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  • Author or Editor: Robert J. Weaver x
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Abstract

Length and width of leaf blade and length of petiole were closely correlated with leaf area in leaves of grape (Vitis vinifera L. cv. Grenache).

Open Access

Abstract

Cuttings from grapevines sprayed with a calcium cyanamide (Ca N-C≡N) mixture broke rest 14 days after their bases were placed in water at 25°C. By 40 days after the beginning of the experiment there was 90% budbreak. Maximum rooting was attained 57 days after the cuttings were placed in water at 25°. Control cuttings did not break rest or produce roots during the experiment, which lasted 100 days. Results similar to those of the control were obtained from cuttings stored at 0° for 3 days or 1 week. After 2 weeks at 0°, some control buds broke and some roots grew, but greater budbreak and root growth occurred in plants that had received the chemical treatment. When cuttings were removed from storage after 4, 8 or 12 weeks, there was little difference in budbreak or root growth between control and treated cuttings. Free ABA in untreated bud meristems (buds without scales) initially dropped and then rose again after 2 weeks of storage. With treated bud meristems the drop for free ABA was less after the beginning of storage than in control buds. In bud scales there was an increase in free ABA after the beginning of storage, especially with calcium cyanamide-treated cuttings. The bound ABA in bud meristems dropped markedly in the first 3 days of storage, both in control and treated cuttings. There was much less bound ABA in the bud scales than in the bud meristems, especially at the beginning of storage. When bud scales were removed, both budbreak and rooting were more rapid than in cuttings with intact buds.

Open Access

Abstract

Girdling reduced, and gibberellic acid or 4-chlorophenoxyacetic acid treatment had no effect on, the incidence of internal browning in ‘Thompson Seedless’ grape berries stored at 0°C. There was a direct relationship between the soluble solids content of the berries and the percentage of berries which developed internal browning. Fruit susceptible to internal browning had high levels of polyphenoloxidase and low levels of dihydroxy-phenolic substrate.

Open Access

Abstract

The effect of 3 abscission-promoting compounds on flower and berry abscission in 4 varieties of Vitis vinifera grapes was studied. A cluster-dipping experiment with Ethrel, abscisic acid, and a morphactin at concentrations ranging from 0.1 to 1,000 ppm, was done using ‘Thompson Seedless’, ‘Carignane’, and ‘Muscat of Alexandria’, at 4 developmental stages. Stimulation of abscission by the growth regulators decreased as flowers and berries became older. The morphactin was the most effective and abscisic acid the least effective in promoting abscission. Spray treatments with the same compounds induced abscission on ‘Muscat of Alexandria’ and ‘Perlette’ at appropriate concentrations. Pretreatment of ‘Muscat of Alexandria’ clusters with 4-CPA eliminated the effectiveness of morphactin and, to some extent, that of Ethrel.

Morphactin at 1 ppm stimulated shoot growth of ‘Muscat of Alexandria’ but marked inhibition occurred at 100 and 1,000 ppm. Ethrel at 10 ppm stimulated shoot growth, but marked inhibition occurred at 100 and 1,000 ppm. With ‘Carignane’ only morphactin produced inhibition of shoot growth. Appropriate concentrations of these compounds applied as sprays thinned ‘Perlette’ grapes, but thinning was quite irregular both within and among clusters.

Open Access

Abstract

At a stage just after bloom, gibberellin (GA3) at 600 ppm induced maximum increase in berry size of ‘Thompson Seedless’ grapes. Seven days after fruit-set, only 25 ppm were required for maximum response. In both instances, regression lines of best fit between GA3 concentration and berry weight indicated a logarithmic response. At both late bloom and early fruit-set stages there was a large increase in berry size, but at a time halfway between these stages the response to GA3 was much less striking. After fruit-set there was a gradual decrease in response to GA3. Increase in berry size due to girdling, on both vines sprayed at bloom and fruit set with GA3 and on unsprayed vines was maximum when berry diameter was 3-10 mm at time of girdling. There was no interaction between berry response to girdling and to gibberellin application. At fruit-set, ‘Perlette’ berries generally responded to increases in GA3 concentration up to 600 ppm.

Open Access

Abstract

Application of ethephon at 200 to 2,000 ppm was made to the grape cvs. ‘Tokay’ and ‘Emperor’, and at 1,000 ppm to ‘Thompson Seedless’ and ‘Carignane’. The soluble solids were significantly increased in some fruits of ‘Carignane’ but not in the other cultivars. Ethephon treatment resulted in reductions in acidity in some fruits of all cultivars. This increased soluble solids to acidity ratios in some ethephon-treated fruits. An increase in anthocyanin content of the colored berries occurred, but not significantly so in ‘Tokay’. Optimum time for treatment was about 2 weeks after initiation of coloring.

Open Access

Abstract

Gibberellin was applied at bloom to the seeded grape cvs. Zinfandel and Tokay. With ‘Zinfandel’ concn from 5 to 20 ppm caused increasing reductions in wt of fruits per vine and in ‘Tokay’ gibberellin at 10 and 20 ppm reduced fruit wt. Gibberellin applications successfully thinned the compact ‘Zinfandel’ and ‘Tokay’ clusters. Formation of unsightly shot berries was not a serious problem on ‘Tokay’. With ‘Zinfandel’, applications at the end of bloom were more effective than those at initiation of bloom.

A comparison of objective methods of measuring cluster compactness revealed that both number and wt of berries per cm of rachis are adequate indicators of the degree of compactness.

Open Access

Abstract

‘Thompson Seedless’ grapes (Vitis vinifera L.) were trained to heights of 1.4, 1.7, and 2.0 m with and without an 0.6-m crossarm. Data were collected from 4 seasons beginning in 1969. Within treatments variability was usually too great to reveal significant differences among treatment means for most parameters measured within a single year. Analysis of the 3-year combined results revealed that the highest trellis resulted in most yield, most clusters, and most berry sugar per vine. Vines on the lowest trellis had the least pruning brush wt. Vines with crossarms had higher wt per berry, soluble solids, sugar, and wt brush per vine than did vines without crossarms.

Open Access

Abstract

‘Black Corinth’ clusters at different stages of development were dipped into 25 ppm potassium gibberellate (KGA3). The most compact clusters resulted from treatment at 75% capfall or at succeeding applications up to 2 weeks after bloom. Most reduction in number of berries occurred at beginning of capfall and at 25% capfall. Berries treated between initiation of capfall and 1 week after full bloom were elongated while treatment at earlier or later stages resulted in round berries. The length-to-diameter ratio was greatest at 95% capfall and 3 days after full bloom.

Clusters were treated with KGA3 at 0, 1, 2, 4, 6, 10, 20, 60, or 100 ppm at 75% capfall, 3 days, or 1 week after full bloom. At the 75% capfall stage, looseness and number of berries was decreased by KGA3 at 100 ppm Berry wt and vol were increased as compared to controls by all concn of KGA3 above 2 ppm. Length, diameter, and the length-to-diameter ratio generally increased progressively as the concn of KGA3 increased.

Open Access