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.     

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.     

Propagating palms in vitro with special emphasis on the date palm (Phoenix dactylifera L.)

Tissue-culture methods are described for the vegetative propagation of several palm species either through shoot tip culture or plantlet differentiation via embryogenic callus. The influence of explant size, medium composition and physical environment required for the establishment of palm shoot tips in vitro was determined. Date palm (Phoenix dactylifera L.) seedling shoot tips of various sizes were cultured in either liquid or agar modified Murashige and Skoog (MS) medium containing 0.0–1.0 mg 1^?1 α-naphthaleneacetic acid (NAA) and 0.0–15.0 mg 1^?1 benzyladenine or N⁶-(Δ²-isopentenyl) adenine (2iP) in order to enhance shoot growth and induce axillary budding. Satisfactory date palm shoot tip growth and proliferation was obtained from explants that were 3 mm in length, consisting of the apical meristem region and 2–5 adjacent leaf primordia. Optimum shoot tip development and axillary budding was obtained by initially establishing explants on an agar medium for 2 weeks, then transferring to a liquid medium. Shoot tips from several palm species were cultured on MS media containing 100 mg 1^?1 2,4-dichlorophenoxyacetic acid (2,4-D), 3 mg 1^?1 2iP and 3 g 1^?1 activated charcoal, or on MS medium containing 1 mg 1^?1 NAA and charcoal, to determine their morphogenetic responses in vitro. Shoot tips of Metroxylon sp., Phoenix canariensis Hort. ex. Chabaud., P. dactylifera ‘Khalasa’, ‘Thoory’ and ‘Zahidi’, and P. roebelenii O'Brien planted on medium with 2,4-D and 2iP initiated callus, asexual embryos and free-living plantlets after 4–8 months in culture. Shoot tips from Erythea edulis S. Wats., P. canariensis, P. dactylifera ‘Khalasa’, Thoory' and ‘Zahidi’, Washingtonia filifera Wendl. and W. robusta Wendl. cultured on medium containing NAA developed into plantlets with well-developed leaves and adventitious roots within 2–6 months from the time of planting. In some cases, cultured date palm shoot tips gave rise to axillary buds.     

Effects of ozone and sulfur dioxide on grapevines

Greenhouse-grown ‘Ives’ and ‘Delaware’ grapevines (Vitis labruscana, Bailey) were fumigated for 4-hours with ozone (O₃) and/or sulfur dioxide (SO₂) at 0.40 and 0.80 mg l^?1. Fumigations were performed in a plexiglass chamber situated within a controlled environment walk-in growth chamber. When applied separately, both gases induced characteristic foliar injury. ‘Ives’ grapevines were much more sensitive to $\text{O}{}_3\text{SO}{}_2$ fumigations than were ‘Delaware’ grapevines. Within each cultivar, leaf necrosis and shoot growth reduction were greatest following fumigation with 0.80 mg l^?1 O₃ plus 0.80 mg l^?1 SO₂. Leaf abscission occurred only on ‘Ives’ and was related to foliar necrosis. Shoot growth following fumigation was less on vines having most foliar necrosis. Yet, ‘Delaware’ vines showing less than 1% leaf area necrosis still had significant reductions in shoot growth. All O₃ and SO₂ fumigations resulted in stomatal opening.     

Nitrogen and calcium nutrition of Petunia × hybrida ‘Coral Sea’

The effects of N and Ca nutrition on plant growth and shoot elemental content of Petunia × hybrida Hort. Vilm. - Andr. ‘Coral Sea’ were evaluated. Nitrogen and Ca were applied separately or in combination in three experiments: (1) N at 0, 100, 200 or 400 mg l^?1; (2) Ca at 0, 75, 150 or 300 mg l^?1; (3) N at 0 or 100 mg l^?1 and Ca at 0 or 150 mg l^?1 combined factorially. Shoot and root dry weights, branch length and flower number were highest when plants received 100 mg l^?1 N. Plants treated with 150 mg l^?1 Ca had the highest shoot and root dry weights. Branch length was maximal at 300 mg l^?1 Ca.Nitrogen and Ca interacted to increase shoot dry weights, branch number and length, leaf area and flower number. Increasing N concentrations increased N and decreased P, Mn and Zn shoot contents. Calcium content of shoots increased while N, P and Mg decreased in response to increasing applications of Ca to petunia plants. Minimal N and Ca tissue concentrations for optimal P. × hybrida growth were 3.3 and 0.67%, respectively.     

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.     

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.     

Micropropagation of red raspberry and the influence of phloroglucinol

Micropropagation of 12 raspberry seedling selections and the cultivar ‘Malling Jewel’ has been achieved. A basic culture medium (Linsmaier and Skoog, 1965) supplemented with benzylaminopurine (BAP), 1.0 mg l^?1, and indol-3-yl butyric acid (IBA), 0.1 mg l^?1, was optimal for shoot proliferation. The presence of phloroglucinol (PG) at a concentration of 162 mg l^?1 significantly increased shoot number at all auxin: cytokinin concentrations. Removal of the cytokinin and increasing the concentration of IBA to 1.0 mg l^?1 resulted in adventitious root formation. PG synergistically promoted the number of roots per rooted culture but did not significantly increase the percentage rooting. Viable plants were produced from all genotypes when transplanted to soil.     

In vitro propagation of garlic by shoot proliferation

Shoot buds (5–8 mm long), excised from dormant cloves of the New Zealand commercial garlic (Allium sativum L.) and a virus-free French cultivar ‘Rose-de-Kakylis’, proliferated both axillary and adventitious shoots on B-5 basal medium supplemented with 0.5 mg l^?1 isopentenyladenine (2-ip) and 0.1 mg l^?1 naphthaleneacetic acid (NAA). An 8-fold increase in shoot number occurred every 6 weeks. Shoots were readily rooted in B-5 + 0.01 mg l^?1 2-ip + 0.2 mg l^?1 NAA and transferred to pots, where about 70% of the shoots formed established plants. The plants raised by this shoot-proliferation method retained the diploid condition of the parents.     

Rapid propagation of Cucurbita pepo L. by culture of meristem tips

A tissue culture technique has been developed for the rapid multiplication of pumpkin (Cucurbita pepo L.) clones. Meristem-tips from seedlings of cultivar ‘Cinderella’ were grown initially on MS medium containing 2.56 mg l^?1 Kinetin and 8 mg l^?1 IAA, and then transferred to experimental media. Maximum shoot proliferation occurred on MS medium containing 1 mg l^?1 BA and no auxin. Cultures were rooted after 2–3 weeks on MS medium containing 8 mg l^?1 IAA and no cytokinin.     

Pre-harvest drop control of ‘Red Delicious’ and ‘Jonathan’ apple (Malus domestica) as affected by the synthetic auxin 3,5,6-TPA

Summary

‘Red Delicious’, the main apple cultivar grown in Israel, and ‘Jonathan’, grown on a smaller scale, are prone to substantial pre-harvest drop. Spraying both cultivars with the synthetic auxin 3,5,6-trichloro-2-pyridyl-oxyacetic acid (3,5,6-TPA) reduced pre-harvest fruit drop and increased yield. Application of 40 mg l^–1 3,5,6-TPA 2 weeks before anticipated harvest (WBH), or 30 mg l^–1 3,5,6-TPA at 4 and 2 WBH gave the best results, and were as effective as 2,4,5-trichloro-phenoxypropionic acid (2,4,5-TP) which was the commercial product commonly in use until being withdrawn. There were no negative effects on fruit quality at harvest, or during 8 months of storage. Therefore 3,5,6-TPA can be recommended for routine use on ‘Red Delicious’ and ‘Jonathan’ apples in Israel.     

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.     

Use of 6-benzylamino purine and Promalin for improved canopy development in selected apple cultivars

Foliar sprays of Promalin (gibberellins A_{4 + 7} + 6-benzylamino purine) applied to 1-year-old apple (Malus domestica Borkh.) trees at the 3–5-cm growth stage significantly increased lateral branching in 5 of 9 cultivars tested. Branching response ranged from 0% (‘Winter Banana’) to 131% (‘Starkrimson Delicious’) of the untreated controls. Total shoot growth was not consistently increased by 6-benzylamino purine or Promalin in tests over 3 years on spur and non-spur 1- and 2-year-old apple trees. Sprays of 50–300 mg l⁻¹ Promalin were ineffective for increased branch development. Sprays of 300–500 mg l⁻¹ increased total shoot numbers and reduced average shoot length. Sprays applied prior to new terminal growth in spring were ineffective. Treatment during periods of active shoot growth were generally effective, but periods of stress may have reduced response. Sprays were more effective for inducing lateral shoot formation than dormant heading or delayed dormant heading (pruning) (10 days after full bloom) in ‘Criterion Golden Delicious’. No difference in branching response was observed between BA and Promalin. Addition of a spray adjuvant (Buffer-X) did not affect branching response. Repeat annual single sprays of Promalin applied to dormant pruned trees were generally less effective for stimulating lateral branching than a single application in a given year. Phytotoxicity was associated with Promalin sprays at 300–500 mg l⁻¹ on ‘Delicious’.     

Development of an in-vitro rooting bioassay using juvenile-phase stem cuttings of Persea americana Mill.

Summary

A rooting test was developed with shoot cuttings taken from aseptically germinated avocado seed. The rooting required treatments in two steps: (1) three days in a medium containing indole-3-butyric acid (IBA) (25 mg l^?1) and (2) four to eight weeks in an auxin-free medium. Rooting was accomplished with both media containing 0.3× strength Murashige and Skoog salts, 3% sucrose, 0.4 mg l^?1 thiamine hydrochloride, 100 mg l^?1 i-inositol, and 0.8% ‘TC’ agar. The auxin-free medium also contained 1 gl^?1 activated charcoal.     

Evaluation,tissue culture propagation,and dissemination of ‘Saba’ and ‘Pelipita’ plantains in Costa Rica

Fruit characteristics of the disease-resistant bluggoe-type (ABB) cooking bananas (Musa × paradisiaca L.) ‘Saba’ and ‘Pelipita’ were compared with those of the susceptible ‘Currare’ (‘Horn’). Yields of ‘Saba’ and ‘Pelipita’ were similar to those of ‘Currare’; however, ‘Saba’ and ‘Pelipita’ yielded fewer hands with a greater number of small fruit when compared with ‘Currare’. Shoot-tip cultures of both clones were readily initiated on a modified Murashige and Skoog (MS) basal medium supplemented with N⁶-benzyladenine (BA) in combination with indole-3-acetic acid (IAA). Propagation cultures were initiated by splitting shoot tips along their longitudinal axis and re-culturing the individual pieces to basal medium supplemented with 5 mg l^?1 BA. Transfer of axillary shoots to hormone-free medium resulted in rapid and extensive root formation. Plantlet survival after transfer to methyl bromide-treated soil exceeded 90%. Establishment in the field was achieved following procedures normally used for vegetative propagation of this crop. Trial plantings of in vitro propagated ‘Saba’ and ‘Pelipita’ were established in various provinces of Costa Rica for grower evaluation and for future comparison of growth and reproductive development with plants of these and other cultivars propagated from corms.     

Adventitious shoot formation from sections of sweet potato grown in vitro

Sweet potato (Ipomoea batatas Lam.) root sections were obtained from the cultivars ‘Centennial’, ‘Redmar’ and ‘Jewel’ with a No. 6 cork borer. These sections were cut into 2–3-mm discs and explanted on to modified Murashige and Skoog (MS) medium consisting of MS high mineral salts, myo-inositol (100 mg l^?1), Staba vitamins, 6-benzyl-aminopurine (2.0 mg l^?1), naphthaleneacetic acid (0.1 mg l^?1), sucrose (30 g l^?1) and agar (10 g l^?1). Root discs from internal regions of the tuberous roots gave rise to calli and meristematic bud-like centers (MBLC's). A small percentage of ‘Centennial’ MBLC's burst open to reveal plantlets which grew and rooted well on the medium. Some of the ‘Jewel’ MBLC's contained only roots, while those of ‘Redmar’ did not differentiate. MBLC-formation occurred most often on discs taken from fresh (unstored) roots of ‘Centennial’. Petiole sections taken from in vitro-cultured plants of all 3 cultivars developed plants quite readily on the medium. Shoots of all 3 cultivars grew rapidly, to yield whole rooted plants which could easily be moved to soil and grown in the greenhouse and field.     

In vitro propagation of ‘Troyer’ citrange from epicotyl segments

Isolated epicotyl, root meristem and root segment tissues of ‘Troyer’ citrange [Poncirus trifoliata (L.) Rat. × Citrus sinensis (L.) Osbeck] were established in continuous culture to compare their regeneration potential. Callus was obtained from these explants on a Murashige—Skoog (MS) medium containing NAA (10 mg l^?1) and BAP (0.1–10 mg l^?1). Formation of shoots from root segments was direct without callus formation on MS medium containing BAP (10 mg l^?1) and NAA (1 mg l^?1). Shoot formation from epicotyl callus occurred on MS medium containing 0.25 mg l^?1 BAP and 0.1 mg l^?1 NAA. Formation of shoots from epicotyl segments occurred on MS medium containing BAP (0.5 mg l^?1) and NAA (0.1–1.0 mg l^?1), while rooting of regenerated shoots occurred in treatments containing 2.0 mg l^?1 NAA alone. This system provides a rapid method for propagation of ‘Troyer’ citrange.     

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.     

In vitro somatic embryogenesis from Mangifera indica L. callus

The nucellus and globular adventitious proembryos were removed from 2-month-old fruits of mango (Mangifera indica L.) cultivars ‘Ono’ and ‘Chino’, and were cultured on sterile, solid Murashige and Skoog (MS) medium that had been modified as follows: half-strength major salts and chelated iron; 20% (v/v) coconut water (CW); 6% sucrose; 100 mg l^?1 ascorbic acid and 400 mg l^?1 glutamine. Embryogenic explants were sub-cultured after 4–6 weeks in liquid modified MS medium containing 2 mg l^?1 2,4-dichlorophenoxyacetic acid (2,4-D) instead of CW. Rapidly growing cultures were established and were sub-cultured monthly. Somatic embryogenesis was induced following sub-culture from MS medium with 2,4-D to MS without growth regulators and with or without activated charcoal (0.5%). Germination of somatic embryos appeared to be enhanced by 1 mg l^?1 benzyladenine (BA); however, most of the germinating embryos became embryogenic.     

Induction of lateral branches in tree fruit nursery stock with propyl 3-t-butylphenoxy acetate (MB 25, 105) and Promalin (GA4+7 + 6-benzyladenine)

Sprays with 250–2000 mg l^?1 propyl 3-t-butylphenoxy acetate (MB 25,105) and 250 and 500 mg l^?1 GA₄₊₇ + 6-benzyladenine (Promalin) were applied to scion growth of first nursery trees of ‘Bartlett’ pear (Pyrus communis L.), ‘Bing’ cherry (Prunus avium L.) and ‘Oregon Spur II Delicious’ apple (Malus domestica Borkh.) to stimulate lateral branching in the nursery. Most treatments significantly increased branching compared to untreated controls. Combination sprays of the two chemicals were usually better than either used alone. Chemical treatment usually produced greater branching and wider branch angles than mechanical heading. Both chemical and mechanical treatments reduced tree height and caliper, but the decrease was not always statistically significant.