maximum level. At the salinity level of 8 dS.m-1, the lowest (2.66%.) and the highest (7.66%) of necrosis was observed in Shahrood 12 grafted on GF677 and Shahrood 12 graft on Tetra, respectively. The results also showed that biochemical traits were affected by salinity stress, so that the highest amount of proline (67.91 μmol.g-1 fresh weight) was obtained in Shahrood 12 grafted on GF677 at 8 dS.m-1 salinity, which was significantly different with other rootstock/scion composition (almond shahrood 12 on other rootstocks) and the studied rootstocks. With increasing salinity from 0 to 8 ds.m-1, the highest (112%) and lowest (41.6%) aldehyde was observed in the Bitter Almond Seedlings and shahrood 12 grafted on GF677 respectively. With an increase in salinity up to 4 dS.m-1, the amount of phenol in all grafted and non-grafted plant was increased and reached to the maximum level, but farther increase in salinity level (up to 8 dS.m-1) significantly reduced their phenol amount.

Based on the results, it can be concluded that among the rootstock/scion compositions and the studied rootstocks, Shahrood 12 cultivar grafted on GF677 rootstock was the most susceptible compound to salinity stress and the same cultivar, which was grafted to the Bitter Almond Seedlings, was the most sensitive combination.