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Michal Fishler, Eliezer E. Goldschmidt, and Shaul P. Monselise

Abstract

The dependence of fruit growth of grapefruit (Citrus paradisi Macf.) upon leaf area was investigated on girdled branches by manipulating leaf and fruit numbers. Leaf areas of 2.0 ± 0.5 m2 per fruit were found to be saturating with regard to fruit growth rate and size. Fruit on internal, shaded branches required larger leaf areas. Fruit on girdled branches weighed 44 to 119% more than fruit in ungirdled branches, which had leaf areas of 0.35 to 0.55 m2 per fruit. This indicates that leaf area is one of the factors limiting fruit growth. Starch accumulated in thin twigs during the fruit growth season, forming a saturation curve similar to those obtained for fruit size when plotted against leaf area per fruit. Increasing leaf area per fruit could involve a decrease in photosynthetic activity, a possibility which now is being investigated further.

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Duane W. Greene and Wesley R. Autio

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each l-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

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Duane W. Greene and Wesley R. Autio

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each l-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

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Duane W. Greene and Wesley R. Autio

A series of experiments were initiated to evaluate the influence of notching on improving lateral branching of young apple trees. Buds on 2-year-old wood of `Redspur' Delicious/MM.111 were notched at 2-week intervals from 6 weeks before bloom to 2 weeks after. Notching increased lateral branching cubically with the greatest response occurring when notching was done 2 to 4 weeks before bloom. Bud break occurred equally well and shoots grew comparably when `Redcort'/M.7 were notched at the tip, middle, or base. Bud break and shoot growth from unnotched buds was greatest at the tip, intermediate in the middle and least at the base. Limbs of `Spygold'/M.7 were spread to a 45 degree angle then one bud from each 1-year-old shoot was notched at either the top, side or on the bottom of the shoot. Notching increased lateral branching from all bud positions, but the greatest response was from buds notched at the top and least from those located at the bottom of a branch. Buds of `Marshall McIntosh' were notched on either 1 or 2-year-old wood. Notching increased lateral branching more on 2-year than on 1-year old wood.

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San-Gwang Hwang, Yi-Ying Li, and Huey-Ling Lin

, horticultural wastes, such as the trimmed branches of fruit trees, are a good source of lignocellulose. However, it is unknown whether pruned fruit tree branches can serve as an alternative substrate for king oyster mushroom growth. In Taiwan, around 5113 ha of

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John Warner

`Sturdeespur Delicious', `MacSpur`, `Summerland McIntosh', `Idared', and `Empire' apple trees (Malus domestics Borkh.) planted in 1986 on various size-controlling rootstock were used to determine the effect of rootstock on primary scaffold branch crotch angle. There were differences in crotch angle depending on rootstock. Rootstock effects were more pronounced with the upright growing `Sturdeespur Delicious' than with `Idared' and `Empire', which have a spreading growth habit. Ottawa 8 rootstock had a tendency to produce primary branches with wider crotch angles than other semidwarf to standard rootstock.

Open access

James R. Schupp, H. Edwin Winzeler, and Melanie A. Schupp

retained and the attendant axillary buds allow release from apical dominance, resulting in localized stimulation of branching. Stubbing is a type of heading cut whereby only a small section of a 2-year-old or older limb is retained to limit the potential

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Roar Moe, John E Erwin, and Will Carlson

The role of irradiance and/or ethylene in inducing mortality and self-branching disorders in Gerbera jamesonii Bolus. seedlings was studied. Seedling mortality increased from 8% to 57% when seed was covered with vermiculite than left uncovered during germination. Supplemental lighting for 30 days after germination decreased seedling mortality and decreased the time to visible bud compared to seed germinated under natural light only. In subsequent experiments, seeds were germinated and then seedlings were water logged or sprayed with ethephon (0.69, 3.45, or 17.25 mM) at four different stages of seedling development. Half of the ethephon-treated seedlings were sprayed with silver thiosulfate (STS). Seedling mortality was greatest after cotyledon expansion but before expansion of the first tree leaf. The highest ethephon concentration caused reduced seedling dry weight after 42 days. Applying STS did not overcome self-branching or meristem necrosis.

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Don C. Elfving and Dwayne B. Visser

A new bioregulator, cyclanilide (CYC, Bayer Environmental Science, Research Triangle Park, NC 27709), was compared with a proprietary formulation of 6-benzyladenine and gibberellins A4 and A7 [Promalin (PR), Valent BioSciences, Walnut Creek, Calif.] for branching effects on sweet cherry trees. CYC stimulated the formation of lateral shoots on current-season's shoot growth under both orchard and nursery conditions. In the nursery CYC was as effective or better for feathering compared to PR in all cherry cultivars tested. There were no synergistic effects of CYC/PR tank mixes on feather development. Crotch angles of induced feathers were not different from the angles of feathers that formed spontaneously. The growth of CYC-induced feathers was sufficient to produce acceptable quality feathered trees. Trunk caliper of nursery trees was either not affected or reduced to a very minimal degree. CYC is effective for lateral branch induction in sweet cherry, especially in the nursery. Chemical names used: 1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid (cyclanilide); N-(phenylmethyl)-1H-purine-6-amine + gibberellins A4 and A7 (Promalin); polyoxyethylenepolypropoxypropanol, dihydroxypropane, 2-butoxyethanol (Regulaid).

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Duane W. Greene and Wesley R. Autio

Apple trees (Malus domestica Borkh.) were notched with a hacksaw blade by removing a 2-mm-wide strip of bark from directly above a bud. The cut extended down to the secondary xylem and around about one-third of the circumference of the stem. The most effective time to notch was ≈2 to 4 weeks before full bloom. Notching was most effective at inducing shoot growth from buds on the top of a branch, less effective for buds on the side, and least effective for buds on the underside of a branch. On untreated controls, the most shoots grew from the upper one-third of 1- or 2-year-old growth, and very few shoots developed buds on the lower one-third. If a bud was notched, however, the pattern was similar and incidence of shoot development was high. The percentage of notched buds that developed into shoots was not influenced by wood age.There was a positive, linear relationship between bud size and the percentage of buds growing into lateral shoots and between bud size and the length of those lateral shoots. Over all years, experiments, and cultivars, notching increased shoot production ≈600%.