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Abstract
Treatment of headed-back 1-year-old dormant shoots of ‘Monroe’, ‘McIntosh’ and ‘Wayne’ apple (Malus domestica Borkh.) with 1% naphthaleneacetic acid (NAA) in latex paint was relatively ineffective and gave inconsistent results; however, treatment of mechanically hedged shoots on established trees gave statistically significant reductions in regrowth, by reducing bud break of dormant buds on older wood. Regrowth in ‘Monroe’ trees was reduced with daminozide primarily by reducing shoot length.
Abstract
Seasonal changes in the relationship between leaf conductance and total water potential in mature apple (Malus domestica Borkh.) shoot leaves were found to be mediated by osmotic adjustment, not changes in the total water potential–relative water content relationship. Leaves at the growing shoot tip were found to have a much higher (1.0 to 2.0 MPa) osmotic potential than mature leaves and showed no seasonal osmotic adjustment, while mature, fully expanded leaves on the same shoots did adjust osmotically. Leaf osmotic potentials differed little among exposed leaves on a shoot once fully expanded.
Abstract
Laboratory and orchard studies were designed to determine the critical temperatures at which injury to flowers of sour cherry (Prunus cerasus L. cv. Montmorency) occurred during spring development. In laboratory freezing tests, the temperature at which 50% of the flowers were killed (LT50) rose rapidly as the buds swelled, reaching −5°C just prior to separation of the bud scales and −3° at full bloom. Comparison of orchard minima with subsequent injury indicated greater sensitivity of unopened buds, but lower sensitivity of expanding flowers, in comparison with laboratory values. Limited comparisons indicated no consistent effect of previous temperatures upon bud hardiness. On the basis of these observations, growers with orchard heating equipment should not permit temperatures to fall below −2° once buds reach the “water bud” stage (40 to 50 mg fresh weight per bud).
Abstract
Eight-year-old, semi-standard ‘McIntosh’ apple trees (Malus domestica Borkh.) were converted from central leader trees to open center trees by removal of the central leader. The productivity of the converted trees was not reduced in the first year due to better fruit set and size, and flowering and yield of the open center and central leader trees were similar in the second year. Open center trees resulted in less damage to the fruit during mechanical harvest, primarily due to reduction in fruit zone height.