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Norman E. Looney

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Norman E. Looney

Abstract

Ethylene-induced endogenous ethylene production was substantial in immature pear fruits, attaining a max rate in samples harvested 60 days after full bloom and declining thereafter. Ethylene production was not dependent on the occurrence of a respiratory climacteric nor related to the rate of respiration. Field applications of succinic acid-2,2-dimethylhydrazide (SADH) suppressed both ethylene production and fruit growth.

Open access

Norman E. Looney

Abstract

A single spray of 2.5 or 5% CaCl2 applied 14 days before harvest significantly reduced breakdown of ‘Spartan’ apples (Malus domestica Borkh.) in each of 4 consecutive years and caused no residual tree or crop damage. Indole-3-butyric acid (IBA) alone or in combination with CaCl2 led to significant reductions in breakdown in only 1 of the 3 seasons in which it was tested. Ca applied in 1 season did not influence fruit Ca levels the next year. Both 2.5 and 5% CaCl2 applied in 1973 significantly increased Ca in fruit peel, flesh and core tissues. Although IBA did not increase fruit Ca levels, a strong negative relationship between fruit Ca and breakdown susceptibility was evidenced by analyses in 3 crop years.

Fruits located near the top of the trees were lower in flesh Ca than those from the bottom. This, plus inadequate spray coverage in the top of the tree canopies, led to poor control of breakdown in these fruits when the sprays were applied at lx, 3x or 6x concentration with an air-blast orchard sprayer using 3342, 1114, and 557 1 of water per hectare, respectively.

Open access

Norman E. Looney

Abstract

Ripening of ‘Bartlett’ pears at 20°C was assessed in samples harvested weekly beginning 4 weeks prior to commercial harvest maturity. Ripening was promoted by delaying harvest, by 1- and 2-week periods of storage at 4.4°C, or both. Early summer treatments with 750 and 7500 ppm succinic acid-2,2-dimethylhydrazide (SADH) delayed ripening but this effect was counteracted by both delayed harvest and postharvest storage at 4.4°C. It is concluded that SADH delays ripening by influencing an endogenous mechanism for controlling ripening in pears.

Open access

Norman E. Looney

Abstract

Succinic acid-2,2-dimethylhydrazide (SADH) applied early in the season and ethylene applied postharvest were found to influence respiration and ethylene production by immature ‘McIntosh’ apples. Ethylene treatment increased respiration of SADH-treated and non-treated fruit equally until July, when SADH began to suppress this ethylene-induced effect. Only fruits treated with ethylene produced measurable quantities of ethylene and a peak in this response was apparent in fruits harvested in mid- to late June in each of the 2 seasons studied. SADH greatly suppressed this response to ethylene.

Open access

Norman E. Looney

Abstract

Fruit quality measurements and taste panel assessments indicated considerable latitude for programming harvest of ‘McIntosh’ apples. Ripening at 20°C was advanced by ethephon-auxin and delayed by succinic acid-2,2-dimethylhydrazide (SADH) and CO2. The rate of softening and acid catabolism at 0°C were not altered by the growth regulator treatments.

SADH suppressed ethylene production and CO2 suppressed both ethylene production and softening of ripening fruits held at 20°C. These effects were greatest in fruits not subjected to cold storage and declined linearly in fruits held 30, 60 or 90 days at 0°C. Neither SADH nor CO2 influenced acid loss at 20°C.

Open access

Norman E. Looney

Abstract

Ethephon (600 ppm applied 3 weeks or 300 ppm applied 1 week ahead of “normal” harvest) combined with either NAA or 10 or 20 ppm 2,4,5-TP increased red color and decreased firmness of fruits harvested 6 or 12 days after each treatment. In neither series did NAA or 2,4,5-TP control drop adequately.

A midsummer treatment with 1000 or 2000 ppm succinic acid-2,2-dimethylhydrazide (SADH) modified these results by enhancing color and firmness and greatly reducing fruit drop relative to fruits treated solely with ethephon-auxin.

Open access

Norman E. Looney

Abstract

Succinic acid-2,2-dimethylhydrazide (SADH) was applied 3 times, at monthly intervals beginning 2 weeks after full bloom, to ‘McIntosh’ apple trees (Malus sylvestris L.). In the month preceding normal harvest, control and SADH treated trees were sprayed on 3 different dates with 2-chloroethylphosphonic acid (ethephon) as an ethylene source and/or 2,4,5-trichlorophenoxypropionic acid (2,4,5-TP), a synthetic auxin. Fruit samples harvested one and two weeks after each treatment revealed that without SADH: 2,4,5-TP moderately advanced ripening as evidenced by enhanced ethylene production, softening, and respiration, but prevented fruit abscission; ethephon greatly advanced ripening, red color development and abscission; and 2,4,5-TP + ethephon resulted in a striking increase in coloration accompanied by the highest rates of respiration, ethylene production and softening, but no abscission. With previous SADH treatment the effect of the other materials was reduced or, as in the fruit coloring response to ethephon, delayed. SADH exerted a pronounced effect on endogenous ethylene formation. It is suggested that SADH specifically inhibits autocatalytic ethylene formation, possibly by maintaining membrane integrity.

Open access

Norman E. Looney

Abstract

Fruits on individual spurs, on branch units, and on whole ‘Spartan’ apple (Malus domestica Borkh.) trees treated with a proprietary mixture of gibberellins A4 + A7 plus benzyladenine (GA4+7 plus BA) were generally heavier and longer than untreated fruits in 2 seasons. The principle effect of treatments applied at first petal fall (FPF) was an increase in the fruit length/diameter (L/D) ratio. Treatments applied 3 days to 5 weeks after FPF increased fruit weight and enhanced the L/D ratio. Ca concentration was reduced by the treatments which enhanced fruit weight and the incidence of ‘Spartan’ breakdown was increased. Fruit firmness and soluble solids were unaltered by the GA4+7 plus BA treatments. Fruit acidity was reduced in one experiment.

Open access

Norman E. Looney

Abstract

Probably the area of horticultural science changing most rapidly in recent years is that concerned with chemical plant growth regulation. Certainly the technology of fruit production has been dramatically influenced by growth regulators and the list of cultural practices that can benefit from growth regulators is growing steadily. Many of us have been hard pressed to keep up with the required field testing. We have little time to explore more fundamental aspects of growth regulator research such as synthesis and formulation of new materials, or even more importantly, to examine the mode of action of plant growth regulators in our particular horticultural systems. It is hoped that these invited papers, with their emphasis on fundamentals, will help many of us to put our research effort into a more realistic perspective.