Callus and axillary-bud culture of Vitis vinifera ‘Sylvaner Riesling’

Healthy growth of serially subcultured callus of the grape Vitis vinifera cultivar ‘Sylvaner’ was obtained by incubation at 30° C in continuous light in a defined culture medium containing 2% w/v sucrose, 1.0 mg l^?1 1-naphthaleneacetic acid (NAA) and 0.2 mg l^?1 kinetin (K). Organogenesis was not induced in this callus by alteration in the absolute or relative levels of NAA and K.Continued shoot initiation was obtained by culture of axillary buds in a medium containing 10^?5 M Benzyladenine (BA). Plantlets could be generated from these shoot buds by transfer to media containing 10^?7 M BA or lacking a cytokinin.     

GA4+7 plus benzyladenine reduce foliar chlorosis of Lilium longiflorum

The effectiveness of two commercial formulations of gibberellin (GA) and benzyladenine (BA) for reducing foliar chlorosis on Easter lily (Lilium longiflorum Thunb.) was compared. On a per liter basis, plants were sprayed with 0, 100, 200, or 400 mg (BA equivalent) of Accel (GA₄₊₇:BA of 1:10) or Promalin (GA₄₊₇:BA of 1:1) when the crop leaf area index (LAI)=3. One group of plants was sprayed with 100 mg of Accel or Promalin (BA equivalent) per liter twice: once at LAI=3 and again 3 weeks later. Plants were harvested when the largest flower bud on each plant measured 13 cm in length, stored for 0 or 3 weeks at 2.5°C in the dark, and then moved into a post-harvest evaluation room at 21°C, where foliar chlorosis was monitored for 3 weeks. Senescence of some lower leaves on plants in every treatment was evident at harvest, and incidence of senescence increased during the 21 days of post-harvest evaluation. Cold storage increased the number of leaves senescing during the subsequent evaluation period. Application of Promalin or Accel significantly reduced leaf senescence compared to that of untreated plants. At harvest, 21% of the leaves on untreated plants were senescent, while plants treated with Promalin or Accel averaged 3 or 9% senescent leaves, respectively. Following 7 days of post-harvest evaluation, Promalin was more effective in preventing chlorosis than Accel at the 400 mg l⁻¹ (BA equivalent) level. Following 14 or 21 days of post-harvest evaluation, Promalin was more effective than Accel for the 100 mg l⁻¹ 2× and 400 mg l⁻¹ (BA equivalent) treatments.Plants in all Promalin and Accel treatments were taller than untreated plants 1 week after sprays were applied. At harvest, plants sprayed with Promalin were between 6 and 14 cm taller than untreated plants, but those treated with Accel were the same height as untreated plants.Neither Promalin nor Accel influenced the occurrence of malformed or aborted flowers in this study. However, cold storage significantly increased the number of plants with aborted buds and malformed flowers. Unstored plants averaged 0.16 aborted buds and 0.02 malformed flowers each, while those stored 3 weeks averaged 0.51 aborted buds and 0.18 malformed flowers each.     

The response of partly cooled tulips to vacuum infiltration with gibberellins

Partly cooled (5°C) tulip ‘Apeldoorn’ were treated with gibberellins GA₃ and GA_{4 + 7} by vacuùm infiltration, with a view to defining conditions suitable for exploiting the effects of GA on forced tulips (faster flowering, control of stem extension, reduction of floral bud blasting).The first experiment showed that GA₃ and GA_{4 + 7} were equally effective in reducing the glasshouse period following 6 or more weeks cold storage; with less than 6 weeks cold storage, effects were less marked. Stem length at flowering was reduced by GA treatments, particularly by GA₃ and following more than 6 weeks cold storage. However, the vacuum infiltration method used (30 min at 10 torr) resulted in serious flower losses.Next, the effect of GA₃ concentration (up to 1500 mg 1^?1) was studied using vacuum infiltration treatments for 1–15 min at 20–510 torr, which resulted in fewer flower losses. Following 4 weeks cold storage, reducing pressure or increasing GA₃ concentration reduced both glasshouse period and stem length, with no effect of duration of treatment; GA₃ concentration was the only factor affecting flower length, which was increased. Following 8 weeks cold storage, increasing GA₃ concentration, vacuum or duration reduced glasshouse period. With all 3 factors at their maximum levels, 16 days earliness was obtained compared with controls. With maximum earliness, stem length was reduced to about 23 cm, compared to about 26 cm for treatments giving about 1 week's earliness, and 32 cm for untreated controls. Increasing vacuum appeared the most economical way of obtaining earliness, 20 torr giving 7 days earliness even at only 250 mg GA₃ 1^?1. Treatments giving earlier flowering also gave larger flowers. For comparison, there was little effect of soaking bulbs at atmospheric pressure even at 500 mg GA₃ 1^?1 for up to 20 h.Further experiments, conducted with vacuum infiltration at 260 torr for 15 min, confirmed these GA effects using formulated GA₃ (as “Berelex”) and GA_{4 + 7} (as “Regulex”). Effects of GA on stem length at flowering had disappeared by the time stems reached their final length. Comparisons with bulb injection of GA showed that this method required less GA than vacuum infiltration for similar effects, and that the greater effectiveness of GA_{4 + 7} compared with GA₃ was less marked using vacuum infiltration.     

Effects of applications of plant growth regulators to papaya on the output and proteolytic activity of latex tapped from immature fruits

SUMMARY

Pistillate seedling plants of the local cultivar of papaya ‘Deshi’, transplanted 40 d after sowing, were sprayed with aqueous solutions of IBA (25 and 50 _ppm), GA₃ (100 and 200 _ppm), kinetin (50 and 100 _ppm), BA (25 and 50 _ppm), ethephon (100 and 200 ppm) or with water (control) 100 d after transplanting, when the experimental fruits borne by them were 15 d old. Latex was collected from the fruits when they were 90-95 d old and continued on four occasions, at 7 d intervals. Highly significant increases in yield and in protease activity of the latex over the control was obtained by application of ethephon. IBA and GA, also increased latex production, but spraying the plants with kinetin or BA solutions gave no clear results     

Responses of day-neutral,June-bearing and everbearing strawberry cultiv ars to gibberellic acid and phthalimide treatments

Field grown day-neutral, June-bearing and everbearing strawberry cultivars responded similarly to GA₃ in most cases. GA₃ stimulated daughter-plant production in ‘Hecker’ (DN) and suppressed it in ‘Guardian’ (June). Fifty mg l^?1 GA₃ increased initial runner production of all cultivars, while both 50 and 100 mg l^?1 GA₃ increased fruit yield the year following treatment. In greenhouse studies, GA₃ initially increased leaf number, petiole length and runner production, but the effects diminished with time. Phthalimide at 1000 mg l^?1 was most effective in increasing leaf number.     

Influence of growth regulators on setting,retention and weight of fruits in two cultivars of litchi

Investigations were undertaken to explore the possibility of improving setting, retention and weight of fruits in ‘Early Seedless’ and ‘Calcuttia’ cultivars of lichi (Litchi chinensis) by means of growth regulators. Indole acetic acid (IAA) at 20, 40 and 80 mg l^?1, 2,4-dichlorophenoxy acetic acid (2,4-D) at 2,4 and 8 mg l^?1 and gibberellic acid (GA₃) at 50, 100 and 150 mg l^?1 were sprayed on panicles in the first fortnight of April, when 50–100% flowers had opened. All 3 growth regulators caused a favourable effect on fruit setting, fruit retention and weight of individual fruits, but IAA at 20 mg l^?1 proved the best for enhancing setting, GA₃ at 50 mg l^?1 for increasing retention and GA₃ at 100 mg l^?1 for improving fruit weight. IAA and GA₃ should, therefore, be used in combination. Between the 2 cultivars tested, ‘Calcuttia’ proved superior to ‘Early Seedless’ in fruit setting, fruit retention and weight of individual fruits.     

Gibberellic acid soak treatments for fully-cooled tulips

In attempts to reduce the glasshouse period of fully-cooled 5°C-forced tulips, ‘Apeldoorn’ bulbs were soaked before planting in aerated and non-aerated gibberellic acid (GA₃) solutions for 2–48 h. A 48-h treatment with 250–500 mg l^?1 GA₃ was the most effective, giving a glasshouse period 7–11 days shorter than for untreated bulbs. Soaks for 24 and 48 h caused root emergence, and 48-h soaks caused perianth segment splitting in one experiment. Aerated or non-aerated GA₃ solutions gave similar results. Soaking in water alone gave a smaller increase in earliness. In general, a shortened glasshouse period was associated with shorter whole stem and last internode lengths. In GA₃ treatments, flower losses were lower than for distilled water treated and untreated bulbs. A practical treatment would be a non-aerated soak for 24 h with between 250 and 500 mg l^?1 GA₃.     

New approaches to the alleviation of barewood in young apple trees

Summary

Precocity is particularly important for the economic production of intensively planted apple trees. Unfortunately some cultivars show a propensity for barewood on young trees, which limits early production on 2 year-old spur sites. The new cultivar, ‘Scifresh’ (Jazz?) has shown serious problems of barewood under New Zealand conditions on M.9 and M.26 rootstocks. Barewood has been associated with excessive flowering on feathers and 1 year-old wood. Weak flower clusters develop towards the base of the shoots which do not set fruit and drop off, leaving blind buds. Although there are larger, more well-developed flower clusters on the distal parts of the 1 year-old shoots, cropping these can result in spur extinction. Therefore, in both cases, there is a lack of spur development for the following season resulting in barewood. Experimental treatments have focused on: 1) the effect of timing (January-May) and concentration (400 and 133 mg l^–1 gibberellic acid GA₃) sprays in the nursery to reduce flowering on 1 year-old wood; and 2) the effect of concentration and timing of localised cytokinin applications in the Spring to re-invigorate blind buds. Two applications of 400 mg l^–1 GA₃ in late January and late February in the first year in the nursery were effective in eliminating flowering on “knip boom” trees in the following Spring after cutting back. Two applications of 400 mg l^–1 GA₃, in early and late January, to “knip boom” trees in their second year in the nursery reduced flowering by over 40% when the trees were planted in the orchard. Twelve months later these trees showed an increased density of spur flowers on the original feathers. Aqueous solutions of the cytokinins benzyladenine and thidiazuron, at 500 mg l^–1 or 2500 mg l^–1 respectively, were applied by brush, prior to, during and post-budbreak, to sections of barewood on 2 year-old or 3 year-old wood on main branches of ‘Scifresh’/M.9 trees. Thidiazuron (at 2500 mg l^–1) was far more effective than benzyladenine at inducing growth of dormant buds, even resulting in multiple bud-breaks at individual sites.     

Effects of cold storage on postharvest leaf and flower quality of potted Oriental-, Asiatic- and LA-hybrid lily cultivars

The effects of cold storage of mature potted plants on postharvest leaf and flower quality were investigated in several cultivars of three major groups (Oriental, Asiatic and LA) of hybrid lilies (Lilium spp.). Mature plants were stored in darkness at 3 °C for 2 weeks before placing them in a postharvest evaluation room (22 °C) and were compared with plants moved directly to the evaluation room. The efficacy of GA₄₊₇ plus benzyladenine (BA) treatments (applied just before cold storage) for preventing cold-induced postharvest disorders in each cultivar was also evaluated. In all cultivars, cold storage caused several adverse effects on postharvest quality, including accelerated leaf yellowing or browning, bud abortion and reduced flower or inflorescence longevity. Leaf abscission was observed only in Oriental-hybrids. Treatment with GA₄₊₇ plus BA significantly reduced these disorders and improved the overall postharvest quality after cold storage. While different cultivars differed greatly in their sensitivity to cold storage, all the cultivars benefited from GA₄₊₇ plus BA treatment. Experiments indicated that GA₄₊₇ plus BA treatments could be applied as early as 2 weeks before the mature bud stage without compromising the positive effects.     

Endogenous gibberellins and their effects on flowering and stem elongation in cabbage (Brassica oleracea var. capitata)

Summary

Endogenous gibberellins were extracted from cabbage shoots and were analysed using gas chromatography and mass spectrometry. Nine gibberellins (GA₁, GA₁₉, GA₂₀, GA₄₄, GA₁₂, GA₄, GA_15, GA₂₄ and GA₂₅) were identified. Two gibberellin biosynthesis pathways were suggested, an early-13-hydroxlyated pathway and a non-13-hydroxylated pathway, to operate in cabbage shoots. GA₁, GA₄ and prohexadione calcium, a gibberellin biosynthesis inhibitor, were applied to the shoot tip of cabbage ‘Sousyu’ and ‘Kinkei No.201’ with or without cold treatment. Without cold treatment, stem elongation was increased by gibberellins and was suppressed by prohexadione calcium in both cultivars. But prohexadione calcium treatment, followed by gibberellin, promoted stem elongation more than gibberellin alone. Flowering was not induced by gibberellin or prohexadione calcium without cold treatment. When gibberellin and prohexadione calcium were applied during a cold treatment, stem elongation after the cold treatment was increased by gibberellins and was suppressed by prohexadione calcium in both cultivars. Flower bud appearance was promoted by GA₁ and GA₄ in ‘Sousyu’, but in ‘Kinkei No. 201’ only GA₄ was markedly effective. Inhibition of stem elongation and delay of flower bud appearance by prohexadione calcium were overcome by applying GA₁ or GA₄. Neither gibberellin nor prohexadione calcium treatment changed the number of leaf nodes at anthesis. These results indicated that stem elongation and flower bud development are regulated by gibberellins, but gibberellins might have little effect on flower induction.     

The physiology of hyacinth bulbs. XI. The effect of gibberellic acid on the growth and flowering of variously chilled bulbs

The effect of gibberellic acid, GA₃, on the growth and flowering of hyacinth cultivars ‘Pink Pearl’, ‘Delft Blue’ and ‘Carnegie’, chilled in a cold room at 5°C or a garden frame for 28, 42 or 81 days, and either rooted or dry, unrooted, was investigated. GA, was applied to the basal plates of the bulbs in a lanolin paste on 10 October 1975.The growth of the inflorescence and leaves of plants originating from dry-chilled bulbs was generally the same as that of those grown from rooted plants. A similar response to GA₃ treatment was observed in all cultivars. Treatment of bulbs with GA₃ decreased the number of days to flowering, stimulated the growth of inflorescences and leaves, and its effect was most pronounced in the plants chilled for shorter periods.     

Effect of GA3, Planofix (NAA) and Ethrel on granulation and fruit quality in ‘Kaula’ mandarin

The effect of GA₃ 15 mg l^?1, Planofix (NAA = 1-naphthalene acetic acid) 300 mg l^?1 and Ethrel 250 mg l^?1 on granulation and fruit quality in ‘Kaula’ mandarin (Citrus recticulata Blanco) was studied during 1975–1976. Three sprays of Planofix reduced the incidence of granulation to 30.7% from 62.7% in control. Three sprays of GA₃ were almost equally effective (31.3% granulation). These treatments also improved the fruit quality and gave the highest fruit weight, pulp percentage, juice, T.S.S., reducing and non-reducing sugars and ascorbic acid, and the lowest acidity, peel and rag. In both these treatments (3 sprays of GA₃ or Planofix) the T.S.S. was 9.3% (8.1% in control). The application of 3 sprays of Planofix 300 mg l^?1 or GA₃ 15 mg l^?1 is, therefore, considered to be successful in reducing the granulation in this cultivar of mandarin.     

Effects of growth regulators on growth and flowering in Hippeastrum hybridum hort

Soaking of bulbs in 3 concentrations of indoleacetic acid (IAA), gibberellic acid (GA₃), 2-chloroethyltrimethyl ammonium chloride (cycocel) or 2-chloroethylphosphonic acid (ethrel) showed various responses on growth and flowering. IAA increased the weight and number of bulblets, GA₃ increased bulb weight. Cycocel (1000 mg l^?1) increased the number of flowers, while GA₃ increased the diameter of the flowers.Application of IAA at 100 mg l^?1 and GA₃ at 10, 100 or 1000 mg l^?1 twice as foliar spray at an interval of 30 days promoted the number of bulblets on the treated plants, while high concentrations of cycocel and ethrel (1000 mg l^?1) increased the weight of bulblets. All concentrations of IAA, GA₃ and 1000 mg l^?1 cycocel increased the number and size of the flowers.     

Effect of gibberellic acid (GA3) on elongation and rooting of ‘St. Julien A’ rootstock in vitro

‘St. Julien A’ (Prunus instititia L.) rootstock was induced to proliferate shoots on a modified half-strength Murashige and Skoog (MS) medium. Cultures treated with 12.5 mg l^?1 gibberellic acid (GA₃) produced elongated shoots suitable for rooting. Elongated shoots were placed in media with indolebutyric acid (IBA) or indole-3-acetic acid (IAA) with or without a 16-day dark incubation. Light (16-h photoperiod) inhibited rooting. IAA (4 mg l^?1) was ineffective in promoting rooting. Rooting was best when shoots were incubated in the dark with IBA (4 mg l^?1). GA₃ was deleterious to shoots, causing chlorosis and apical die-back. Light regime interacted with auxin treatments in affecting shoot condition. Shoot condition was better on shoots treated with IBA and dark-incubated; while those treated with IAA were better when light-incubated.     

The effect of sucrose,silver thiosulphate and 8-hydroxyquinoline citrate on the quality of Lilium inflorescences cut at the bud stage and stored at low temperature

A continuous supply of sucrose together with 8-hydroxyquinoline citrate to cut Lilium Asiatic hybrid ‘Prima’ inflorescences resulted in buds opening satisfactorily and increased their longevity. The best results were obtained using 30 g l^?1 sucrose. Cut Lilium inflorescences could be stored at 1°C for 4 weeks without a great loss in potential vase-life and decorative value when the inflorescences were pre-treated with silver thiosulphate + 100 g l^?1 sucrose for 24 h before cold storage, kept in a cold room in a solution containing 50 mg l^?1 silver nitrate, and after cold storage kept in a solution containing 30 g l^?1 sucrose and 200 mg l^?1 8-hydroxyquinoline citrate. Such treatment greatly improved bud opening, increased the diameters of individual flowers and prolonged their life.     

In vitro germination of walnut (Juglans regia L.) embryos

The present studies were undertaken with a view to standardize the medium and culture conditions for embryo culture of five cultivars of walnut viz., ACO 38853, Netar Akhrot, Gobind, Solding Selection and Blackmore. Embryos from mature fruits were aseptically excised and cultured on MS medium supplemented with different combinations of BAP, kinetin and GA₃. Best performing medium was MS with 0.5 mg l⁻¹ kinetin, 0.5 mg l⁻¹ BAP and 2 mg l⁻¹ GA₃ yielding 66.6% germination in Netar Akhrot after 12 days of culturing. Percent germination of excised embryos was higher when GA₃ and cold treatments were simultaneously applied as compared to those when applied separately. Netar Akhrot was found to be the best responding cultivar, which had a range of 25–66.6% embryo germination under different culture conditions. Plantlets with shoots and roots have been obtained in Netar Akhrot and ACO38853 and are transferred to soil after hardening.     

The Effects of Some Growth Regulators on Peach Flower Bud Abscission

Applications of growth regulators to detached peach laterals in winter had variable effects on flower bud abscission. GA₃ and GA₄₊₇ increased bud abscission while IAA, BA and ABA inhibited abscission. Ethephon had a variable effect. Interactions were obtained between the compounds generally with IAA or GA playing the major role. GA had a peak of activity during a critical period in late winter indicating a variation in responsiveness. Variations in sensitivity to GA were obtained for different cultivars. Field applications of GA₃, GA₄₊₇, and ethephon to Elberta peach trees in winter, alone and in various combinations, promoted bud abscission.     

Vegetative growth and nutritional status as influenced by auxins and gibberellic acid,and their effect on fruit yield in lemon

Application of 2,4-D and 2,4,5-T at concentrations ranging from 5 to 20 mg l^?1 to 5-year-old ‘Pant Lemon-1’ (Citrus limon Burm) trees reduced the vegetative growth in terms of height, spread, shoot length, number and size of the leaves in the autumn flush. Various NAA treatments (5–20 mg l^?1), however, enhanced growth, but not to the extent that was observed after GA₃ treatments. Application of GA₃ at 10–40 mg l^?1 significantly enhanced all aspects of growth, and the effects were most pronounced at 20 and 40 mg l^?1. Nutritional status of the leaves showed a slight variation in relation to vegetative growth under various treatments.Some 2,4-D- and 2,4,5-T-treatments increased the fruit yield over the control, which could suggest mobilization of foods even at the expense of reduced vegetative growth. On the other hand, NAA, particularly at 10 mg l^?1, increased both vegetative growth and yield, suggesting that the transport of the photosynthates from the leaves to the fruits was not at the expense of new growth extension. Due to excessive growth enhancement under higher concentrations of GA₃ (20 and 40 mg l^?1), comparatively fewer nutrients were translocated to the fruit “sinks”, thereby resulting in a non-significant decrease in yield.     

Flowering,vegetative growth and mineral nutrition of pot chrysanthemums in sawdust and peat-life media

Plants of Chrysanthemum morifolium Ramat ‘Mountain Peak’, ‘Goldstar’ and ‘Cir Bronze’ were grown in sawdust, sawdust mixed with Ca(NO₃)₂ 7 weeks before planting and held at 20°C (unheated), or at 43°C (heated), and in a sphagnum-peat/vermiculite mix (peat-lite). C:N ratios for the sawdust media at planting were 265.9, 125.7 and 123.3, respectively. Plants grown in each medium received nutrient irrigation containing macro- and microelements, with N at 150, 200 or 250 mg l^?1.Days to full flower development, and flower diameter at harvest were not influenced by medium or irrigation N concentration. Plants grown in peat-lite produced the thickest and longest stems, although the stature of plants in all media was judged to be commercially acceptable. Plants grown in unheated sawdust pre-mixed with Ca(NO₃)₂ produced the thinnest and shortest stems.Leaf concentrations of N, P, K and Mg at harvest were highest in plants grown in peat-lite. Accumulation of Ca, B, Fe, Mn, Cu and Zn was more variable. With the exception of P, foliar nutrient concentrations in all plants were optimal or above published optimal ranges. The onset of flower senescence occurred an average of 1 day earlier in sawdust-grown plants.