Benzyladenine (BA), carbaryl (CB), daminozide (DM), and naphthaleneacetic acid (NAA) were applied postbloom, as fruitlet thinning agents, to mature `Empire' apple trees. Although fruit set and yield were similar for BA, NAA, and CB, BA-treated fruit were larger, indicating BA increased fruit size beyond the effect attributable to thinning. BA applied at 100 mg·liter–1 increased the rate of cell layer formation in the fruit cortex, indicating that BA stimulated cortical cell division. The maximum rate of cell division occurred 10 to 14 days after full bloom (DAFB) when fruit relative growth rate and density reached a maximum and percent dry weight reached a minimum. Cell size in BA-treated fruit was similar to the control. Cell division ended by 35 DAFB in the control and BA-treated fruit when percent dry weight and dry weight began to increase rapidly and fruit density changed from a rapid to a slower rate of decreased density. These data support the hypothesis that BA-induced fruit size increases in `Empire' apple result largely from greater numbers of cells in the fruit cortex, whereas the fruit size increase due to NAA or CB is a consequence of larger cell size.
Paul T. Wismer, J.T.A. Proctor and D.C. Elfving
Thomas H. Boyle
Investigations were performed to determine the effects of timing of application and concentration of BA on the vegetative growth of Easter cactus [Rhipsalidopsis gaertneri (Regel) Moran `Crimson Giant']. BA was applied to rooted phylloclades at 27, 37, and/or 47 days after propagation (DAP) at 200 to 1000 mg·liter-1. At 80 DAP, the number and cumulative length of secondary (2°) phylloclades (those developing from the rooted phylloclade) of BA-treated plants exceeded those of the controls. Number and cumulative length of 2° phylloclades increased linearly with increasing BA concentration. At 316 DAP, there were no differences between BA-treated plants and controls in numbers of 2° and apical (terminal) phylloclades. BA also was applied to plants at either 95 or 187 DAP. Treatments included 10, 50, 100, and 200 mg BA/liter and an unsprayed control. Number of new phylloclades (those developing after treatments) and percentage of old phylloclades with new phylloclades increased linearly in response to increasing BA concentration. Relative to the controls, one application of BA at 50, 100, or 200 mg·liter-1 resulted in a ≈50% to 400% increase in total dry weight of new phylloclades accompanied by a ≈4% to 30% decrease in total dry weight of old phylloclades. Branching of mature plants, i.e., with three to five tiers of phylloclades, was significantly affected by timing of application and concentration of BA. BA may be useful for modifying plant architecture of Easter cactus to increase flowering and product marketability. Chemical name used: N- (phenylmethyl) -1H- purine-6-amine[benzyladenine (BA)].
Susan S. Han
The effects of the duration of cold storage, as well as the concentration, timing, and means of application of a solution containing 25 mg·L-1 each of benzyladenine (BA) and gibberellins (GA4+7) on the postharvest quality of cut Asiatic and Oriental lilies (Lilium sp.) were evaluated. Depending on the cultivar, lower leaves began to turn yellow between 1 and 2 weeks after placing non-cold-stored stems in a 20 °C room illuminated 12 h·d-1 with 8 μmol·m-2·s-1 from cool-white fluorescent lamps. Leaf yellowing continued to progress upward until the end of the vase life. Cold storage (3.3 °C) worsened the leaf disorder, particularly, on the Oriental lily `Stargazer'. The longer the duration of cold storage, the earlier the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. In addition, cold storage induced bud blasting, inhibited flowers from fully opening, and reduced the longevity and fresh weight of open flowers and the vase life of cut stems. Spraying leaves with a solution containing 25 mg·L-1 each of BA and GA4+7 significantly reduced cold-storage-induced leaf yellowing, bud blasting, and vase life of three of the four cultivars tested. The development of leaf yellowing declined with increasing concentration of BA+GA4+7. The susceptibility of `Stargazer' to cold-storage-induced leaf yellowing and bud blasting can be counteracted by a concentration of growth regulators higher than that which was effective for the other cultivars. Timing of the BA+GA4+7 application was not critical, as there were no differences in leaf yellowing or bud development when the solution was sprayed before or after the cold storage. Addition of BA+GA4+7 (0.5 or 2.5 mg·L-1 of each) to the preservative solution or a pulsed treatment in solutions containing 25 mg·L-1 each of BA and GA4+7 for 4 hours prevented leaf yellowing, but increased bud blasting. For practical applications, growth regulators can be sprayed prior to or after cold storage in order to improve the postharvest leaf and flower quality of cut lilies.
J.M. Goatley Jr. and R.E. Schmidt
This study was conducted to determine if foliar-applied biostimulators could enhance harvestability and transplanting of Kentucky bluegrass (Poa pratensis L.) sod. The systemic triazole fungicides propiconazole at 42 mg·m-2 and triadimefon at 150 mg·m-2 enhanced post-transplant rooting and sod strength of bluegrass. Propiconazole had the best sod enhancement effect, increasing sod tensile strength 23% and increasing transplant root lift strength 64% across three experiments. The synthetic cytokinin benzyladenine (BA) at 6 mg·m-2 and seaweed extract (SWE, a freeze-dried extract of the seaweed Ascophyllum nodosum) at 0.3 ml product/m 2 had little effect. The response to triadimefon was intermediate. Foliar applications of chelated Fe phosphate citrate at 112 mg·m-2 did not enhance sod strength or rooting of Kentucky bluegrass when applied either alone or in combination with the biostimulator materials. Chemical names used: l-(2-(2,4 -dichlorophenyl)-4-propyl-l,3-dioxo1an-2-ylmethyl)-lH-l,2,4-triazole(propiconazole);1-(4-chlorophenoxy)-3,3-dimethyl-lH-(l,2,4-triazo1-l-yl)-butanone (triadimefon);6-benzylaminopurine (BA, benzyladenine).
John L. Edson, David L. Wenny and Annette Leege-Brusven
In vitro—derived microshoots of antelope bitterbrush, incubated for 1 month in media supplemented with 0.44 μm BA, grew 0.8 and 1.1 cm longer in woody plant medium (WPM) compared to full-strength and half-strength Murashige and Skoog (MS) media, respectively. Explants cultured in WPM supplemented with 0.44 μm BA and 0.54 μm NAA produced a mean of five axillary shoots per explant. Explants dipped in 0.1% IBA or 0.1% NAA rooted best in 0.1% IBA with 89% success ex vitro vs. 60% success in vitro. Survival of acclimatized plantlets rooted ex vitro was 95%, while 50% survived when rooted in vitro. After 1 year of greenhouse growth, 98% of plantlets survived and flowered. Chemical names used: benzyladenine (BA), 3-indolebutyric acid (IBA), 1-naphthaleneacetic acid (NAA).
Mohamed F. Mohamed, Paul E. Read and Dermot P. Coyne
A new in vitro protocol was developed for multiple bud induction and plant regeneration from embryonic axis explants of four common bean (Phaseolus vulgaris L.) and two tepary bean (P. acutifolius A. Gray) lines. The explants were prepared from two embryo sizes, 3 to 4 mm and 5 to 7 mm, corresponding to pods collected after 15 and 25 days from flowering, respectively. The embryonic axis was cultured on Gamborg's B5 basal medium with 0, 5, 10, or 20 μm BA in combinations with 0, 1, or 2 μm NAA. The cultures were maintained at 24 to 25C under continuous light or incubated in darkness for 2 weeks followed by continuous light before transfer to the secondary B5 medium (0 or 2 μm BA or 2 μm BA plus 4 μm GA3). Adventitious roots or a single shoot with roots formed on the explants cultured on media without plant growth regulators. Multiple buds were induced on all BA media, but more were produced with 5 or 10 μm for most lines. Dark incubation greatly enhanced multiple bud initiation. Shoot buds were not produced on media containing NAA alone or in combinations with BA. On the secondary medium, six to eight shoots per explant for common bean and up to 20 shoots per explant from tepary bean were observed after 3 weeks. Mature, fertile plants were produced from these shoots. Chemical names used: benzyladenine (BA); 1-naphthaleneacetic acid (NAA); gibberellic acid (GA3).
Anil P. Ranwala and William B. Miller
The effects of Promalin® [PROM; 100 mg·L–1 each of GA4+7 and benzyladenine (BA)] sprays on leaf chlorosis and plant height during greenhouse production of ancymidol-treated (two 0.5-mg drenches per plant) Easter lilies (Lilium longiflorum Thunb. `Nellie White') were investigated. Spraying with PROM at early stages of growth [36 or 55 days after planting (DAP)] completely prevented leaf chlorosis until the puffy bud stage, and plants developed less severe postharvest leaf chlorosis after cold storage at 4 °C for 2 weeks. When PROM was sprayed on plants in which leaf chlorosis had already begun (80 DAP), further leaf chlorosis was prevented during the remaining greenhouse phase and during the postharvest phase. PROM caused significant stem elongation (23% to 52% taller than controls) when applied 36 or 55 DAP, but not when applied at 80 DAP or later. The development of flower buds was not affected by PROM treatments. Although PROM sprays applied at 55 DAP or later increased postharvest flower longevity, earlier applications did not. Chemical names used: N-(phenylmethyl)-1H-purine 6-amine (benzyladenine, BA); α-cyclopropyl-α-(p-methoxyphenyl)-5-pyrimidinemethanol (ancymidol).
Victor Gaba, Chassia Elman, Abed A. Watad and Dennis J. Gray
Cotyledonary explants of melon (Cucumis melo L. cv. Galia) regenerate primordia and buds in vitro induced by benzyladenine. The anti-gibberellin ancymidol can stimulate the rate of regeneration on melon explants in the presence of benzyladenine. Concentrations of benzyladenine plus ancymidol that are individually ineffective can act synergistically to stimulate regeneration. Gibberellic acid reduces the rate of regeneration induced by benzyladenine or benzyladenine plus ancymidol. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine (benzyladenine); alpha-cyclopropyl-alpha-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol).
I-lun Lu, David W. Burger and Ellen G. Sutter
Long term exposure to high benzyladenine (BA) concentrations inhibited shoot elongation and root growth of Cymbidium cv. Yuh Hwa rhizome explants. Through transfer experiments, it was determined that the commitment to shoot induction occurred between 10 and 14 days of exposure to at least 2.5 μM BA. BA when supplied at 20 μM during the fit 14 days of culture was found to be sufficient to induce shoot formation. Both shoot elongation and root formation were greatly improved by decreasing the BA concentration. By using radiolabelled BA, adenine was found to be a major metabolite in the rhizome tissue. Free IAA levels, quantitated by GC-MS, did not correlate well with the organogenesis of rhizomes, nor did the levels of free IAA correlate well with the activities of peroxidase and IAA oxidase, indicating a complex relationship between hormone concentration and differentiation.
John A. Cline, Mary Bom and Donald C. Elfving
A series of seven fruit thinning experiments with benzyladenine (BA), benzyladenine and GA4+7 (10:1 BA:GA4+7, Accel), carbaryl (CB), and NAA were conducted at the Horticultural Experiment Station, Simcoe, during the 1993 and 1994 growing seasons. In 1993, BA and Accel at 0, 100, 200, and 300 mg of BA/liter were applied to mature `Redspur Delicious'/M.26 and `Empire'/M.26 trees when fruit were ≈10 mm in diameter. In one set of experiments in 1994, Accel was applied at 0, 25, 50, 100, 150, and 200 mg of BA/liter to mature `McIntosh'/M.26 and `Empire'/M.7 trees. In a second set of experiments in 1994, Accel was applied at 0, 50, and 100 mg of BA/liter to mature `Idared'/M.26, `Empire'/M.26, and `Marshall McIntosh'/Mark trees when fruit were ≈10 mm in diameter. Additional treatments included bloom sprays of Accel at 50 mg of BA/liter, and sprays of BA at 50 mg a.i/liter, NAA at 10 mg a.i./liter, CB at 1000 mg a.i./liter, and a “low” (two fruit remaining/flower cluster) and `”high” (one fruit remaining/flower cluster) rate of hand thinning. In all experiments, thinning response to BA and Accel increased with concentration. Concentrations below 50, 100, and 300 mg BA/liter were generally ineffective for thinning `Empire', `Idared', and `McIntosh', and `Delicious', respectively. Fruit size of `Idared' and `Empire' was increased at rates of 50 mg BA/liter, whereas rates of 100 mg BA/liter were needed to increase fruit size of `McIntosh'. Accel applied to `Empire' at 150 mg BA/liter decreased the number of seeds per fruit and increased fruit length:diameter (L:D) ratios. Concentrations of Accel exceeding 100 mg BA/liter in `Red Delicious' decreased the number of seeds per fruit, while having little effect on fruit L:D ratios even though lower concentrations increased fruit L:D ratios. Diametric fruit growth measurements in 1994 indicated a temporary, but sharp, decline in growth rate immediately following treatment imposition for trees that responded positively to thinning. Additional data describing treatment effects on fruit size distribution, vegetative growth, and fruit maturity will be presented and discussed in relation to crop load.