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Yin-Tung Wang

Foliar application of 500 or 1000 mg BA or PBA/liter to stock plants of golden pothos [Epipremnum aureum (Linden & Andre) Bunt.] induced axillary bud elongation but did not promote growth of cuttings taken from these stock plants. Cuttings from plants treated with BA + GA4+7, each at 1000 mg·liter-1, died. Plants grown under 1000 μmol·s-1·m-2 had more but smaller leaves than those under 420 μmol·s-1·m-2. Cuttings produced under the higher light level grew more rapidly. Leaf area increased while stem length decreased as Osmocote slow-release fertilizer (18N-2.6P-10K) increased from 4 to 16 kg·m-3. A 24N-3.5P-13.3K water-soluble fertilizer applied at the rate of 0.42 g/500 ml weekly produced the best plants and resulted in the best cutting growth. Cuttings taken from stock plants receiving Osmocote at 4 kg·m-3 grew slower than those produced at other rates. Placement of cuttings in a mist-propagation bed for 1 or more weeks resulted in an accelerated growth rate relative to nonmisted cuttings. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); N-(phenylmethyl)-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-amine (PBA); (1α,2β,4aα,10β) 2,4a,7-trihydroxy-l-methyl-8-methylenegibb-3-ene-1,10-dicarboxylic acid l,-4a-lactone (GA4+7).

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Wen-Shaw Chen

The changes in cytokinins and gibberellins in xylem sap of lychee (Litchi chinensis Sonn. cv. Heh yeh) trees were investigated at the stages of leaf expansion, dormant bud (when apical leaves are dropped), 30 days before flower bud formation, flower bud formation, and full bloom of grafted field-grown lychee trees. Also; the diffusible IAA and ABA in diffusate from shoot tips were examined at the successive stages of development. High gibberellin was found in the xylem sap at the stage of leaf expansion. A constant level of IAA was maintained through the five growth stages. At 30 days before flower bud formation, ABA increased dramatically. Concurrently, total cytokinin content increased in the xylem sap, reaching a maximum during flower bud formation and full bloom. Gibberellin content in the xylem sap was at a low level 30 days before flower bud formation and through the stage of flower bud formation.

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Ernest P. Hayman and Henry Yokoyama

A 26-μm DCPTA seed treatment for guayule (Parthenium argentatum Gray) was developed. We obtained a 23% increase in germination rate as measured by the coefficient of velocity (C.V.). Greenhouse seedlings grown from DCPTA-treated seeds exhibited a 22% increase in dry weight and a 95% increase in survival rate under water-limiting conditions. In field-grown guayule, multiple foliar applications of 8.2 mm DCPTA increased the total amount of rubber in roots as much as 58% without affecting the rubber content in the stems. Chemical name used: 2-Diethylaminoethyl-3,4-Dichlorophenylether (DCFTA).

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Gary L. McDaniel, Effin T. Graham, and Kathleen R. Maleug

The effects of growth-retarding chemicals on stem anatomy were compared on poinsettia (Euphorbia pulcherrima Wind. `Annette Hegg Dark Red'). Micrographic examinations revealed that secondary walls of nonsclerotic phloem fiber cells were either completely or greatly reduced by retardant treatment. Wall thickening of phloem fiber cells was eliminated by paclobutrazol foliar sprays at 25 mg·liter-1. Fiber cell development was reduced, but not eliminated, by sprays of chlormequat and ancymidol at standard rates, while the triazole uniconazole at 10 mg·liter-1 permitted only limited fiber wall thickening. Chemical names used: (2-chloroethyl)-trimethyl ammonium chloride (chlormequat); α -cyclopropylα- (4-methoxyphenyl) -5-pyrimidine methanol (ancymidol); (E)-(p -chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol (uniconazole): and (R*,R*)- β -[(4-chlorophenyl)methyl]- α -(1,1-dimethylethyl)- 1 H-1,2,4,triazole-1-ethanol (paclobutrazol).

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Stephen M. Southwick and James T. Yeager

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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R. Nunez-Elisea, M. L. Caldeira, and T. L. Davenport

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Daniel L. Ward and Bradley H. Taylor

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Sher-Muhammad and Bradley H. Taylor

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Moritz Knoche and Martin J. Bukovac

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES