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- Author or Editor: David E. Ramos x
Heading back of 2nd flush growth to basal buds on vigorous young trees at different times of the year indicated that buds were converted from a vegetative to a reproductive state within 4 weeks after they were formed at the shoot apex. Defoliation or defoliation plus etiolation of 7 terminal nodes in July did not deter the buds at these nodes from differentiating pistillate flowers for the next season. Pruning greatly accelerated the differentiation processes.
‘French’ prune (Prunus domestica L.) leaves on nonbearing trees and large scaffold limbs had greater percent dry matter and specific leaf weight than those from bearing ones early in the season. This difference disappeared as the season progressed. Much of the difference could be attributed to the greater accumulation of starch, which displaced water. The demand for photosynthates by the crop was also reflected by lower starch content in 1-year-old shoot, limb bark, and roots, but no difference in the soluble carbohydrate content nor in the ratio of sorbitol + sucrose/glucose + fructose was observed. Leaf K content was influenced by the crop but not Ca and Mg contents. Unlike K contents, Ca contents in fruiting spurs and 1-year-old shoots tended to be greater than those from nonbearing samples; no differences were noted in root samples. These data and those of other workers indicate that K deficiency in this cultivar stems from its strong K demand by the fruit and from the lack of carbohydrates being translocated to the roots, which in turn, limits growth and nutrient uptake, especially K, which is limiting in these soils.
During 2 successive seasons, and several experiments, trees of Juglans regia cvs. Payne and Hartley were shaken and the walnuts were allowed to remain on the ground in sun or shade up to 72 hr before drying. Kernel temperature exceeded air temperature, sometimes by more than 10°C in those walnuts which were exposed to the sun, while those in the shade remained below air temperature. When the ambient air temperatures exceeded 35°C, extensive kernel quality loss occurred in shaded walnuts. At lower air temperature the market value of sun-exposed walnuts was decreased. Under high air temperature sun-exposed walnuts with hulls lost more market value than walnuts without hulls. Moisture content of the hull at time of exposure had no major effect on kernel quality. The greatest loss of kernel quality occurred when walnuts were exposed to midday sun.
Foliar sprays of (2-chloroethyl)phosphonic acid (ethephon) were applied at 50, 100, and 150 ppm to French prune trees at 50% petal fall and when seed length was 8.3 to 9.4 mm. All concentrations thinned fruits within 3 to 4 weeks after treatment. The treatments increased soluble solids and fruit size, and in some instances decreased dry tonnage. Return bloom the following year was greater on treated trees than on controls. Also, fall coloration patterns appeared earlier on the treated trees. No phytotoxic effects from the treatments were evident on the fruits.