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  • Author or Editor: J. P. Sterrett x
  • Journal of the American Society for Horticultural Science x
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Abstract

Paclobutrazol [(2RS,3RS)-1-(4-chlorophenyI)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-)pentan-3-ol)] was injected into bean plants (Phaseolus vulgaris L. ‘Black Valentine’), California privet seedlings (Ligustrium ovalifolium Hassk.), saplings of red maple (Acer rubrum L.), yellow poplar (Liriodendron tulipifera L.), white ash (Fraxinus americana L.), American sycamore (Platanus occidentalis L.), and one-year-old trees of ‘Golden-Delicious’ apple (Malus domestica Borkh), to evaluate growth inhibition response. Also, the extent of translocation and metabolism of injected 14C — paclobutrazol was determined in apple. The height growth, weight, and leaf size of bean plants decreased as the dose of paclobutrazol increased from 0.01 to 1,000 μg/plant. Sprout growth from stumps of privet was reduced as the dose of paclobutrazol increased from 1 μg to 1000 μg/tree. The shoot growth of sapling trees in the field was controlled for at least 2 months with doses of paclobutrazol ranging from 5 mg to 40 mg per tree. When obvious inhibition occurred in apple trees (27 days after injection), 23% of the 14C-activity had been translocated acropetally to the apical shoots. A high percentage of 14C-activity detected was paclobutrazol; 90% of the 14C-activity found in the xylem and phloem and over 85% in the shoot tissue chromatographed with paclobutrazol.

Open Access

Abstract

A pressure injection method was used with abscisic acid (ABA) and 6-benzylamino purine (BA) to control bud break of one-year-old trees of ‘Yellow Delicious’ apple (Malus domestica Borkh). When dormant trees were injected with 3 ml of 250 ppm (wt/vol) ABA, 58% of buds were inhibited after 28 days compared to 31% of the buds of the controls; injections of 3 ml of 200 ppm (wt/vol) BA above the ABA-injection site, induced 52% of the inhibited buds to open. Radioassays of apple stems collected 11 and 9 days after injection, respectively, with 14C-ABA or 14C-BA indicated highly significant increases in radioactivity in the phloem, buds and new shoots compared to radioassays taken immediately after injection.

Open Access

Abstract

Flurprimidol was injected into several species to evaluate effects on growth. Height growth was inhibited 85% in bean (Phaseolus vulgaris L. ‘Black Valentine’) and 90% in California privet (Ligustrium ovalifolium Hassk.) by the lowest flurprimidol doses (125 and 625 μg/plant, respectively). Shoot growth was further suppressed as doses increased. Gibberellic acid reversed the inhibitory effect of flurprimidol on privet. In June, height growth of field-grown yellow-poplar (Liriodendron tulipifera L.) and American sycamore (Platanus occidentalis L.) was uniformly reduced 35% by all flurprimidol doses. By late July, height growth increment decreased linearly as flurprimidol increased from 5 to 40 mg/tree. Thirty-five days after injection of 2.5 mg 14C-labeled flurprimidol in 1-year-old apple (Malus domestica Borkh.), 10% had moved into the new shoots, 1.5% into the scion phloem, and 80% remained near the injection site. A high percentage of the 14C activity was unmetabolized flurprimidol; 95% of the 14C activity in the xylem, 86% in the phloem, and 75% in the shoot. Although it is not highly mobile, flurprimidol effectively inhibits shoot growth, apparently inhibiting gibberellin synthesis. Chemical names used: α-(1-methylethyl)-α-[4-(trifluoro-methoxy)phenyl]-5-pyrimidinemethanol (flurprimidol).

Open Access

Abstract

To explain the synergistic interaction on abscission between 7-oxabicyclo(2,2,l)heptane-2,3-dicarboxylic acid (endothall) and (2-chloroethyl)phosphonic acid (ethephon), absorption and translocation of foliarly-applied 14C-ethephon alone or together with endothall were determined with (Phaseolus vulgaris L. cv. Red Kidney) plants using liquid scintillation, autoradiography, and gas chromatography. More l4C-ethephon remained in the treated leaf when applied in combination with endothall than when applied alone. These results suggest that the synergistic interaction between endothall and. ethephon can be attributed to transport inhibition thereby increasing the availability of ethylene for the abscission process.

Open Access