A range of concentrations and timings of CPPU application were evaluated in attempt to identify situations in which fruit size, flesh firmness, and soluble solids could be increased while minimizing increased incidence of fruit asymmetry and reductions in flower bud formation and fruit surface red color on 'McIntosh' apples (Malus×domestica Borkh.). The greatest response to CPPU for most attributes evaluated occurred when it was applied at fruit size between 6 mm and 16 mm. The conclusion from this series of experiments is that differential response to CPPU could not be established by altering the time of application. The response to CPPU is linear with increasing concentration. Results suggested that use of 4 to 6 mg·L-1 CPPU on apples to increase fruit size was the maximum and appropriate range to use without causing fruit asymmetry. Chemical name used: N-(2-chloro-4-pyridyl)-N′-phenyl urea (CPPU)
Shoot tip and stem segment explants collected from greenhouse-maintained plants of Hymenoxys acaulis var. glabra were cultured in vitro for shoot initiation on a Murashige and Skoog (MS) medium supplemented with 30 g·L-1 sucrose, 2.5 μm BA, and 7 g·L-1 agar at a pH of 5.7. Unbranched shoot explants were subcultured to MS medium with 0.0, 0.5, 1, 2, 4 or 8 μm BA for shoot proliferation. A maximum of 10.3 shoots per explant was produced on the medium with 2.0 μm BA. Nonrooted shoots were subcultured to MS medium with 0.0, 0.5, 2, or 8 μm K-IBA for rooting. Maximum rooting was 90% on MS medium with 0.5 μm K-IBA. Rooted shoots were greenhouse-acclimatized for 10 days. Overall survival was 75%. Chemical names used: 6-benzyl adenine (BA); potassium salt of indole-3-butyric acid (K-IBA).
In vitro propagation systems were developed for Carnegiea gigantea (Engelm.) Britt & Rose, Pachycereus pringlei (Berger) Britt & Rose and Stenocereus thurberi (Engelm.) Buxb, three North American species of columnar cacti. In vitro germinated seedlings were used as a source of explants. Multiple shoot formation from areoles was achieved for three types of explants (apical, lateral, and transverse) cultured on Murashige and Skoog (MS) basal media supplemented with 3% sucrose, 10 g·L-1 agar and various treatments with growth regulators. The highest shoot production efficiency for C. gigantea was obtained on transverse explants cultured on a medium with 2 mg·μmL-1 (8.87 μm) BA, where 5.3 shoots per explant were obtained. In P. pringlei and S. thurberi the best response was obtained using transverse explants on medium with 1 mg·L-1 (4.44 μm) BA (3.8 and 4.3 shoots per explant, respectively). Rooting of the in vitro generated shoots was achieved most efficiently on MS basal media with 3% sucrose, 10 g·L-1 agar and 1 mg·L-1 (4.9 μm) indole-3-butyric acid. Rooting frequencies were 92%, 88%, and 96% for C. gigantea, P. pringlei and S. thurberi, respectively, and the frequency of survival of the plants once transferred to soil was 86% on average. Chemical name used: benzyladenine (BA).
The postharvest quality of potted Asiflorum lily `Donau' (Lilium hybrid) was evaluated after plants were sprayed with 0, 50, 250, or 500 mg·L-1 (BA equivalent) of Promalin (GA4+7 to BA ratio was 1:1) or Accel (GA4+7 to BA ratio 1:10) and stored at 2 to 3 °C for 0, 10, or 20 days. As storage was prolonged, more leaves senesced once plants were removed for evaluation. Leaf senescence declined with increasing concentrations of either Promalin or Accel, but Promalin was more effective. Application of 250 mg·L-1 Promalin completely eliminated leaf senescence over the 20-day shelf-life evaluation period, irrespective of duration of cold storage. The treatments did not affect flower bud opening or plant height. Chemical names used: gibberellin (GA4+7); benzyladenine (BA).
Abstract
Embryo germination of olive (oleo europaea L.) was inhibited by 10 ppm abscisic acid (ABA); no embryo germination effects were found with treatment of gibberellins (GA3 or GA4+7) or 6-benzylamino purine (BA). Whole seed germination was reduced by 100 ppm GA3. Only ABA was found in extracts of olive seed tissues. Young developing embryos contained up to 600 ng/g fresh weight ABA which declined to nondetectable amounts at seed maturity. ABA was not detected in endosperm plus seedcoat until seed maturity, then at 8 ng/g dry weight. In early stratification, no ABA could be detected in any seed tissues. It seemed evident that embryo tissues were more sensitive to ABA as seed maturity approached, and by then seed germination may be prevented by ABA at 8 ng/g dry weight found in endosperm and seedcoat.
Abstract
The effects at 2 different rates of the gibberellins A4 and A7 plus 6-beneyladenine (GA4+7 + BA) on the length/diameter (L/D) ratios of both standard- and spur-type ‘Delicious’ apples (Malus domestica Borkh.), when combined with bloomperiod fungicides applied at different stages of blossom development, were evaluated. The effectiveness of GA4+7 + BA was not reduced by combining it with selected fungicides. GA4+7 + BA at twice the suggested rate usually resulted in increased fruit L/D ratios. Full-bloom applications were most effective for fruit elongation of spurtype strains, whereas full-pink applications were most effective for standard-type strains.
Abstract
Dormant bud explants taken from mature trees of Japanese persimmon cv. Hiratanenashi were established successfully on modified Murashige and Skoog's medium with nitrate reduced to half-strength [MS (½NO3)] or woody plant medium, both supplemented with 22.2 μM (5 mg°liter−1) BA. Shoot proliferation in subcultures also was best at 22.2 μM (5 mg°liter−1) BA in MS (½NO3) medium, but growth was of the rosette type. Shoot elongation, however, was stimulated the most in the same medium supplemented with 24.6 μM (5 mg°liter−1) 2iP instead of BA. Rooting of the proliferated shoots was enhanced by the treatment with IBA at 1.23 mM (250 mg°liter−1). Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA), N-(3-methyl-2-butenyl)-1H-purin-6-amine (2iP), 1H-indole-3-butanoic acid (IBA).
Thidiazuron (THI) applied at full bloom (FB) at 10 or 50 mg·liter–1 thinned `McIntosh' apples (Malus domestica Borkh.) and reduced return bloom. The same concentrations applied at 22 days after FB (DAFB) thinned excessively and inhibited return bloom even more. THI at 1, 5, or 15 mg·liter–1 did not thin `Empire' at FB, but when applied 18 DAFB, these concentrations achieved thinning, with 5 mg·liter–1 reducing crop load to near ideal commercial levels. Return bloom of `Empire' was not influenced by THI at these concentrations. THI increased fruit weight, flesh firmness, soluble solids concentration, and fruit asymmetry on `McIntosh' and `Empire' and reduced red pigmentation and seed count on `McIntosh', especially when applied 22 DAFB. A FB application of CPPU and THI, each at 5 or 10 mg·liter–1, on `Delicious' increased the fruit length: diameter (L: D) ratio and flesh firmness (at harvest and following 26 weeks of refrigerated storage and reduced return bloom). CPPU at either 5 or 10 mg·liter–1 increased the fruit L: D ratio more than 25 mg Promalin/liter. Chemical names used: N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron); N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU); N-(phenylmethyl)-1H-purine-6-amine plus gibberellins A4+7 (Promalin).
Callus cultures were initiated in the dark from leaf primordia, stem internodes, and young leaves of adult Japanese persimmon (Diospyros kaki L.) to induce adventitious buds. A high frequency of regeneration occurred on Murashige and Skoog medium (MS) with half the normal NH4NO3 and KNO3 concentration (1/2N) and containing 10 μm zeatin or 1 μm 4PU-30 in combination with 0.1 μm IAA, or MS(1/2N) medium containing 0.03 to 0.1 μ m IAA or 0.01 to 0.03 μm NAA combined with 10 μm zeatin. No significant differences in the capacity of regeneration were observed among the calli from different explant sources. Only eight of 16 cultivars formed adventitious buds on MS(1/2N) medium containing 10 μm zeatin and 0.1 μm IAA, with the percentage of explants forming adventitious buds ranging from 2% to 72%. Chemical names used: indole3-acetic acid (IAA); 1-naphthaleneacetic acid (NAA); N-phenyl-N'-(2-chloro-4-pyridyl)urea (4PU-30).
The effects of NAA, BA, or Accel on CO2 assimilation of shoot leaves of mature bearing Redchief `Delicious' and `Empire' apple (Malus ×domestica Borkh.) trees were evaluated over two seasons. BA at 50 mg·L-1 did not significantly affect any of the gas-exchange parameters measured. NAA (15 mg·L-1) consistently suppressed CO2 assimilation rate (from ≈10% to 24% below that of the control). This suppression was NAA-concentration dependent, continued for >15 days after treatment, and was completely overcome in `Empire', but only partially or not at all in `Delicious' when BA was combined with NAA. These results are discussed in relation to fruit thinning and NAA-induced inhibition of fruit growth in spur-type `Delicious'. Chemical names used: 2-(1-napthyl) acetic acid (NAA); N-(phenyl)-1H-purine-6-amine (BA); BA + gibberellin A (GA)4+7 (Accel).