Abstract
Nonchilled, nursery-grown apple (Malus domestica Borkh.) trees were subjected to all combinations of root and/or shoot chilling (5°C) or nonchilling (16°) temperatures for 1500 hr. Trees then were given one of the following six plant growth regulator treatments prior to greenhouse forcing for 30 days: no plant growth regulator; 10-sec shoot dip of either 6-BA, GA4+7, or Promalin; 10-sec root dip of IBA; or IBA on root plus Promalin on shoot. Chilling either the root or shoot alone resulted in partial budbreak, while chilling the entire tree increased budbreak and dry weight of new shoots significantly. New root growth depended primarily on chilling the root. Treatment of the shoot with 6-BA, GA4+7, or Promalin increased budbreak and replaced the requirement for root chilling for this response, but did not affect new shoot dry weight or root growth. Treating the root with IBA significantly increased new root growth, budbreak, and new shoot dry weight, and replaced the requirement for root chilling for these responses. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); gibberellic acid (GA4+7); 1H-indole-3-butanoic acid (IBA); mixture of BA and GA4+7 (Promalin).
Abstract
Spray applications of 1000 and 2000 ppm Promalin to scion growth of first year nursery trees of ‘Bartlett’ pear (Pyrus communis L.), ‘Bing’ cherry (Prunus avium L.), and ‘Oregon Spurr II Delicious’ apple (Malus domestica Borkh.), when scion growth was 40 to 60 cm, generally caused increased lateral branching in the nursery. Double applications of Promalin at reduced concentrations also showed promise. Chemical treatments usually affected neither branch angle or length on pear, often increased branch angle on apple, and often increased both length and angle on cherry. Tree height and caliper usually were unaffected, Chemical name used: GA4+7 + BA (Promtalin).
Abstract
Branch growth of compact (CT) and “Pillar” (PI) peach [Prunus persica (L.) Batsch.], a columnar growth type, and progeny of CT × PI was analyzed. PI trees were distinguished from CT trees by narrower branch angles and relatively fewer and longer branches. CT × PI hybridization produced two distinct classes of trees in a 1:1 ratio—globe shape (GL) and upright (UP). GL trees had a large number of branches, resembling CT trees, but had narrower branch angles. UP trees resembled PI trees, but with wider branch angles. Analysis of seedling growth at 1, 2, and 3 months indicated that height and number of lateral branches could be used to classify UP and GL mature tree form. Branch angle measured at 2 months was important in distinguishing GL from CT seedlings. Such measurements on young seedlings may be used for early selection of growth habit. The reported results indicate that peach tree form, in respect to branching density and branch angle, can be readily manipulated through hybridization of the appropriate growth types. The columnar form of the PI tree suggests its potential for high-density production systems and its use as a parent in developing narrow canopied trees.
Abstract
A protocol for in vitro propagation was developed with two dry bean (Phaseolus vulgaris L.) cultivars. Shoot cultures were initiated by placing seedling shoot tips (1.0 to 1.5 cm) on Murashige and Skoog (MS) medium in which the effects of kinetin and BA alone or in combination with IAA or NAA were examined with regard to shoot multiplication and root or basal callus formation. The combination of BA (3.0 mg liter–1) and NAA (0.1 mg·liter–1) was most effective in shoot multiplication. At high concentrations of BA or kinetin (>10 mg·liter–1), shoot production and internode elongation decreased markedly and rosette-like cultures with multiple buds developed. Shoots were rooted on basal MS medium. Ramets grew to maturity in the greenhouse or field and produced fertile flowers, pods, and seeds. Chemical names used: N-(2-furanylmethyl)-1H-purin-6-amine (kinetin); N-(phenylmethyl)-1H-purin-6-amine (BA); 1H-indole-3-acetic acid (IAA); 1-naphthaleneacetic acid (NAA).
BA thinned apple (Malus domestica Borkh.) fruits when applied to either the leaves or the fruit, although it was much more effective when applied to the leaves. BA increased fruit size independent of its effects on reducing crop load, but only when applied directly to the fruit. When applied to one of two fruit in a cluster, BA had no influence on abscission, fruit size, or fruit characteristics of the adjacent nontreated fruit. BA reduced fruit flesh Ca only on treated fruit and the response was inversely proportional to the increase in fruit size. More than 60% of the BA applied to a fruit was absorbed during 24 hours, and this amount was considerably larger than penetration through either the abaxial or adaxial leaf surface. BA treatments that thinned also increased ethylene production linearly in both leaves and fruit 24 hours after application, but the magnitude of increase was not considered large enough to be the primary cause for thinning. BA thinned spurs with two or three fruit more than spurs with one fruit, and it did not selectively thin to just one fruit per cluster. Chemical name used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)].
Abstract
Concentration of abscisic acid (ABA), abscisic acid-glucose ester (ABA-GE), indoleacetic acid (IAA), zeatin (Z), zeatin riboside (ZR) and gibberellic acid (GA) were measured in ‘Winter Nebs’ pear (Pyrus communis L.) receptacles from anthesis to 12 days thereafter. Concentration of GA or IAA may signal subsequent growth rate for GA3-treated and pollinated receptacles. No correlations with growth were evident for Z or ZR. ABA-GE began massive accumulation prior to the senescence and abscission of control receptacles.
Encouraging results from previous trials on field vegetables led to the expectation that a kinetin foliar spray from the commercial product KIN-Gro (5000 ppm kinetin) on greenhouse vegetables would positively affect their growth and productivity. Thus, in this study, we evaluated the usefulness of this product on rockwool-grown `Bodega' cucumber (Cucumis sativus), `Rapsodie' tomato (Lycopersicum esculentum), and `4-Ever' and `444' pepper (Capsicum annuum) at the Greenhouse and Processing Crops Research Centre of Agriculture and Agri-Food Canada, Harrow, Ont. Two replicated experiments were conducted to study the effect of kinetin spray on growth and production of all three crops: the first in Spring-Summer 2004 and the second in Fall-Winter 2004. Foliar sprays of kinetin at 2.5, 5, and 10 ppm concentrations were tested against a water spray (control) on each crop. A 2.5-ppm kinetin spray had beneficial effects on the growth of cucumber transplants (taller plants and greater leaf area and fresh weight of leaves and stems). Furthermore, this treatment resulted in higher marketable yield in the Spring-Summer crop and in larger fruit size in the Fall-Winter crop. Regression analysis showed that cucumber marketable yield had an overall quadratic response to kinetin spray concentration in Spring-Summer season maximizing at 5.1 ppm kinetin. Kinetin spray also had beneficial effects on the growth of tomato seedlings, but not on yield. On the other hand, significant beneficial effects were observed on the growth of pepper seedlings and on marketable yield and fruit quality. Regression analysis showed that the response of pepper marketable yield to kinetin spray concentration was positive and linear. It must be noted that, given the rather short-term nature of our experiments, the observed beneficial effects of the kinetin sprays on yield can only be interpreted as beneficial effects on early yield rather than on the total yield. We concluded that under our growing conditions, cucumber production would benefit from a dilute (2.5 ppm) kinetin spray, and pepper production from a high concentration spray (10 ppm); tomato transplant growth will also benefit from a kinetin spray at 2.5 ppm. The results of this study could be of considerable significance to the greenhouse vegetable industry.
feasibility of shoot micropropagation of L. macrantha has yet to be investigated. The provision of exogenous cytokinins to the explant through the culture medium at the shoot multiplication stage stimulates the formation of microshoots ( Hartmann et al
regenerated shoots were kept routinely by subculturing once every 4 weeks on MS medium without PGR and used as plant materials to conduct the experiments. Culture conditions. The cytokinins and auxins were added to MS basal medium, thereafter, the pH of all
A new bioregulator, cyclanilide (CYC, Bayer Environmental Science, Montvale, N.J.), was tested for growth-related effects on apple trees over three years. Although treatment with CYC produced small reductions in shoot length, its principal effect was to stimulate the formation of lateral shoots on current-season's shoot growth and from spurs on older wood. CYC treatment of `Scarletspur Delicious' apple trees in the nursery more than doubled the formation of well-developed feathers with wide crotch angles (≈60°) and with no effect on final tree height. CYC appeared to flatten the apples and reduce fruit size in one trial. CYC appears promising for lateral branch induction in apple, especially in the nursery. Chemical names used: 1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid (Cyclanilide); calcium 3-oxido-4-propionyl-5-oxo-4-propionylcyclohex-3-enecarboxylate (prohexadione-Ca, Apogee); N-(phenylmethyl)-1H-purine-6-amine + gibberellins A4A7 (Promalin); polyoxyethylenepolypropoxypropanol, dihydroxypropane, 2-butoxyethanol (Regulaid).