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Abstract

Spray application of 2-chloroethylphosphonic acid (ethephon) to walnut trees caused dehiscence of hulls and enabled complete nut removal with a single mechanical shaking operation as much as 3 weeks earlier than normal. Walnuts were hullable and the quality was generally superior to that of the controls. In some instances considerable leaf fall resulted from the treatment.

Open Access

Abstract

‘Tan-ginbozu’ dwarf rice was responsive to root-applied gibberellins which had previously been separated by thin layer chromatography on glass fiber sheets. A 3-day test was less variable than 4, 5, 6 or 7-day tests. Seven replications enabled 50% differences in growth to be discernible with 95% confidence among 3 treatments; with 2 treatments, 50% differences in growth were discernible with 4 replications.

Open Access

Abstract

Historians tend to find what they are looking for. My bias in developing historical aspects of Growth Regulators (GR) in Pomology has been positive, as I believe that control of plant growth will eventually be possible. The thought processes and actions taken by individuals who led the way to eventual use of GR are difficult to access. Perhaps the beginnings were initiated by those who had the time to observe plant growth and write down what they saw. To credit any one individual would be of doubtful accuracy. Historically, the one who accumulates fame for a breakthrough put the finishing touches on an idea which had evolved over a long period of time.

Open Access

Abstract

None of the physiological events in plant growth and development is truly independent. Photosynthesis, flowering, and mineral transport are sharply focused areas of research; yet these phenomena are not separable from other metabolic events in the plant. This feature of interdependence may be called correlations (26) or growth correlations (49, 50). The control exerted by the growth zone emanates from a meristem; these meristems include the root or shoot apex, cambium, flowers, fruit, pollen on stigma, and the ovule or seed in a fruit.

Open Access

Abstract

Large differences in abscisic acid (ABA) concentrations were found among persisting fruit of ‘Winter Nelis’, seeded ‘Bartlett’ and parthenocarpic ‘Bartlett’ pear (Pyrus communis L.) even though fruit set and fruit growth rates were similar. Concentration of ABA was positively correlated with rate of fruit and seed growth in these 3 pear types. The concentration of ABA was greater in the seed than in fruit flesh, and in the integuments plus endosperm than in the embryo.

Open Access

Abstract

Flowers of caged ‘Winter Nelis’ pear (Pyrus communis L.) set parthenocarpic fruit that persisted until maturity after a single treatment with the gibberellin GA3, GA3 + CaCl2 or the pear gibberellin GA45. Cytex (a zeatin-like cytokinin), abscisic acid (ABA), GA9, GA17 and GA25 were ineffective. The persisting fruits treated with GA3 or GA3 + CaCl2 were significantly smaller than the controls and the GA3 + CaCl2 treated fruits were significantly smaller than those treated with GA45.

Open Access

Abstract

Analysis for hormones in plant material received impetus from the early studies of Went (4). Since that time, scientists have used living plant materials to estimate the presence of specific hormones. Among the advantages of the bioassay are sensitivity to the nanogram and in some cases, picogram range, ease of use, functionality with high levels of contaminants, and low cost of operation. The disadvantages include lack of specificity, variable response, and, in most instances, the need to use a species foreign to the one under examination.

Open Access

Abstract

In the paper “Determination of moisture in walnut seeds by near-infrared spectrophotometry” by Robert C. Campbell and George C. Martin, (HortScience 11(5):494. 1976), two errors on page 495 have been noted.

Open Access

Abstract

Spur buds of apricot were sampled at intervals from late July, 1968, until bloom in 1969, and from 1 month after bloom until the end of September. The samples were freeze-dried and then extracted with 80% methanol. The extracts were partitioned into 4 phases: water, neutral ethyl acetate, acidic ether, and acidic butanol, and then bioassayed for auxins, inhibitors and gibberellins. Although an inhibitor and gibberellin-like activity were present in the extracts, no consistent auxin-type activity was found. The end of rest was correlated with a decrease in the level of inhibitor and gibberellin-like activity, with the inhibitor increasing again towards anthesis. The onset of rest in May, 1969, was correlated with a decrease in inhibitor and increase in gibberellin-like activity. The inhibitor was present in scales and floral parts of buds, while gibberellin-like activity was confined mainly to the floral parts.

Open Access