Search Results
Abstract
Eight different light treatments did not affect shoot length, leaf number, or total leaf area of young ‘Red Yorking’ apple (Malus pumila Mill.) trees grown in a greenhouse. Dry weights of leaves and stems were suppressed by 80% shade. Net photosynthesis (Pn), dark respiration (Rd), and specific leaf weight (SLW) were higher in sun than in shade leaves and adaptations in all 3 parameters occurred as a result of changing light conditions, even after leaf expansion had ceased.
Abstract
A combination of succinic acid-2,2-dimethylhydrazide (daminozide), (2-chloroethyl)-phosphonic acid (ethephon) and straight chain fatty alcohols (Off-Shoot-T85) or methyl esters of straight chain fatty acids (Off-Shoot-0) applied 30 days after bloom to nonbearing ‘Topred Delicious’ apple trees (Malus domestica Borkh.) induced spur development on current season growth, increased the number of flower buds per tree, and suppressed terminal growth, one-year-old shoot diameter, and trunk diameter. The combination of daminozide and ethephon did not induce spurs to develop on current season growth; however, slightly enlarged buds on one-year-old growth flowered the spring following treatment.
Abstract
The performance of young container grown apple trees of two ‘Delicious’ strains was studied under greenhouse conditions in a 2 year experiment. ‘Redspur Delicious’, a spur type strain, and ‘Richared Delicious’ were grown on seedling rootstocks in the first season and on seedling, MM 106, and M VII-A rootstocks the following year. Net photosynthesis (Pn) of ‘Redspur’ leaves tended to be higher than the Pn of ‘Richared’ leaves. One season’s data indicated that the Pn of leaves of greenhouse grown trees on seedling rootstocks was higher than those on MM 106. Leaves of trees on M VII-A were intermediate in Pn. The respiration rates were not affected by strains or rootstocks. Standard ‘Delicious’ trees were more vigorous than trees of the spur type as indicated by greater shoot length, internode length, leaf number and total leaf area. The spur type trees had, however, a greater bark-wood ratio. Rootstocks affected both leaf size and leaf dry weight, but strains did not.
Abstract
Of 33 chemicals tested, 21 had no effect on net photosynthesis (Pn) or dark respiration (Rd) of apple (Malus pumila Mill.). Of the 12 having an effect, most reduced Pn, 2 increased Pn, and 1 increased Rd. Oil and emulsifiable concentrate formulations generally reduced Pn, while Plictran and formetanate hydrochloride increased Pn. In 1 test qxythioquinox increased Rd whereas other materials had little or no effect in any test. There was no difference in response by cultivar or to environment, but the method of treatment introduced wide variation in the effects of certain chemicals.
Abstract
Concentrations up to 4000 ppm of (2-chloroethyl)phosphonic acid (ethephon) did not affect the net photosynthesis (Pn) of leaves on greenhouse grown apple trees. Leaf respiration was increased by 4000 ppm ethephon, but not by lower concn. Pn rates did not differ between cvs., but respiration of ‘Golden Delicious’ leaves was greater than that of ‘York’ leaves.
Abstract
Ethephon, (2-çhloroethyl)phosphonic acid, was applied at rates of 125 ppm and higher to young apple trees in 3 greenhouse experiments. Leaf expansion and total number of leaves were reduced by ethephon; the effective concentration became lower as the growing season progressed. Leaf area on the primary shoot was reduced by 1,000 and 4,000 ppm ethephon, but was increased on the lateral branches by 4,000 ppm. Total leaf area was suppressed only by the 1,000 ppm treatment. Leaf necrosis occurred at 625 ppm and higher concentrations in 1 experiment. Lateral bud scales abscised and a proliferation of cells under the leaf scar occurred on trees treated with 7,500 and 10,000 ppm ethephon. Many lateral buds abscised on the lower two-thirds of trees treated with 10,000 ppm. Leaf abscission was induced by ethephon, and the higher concentrations caused earlier and more rapid leaf drop. The oldest leaves abscised first, and most leaves became somewhat chlorotic prior to abscission. Leaves apparently had to be of a certain physiological age before they could be induced to abscise.
Abstract
Sprays of (2-chloroethyl)phosphonic acid (ethephon) were applied to young apple trees in 2 greenhouse experiments. Ethephon suppressed terminal growth, internode length, and elongation of the pre-treatment stem. Ethephon applied at 4,000 ppm, 64 days after bud break resulted in abscission of some shoot apices. Lateral branching was induced by ethephon, but it was not dependent on abscission of the shoot apex. Whereas dry weight of the lateral branches was increased at 4,000 ppm, total stem dry weight was decreased by ethephon.
Abstract
Two experimental growth regulators, CGA-15281 (beta-chloroethyl-methyl-bis-benzyloxy-silane) and an analogue, CGA-17856, induced leaf abscission in peach (Prunus persica (L.) Batsch). Responses paralleled temperature following treatment. Older leaves were more responsive than younger ones and abscission occurred prior to leaf senescence. Applications prior to rainfall indicated about 6 hours without wetting was needed for maximum chemical activity. CGA-17856 tended to cause more leaf abscission than CGA-15281.
Abstract
Several summer pruning treatments were applied in August to ‘Stayman’/Malling Merton (MM) 111 apple (Malus domestica Borkh.) trees measuring 4m high and 5m wide to examine the resulting changes in light climate. Diffuse photosynthetically active radiation (PAR) increased immediately by about 1/5 on the periphery and 1/10 within the canopy from 2 types of summer pruning. These changes in PAR had no effect on net photosynthetic (Pn) potential, dark respiration (Rd), or specific leaf weight (SLW) determined 21 and 54 days after pruning. One method of summer pruning reduced penetration of PAR into inner canopy positions the year following treatment.
Abstract
Changes in photosynthetic parameters in ‘Stayman’/Malling Merton (MM) 111 apple (Malus domestica Borkh.) trees measuring 5 m wide and 4 m high were studied for an entire growing season. Parameters investigated included penetration of photosynthetically active radiation (PAR), changes in spur leaf net photosynthetic (Pn) potential, dark respiration (Rd) and specific leaf weight (SLW). As measured by changes in PAR penetration, canopy development was generally complete by mid-May. Pn, Rd, and SLW were modified by canopy position. SLW was influenced by the previous light environment as peripheral canopy leaves had higher SLW’s than interior leaves.