Some factors affecting the in vitro propagation of gladiolus

Callus tissue cultures have been established from the excised segments of the inflorescence, flower stalks, denuded flower, bract, perianth and leaf segments of 2 cultivars of Gladiolus grandiflorus. Of all the explants and the media tested, the best callus was obtained from the segments of the flower stalks, cultured on a basal medium supplemented with naphthalene acetic acid and kinetin. The callus mostly underwent rhizogenesis, and occasionally differentiated shoots. Complete plants were regenerated from the in vitro cultured cormels, cormel tips and the axillary buds, and 6 plants were formed from the segments of 1 cormel, whereas in nature only 1 plant is obtained per cormel. Cultured young anthers callused and developed leaf-like petaloid structures, and occasionally showed multicellular pollen.     

Effects of photoperiod on shoot elongation and endogenous gibberellins in the glasshouse carnation

Plants of glasshouse carnation were grown in photoperiodic cycles comprising 8 h natural daylight followed by either 16 h of darkness (short-day treatment) or by 16 h of low-intensity lighting from tungsten filament lamps (continuous-light treatment). When plants were transferred from short days to the continuous-light treatment, rates of shoot elongation were increased and flower initiation was promoted. Shoot tips of plants grown in continuous light yielded greater amounts of diffusible gibberellin-like substances than shoot tips of plants grown in short days. Yields of diffusible gibberellins increased with increases in the duration of the continuous light treatment up to 28 days, by which time flower initials were present. Application of GA₃ to the plants resulted in increased rates of shoot elongation, but no effect on flowering was observed.     

Influence of the Cytokinin, 6-Benzylamino-9-(Tetrahydropyran-2-yl)-9H-Purine,on the Growth and Development of Some Ornamental Crops

Foliar sprays of the synthetic cytokin, 6-benzylamino-9-(tetrahydropyran-2-yl)-9H-purine (PBA), increased branching in carnation, chrysanthemum, poinsettia, petunia and fuchsia, which showed varying levels of tolerance. In no instance did PBA reduce plant height. Applications of PBA to carnation and chrysanthemum stimulated branching in both intact and pinched plants. Treatment a few days prior to pinching produced more uniform development of new laterals. Response to the compound was most favourable under optimum growing conditions. Under relatively poor light intensity the laterals exhibited a reluctance for continued elongation and showed marked chlorosis. Application of PBA to flower buds at an early stage of development increased both the diameter and the fresh weight of carnation flowers or chrysanthemum inflorescences when fully open. Response to the compound decreased with age of the bud at the time of treatment. In carnation the effects on size were accompanied by an increase in petal area together with an increase in the number of primary petals produced. Relatively high concentrations also induced the formation of secondary growing centres from which varying numbers of additional petals were produced. Relatively large numbers of these secondary centres within a flower resulted in an increased incidence of calyx splitting. These centres were not observed in chrysanthemum. The formation of secondary growing centres could also be induced by GA₃ and IAA. However, while these growth substances increased the diameter and fresh weight of carnation flowers, unlike cytokinins they had no apparent effect on the number of primary petals formed. Finally PBA was also observed to increase the longevity of cut flowers of carnation. This was particularly apparent at relatively low temperatures.     

The influence of fruiting on the bud sprouting and flower induction responses to chilling in Citrus

Summary

The effect of chilling temperatures on bud sprouting and flower formation was compared on fruiting and non-fruiting ‘Owari’ satsuma mandarin (Citrus unshiu Marc) trees. On non-fruiting trees, bud dormancy was weak, and a significant proportion of buds were able to sprout at high temperatures without being chilled. Separate effects of low temperatures on bud sprouting and flower induction were demonstrated. On fruiting trees these two effects of low temperatures were also demonstrated on summer-flush buds, but not on older (spring-flush) buds. The spring-flush buds from fruiting trees scarcely sprouted without being chilled. These buds required a longer chilling period for dormancy release than for flower induction, and it was not possible to separate the effect of low temperature on flower induction from the effect on dormancy release. The presence of fruit reduced flower formation by reducing bud sprouting. Furthermore, fruit had a direct inhibitive effect on vernalization which resulted in increased formation of vegetative shoots. The effect of fruit and low temperature on flowering was unrelated to carbohydrate accumulation in the leaves or the roots.     

Changes in carbohydrate contents in shoot tips,leaves and roots of strawberry (Fragaria × ananassa Duch.) during flower-bud differentiation

Flowering is an important step in crop production. Under flower-inducing conditions, biochemical or physiological changes can be recognized. Changes in carbohydrates have an important role in flower development in plants; however, carbohydrate changes during flower bud differentiation in strawberry have not been thoroughly investigated. In this study, runner plants potted in 18 cm diameter pots and grown under non-inducing conditions (28 ± 3/22 ± 3 °C day/night; 16 h day length). When the plants were established, half of the plants then were put under inducing conditions (23 ± 3/13 ± 3 °C day/night; 8 h day length). After the induction period of 21 short-day cycles, plants were brought to non-inductive conditions again. In order to evaluate the carbohydrate changes during flower differentiation, shoot tips, leaves and roots were sampled from four replicated plants collected weekly for the period of 7 weeks. Sucrose, glucose and fructose contents were determined by HPLC, and starch by the anthrone method. The results obtained indicated that the most abundant soluble sugar in all organs tested was sucrose. Sucrose in the shoot tips of induced plants at 42, 56 and 70 days after the start of the short-day treatment were significantly higher than corresponding time in non-induced plants. However, the glucose, fructose and starch contents in shoot tips, leaves and roots of non-induced plants in most sampling dates were greater than those of induced plants. In other words, the shoot tips (bud) of induced plants acted as strong ‘utilizing sink’ and preferentially metabolized carbohydrates rather than storing them. It seems that non-structural carbohydrate contents in shoot tips, leaves and roots of strawberry may have an important role in flower-bud differentiation.     

The effect of chlormequat chloride (CCC) application at the bolting stage on the flowering and seed production of lettuce plants previously treated with water or gibberellic acid (GA3)

Lettuce plants were sprayed with gibberellin (GA₃) or water at the rosette (8-leaf) stage and subsequently with water or CCC (500 or 1500 ppm) at the onset of bolting. GA₃ induced rapid bolting and increased seed yield, but seed stalks were longer and thinner than those that had been sprayed with water at the same stage. Treatment with CCC (500 ppm) at bolting decreased the flower stalk height of plants that had been sprayed with water at the rosette stage, but not that of GA₃ treated plants. CCC (500 ppm) increased the number of inflorescence branches per plant as well as seed yield in the autumn sown crop, but had no effect on the winter sown crop. When a higher concentration of CCC (1500 ppm) was applied at bolting, flower stalk height decreased, irrespective of whether the plants had been previously treated with GA₃ or not, and seed stalk diameter increased. However, 1500 ppm CCC reduced the number of inflorescence branches per plant and mean seed yield. It is concluded therefore that although the application of 500 ppm CCC at the onset of bolting may increase seed yield in the autumn sown crop, this treatment does not improve the seed stalk strength (e.g. increasing diameter or reducing height) of GA₃ treated plants. On the other hand, whereas a higher concentration of CCC (1500 ppm) improves seed stalk characteristics, it reduces seed yield.     

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.     

Improved Culture of Apical Tissues for Production of Virus-Free Strawberries

Strawberry plants of fourteen varieties were raised from dissected apices of stolon tips and axillary buds excised at a length of less than 0·80 mm.

Two different media were used. On one of them 50% of tips from non-heat-treated plants developed roots and of these 54% survived to maturity; on the other medium (White’s augmented with coconut milk and sucrose) only 35% developed roots but 80%of these rooted tips grew to mature plants.

Tips excised from heat-treated plants grew more rapidly, and a higher proportion reached maturity, than those grown from untreated plants.

The smaller tips (<0·4 mm.) rooted less readily than larger ones (0·4–0·8 mm.) and grew more slowly to a size suitable for potting.

The plants of nine varieties were tested for virus infection by grafting to Fragaria vesca and F. virginiana 12–18 months after excision. One variety was freed from yellow edge (virus 2), three varieties from vein chlorosis (virus 4), two from crinkle (virus 3), and two from latent A virus.     

Shoot-tip culture and the eradication of viroid-RNA

Citrus exocortis viroid was eradicated from infected tomato plants (Lycopersicon esculentum Mill. ‘Rutgers’) by in vitro shoot-tip culture of axillary buds excised from greenhouse-grown plants. Plantlets developed from 23 of 67 shoot tips excised. The 6 plantlets that demonstrated normal root development were shown to be free of CEV by polyacrylamide gel electrophoresis and bioassay. Fully developed recovered plants showed the same characteristics as the ‘Rutgers’ seedlings.     

李离体茎尖的超低温保存

 以简单玻璃化法为基本方法,研究了影响李离体茎尖超低温保存的因子—继代培养时间、低温驯化时间、PVS3处理时间以及化冻后茎尖存活检测;建立了较为简单的李离体茎尖超低温保存技术程序：即选择继代培养120 d的试管材料,经过5 ℃低温驯化21 d,0.7 mol·L^-1蔗糖预培养1 d,PVS3处理100 min,浸入液氮。化冻后茎尖存活率可达60 %以上。     

Effect of fruit load on 9,10-ketol-octadecadienoic acid (KODA), GA and jasmonic acid concentrations in apple buds

The relationship between 9,10-ketol-octadecadienoic acid (KODA), GAs and jasmonic acid (JA) and flower bud formation influenced by fruit load in apples (Malus domestica Borkh.) was investigated. The endogenous KODA and JA concentrations in apical buds in plants subjected to flower thinning treatment (FTT), under which all flowers were removed were higher than those in plants subjected to heavy crop treatment (HCT), under which the number of leaves per fruit was adjusted to 20 from 60 to 120 days after full bloom (DAFB). In contrast, the gibberellic acid concentrations [total of gibberellin A₁ (GA₁) and gibberellin A₄ (GA₄)] in FTT plants were low compared with those in HCT plants. The result suggests that KODA and JA in contrast to GAs may have opposite effects on flower bud formation which is significantly influenced by fruit load in apples and that KODA and JA may also be associated with flower bud formation in apples.     

香蕉茎尖的玻璃化法超低温保存及其植株再生

 以香蕉(Musa spp. ) 为试材, 对其离体培养茎尖玻璃化法超低温保存影响因素进行研究。结果表明, 不定芽在MS + 3.0～5.0 mg/L 6-BA + 0.1 mg/L NAA的培养基上分化较好。香蕉茎尖超低温保存较佳体系是: 2.0～3.0 cm的茎尖在含0.4 mol/L蔗糖培养基上预培养2 d, 剥取带1～2个叶原基的茎尖(长1.0～1.5 mm) , 室温(25℃) 下装载液(MS + 2 mol/L甘油+ 0.4 mol/L蔗糖) 装载20～30 min, 然后用玻璃化溶液( PVS2 ) 于0℃下处理40 min, 换1次PVS2后迅速投入液氮。保存至少1 h后, 在40℃水浴中化冻90 s, 用1.2 mol/L蔗糖培养液洗涤2次, 每次10 min, 然后转入含0.3 mol /L蔗糖的MS培养基上,暗培养10～15 h后转移到含0.5 mg/L 62BA的MS培养基中, 暗培养1周后转移到正常光下, 3个香蕉品种(巴西蕉、广东香蕉2 号、广东粉蕉1 号) 的成活率分别为75.9%、40.0%和69.6% , 再生率分别为63.4%、35.0%和63.4%。再生植株生长和分化正常, 生根后可移栽成活。     

Cryopreservation of in vitro almond shoot tips by vitrification

Summary

Shoot tips of two almond scion cultivars, ‘Ne Plus Ultra’ and ‘Nonpareil 15-1’, and one almond/peach hybrid rootstock were successfully cryopreserved using a one-step vitrification technique. Three week old in vitro cultures were cold-hardened at 4°C on the multiplication medium (Murashige and Skoog for ‘Ne Plus Ultra’ and the hybrid rootstock; Almehdi and Parfitt for ‘Nonpareil 15-1’) for three weeks. Shoot tips, 2–2.5 mm long, were excised and precultured for 1 d at 4°C on the same basal medium, without plant growth regulators, supplemented with 0.7 M sucrose. After the preculture, the shoot tips were incubated in vitrification solution at 25°C for 45 min for the almond scion cultivars and 60 min for the hybrid rootstock, and then stored under liquid nitrogen (LN) for at least 3 d. After rapid thawing at 30°C, the shoot tips were washed with the appropriate liquid basal medium containing 1.0 M sucrose and then cultured on the same basal medium, solidified with agar, but excluding NH₄NO₃ or (NH₄)₂SO₄. Shoot regeneration was usually observed within 2–3 weeks. Survival after LN, recorded as the percentage of shoot tips that produced at least one new shoot four weeks after thawing, was 87.5, 60.0 and 72.5% for ‘Ne Plus Ultra’, ‘Nonpareil 15–1’ and the hybrid rootstock respectively. The one-step vitrification method is a promising simple technique for cryopreserving almond scion and rootstock shoot tips from in vitro cultures.     

桃离体茎尖的超低温保存及植株再生

 以简单玻璃化法为基本方法, 研究了影响桃离体茎尖超低温保存后存活率的因子———低温驯化时间、蔗糖预培养时间、玻璃化液处理时间及化冻后植株再生条件; 建立了较为适宜的超低温保存技术程序———选择继代培养30 d的试管材料, 5℃低温驯化3～4周, 在含017 mol/L蔗糖的固体培养基预培养2 d, 再经玻璃化液PVS3处理100 min后浸入液氮, 化冻后茎尖存活率可达60%以上。     

激素和多胺对苦瓜性别分化的影响

研究了ＧＡ３（赤霉素）和ＣＣＣ（矮壮素）处理下株洲长白苦瓜植株，从苗龄８～７０天茎尖内源激素的变化。结果表明，第一雌花形成与茎尖内源ＧＡ３含量增高有关。开花盛期，茎尖内源ＩＡＡ含量下降越小，ＺＴ含量下降越大，植株的雌花数和♀／♂越大。分析表明，雌、雄花中内源多胺（ｃａｄ）含量都明显高于无性组织，可能与性别分化有关，内源亚精胺（ｓｐｄ）含量变化可能与雌花的发生和发育有关，内源腐胺（ｐｕｔ）含量的上升可能与雄花的分化有关     

Possible role of non-structural carbohydrates in flower induction in strawberry

Summary

Flower-induction is the event that initiates the transition of a vegetative apex into a floral apex in response to an environmental or developmental cue. Under flower-inducing conditions, biochemical or physiological changes can be recognised. One possible change that could occur is in sugar content. In this study, levels of non-structural carbohydrates (e.g., sucrose, glucose, fructose and starch) were measured in shoot tips, leaves and roots of strawberry (Fragaria ananassa cv. ‘Kordestan’) under flower bud-inducing conditions, and compared with non-induced plants. Runner plants were potted and grown for 4 weeks under non-inducing conditions (31º/25°C day/night; 16 h daylength). Half of the plants were then put under flower-inducing conditions (25°/15°C day/night; 8 h daylength) for 3 weeks. Samples for carbohydrate analysis were taken from induced and non-induced plants every 3 d over 3 weeks, and sucrose, glucose and fructose contents were determined by HPLC, and starch concentrations by the anthrone method. The most abundant soluble sugar, in all organs tested, was sucrose. Sucrose levels in shoot tips and leaves decreased at the beginning of the induction treatment, but soon increased to the levels recorded in non-induced plants. Fructose increased markedly in shoot tips of induced plants 3 d after the start of the short-day treatment, and declined thereafter. Starch contents in shoot tips, leaves and roots of non-induced strawberry plants were higher than those in induced plants on most sampling dates. From the results of this study, it appears that soluble carbohydrate contents in different organs of June-bearing strawberry may have a decisive role on flower-bud induction.     

Factors affecting haploid induction through in vitro gynogenesis in summer squash (Cucurbita pepo L.)

Haploid production using in vitro ovule cultures has long been recognized as an important tool to produce haploid and homozygous double-haploid plants for genetic studies and plant breeding programs. In the present study, four experiments were carried out to study the influence of genotype, position of female flowers on plant stem, temperature and sucrose concentration on the in vitro gynogenesis induction of squash. (1) Ovules of 12 genotypes were excised from female flowers, 1 day before anthesis, and cultured onto MS medium containing 3% sucrose and 1 mg l⁻¹ from each of kinetin and 2,4-D (2,4- dichlorophenoxy acetic acid). Differences in response among genotypes were demonstrated. Raad F₁ showed the highest percentage of responding ovules and number of plantlets per dish with 48.8% and 15 plants, respectively. The results revealed that genotype is a key factor influencing the in vitro gynogenesis in squash. (2) Ovules were excised from first, second and third female flower of two hybrids (Giad and Raad) and cultured onto the mentioned above medium. The highest percentage of responding ovules and number of plantlets per dish were obtained from ovules excised from the second female flower on the plant stem. (3) Effect of temperature (4 and 32 °C) for 0, 4, 7 and 12 days on the ovule culture of Queen F₁ was studied. Ovules incubated at 4 or 32 °C for 4 days produced a better embryogenic response. (4) Three sucrose concentrations (30, 60 and 90 g l⁻¹) were tested with the ovule cultures of the local cultivar (Eskandrani). Differences among sucrose concentrations were statistically significant and ovules cultured on the MS medium containing 30 g l⁻¹ produced the best result. MS medium containing 90 g l⁻¹ did not produce gynogenic ovules.     

Manipulation of bolting and flowering in celery (Apium graveolens L. var. dulce). III. Effects of photoperiod and irradiance

SUMMARY

Photoperiods of 8 and 16 h during chilling at 5°C had no effect on bolting and macroscopic flower appearance in celery cv. New Dwarf White. Eight hour photoperiods during chilling however markedly increased the number of plants forming sessile flowers. Short photoperiods (8 h) after chilling decreased the proportion of young, but competent plants that bolted and flowered. Total darkness during chilling completely prevented any subsequent vernalization response either as bolting or as flowering. Reducing irradiance receipt by the plants during chilling from 85 to W m"2 (PAR) had no effect on their vernalization response. After chilling, a reduction in mean daily total irradiance in the glasshouse from 4.05 to 1.57 MJ m"2 d-1 had no effect on bolting and flowering. Confinement of competent plants to darkness for 4-8 d at 20°C just prior to chilling resulted in a highly significant delay (F>0.001) to bolting and reduced the number of plants flowering. Two days of darkness had no significant effect. The inhibitory effects of dark treatments prior to chilling was greater in plants chilled subsequently for six weeks than for nine weeks.     

Cryopreservation of carnation (Dianthus caryophyllus L.) shoot tips by encapsulation-vitrification

Shoot tips excised from in vitro cultured plants of Dianthus caryophyllus L. (cv. Pallas, cv. Pink Candy and cv. Wanessa) were successfully cryopreserved using an encapsulation-vitrification method. Shoot tips (2–3 mm in length) were encapsulated in sodium alginate, precultured on liquid Murashige and Skoog (1962) medium supplemented with various sucrose concentrations (0.25, 0.5, 0.75, 1.0 M) for 24 h or 48 h and dehydrated with the vitrification solution PVS2 (up to 4 h) at 24 °C or 0 °C prior to direct immersion in liquid nitrogen (−196 °C). A maximum of shoot regeneration from cryopreserved shoot tips was obtained with the following combinations: preculture in 0.5 M sucrose and 180 min dehydration treatment at 0 °C for cv. Pallas (60% shoot formation), or preculture in 0.75 M and 200 min dehydration at the same temperature for cv. Pink Candy (66.6% shoot formation) and cv. Wanessa (73% shoot formation).     

大叶风兰组培快繁技术体系的研究

通过大叶风兰的花梗腋芽诱导出无菌植株,再利用无菌植株茎尖诱导形成原球茎,成功地诱导分化形成了再生植株,筛选出了花梗腋芽启动、原球茎诱导、增殖、生根以及过渡培养等培养基配方,形成一套完整的大叶风兰组培快繁技术体系。