Micrografting of almond (Prunus dulcis Mill.) cultivars “Ferragnes” and “Ferraduel”

The success of various in vitro micrografting techniques, establishment of the rootstock, size of the microscion, and the effects of culture medium on the grafted seedling development for almond cultivars “Ferragnes” and “Ferraduel” were studied. In vitro germinated wild almond seedlings developed from seeds were used as rootstocks. Shoot culture initiation was successfully achieved from the above almond cultivars by culturing mature shoot tips from forced nodal buds, about 3–5 mm, on 0.7 mg/L BA and 0.01 mg/L NAA containing a MS medium. The regenerated adventitious shoots from in vitro cultures were maintained and proliferated by sub-culturing on a fresh medium every three to 4 weeks. Regenerated shoot tips, which were micrografted onto in vitro seedlings, resulted in the restoration of shoot proliferation. The results indicated that the most successful method for the grafting of tested almond cultivars was slit micrografting. High levels of micrograft take were achieved with all ranges of scions (4–15 mm) obtained from the regenerated shoot tips. Slow growth and lack of axillary shoot development on the micrografts were noticeable when the micrografts were cultured on hormone-free germination medium. In vitro micrografted plantlets were successfully acclimatized and no problems were encountered with the establishment of micrografted plants in vivo. The developed technique has demonstrated a high potential for application in the micropropagation of almond cvs. “Ferragnes” and “Ferraduel” and thereby, represents a feasible method for the renewal of almond orchards in Turkey and elsewhere in the world.     

Endogenous hormone concentrations and bud-break response to exogenous benzyl adenine in shoots of apple trees with two growth habits grown on three rootstocks

Summary

Scions from two siblings of a ‘Goldspur Delicious’ × ‘Redspur Delicious’ cross were budded to three rootstocks with different levels of vigour [M.9, M.7, and Malus domestica ‘Antanovka’ seedling] and planted in the field in 1997. The scions had two contrasting growth habits: one with narrow crotch angles, numerous short branches and an upright narrow (UN) canopy; and the other with wide crotch angles, few short branches, and a spreading round (SR) canopy. Shoot tips were collected at the time of bud-break in April 2004 and analysed for auxin (AUX), cytokinins (CK), and abscisic acid (ABA) to determine relationships between scion growth habit, size-controlling rootstock, and shoot tip hormone concentrations. Although not statistically different, the UN growth habit had numerically higher AUX, lower ABA, and equivalent CK levels as the SR growth habit. These differences resulted in statistically higher AUX:CK ratios (ACR). It is possible that the higher ACR contributed to the UN growth habit, which had more anti-gravitrophic shoot growth and appeared to have greater apical dominance than the SR growth habit. Either growth habit, grown on seedling rootstock, had nearly twice the ACR than on M.7 or M.9 rootstocks. The synthetic CK, 6-benzyl adenine (BA), was applied to 30 cm shoot explants of both growth habits in a greenhouse in March 2006. An 8.7 mM BA concentration stimulated bud-break in both growth habits, compared with controls, and bud-break was increased more in the UN than the SR growth habit. The results indicate that the ACR may be a factor regulating bud-break and the development of growth habit in apple scions, and that rootstock modified the hormone concentrations in shoot tips.     

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.     

Screening wild Eriobotrya species as rootstocks for loquat

Summary

Six wild species of Eriobotrya were evaluated as rootstocks for domesticated loquat. Twelve-month-old seedlings of Oak leaf loquat (an Oak Leaf loquat ‘Zaozhong No. 6’ hybrid) and wild Fragrant loquat (E. fragrans Champ) had higher root-to-shoot fresh weight (FW) ratios than other wild species. When the domesticated loquat, ‘Zaozhong No. 6’, was grafted onto seedlings of six different wild loquat species, differences in compatibility were observed. Graft compatibility was lower for all combinations compared to ‘Zaozhong No. 6’ grafted onto domesticated loquat seedlings. When wild Henry loquat was used as a rootstock, delayed incompatibility was observed. Differences in soluble sugar contents (SSC) between scion and rootstock were observed, and there was a significant negative correlation between graft compatibility and the difference in SSC values. The influence of the rootstock on anatomical changes at the graft union were observed using a scanning electron microscope (SEM). Wild rootstocks also influenced scion growth, fruit bearing, and fruit quality. Graft combinations which used wild Fragrant loquat as the rootstock had increased cold tolerance and improved scion growth. Wild Fragrant loquat therefore appears to have value as a rootstock for domesticated loquat.     

影响苹果试管嫁接苗培育的因素

用苹果试管苗Ｍ２６作砧木，‘Ｇａｌａ’作接穗，成功地获得试管嫁接苗。嫁接苗在ＭＳ液体纸桥培养基上的生长量与嫁接成活率显著高于ＭＳ固体培养基。但是，液体培养基导致砧木基部膨大，形成玻璃苗。随ＢＡＰ浓度升高，嫁接部位愈伤组织形成快、成活率高，接穗生长量明显增加。过高浓度的ＢＡＰ（≥０．８ｍｇ·１~(-１)），诱导砧木侧枝大量形成、砧木基部膨大、产生玻璃苗，并且显著降低砧木的生根力。试管嫁接苗建立阶段最适的ＢＡＰ浓度为０．４ｍｇ·１~(-１)。试管嫁接苗的生根力随ＩＢＡ浓度升高而显著提高，在１．０ｍｇ·１~(-１)浓度时达最适水平。ＩＢＡ浓度对试管嫁接苗接穗生长的影响与生根力是一致的。     

The effect of rootstock shoot growth on the level of bud-grafting success in apple

Poor stands of ‘Queen Cox’ apple bud-grafted in summer onto M.9 rootstock were shown to be due to the scion bud not growing, or growing too late to produce a worthwhile ‘maiden’ tree, despite virtually all scion graft-chips forming unions with the rootstock. This problem was caused by raising the budding height to 30 cm above ground, as a method of increasing the height of lateral branches. The key element in higher budding which depressed subsequent scion bud growth was the complete removal of all rootstock shoots to a height of 35 cm to give a traditional ‘clean leg’ during the budding year. Removing rootstock shoots only at the budding position gave good stands of high quality trees. This appears to be a general effect, with the benefits of retaining rootstock shoots applying also to Malus tschonoskii when budded at 30 cm on M.9 rootstock. For both ‘Queen Cox’ and M. tschonoskii, failure of scion buds to grow vigorously often resulted in the development of ‘papery bark canker’ on the M.9 rootstock. The main benefit of root- stock shoots retained in the budding year was to ensure that scion buds grew early in the following ‘maiden’ year, whereas allowing these and new rootstock shoots to remain for the first two months of ‘maiden’ growth reduced the number of secondary scion buds which developed, and raised the height of laterals by delaying their emergence.     

Metabolic stability of plants regenerated from cryopreserved shoot tips of Dioscorea deltoidea – an endangered medicinal plant

Shoot tips of Dioscorea deltoidea, a medicinal yam, were cryopreserved using the vitrification and encapsulation-dehydration technique resulting in high-frequency direct plant regeneration. The biochemical stability of the plants derived from cryopreserved shoot tips was assessed using HPLC analysis. The diosgenin content of plants regenerated from cryopreserved shoot tips was found to be same as that of control plants. Thus plants confirming our cryopreservation experimental conditions ensure the biochemical stability of regenerated D. deltoidea plants.     

Investigations into inconsistent and low bud-grafting success in Acer platanoides ‘Crimson King’

Causes of variable and inconsistent bud-grafting success in chip-budded Norway maple (Acer platanoides) were investigated using the red-leaved scion ‘Crimson King’. Large differences in bud-take were associated with the year of budding, which over a 14 year period ranged from 22 to 94%. The ‘year effect’ could not be explained by weather, or by differences in budding success found between commercial sources of red-leaved scions. Neither was incompatibility between the ‘Crimson King’ scion and individual genotypes among the seedling rootstocks implicated, although there were reasons why at first sight incompatibility was thought to be present. The size of rootstock when planted was not correlated with subsequent budding success, although large differences in the quality of rootstock growth at budding were associated with large differences in bud-take, but these were confounded with year and with the fields used for the experiments. The ‘year effect’ was best explained by the field in which budding took place. One field gave consistently poor results, associated with a readily compacting soil, pointing to the strong possibility that bud-take is determined by conditions which affect shoot and/or root growth during the budding season or specifically while the union is forming in late summer. It was shown also that the presence of the scion bud on the chip-graft contributed to union formation, and that infection of the rootstock with the soil-borne verticillium wilt disease depressed bud-take, but this did not explain the ‘field effect’.     

Aseptic micropropagation of Rhododendron P.J.M. hybrids

Summary

Shoot tips established in vitro better than single nodes. Five-cm shoot tips gave better Stage I results than 2-cm shoot tips. The best microshoot proliferation rates were obtained with isopentenyladenine (2iP) at 5 and 10 mg l^?1; tetrahydropyranyl-benzyladenine was ineffective. Microshoots rooted well, regardless of the level of 2iP in the Stage II medium. Stem-cutting-macropropagated plants generally were more variable in height, had less basal branching and were more erect than plants from microculture.     

兰州地区引种的美国扁桃的越冬伤害与临界致死低温

 通过田间越冬指数调查、组织变褐法和电导法配合Logistic 方程求拐点温度的方法, 对7 个从美国引入的扁桃品种的抗寒性进行评价。结果表明: 扁桃幼树1 年生休眠枝的低温半致死温度( LT50) 为- 18. 0 ~ - 24. 5; 其中 Butte和 Padre的抗寒性较强, 半致死温度约为- 24. 5; Nonpareil、Price! 和 Monterey! 的抗寒性中等, 半致死温度约为- 20. 9; Ne Plus! 和 Sonora! 的抗寒性较弱,半致死温度约为- 18. 3。     

The influence of rootstock lateral buds on bench-chip-budded ‘Mirandy’ field roses

A positive correlation existed between the development of shoot and root systems of ‘Mirandy’ roses. Scions bench-chip-budded below rootstock lateral shoots were inhibited by apical dominance. Inhibition of scion apices was overcome by pruning the top of each rootstock above the graft. Rootstock axillary buds were necessary for adequate initial root-system establishment, but should be eliminated early in the growth cycle to maximize scion development of rose bushes and reduce field production time.     

Differential tolerance to iron deficiency of citrus rootstocks grown in nutrient solution

We studied the effects of Fe deficiency on physiological parameters of citrus rootstocks grown in nutrient solution. Three 4-week old rootstocks (‘Troyer’ citrange – Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf., Citrus taiwanica Tan. and Shim., and ‘Swingle’ citrumelo – Poncirus trifoliata (L.) Raf. × Citrus paradisi Macf.) were grown in nutrient solutions with 0, 5, 10, 15 and 20 μmol Fe dm⁻³. Calcium carbonate (1 g dm⁻³) was added to all solutions to mimic the natural conditions in calcareous soils. For each rootstock, shoot length, number of leaves, and root and shoot dry weights were measured at the end of experiment. Chlorophyll concentration was estimated using a portable SPAD-502 meter calibrated for each rootstock. The amount of nutrients (P, K, Mg, Ca, Fe, Zn, Mn, and Cu) was determined in shoots. Chlorophyll fluorescence parameters (F₀: basal fluorescence; F_m: maximum fluorescence; F_v = F_m − F₀: variable fluorescence) were measured with a portable fluorimeter. ‘Troyer’ citrange rootstock was the most tolerant to Fe deficiency. These plants grew more and accumulated more chlorophyll and nutrients than the others in the presence of low levels of Fe (10 μmol Fe dm⁻³). ‘Swingle’ citrumelo plants needed 20 μmol Fe dm⁻³ in the nutrient solution to secure adequate growth. ‘Taiwanica’ orange rootstock had an intermediate behaviour, but could be distinguished from ‘Troyer’ citrange based on fluorescence parameters, since there was a variation in the basal fluorescence in the former, whereas in ‘Troyer’ citrange the basal fluorescence was not affected by the supply of Fe.     

Molecular marker analyses of pistachio rootstocks by Simple Sequence Repeats and Sequence-Related Amplified Polymorphisms

Summary

Simple Sequence Repeat (SSR) and Sequence-Related Amplified Polymorphism (SRAP) molecular marker systems were used to analyse four commercially important pistachio rootstocks: two species of Pistacia atlantica (cv. ‘Standard Atlantica’), P. integerrima (cv. ‘Pioneer Gold’) and two interspecific hybrids of the same, ‘Pioneer Gold II’ (‘PGII’) and ‘University of California at Berkeley 1’ (‘UCB-1’). A total of 35 putative alleles were detected by 12 SSR primer pairs with an average of 2.9 alleles per locus. The number of putative alleles ranged from 2 to 5 in the pistachio rootstocks tested. The number of bands produced by the SRAP protocol was highly variable, ranging from 11 to 38, with an average of 25.2 per primer combination. Eight primer combinations resulted in 104 (51%) polymorphic markers in these samples. SSR and SRAP markers successfully identified all pistachio rootstocks tested from their unique fingerprints. Both SSR and SRAP molecular markers confirmed that the observed variation in ‘UCB-1’ rootstock is genetic.Thus, there will always be variation among ‘UCB-1’ hybrid seedling progeny due to the segregation of alleles when propagated by seed.We also found evidence of contaminating pollen other than from P. integerrima in some hybrid ‘UCB-1’ rootstock progeny produced by closed pollination. Only alleles from the cultivar ‘Standard Atlantica’ were observed in abnormal ‘UCB-1’ rootstock in the nursery. We found that the poor performance of the scion cv. ‘Kerman’ on ‘UCB-1’ rootstock was not due to ‘UCB-1' rootstocks displaying abnormal behaviour in the nursery. We have successfully developed two efficient marker systems for genome analyses in pistachio, which can be used for identification and management in pistachio rootstock production.     

马铃薯茎尖小滴玻璃化法超低温保存及其再生植株的遗传稳定性

以马铃薯试管苗为试材,对其茎尖小滴玻璃化法超低温保存的影响因素进行了研究,并对再生植株进行了遗传稳定性检测。结果表明,马铃薯茎尖依次在含有0.3 mol · L-1和0.5 mol · L-1蔗糖的液体MS培养基中预培养各1 d后,在0 ℃下PVS2处理30 min,转到铝箔条上PVS2小滴上（约15 μL）,将粘有茎尖的铝箔条在液氮里蘸一下,然后直接装入盛满液氮的冷冻管中,投入液氮至少保持1 h。室温下用含有1.2 mol · L-1蔗糖的MS液体培养基解冻并洗涤30 min后,接种到MS + 0.5 mg · L-1 Zeatin + 0.1 mg · L-1 NAA＋1.0 mg · L-1 GA3恢复培养基上,存活率和再生率最高达79.91%和62.52%。通过SSR分子标记检测,再生植株的遗传稳定性没有发生改变。     

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.     

Root shoot interactions in passionfruit (Passiflora sp.) under the influence of changing root volumes and soil temperatures

Summary

Passionfruit are grown in the tropics and subtropics where mean monthly soil temperatures at 15 cm range from about 10° to 30°C. The choice of rootstock can also influence production with most industries exploiting either the purple (Passiflora edulis f. edulis) or golden passionfruit (P. edulis tflavicarpa). We examined the relationship between shoot and root growth in purple x golden hybrid E-23 grafted onto golden passionfruit seedlings. Growth was manipulated by varying the volume of the soil available to the roots or temperature of the root zone. Shoot and root growth increased as root zone volume increased from 0.3, 1.4, 4, 12 to 24 1. Shoot weight (W_s) was correlated with root weight (W_R):W_S = 12.697 + 5.272 W_R + 0.195 W_R² (r² = 91%, P<0.001), with the plants allocating a smaller proportion of dry matter to the roots as root weight increased. Differences in shoot growth with pot volume were not due to changes in water or nutrient status. In the temperature experiment, the two critical root zone temperatures at 90% of maximum growth were about 20° and 35° C for vine extension, leaf area, node and leaf production, and 20° and 30°C for flower production. Leaf and stem dry weight were optimal between about 18° and 34°C, while maximum root growth occurred at 38°C. There was a weak relationship between shoot (W_s) and root dry weight (W_R): W_s = ?19.346 + 24.500 W_R ?1.046 W_R² (r² = 53%, .P<0.001). Apparently, variations in shoot growth at different soil temperatures cannot be explained solely by differences in root growth. Reduced growth at 10°C was associated with lower chlorophyll concentration, stomatal conductance and net CO₂ assimilation, but not lower leaf water potential. The concentration of most nutrients were lower at 10°C than at higher temperatures, but none was outside the range which would be expected to restrict growth. There appears to be a co-ordination of shoot and root growth as the soil volume available for root growth increases, whereas root temperature affects the roots and tops differently. The results of the pot volume experiment demonstrate the importance of rootstock vigour in passionfruit breeding. Productivity would be affected in cool subtropical areas with soil <20°C and in tropical areas with soil >30°C.     

Production in Vitro of Rootstock/Scion Combinations of Prunus Cultivars

Shoot meristems (0-2-0-5 mm) of the plum scion cv Victoria (Prunus domestica) and the plum rootstock cv Pixy (P. insititia) were micrografted in vitro onto rooted shoots of the peach rootstock GF305 (P. pérsica) produced by in vitro propagation. These procedures, which resulted in 40—50% successful grafts, are preliminaries to providing a more controlled system for research into rootstock influence on scion growth and development.     

Micro-grafting shoot-tip culture of citrus on three trifoliolate rootstocks

Simple techniques and growth regulator treatments to improve micro-grafting success of ‘Mexican’ lime, ‘Valencia’ orange and ‘Star Ruby’ grapefruit were studied. Most scion cultivars grafted best on ‘Carrizo’ citrange [Poncirus trifoliata (L.) Rat. x Citrus sinensis (L.) Osbeck]. Dipping the shoot-tip in 2,4-D or kinetin before grafting doubled the percentage of successful grafts. Highest grafting success occurred when the scion shoot-tip was placed in an inverted-T incision on the epicotyl of the rootstock.     

The effect of grafting on nitrogen use in determinate field-grown tomatoes

Grafting tomato (Solanum lycopersicum L.) onto disease resistant rootstocks has grown in use in North America over the past two decades. Rootstocks have traditionally been bred and used for their resistance packages to numerous soil-borne diseases but some rootstocks appear to improve scion yield and vigour in comparison to non-grafted plants in conditions lacking disease challenge. In this study, the tomato rootstocks ‘Maxifort’ or ‘RST-106’ were used to determine if vigour improved ‘Tribute’ scion traits, especially yield, and if marketable yield could be maintained in grafted plants at reduced nitrogen fertiliser inputs. Plants were grown in an open-field plasticulture production system at five rates of nitrogen from 0 kg ha^?1 to 224 kg ha^?1 applied via drip irrigation. Marketable yield was significantly affected by nitrogen rate and rootstock in both years. ‘Tribute’ grafted onto ‘Maxifort’ rootstock had the greatest, most consistent impact and increased marketable yield 15% and 30% in 2013 and 2014, respectively, compared to the non-grafted ‘Tribute’. Our findings suggest that some rootstocks can increase scion growth and yield but do not differentially respond to decreased nitrogen rates.     

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).