Prunus scoparia, a suitable rootstock for almond (Prunus dulcis) under drought condition based on vegetative and fruit characteristics

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Almond is one of the most important nut crops in the world and thus rootstock selection is an important decision when planting an almond orchard. With the aim of introducing Prunus scoparia as a suitable rootstock for almond under drought condition, the present study was carried out with two scion/rootstock combinations including: A-1) Prunus dulcis cv. ‘Rabiee’ scion/P.dulcis cv. ‘Estahban’ rootstock (under irrigated condition), A-2) P. dulcis cv. ‘Rabiee’ scion/P. dulcis cv. ‘Estahban’ rootstock (under rainfed condition), and B) P. dulcis cv. ‘Rabiee’ scion/P. scoparia rootstock (under rainfed condition). P. scoparia is a wild species, usually living on dry calcareous soils at rocky mountain and has been used as a grafting rootstock for almonds to provide drought resistance. Result showed that the vegetative characters of ‘Rabiee’ scion including tree height, trunk diameter, annual year’s growth and internode length were statistically significantly affected by rootstock combinations which trees grafted onto P. scoparia represented lower values for these characters. The lowest tree height was observed for trees grafted onto P. scoparia (110.00cm), while the highest was in trees grafted onto irrigated ‘Estahban’ rootstock (516.00cm). Thus, P. scoparia may reduce height of ‘Rabiee’ scion and can be used as a dwarfing rootstock for almond. In addition, fruit yield of ‘Rabiee’ scion showed statistically significant differences among its trees grafted on different rootstocks. Trees grafted onto irrigated ‘Estahban’ rootstock showed higher yield compared with others, but differences among trees grafted onto irrigated ‘Estahban’ rootstock and trees grafted onto P. scoparia was insignificant for this trait, while they showed significant differences with trees grafted onto rainfed ‘Estahban’ rootstock. Nut length, nut width and kernel thickness showed statistically significant differences among trees grafted onto different rootstocks. Trees grafted onto P. scoparia showed higher values for means of nut length (35.66mm) and nut width (26.59mm). Nut weight was higher in trees grafted onto P. scoparia (4.97g) and irrigated ‘Estahban’ rootstock (5.02g) than in trees grafted onto rainfed ‘Estahban’ rootstock (3.99g). Qualitative characters of kernel (shape, color, uniformity and shriveling) were not affected by different rootstock combinations. In conclusion, P. scoparia may reduce plant height and increase fruit yield of almond scion under drought stress and can be used as a dwarfing rootstock for almond.