Impact of Foliar-Applied Dormancy-Breaking Chemicals on Budburst and Metabolic Changes in Chemical Constituents of Leaves and Fruits of <i>Malus sylvestris</i> "Ein Shamer"

Abstract

This study was carried out during the two successive seasons of 2016 and 2017 to investigate the impact of dormex, dormex plus mineral oil, dormex plus potassium nitrate, dormex plus calcium nitrate and dormex plus thiourea on bud break, growth, yield and some chemical constituents of Malus sylvestris "Ein Shamer". The trees were grown in loamy sand soil, and sprayed with six treatments (dormex (4%), (dormex (2%) plus mineral oil (2.5%),(dormex (2%) plus potassium nitrate (4%),(dormex (2%) plus calcium nitrate (4%) and (dormex (2%) plus thiourea (1%) and control. Generally, it was found that all studied growth parameters , date of flower bud break, percentage of bud break, fruit-setting ,fruit weight, fruit size, fruit number/tree, yield/tree (kg) and some chemical constituents of leaves (total chlorophyll ,total carbohydrates, total protein, nitrogen, phosphorous and potassium contents) and some chemical constituents of fruits (total soluble solids(T.S.S.), T.S.S/ acid ratio, vitamin C, water content %, total free amino acids, total carbohydrates, total sugars and reducing sugars) were increased with the application of the different treatments. The best results were obtained from the treatments of dormex at 4% followed by (dormex (2%) plus mineral oil (2.5%). On the contrary, the same treatments decreased total acidity and total phenols in fruits as compared to the control. It could be recommended to use dormex at 4% and (dormex (2%) plus mineral oil (2.5%) for improving bud break, growth, yield and chemical constituents of apple trees or fruits.

Exogenous Dormancy-Breaking Compounds on Flowering Behavior, Yield, Fruit Quality and Some Chemical Constituents of “Anna” Apple Trees

“…Most temperate zone perennials undergo an annual period of bud dormancy, which is a physiological state that reduces the ability of bud to burst in a reversible manner. Endodormancy, coinciding with winter, is an inhibition controlled from within the bud itself and released upon exposure to chilling (Petri and Leite, 2010;Seif El-Yazal, 2019a, 2019b2019c;2020;2021a;2021b). Hence, to resume growth, tree bud must receive an amount of chilling which is genetically controlled and varies among genotypes (Egea et al, 2003) However, it is difficult to determine the precise amount of cold that is required to get out of lethargy (Carvajal-Millan et al, 2000;Seif El-Yazal et al, 2018a;2018b;2018c;2018d).…”

“…The beneficial effect of dormex, mineral oil, potassium nitrate, calcium nitrate and thiourea on bud break, growth, yield and some chemical constituents of different fruit species were studied by several workers (El-Shewy et al,1999a;1999b;1999c;1999d;Petri and Leite, 2010;Abd El-Rzeket et al, 2011;2020;2021;Seif El-Yazal, 2021b).…”