Effect of Foliar Spraying with Ascorbic Acid and Dry Yeast Extract on Some Vegetative Growth Traits and Chemical Content of Bitter Almond (Prunus Amygdalus Var. Amara) Seedlings

Abstract

Bitter almond seedlings are an important rootstock of sweet almond and other stone fruit species. The suitable stem diameter of rootstock for budding and grafting is the aim of nurseries. Thus, the seedlings are treated with nutrients, hormones and organic materials to enhance the vegetative growth and produce healthy and typical rootstocks. In this study, the emerged bitter almond seedlings were sprayed with three concentrations of ascorbic acid (AsA) (150, 300 and 450 mg. L−1), two concentration of dry yeast extract (DY) (4 and 8 g. L−1) and their interactions, as well as the control treatment (Tap water). The treatments were applied three times throughout the 2017 growing season. The results showed that the ascorbic acid spraying especially 300 mg.L−1 significantly increased leaf area, total leaves area per plant, seedling height, stem diameter, branches length and leaves’ content of phosphorus and ascorbic acid. Meanwhile the effect of dry yeast extract treatments when separately sprayed were less than expected, but the interaction treatments affected positively on some studied measurements. The foliar spray with 150 mg.L−1 AsA + 4.0 g.L−1 DY gave the highest values of stem diameter, branch length and carbohydrate concentration in leaves of bitter almond seedlings. Finally, the foliar spray with 300 mg. L−1 AsA alone or 150 mg.L−1 AsA + 4.0 g.L−1 DY are the recommended to obtain rootstocks of suitable diameter to budding or grafting during one growing season.