Search Results

You are looking at 1 - 10 of 25 items for

  • Author or Editor: J. A. Barden x
Clear All Modify Search
Author:

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.

Open Access
Authors: and

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.

Open Access
Authors: and

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 2 ‘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.

Open Access

Abstract

Ethephon, (2-çhloroethyl)phosphonic acid, 3 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.

Open Access

Abstract

Sprays of (2-chloroethyl)phosphonic acid (ethephon) 3 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.

Open Access

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.

Open Access

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.

Open Access

Abstract

Weeping fig (Ficus benjamina L.) plants were greenhouse-grown under full sun or 75% light exclusion. Shade-grown leaves were larger, thinner, flatter, and darker green than sun-grown leaves. Sun- and shade-grown plants had the same total leaf area and were the same height. Shade-grown leaves had a single, poorly developed palisade layer with large chloroplasts dispersed throughout the palisade cells. Sun-grown leaves had one or two layers of well developed palisade cells with the chloroplasts aligned primarily along the radial walls. Stomatal density was greater in sun-grown leaves, but shade-grown leaves had more stomata per leaf.

Open Access

Abstract

Suitable conditions for determining net photosynthesis (Pn) of individual sun- and shade-grown leaves of weeping fig (Ficus benjamina L.) were 21°C dew point and an air flow rate between 1 and 3 liters/min. A diurnal trend in Pn occurred for sun leaves, with maximum rates between 0800 and 1200 hr; shade leaves did not decline in Pn until mid-afternoon. Leaves which originated from nodes 4 through 10 (from the shoot apex) did not differ in Pn, transpiration (Tr), specific leaf weight (SLW), or leaf water content. Shade-grown leaves had a photosynthetic advantage over sun-grown leaves at levels of photosynthetically active radiation (PAR) below 77 μE m−2s−1, whereas at PAR levels above 100 μE m−2s−1 the reverse was true. Sun-grown leaves had higher Tr rates than shade grown leaves at all PAR levels used.

Open Access

Abstract

Weeping Hg (Ficus benjamina L.) plants grown under 3 light regimes (full sun, full sun followed by 8 weeks acclimatization under 75% shade, and 75% shade) were placed in a low-light simulated interior environment (SIE) for 12 weeks. Acclimatized and shade-grown leaves had higher net photosynthesis (Pn) rates, lower dark respiration (Rd) rates, and lower light compensation points (LCP) than sun-grown leaves after 12 weeks in the SIE. No treatments increased total plant dry weight during the 12 weeks of SIE. However, percent dry matter of sun plants was redistributed with additional leaves produced at the expense of root carbohydrate reserves. Leaf production exceeded abscission in all treatments. Anatomical observations prior to and following the SIE indicated chloroplast reorientation in all treatments. The development of large, heavily stained chloroplasts suggest ultrastructural changes may also occur as a result of low light.

Open Access