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- Author or Editor: Joseph W. Braun x
- Journal of the American Society for Horticultural Science x
Abstract
Butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide) (2000 and 4000 ppm) was applied to ‘Heritage’ primocane fruiting red raspberry (Rubus idaeus L.) primocanes at combinations of several dates, when the canes averaged 19, 42, 65, and 79 or 91 cm in height. Daminozide-treated plots achieved 50% of the eventual final yield an average of 8 days earlier (averaged for 5 treatments involving daminozide application at 42 cm) than controls. This advance of the production curve resulted in an average yield increase of 51% during the first 28 days of production. However, while early yields were increased, total yields were unaffected. Increasing the concentration of daminozide from 2000 to 4000 ppm did not increase the effects. Double application of daminozide (2000 ppm) at 65 and 79 cm and single application at 91 cm reduced yield during the 14 to 28 day harvest period compared to that of the single 65 cm application. This reflects, in part, the reduced berry size during the early harvest period resulting from the later (79 or 91 cm) applications of daminozide. Daminozide reduced the number of nodes formed and advanced the date of anthesis. Application of (2-chloroethyl)phosphonic acid (ethephon) (300 ppm at 19 and 42 cm) increased the number of nodes formed, delayed anthesis by about 13 days, delayed fruiting, and reduced total production.
Abstract
Permeation via acetone of fusicoccin (FC), or of a combination of the three growth regulators, kinetin (K), 2-chloroethyl(phosphonic acid) (ethephon) (E), and gibberellic acid (G) into dry lettuce (Lactuca sativa L. cvs. Grand Rapids and Mesa 659) seeds markedly relieved the inhibiting effects of stress on germination and seedling emergence. Permeation with FC or K+E+G increased dark germination by 80 to 90% at 30°C. At 35°, germination of ‘Grand Rapids’ seeds was enhanced much more by FC than by K+E+G. Both FC and K+E+G increased germination in solutions of NaCl (−4.95 bars) or polyethylene glycol-6000 (−3 bars). In saline medium at 30 and 35°, FC was more active than K+E+G. Hypocotyl and radicle elongation was greater for seeds treated with FC than for seeds treated with other materials in both aqueous and saline media. In soil moistened with water or 0.1 NaCl, emergence of unpermeated ‘Mesa 659’ seeds was 0 to 2% at 25°. Permeation with FC or K+E+G enhanced emergence 65–80% in water, 48–55% in NaCl. FC produced more vigorous seedlings in terms of fresh weight and size than any other treatment including K+E+G. Furthermore, FC generally shortened the emergence time more than K+E+G treatment, the difference being more marked in saline soil.
Abstract
In axillary meristems laid down just prior or subsequent to commencement of growth regulator applications, exogenous gibberellic acid (GA) alone promoted runner formation. Strongly-inhibited axillary buds with leaf primordia responded to GA + BA (benzyladenine) with runner formation in the June-bearer ‘Fortune’. Few of the inhibited buds of the everbearer ‘Geneva’ responded to GA or GA + BA. Following application of BA alone, inhibited buds of June-bearing cultivars formed lateral crowns (‘Fortune’) or runners (‘Earlidawn’). Runner formation following chilling of June-bearing ‘Fortune’ plants exposed to short days (SDs) occurred from meristems initiated after satisfaction of the cold requirement. Comparable buds on plants receiving no chilling during SDs remained inhibited, as did axillary meristems present during SDs. In contrast, runners formed by chilled, everbearing ‘Geneva’ plants originated from axillary meristems initiated prior to chilling but not from subsequent meristems. Chilling ‘Geneva’ plants during exposure to SDs removed the inhibition from existing axillary meristems and promoted runner formation. Runnering did not occur in activley growing ‘Geneva’ plants maintained under long days (LDs).
Abstract
Treatments to modify the available photosynthetic assimilate supply and partitioning pattern of developing laterals were imposed on canes of red raspberry (Rubus idaeus L.). Removal of alternate buds on the entire floricane or all buds on the lower half of the floricane did not influence productivity of the remaining fruitful nodes. Removing upper buds substantially increased the productivity of lower fruitful nodes (150–184%). The increased number of fruit produced by laterals at the lower nodes arose from an increase in the percentage of fruitful nodes on the laterals (lateral nodes), and from an increase in the number of fruit per lateral node. The region of fruitful lateral nodes itself was not extended. The increased number of fruit produced at the lower fruitful cane nodes was a response by initiated buds during the early stages of spring growth. The increase in berry size (weight) was favored in 1 of the 2 experiment years after upper bud removal. Training canes horizontally, to balance the exposure to light of laterals along the cane, did not influence yield.
Abstract
Petiole and scape elongation, leaf expansion, and runner formation were reduced by soil application of paclobutrazol (PP333). Runner number was reduced 90–100% by paclobutrazol dosages of 0.2–0.4 mg a.i. per 15-cm pot, accompanied by smaller reductions in leaf expansion (14–29%), petiole elongation (31–59%), and scape elongation (24–47%). Subsequent foliar applied gibberellic acid (GA3) at 50 ppm alleviated the effects of paclobutrazol. Lateral crown formation was promoted in several experiments. Fruit weight was not affected at 0.6 mg a.i. paclobutrazol per pot, but scape elongation was reduced by 51%. Chemical names used: β-[(4-chlorophenyl)methyl]α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).