Leaves, shoots and flower buds of 3 peach cultivars differing in cold hardiness were compared biochemically throughout the year. The analyses included starch, reducing and total sugars, total protein, and total and individual amino acids, (a) Starch in leaves and shoots was low in early spring, but increased to peak concentrations in fall. Flower buds were devoid of starch, (b) Reducing and total sugars in leaves and shoots were high in early spring and decreased to a minimum in fall, but increased to a maximum in the shoots during winter. In flower buds reducing and total sugars were relatively high during winter and increased to peak concentrations in early spring, (c) Protein in leaves was high in spring but decreased to a minimum in summer, then steadily increased to a peak concentration in fall. A similar but less pronounced trend occurred in shoots. In flower buds a steady increase in protein occurred during dormancy and reached a maximum in early spring, (d) Total free amino acids in leaves was high in the spring, but decreased rapidly to a minimum in the fall. In shoots the level was relatively high in the spring, decreased in early summer, but increased to a maximum in late summer, then gradually leveled off during the fall and winter. In flower buds the level was relatively high in winter, but increased rapidly in early spring.
Some correlation existed between the levels of the biochemical constituents and the degree of hardiness in the 3 peach cultivars.
Levels of soluble sugars in bark, leaves, leaf buds and flower buds of 2 cultivars of peach (Prunus persica (L.) Batsch) differing in cold hardiness were compared throughout the year. Thirteen sugars — galactose, glucose, fructose, xylose, stachyose, sucrose, raffinose, rhamnose, maltose, trehalose, arabinose, ribose and mannose — were present in measurable and variable concentrations. In general, oligosaccharides accumulated, particularly in the bark, during fall and winter, whereas monosaccharides accumulated during periods of active growth. These data do not show significant differences between the 2 cultivars regarding the accumulation of these sugars and cold hardiness.
Fruit buds of 5 peach cultivars—‘New’, ‘Daroga’, ‘Redskin’, ‘Mayflower’, and ‘Loring’—grown in Kentucky and exhibiting varying degrees of cold hardiness, were compared biochemically. Fruit bud analysis for total and reducing sugars, starch, total protein, and total and individual free amino acids indicate some correlation between the degree of hardiness and the biochemical make-up of these cultivars. Generally, a high sugar and protein content, and a low total free amino acids were associated with increase in hardiness. Specifically, significant correlation was found between hardiness and a high sugar and protein content when buds were frozen at −2½° F. Significant correlation was also found between 2 amino acids (arginine and γ-NH2 butyric) and hardiness at both −2½° and −5°.