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.

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Comparisons were made of MM.111, MM.106 and EM.IX as rootstocks and ‘Red Delicious’ (RD), MM.106 and EM.IX as 1-, 3-, 5- and 7-inch interstems. The dwarfing effects of the rootstocks were greater than those of the interstems. Interstems reduced the growth of most plant parts in direct proportion to the degree of dwarfing of the interstem and there were few significant differences among plants with different interstem lengths. However, plants with interstems of 1 and 3 inches had higher percentage increases in root weight than those with 5 and 7 inch interstems. Plants with EM.IX interstems showed similar patterns of total plant, leaf and new growth weights. Weight increases of RD interstems were lower than those of MM. 106 and EM.IX interstems. The EM.IX rootstock weights were 101 percent of the weights of the plant tops, whereas rootstock weights were approximately 50 percent of the weights of plant tops for all other treatments.

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°.

‘Thompson Seedless’ and ‘Ruby Seedless’ vines were girdled and/or treated at bloom with GA3 (‘Thompson Seedless’ at 5 ppm and ‘Ruby Seedless’ at 1, 5, and 20 ppm), and/or at fruit set (just after berry shatter) at 20 and 40 ppm. Results for ‘Thompson Seedless’ grapes (Vitis vinifera L.) indicate a significant increase in berry weight resulting from GA3 spray or girdling at fruit set. The greatest increase was obtained from a combination of girdling and GA3 spray. Soluble solids and titratable acidity were not significantly affected. Results for ‘Ruby Seedless’ grapes indicate significant fruit thinning at 5 and 20 ppm but not at 1 ppm. No increase in berry size was recorded, but a significant increase in soluble solids and a decrease in acidity were obtained with bloom-sprayed vines at 5 and 20 ppm.