Effect of nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings

The effect of the nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings was studied in sand culture under high, medium and low levels of nitrogen.

Nitrogen starvation induced rooting. Exogenous application of the auxins IAA (indol-3yl-acetic acid), IBA (indol-3yl-butyric acid) and NAA (naphth-lyl-acetic acid) greatly increased the rooting response of cuttings from-stock plants grown with small amounts of nitrogen.

The root-promoting effect of a low nitrogen supply was associated with a retardation of growth in the stock plants from which the cuttings were made. High C/N (total available carbohydrates/total nitrogen) and P/N (total phosphorus/total nitrogen) ratios increased anthocyanin pigmentation in the shoot, and increased rooting cofactor activity in the tissues of cuttings. The phenolic compounds, ferulic acid, p-hydroxybenzoic acid and p-coumaric acid were present in the shoots of all three nutritional treatments and acted as important cofactors in the cuttings. In general, rooting cofactor activity was inversely related to nitrogen supply and the activity was highest under low nitrogen.

The cuttings taken from plants grown under different levels of nitrogen interacted differentially with the exogenously applied auxins.     

In vitro adventitious rooting of Cornus florida microshoots

Cornus florida L. (flowering dogwood) has been successfully micropropagated, but low rooting of microshoots makes the system inefficient. This study was conducted to increase rooting efficiency of flowering dogwood microshoots over that previously achieved. Microshoots originating from acclimatized axillary and nodal bud stock cultures were excised and treated with different concentrations and combinations of various auxins including indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA). Effect of microshoot age on rooting efficiency was also examined. Of the auxins tested, maximum rooting was observed with 4.4 μM IBA. The age of microshoot explants had a significant effect on rooting. Five to seven-week-old microshoots treated continuously with 4.9 μM IBA in Woody plant medium (WPM) consistently had the best and most consistent rooting efficiency (about 83%).     

Rooting-enhancement of Rosa hybrida for tissue culture propagation

The effect of combinations of auxin sources and concentrations, temperature shifts, light intensity and light reduction on shoot-tips were studied relative to root formation of Rosa hybrida L. ‘Bridal Pink’ propagated in vitro. 2,4-dichlorophenoxyacetic acid alone was almost ineffective, and similarly its combinations with other auxins were less effective than other auxin combinations. While indolebutyric acid (IBA) alone did not stimulate rooting, both indoleacetic acid (IAA) and naphthaleneacetic acid (NAA) were effective. Combinations of NAA and IBA and NAA and IAA were equally effective in stimulating rooting and also enhanced rooting more than IAA, IBA or NAA alone. When root quality is considered, the combination of NAA and IBA was better than that of NAA and IAA.An additive effect on rooting existed between NAA and IAA at most concentrations used. A similar effect was evident between NAA and IBA except when NAA was used at 0.025 mg/l, in which cases synergistic effects were observed. Light reduction to the rooting area, light intensities of 1.0 K lux or lower and holding the cultures for 1 week at 5°C all enhanced rooting.     

Effect of glucose on in vitro rooting of mature plants of Bambusa nutans

A high-frequency in vitro rooting method was developed for Bambusa nutans, one of the economically important bamboos in India. Two clones of approximately 10-year-old B. nutans were used for axillary bud proliferation. The effect of carbohydrate source (glucose and sucrose) and auxins (IAA, IBA and NAA) on the in vitro rooting response was evaluated. Rooting percent, mean number of roots and root length were recorded after 14 days of treatment. Successful treatment (49.0 μM IBA and 88 mM glucose in the induction phase for 3 days followed by MS salts with 88 mM sucrose) was repeated four times each with 100 shoots to ascertain the practical utility of the protocol. Addition of glucose along with 49.0 μM IBA during the root induction phase gave 85% rooting success. Anatomical studies in the nodal regions were conducted to determine the effect of glucose on root primordial development and elongation. It was observed that the presence of glucose in the root induction medium is required to recruit more number of root initials. A simple protocol was developed for the large-scale production of B. nutans, where rooting of microshoots developed from mature tissues is always difficult. This study showed that glucose as carbon source and auxin type IBA is essential for in vitro root formation in the cultures raised from mature tissues.     

Black Currant Leaf Spot: II. Laboratory Tests of Fungicides for the Prevention of Sporing of Pseudopeziza Ribis on Overwintered Leaves

Summary

We have developed a two-step procedure for rooting of tea microshoots in vitro. The effectiveness of different auxin treatments for root formation was found to differ. Among the auxins tested, 25 μM -naphthalene acetic acid (NAA) gave the best results, with 100% rooting, compared to 25 μM indole-3-butyric acid (IBA) or 25 μM indole-3-acetic acid (IAA), which induced 17% and 58% rooting, respectively. Incubation of tea microshoots on 0.33 Murashige and Skoog (MS) medium, supplemented with 25.0 μM NAA or 175.0 μM IBA for 10 d, followed by transfer to auxin-free 0.33 MS medium resulted in 100% rooting, whereas 50.0 μM IAA induced 91.7% rooting. Besides the different auxin treatments, the strength of the MS medium, the duration of incubation of microshoots in auxin-containing medium, the sucrose concentration, the gelling agent, the pH of the medium, the incubation temperature, the light intensity, and the quality of the shoots also played a significant role during in vitro rooting of micropropagated tea shoots. Among the combinations tested, the most effective results were obtained when green microshoots were incubated on 0.33 MS medium supplemented with 25.0 μM NAA, 50.0 mM sucrose, pH 5.5, gelled with 0.2% (w/v) Phytagel^TM for 10 d at 25° – 30°C at a light intensity of 40 μmol m^–2 s^–1, followed by transfer of shoots to auxin-free 0.3 MS medium. This resulted in 100% rooting and, on average, 11 long roots were formed per shoot. Anatomical changes during adventitious rooting of micropropagated tea shoots in vitro were also studied to understand the process of rooting.     

A comparison of conventional cloning options for annatto (Bixa orellana L.)

Summary

Annatto (Bixa orellana L.) is a tree indigenous to tropical America that has been naturalised throughout the Indian sub-continent. The plant is chiefly valued for its carotenoid pigments, annatto. Methods for the clonal propagation of hardwood and softwood cuttings, air-layering, budding, and grafting of annatto were investigated. Hardwood cuttings collected during the wet Summer months (June-July) were treated with indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), or naphthaleneacetic acid (NAA) at varying concentrations. The highest percentage rooting (63.4%), along with highest number of roots (8.33 per cutting) were achieved by hardwood cuttings after 12 h of 2.5 mM IAA treatment. Among the various auxin treatments of softwood cuttings, 5.0 mM IBA in combination with 5.0 mM NAA for 5 min resulted in a significant (P < 0.05) rooting percentage (56.7%). The responses of softwood cuttings to an auxin analogue (boric acid) and/or to thiamine hydrochloride (vitamin B) were inferior to synthetic auxins. When subjected to air-layering, hardwood branches gave 100% rooting without any application of hormone. Among the different types of budding methods attempted (patch, T, or I), patch budding produced the highest efficiency (78%) of propagation. Splice-grafting could also be used for conventional propagation of annatto, with a 50% survival rate. Annatto can therefore be cloned by adopting these methods. Propagation based on softwood cuttings facilitated moderate-scale cloning of this valuable, elite germplasm.     

Adventitious root formation in Grevillea (Proteaceae), an Australian native species

Grevillea (Proteaceae) is a native Australian plant genus with high commercial value as landscape ornamentals. There has been limited research on the culture and propagation of Australian native species. The effect of indole-3-butyric acid (IBA) on the rooting of G.‘Royal Mantle’ and G.‘Coastal Dawn’ in winter, spring and summer was evaluated at University of Queensland Gatton, Southern Queensland in order to determine the rooting ability of this species in different seasons. Both Grevillea cultivars showed seasonal rooting. The more difficult-to-root G.‘Coastal Dawn’ had a reduced response to IBA application than G. ‘Royal Mantle’. Stem and leaf indole-3-acetic acid (IAA) levels were not different between cultivars, therefore rooting ability between the two cultivars does not appear to be due to the differences in endogenous IAA levels.     

An investigation on the effect of different plant growth regulating compounds in in vitro shoot tip and node culture of lemon seedlings

The possible application of some less commonly used in vitro growth regulating compounds is outlined. A number of treatments were applied to determine the best way of inducing in vitro shoot proliferation and rooting on a modified Driver–Kuniyuki [HortScience 19 (1984) 507] basal medium of lemon (Citrus limon (L.) Burm, f. cv. Interdonato) seedlings. 6-Benzyladenine (BA) alone (1, 2 and 4 mg l⁻¹) and in combination with either orange juice (10%, v/v), silver nitrate (3 mg l⁻¹), gibberellic acid (GA₃) (0.1 mg l⁻¹ at the establishment stage and 0.5 mg l⁻¹ at all combinations during the proliferation stage) or abscisic acid (ABA) (0.2 mg l⁻¹ only at the establishment stage) were used to stimulate shoot formation during the establishment and the proliferation stage. The combination of BA with ABA gave a high rate of shoot formation, while GA₃ and silver nitrate enhanced shoot elongation. When these shoots were transferred to the rooting stage, the effect of application of two different auxins (indole-3-butyric acid (IBA) and α-napthaleneacetic acid) was examined, as well as different methods of application (auxin added to the basal medium and auxin application by dipping the base of the explant in auxin solution). Dipping the base of the explants in a 50% ethanol solution of IBA at 1000 mg l⁻¹ for 5 s resulted in 80% rooting with subsequent 90% survival of these explants, during acclimatization under mist.     

Auxin induced morphogenetic responses in long-term in vitro subcultured Mammillaria san-angelensis Sánchez-Mejorada (Cactaceae)

Observations were made as to the influence of auxins, as the sole exogenous growth regulator, on the morphogenesis of long-term in vitro subcultured plantlets of the severely endangered cacti Mammillaria san-angelensis. Sections of long-term subcultured shoots were exposed to different auxins at various concentrations, and plant regeneration was recorded as a direct effect of auxin concentration. It was found that morphogenetic potentiality was retained in long-term subcultures, and that the best regeneration was seen in the presence of IAA (34.25 μM). Histological analysis revealed two processes leading to regeneration: de novo production of shoots and axillary meristem activation. Of the two, de novo shoot production was found to occur both in controls and in explants growing in the presence of IAA, while axillary meristem activation was observed only in the presence of IAA.     

不同基质与植物生长调节剂对扶桑插条生根的影响

研究了珍珠岩、蛭石、河沙、菜园土、腐殖营养土等不同基质配比、不同生长素调节剂(IBA、IAA、NAA)及其浓度、生长调节剂与多效唑(PP333)混合使用对扶桑插条生根的影响。结果表明:河沙+腐殖营养土等体积混合的基质对生根的效果最好;IBA处理的生根效果较好,其中以IBA 150mg/L处理的生根率最高,为93.67%;IAA的处理中,以低浓度50mg/L的生根率最高,为90.67%;较高浓度NAA的处理平均生根数较多,但生根率较低。用含PP33320mg/L与IAA 50mg/L或与IBA 150mg/L的混合液处理均能提高扶桑插条的生根效果。     

In vitro propagation of Blandfordia grandiflora (Liliaceae)

Multiple shoots were obtained when single shoot tips of Blandfordia grandiflora were exposed to different concentrations of kinetin, N6~ benzylaminopurine (BAP) and N6- isopentenylaminopurine (2iP). The best multiplication results were obtained when explants were subjected to kinetin at 8 (iM BAP at 0.5,2 and 8 (iM and 2iP at 2,8,32 and 128 |iM. Preliminary rooting trials were performed with three different auxins: indo- lebutyric acid (IB A), naphthalene acetic acid (NAA) and indole acetic acid (I A A). IB A at a concentration of 8 |iM and IAA at a concentration of 32 |xM gave highest root number, but when transplanted to the glasshouse, the best surviving plantlets were those treated with 2 |xM of IBA or 0.5 μM of IAA.     

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.     

In vitro shoot proliferation and enhancement of rooting for the large-scale propagation of yellow bamboo (Bambusa vulgaris ‘Striata’)

Continuous and rapidly proliferating axillary shoots were raised from axillary buds in secondary branches of adult field culms and nursery grown 1-year-old tissue culture-raised plants of Bambusa vulgaris ‘Striata’. Shoots continuously proliferated in a MS medium containing 4 mg L⁻¹ 6-benzyladenine (BA). The effects of indole butyric acid (IBA) levels, a pretreatment with thidiazuron (TDZ) (1-phenyl-1-([1,2,3-thidiazol-5-yl])urea) and illumination on rooting, were investigated after 6 months of shoot proliferation. A rooting medium with IBA at 3 mg L⁻¹ was optimum for root induction. Shoots of adult field culms that were proliferated in the presence of BA when induced to root in this medium resulted in 40% rooting in 27 days. In vitro shoots raised from 1-year-old tissue cultured plants showed 92% rooting under the same conditions. Rooting was enhanced when the relatively difficult-to-root in vitro shoots from adult field culms were pretreated with 0.5 mg L⁻¹ TDZ for two to three subcultures before placing in the root induction medium. Continuously illuminated shoots pretreated with TDZ for three subcultures showed 100% rooting compared to 83% rooting of shoots that were exposed to a 12 h photoperiod. These findings have been applied in the large-scale propagation of this species.     

Morphogenetic responses of Salpiglossis sinuata L. leaf explants and callus

Leaf explants of Salpiglossis sinuata L. were cultured on MS medium containing the auxins 2,4-D, IAA, NAA, or the cytokinins 6-BAP, 2ip, or K singly or NAA + 6-BAP combinations (0.01 to 10.0 mg/l) to determine their morphogenetic responses. IAA and NAA induced callus or roots at all levels except IAA at 0.01 mg/l. Callus varying in friability was obtained on MS + 2,4-D at various concentrations. Friable, uniform dividing callus was obtained on UM medium. Optimum adventitious shoot formation occurred on leaf sections and from callus cultures placed on MS + 2ip. Rooting-difficulties were encountered, but 75% rooting efficiency was obtained on shoots cultured in MS + 0.001 mg/l 2,4-D. Rooted plants were readily transferred to the greenhouse, and flowered.     

In vitro propagation of Pyrus pyrifolia

A micropropagation method for an adult seedling tree of Pyrus pyrifolia Burm. f. is described. Shoot cultures were established and multiplied on media containing benzylamino purine and naphthaleneacetic acid, rooted on media containing naphthaleneacetic acid and phloroglucinol, and transplanted to potting mix. Addition of phloroglucinol to the rooting medium enhanced both the percentage of shoots forming roots and the survival of plantlets after transplantation. However, about 30% of the plants raised in vitro were lost owing to a shoot-collapse which was not prevented by the application of fungicides.Establishment and multiplication of shoot cultures was also achieved with 5 named cultivars of P. pyrifolia, but rooting of the shoots of these cultivars has not been satisfactory.     

Spraying Experiments Against Apple and Pear Scab at Long Ashton and in the West Midlands,Season 1951

Ether extracts were made of samples of black currant berries (var. Seabrook’s Black) collected at weekly intervals from 18 days prior to fertilization until maturity. The extracts were shown to contain two acid auxins (a₁ and a₂), one neutral auxin (a₃), and one acid growth inhibitor (l₁), which could be separated by paper chromatography and assayed in biological tests. The changes in concentration of the three auxins throughout the season were studied in relation to seed and fruit development, fruit growth and fruit drop (“ running off ” and pre-harvest drop). It is suggested that the auxins are produced as by-products of either protein synthesis or hydrolysis taking place in different tissues and organs in a pre-determined order during the growth of the fruit. The rate of fruit growth showed a positive correlation with the concentrations of auxins I and 3, whereas fruit drop was negatively correlated with the concentration of auxin 2.     

Locust bean gum (LBG) as a gelling agent for plant tissue culture media

Locust bean gum (LBG) is a natural hydrocolloid extracted from the seeds of carob tree (Ceratonia siliqua L.). This work describes the successful use of LBG as a gelling agent in combination with agar for shoot multiplication and rooting of carob tree and Iberian rose shoots. Its presence did not affect the multiplication rate of both species. The rooting frequency of carob shoots was even significantly increased in the presence of 5 g of LBG plus 4 g of agar to the medium compared to medium solidified with 9 g of agar. Iberian rose shoots rooting was not influenced by the addition of this gum to the rooting medium. Results obtained show that LBG can be used in combination with agar in culture medium as a gelling agent without negative effect on plant material and with the advantage of reduced medium costs.     

Effect of synthetic auxins on fruit development of ‘Bing’ cherry (Prunus avium L.)

The main cherry cultivar grown in the warm climate of Israel, ‘Bing’, produces relatively small fruit. Over three consecutive years (2003–2005), application of 50 mg l⁻¹ 2,4-dichlorophenoxypropionic acid [2,4-DP; as its butoxyethyl ester (Power™)], 10 mg l⁻¹ 3,5,6-trichloro-2-pyridyloxyacetic acid [3,5,6-TPA; as the free acid (Maxim^®)], or 25 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) plus 30 mg l⁻¹ naphthaleneacetic acid (NAA; 0.3% Amigo™), at the beginning of pit-hardening when fruitlet diameter was ca. 13 mm caused appreciable and significant increases in fruit size and total yield, except when the crop load was heavy. Anatomical studies revealed that the main effect of these synthetic auxins was via direct stimulation of fruit cell enlargement. The above auxins had no negative effect on fruit quality, either at harvest or after 1 month of storage at 0 °C, or on return yield in the following year.     

In vitro propagation of olive (Olea europea sativa L.) ‘Kalamon’

A micropropagation method is described for olive (Olea europea sativa L.) ‘Kalamon’ using single-node explants collected from shoots produced from olive ovules grown in a growth chamber. Shoot proliferation was obtained on OM modified medium supplemented with 0.5 mg r¹ cystine, 10 mg I^-1 pantothenic acid calcium, 0.5 mg I^-' gibberel- lic acid (GA₃), 0.1 mg T¹ indole-3-acetic acid (IAA) and 10 mg I^-1 zeatin riboside, or 7.5 mg I^-1 benzyladenine (BA), or 10 mg I^-1 N⁶-2-isopentenyladenine (2ip). Explants were rooted on a medium similar to that for shoot development, but without cytokinins and with a-naphthaleneacetic acid (a-NAA), and indole-3-butyric acid (IBA) at 1, 2 and 3 mg I^-1 for both auxins. a-NAA at all concentrations was more effective than IBA. Shoot proliferation and rooting were improved by the addition to the nutrient media of 20 mg I^-1 and 50 mg I^-1 crude extract from olive ovules, respectively. Rooted explants were transferred to pots containing equal volumes of peat and vermiculite; about half survived.     

Analysis of adventitious root formation in isolated stem explants of Rhododendron

Factors affecting adventitious root formation were studied in isolated stem segments of three Rhododendron cultivars, ‘Catawbiense Album’, ‘Pink Pearl’ and ‘Van Weerden Poelman’, having different rooting ability. The experiments consisted of varying certain factors, while keeping the others constant.Root formation was always less in ‘Van Weerden Poelman’ than in the easy-to-root cultivars. Rooting usually occurred only in segments from young soft shoots. The length of the explants did not affect rhizogenesis. Removal of a strip of bark promoted adventitious root formation. Oxygen supply appeared to be essential since only inverted segments were capable of forming roots. Darkness was essential for rooting. The optimum temperature was 25°C. Root formation occurred only when a sugar was present in the medium. Rooting decreased with increasing osmotic pressure. Macroelements, boric acid and the pH of the medium did not play an essential role. Auxin was an absolute requirement for rooting, the kind and concentration depending on the cultivar used. Benzylamino purine at low concentrations increased root dry weight. GA₃ and abscisic acid decreased rooting.