The effects of volatile oils on in vitro potato sprout growth

Summary The effects of 10 volatile oils and their main compounds on potato sprout growth were investigated in vitro. Sprout growth was inhibited especially by the volatile oils fromOriganum onites, Rosa damascena, Carum carvi, Mentha piperita, Echinophora tuneifolia andCoriandrum sativum. The major compound of volatile oils was carvacrol (78.2%) inO. onites, citronellol (46.7%) inR. damascena, S-(+)-carvone (54.9%) inC. carvi, menthol (44.1%) inM. piperita, α phelladrene (45.9%) inE. tuneifolia and linalool (76.5%) inC. sativum. The results showed that some volatile oils rich in monoterpenic compounds such as carvacrol, citronellol, geraniol, nerol and S-(+)-carvone were able to prevent the growth of sprouts and extend the storage-life of the potato tubers.     

Dormancy and sprout development of some South African potato cultivars during cold storage

Summary Observations were made on dormancy and sprout growth of nine potato cultivars stored at 3–4°C, 7–8°C and 11–12°C, respectively. Tubers of the cultivar Vanderplank had a very long dormant period (232 days at 3–4°C) and showed little sprout growth at 180 days. The cultivar Koos Smit had a very short dormant period (92 days at 3–4°C) and developed considerable sprout growth at the higher temperatures. The reaction of tubers of Up-to-date and BP₁ were approximately the same, and intermediate between those of Vanderplank and Koos Smit.     

Inhibition of potato sprout growth by carvone enantiomers and their bioconversion in sprouts

Summary The monoterpenes (R)-(−)-carvone and (S)-(+)-carvone inhibited sprout growth in a model system consisting of sprouts growing from potato eye pieces. The sprout tissue was not necrotic after carvone treatment and the inhibition was reversible, since after treatment the sprouts showed regrowth either by continued top growth or by branching. However, the effect of both isomers on sprout growth differed, and (S)-(+)-carvone inhibited the elongation of the sprouts sooner than did (R)-(−)-carvone. This might be explained by a faster uptake of the former, since the concentration of (S)-(+)-carvone and its derivatives was twice as high during the first 4 days compared with (R)-(−)-carvone-treated sprouts. The sprouts were able to reduce (R)-(−)-carvone mainly into neodihydrocarveol, and (S)-(+)-carvone into neoisodihydrocarveol; in addition hydroxylated compounds were also detected. To whom correspondence should be addressed     

The conservation of potato cultivars

Summary To prevent the loss of important genetic information cultivars are conserved in several collections of gene banks. In principal, there are two options for the medium to long-term storage of potato cultivars: storage as in vitro plantlets or microtubers and storage of meristems or shoot-tips in liquid nitrogen. In the Braunschweig potato cultivar collection, 360 cultivars are maintained under slow-growth conditions. Ten microplantlets of each cultivar are stored in test tubes containing filter paper bridges and 5 ml Murashige and Skoog (MS) liquid medium. The cultures were maintained at 10°C with a light intensity of 2 klux and 16 hours-day and can be stored under these conditions up to three years. Two hundred and forty-five cultivars are cryostored in liquid nitrogen. About 300 trimmed shoot-tips of each cultivar are incubated in MS-Towill-medium and then transferred into the cryoprotective solution. After an incubation time of about 2 hours trimmed shoot-tips fixed on an aluminium foil were put in cryo vials and stored in a container. The survival rate of the thawed, trimmed shoot-tips varies from 55%–100%. More important for a gene bank, however, is the plant regeneration. The average regeneration of all cultivars is about 40%.     

The effect of controlled atmosphere storage at 4°C on crisp colour and on sprout growth,rotting and weight loss of potato tubers

Summary After three weeks curing at 10°C, potato tubers cv. Record were stored at 4°C under different controlled atmospheres (CA) for six months to study the effect on crisp fry colour, sprout growth and rotting. Combinations of low levels of CO₂ (0.7–1.8%) and low levels of O₂ (2.1–3.9%) gave a significantly lighter crisp colour, low sprout growth and fewer rotted tubers compared with 0.9% CO₂ and 21.0% O₂. Tubers stored in these conditions. showed a significantly higher weight loss and shrinkage after reconditioning. High CO₂: low O₂ combinations during storage completely inhibited sprout growth and caused the darkest crisp colour, but after reconditioning tubers gave the same level of sprouting and crisps as light as the other CA combinations. Furthermore these combinations, especially CO₂ at 10 or 15%, increased the onset of rotting. Also our results showed that at low concentrations of CO₂ (0.7–1.6%), and low O₂ (2–2.4%) there was an increase in tuber rotting.     

Effect of nitrogen source on growth and morphogenesis of three micropropagated potato cultivars

Summary Different nitrogen sources (NO₃ ⁻, NH₄ ⁺, glutamic acid and their combinations) influenced the growth and morphogenic responses (node number, shoot length, and stem, leaf and root dry weight) of three micropropagated potato cultivars (Spunta, Kennebec, Huinkul). Addition of reduced nitrogen (NH₄ ⁺ or glutamic acid) in a nitrate medium increased shoot length and leaf number. The large increase in growth in plants fed with NO₃ ⁻, NH₄ ⁺ could be explained by higher organic nitrogen content and enhanced dry matter partition to the shoot. This suggests that reduced nitrogen source is required, at least as a supplement to NO₃ ⁻, to enhance N assimilation and growth.     

Osmotic priming of true potato seed: Effects of seed age

Summary The effects on germination and early seedling growth of presowing true potato seed in water or gibberellic acid (GA) at 1500 ppm and of priming in −1.0, −1.25 and −1.5 MPa solutions of KNO₃+K₃PO₄ were studied using 30, 18, 6 and 3/4 month-old seed. The influence of light during presowing on the effectiveness of treatments was also investigated. Overall, priming in the light at −1.0 MPa was the most, and GA the least successful treatment for enhancing emergence and subsequent seedling growth. Though GA increased final emergence from about 20 to 70% in the most recently harvested lot (3/4 mo), the rate and extent of final germination or emergence in this dormant seed was still much lower than that of the nondormant lots (6–30 mo), especially when the latter were primed. For all lots, dry weight per seedling was 40% lower in dormant than in nondormant seed, and 20% higher when seeds were primed at −1.0 MPa than when GA treated. In conclusion, the use of nondormant seed may be a requirement for both effective priming and sowing of potato crops via true seed.     

Effects of naphtalenacetic acid on potato meristem tip development

Summary 0.4 μmol/l naphtalenacetic acid (NAA) stimulated early root formation and caused highly significant increases in numbers of rooted plantlets (from 55 to 74%) when potato meristem tips were cultured in a medium supplemented with gibberellic acid (GA). When the medium lacked GA, 0.1 μmol/l NAA induced complete development in about 30% of the explants. Higher concentrations inhibited root and shoot growth and induced conspicuous callus formation, both in the presence and absence of GA. Low NAA concentrations were thus useful in obtaining accelerated and more uniform development in the potato meristem tip population.     

Interaction between jasmonic and gibberellic acids on in vitro tuberization of potato plantlets

Summary A reverse of the delaying effect of gibberellic acid (GA₃) was observed in in vitro tuberization of potato plantlets when the medium contained 0.8×10⁻⁵ M jasmonic acid (JA). The promoting effect of JA seemed to be correlated with the initial absence of growing roots, probably through direct activity of JA in microtuber-producing buds in the stoloniferous shoots. This is based on the fact that JA did not inhibit root growth a posteriori. Endogenous gibberellins (GAs) synthesized by roots did not interfere with the previous activity of JA in tuberization. The absence of a JA promoting-effect on tuberization of previously-rooted plantlets could be related to the capacity of potato roots to synthesize endogenous GAs which might antagonize the JA effect on buds of stoloniferous shoots.     

The effect of a seaweed concentrate on the in vitro growth and acclimatization of potato plantlets

Summary The seaweed concentrate ‘Kelpak’ is used commercially in the greenhouse and field to improve plant quality. ‘Kelpak’ was added to the in vitro culture medium of potato cv. ‘BP1’ and also applied as a leaf/soil drench immediately after transplanting. The addition of 0.25% seaweed concentrate to the medium improved plantlet quality and led to better establishment in the greenhouse. No beneficial effect of seaweed concentrate in the tissue culture medium was observed if a second cutting was part of the micropropagation process. Additional application of 0.5% seaweed concentrate in the greenhouse to plantlet cuttings derived from tissue culture was not beneficial.     

A potato bud bioassay for use in assessing activities of endogenous growth substances in the potato

Summary A method is described for assessing the activities of growth substances using excised potato buds. Plugs containing an apical bud were excised and the cut surfaces wrapped in vitafilm. The buds were held for up to thirty days at 20°C without rotting. Daily treatment of buds for 5 days after excision, with either gibberellic acid or an extract of potato sprout promoted breaking of dormancy and growth of sprouts.     

Dimethylnaphthalene and diisopropylnaphthalene for potato sprout control in storage: 1. Application methodology and efficacy

Dimethylnaphthalene (DMN) and diisopropylnaphthalene (DIPN) isomers applied as sprout suppressants to stored potatoes (cv. Russet Burbank) were evaluated for effects on sprout length and weight compared to chlorpropham (CIPC). One application of CIPC at 22 mg a.i. kg^-1 of tuber fresh weight (f.w.), and one or two applications of DMN and DIPN at 100, 200, and 300 mg a.i. kg^-1 f.w. were applied as thermal aerosol fogs. Two applications of DIPN at 300 mg a.i. kg^-1 f.w. were as effective as CIPC in suppressing sprout growth during ten months of storage. DMN also suppressed tuber sprout growth but was not as effective as two applications of DIPN or one application of CIPC. One application of DIPN or DMN at 300 mg a.i. kg^-1 f.w. was an effective suppressant of sprout growth on a short-term basis. Whole tuber residue analyses were also conducted. After ten months in storage, DMN and DIPN residue concentrations were equal to or less than those of CIPC.     

Effect of sprout inhibitors on potato tubers (Solanum tuberosum L.) stored at ambient or reduced temperatures

Summary Single and combined applications of three sprout inhibitors, maleic hydrazide (MH), isopropyl 3-chlorophenylcarbamate (CIPC) and isopropyl phenylcarbamate (IPC) mixed with CIPC in a commercial formulation coded AMK (Tixit-C, Sandoz, S.A.E., Barcelona, Spain; 2.0% IPC +0.7% CIPC) were tested on potatoes stored from March to June under ambient conditions (20–30°C, 30–80% RH), and in a store with passive evaporative cooling (16–30°C, 75–95% RH). All treatments were more effective in reducing physiological losses, sprouting, and sprout growth in the cool than in the ambient store. AMK, CIPC and MH+AMK caused most sprout suppression. All treatments increased tuber rotting but there were no significant differences in numbers rotted by MH, MH+CIPC, CIPC (single treatment) and the untreated control. Nevertheless, the treatments can usefully extend storage life of potatoes under non-refrigerated conditions.     

Effect of exposure time of ethylene on potato sprout development

Sprouted Russet Burbank seed potato pieces were exposed from 2 to 14 days at a low concentration of ethylene, lμl l^-1, at 20 C. The longer the initial exposure time to ethylene the greater the rate of decline in sprout growth and increase in auxiliary branch growth after removal from ethylene. Sprouts were swollen, with enlarged lenticels and had retarded root development after 6 days’ exposure to ethylene. Root growth was more sensitive to ethylene than sprout growth. The implications of the similarity of sprout growth responses to ethylene under controlled conditions and sprout growth found under stress conditions in storage and field soil are discussed.     

Physiological regulation of potato tuber dormancy

At harvest, potato (Solanum tuberosum L.) tubers are dormant and will not sprout. As the period of postharvest storage is extended, tuber dormancy is broken and sprout growth commences. The loss of tuber dormancy and onset of sprout growth is accompanied by numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous hormones have been proposed to play a significant role in tuber dormancy regulation. The involvement of all major classes of endogenous hormones in tuber dormancy is reviewed. Based on available evidence, it is concluded that both ABA and ethylene are required for dormancy induction, but only ABA is needed to maintain bud dormancy. An increase in cytokinin sensitivity and content appear to be the principal factors leading to the loss of dormancy. Changes in endogenous IAA and GA content appear to be more closely related to the regulation of subsequent sprout growth.     

Increased calcium availability improves potato micropropagation and microtuberization

Summary Liquid scintillation counting (LSC) was used to screen six potato cultivars (Alpha, Bintje, Green Mountain, Kennebec, Russet Burbank, and Shepody) and two wild species(S. microdontum andS. kurtzianum) for ability to take up the tracer⁴⁵Ca²⁺ from treatment solutions containing high (15 mM) or low (5 mM) Ca²⁺ levels. In vitro potato micropropagation, microtuberization, and tissue calcium content, determined by flame atomic absorption spectrophotometry (FAAS), were compared for the six cultivars when Murashige-Skoog basal medium Ca²⁺ level was increased from 3, to 5 or 15 mM. All aspects of growth were improved when medium Ca²⁺ level was 15 mM. Microtuber induction occurred earlier, leading to improved yield (19–31%), and microtuber tissue Ca²⁺ concentration was greater (38–226%). Cv. Bintje was the most efficient genotype at accumulating Ca²⁺ from treatment solutions or growth media containing high or low Ca²⁺ levels. It could be identified as a calcium-packer using either LSC or FAAS screening.     

Plant regeneration from tuber discs of potato (Solanum tuberosum L.) using 6-benzylaminopurine (BAP)

Summary Shoots, roots and callus were formed from tuber discs of potato, cultivar Désirée, when grown in vitro on the basal medium of Murashige & Skoog (1962) (MS) supplemented with 2,4-D and/or BAP. Callus was formed in MS medium with 1 mg l⁻¹ BAP plus 0.5 mg l⁻¹ 2,4-D, callus and roots were formed in MS with 1 mg l⁻¹ BAP plus more than 0.5 mg l⁻¹ 2,4-D and shoots were formed directly on tuber discs cultured on MS medium with 1 mg l⁻¹ BAP without the addition of 2,4-D. Nodules produced at the explant surface after the 4th week increased in size following subculture onto the same medium (MS+BAP alone), and 2 to 6 shoots developed from each nodule. After 9 weeks total time in culture, these shoots were excised and transferred as cuttings to MS medium without growth regulators, after which roots developed and plantlets were formed. A histological study of the explants at the sites of nodule formation indicated that the shoots developed from meristematic zones initiated within small outgrowths of tissue similar to those occuring in adventive organogenesis but the presence of shoot and root meristems associated with the same axis suggests the formation of somatic embryos.     

Effects of low temperature on sprout growth of several potato varieties

Summary Two experiments are reported which compared the effects of a period of low temperature (3 C). before placing to sprout at ambient temperature, with continuous storage at ambient temperature, on sprout growth in thirteen potato varieties. In four varieties. Désirée, Majestic, Pentland Meteor and Vanessa, the period of low temperature induced an earlier onset of sprout growth and increased total and individual sprout length per tuber. In the varieties Civa, Craig’s Alliance, Dunluce. Home Guard. Arran Comet and Ulster Sceptre, the period of cold did not hasten the onset of sprout growth but markedly increased the numbers of growing sprouts and total sprout length, although individual sprout length was reduced. In the remaining varieties the period of low temperature had no effects on onset of sprout growth or sprout lengths at the end of storage.

---

Zusammenfassung Es wird über zwei Versuche berichtet, die den Einfluss einer Periode niedriger Temperatur (3 C) vor dem Beginn normaler Keimungsbedingungen mit fortw?hrender normaler Lagerung auf das Keimwachstum vergleichen. In vier Sorten, Désirée (mittelfrüh). Majestic (mittelfrüh). Pentland Meteor (früh) und Vanessa (früh), induzierte die Periode niedriger Temperatur einen früheren Beginn des Keimwachstums als fortw?hrende Lagerung unter normalen Bedingungen (Abb. 1). Bei diesen Sorten waren die Gesamtl?nge und die individuelle Keiml?nge am Ende der Keimung gesteigert (Tabellen 1 und 2). Bei Civa, Craig’s Alliance. Dunluce. Home Guard. Arran Comet und Ulster Sceptre (alles frühe Sorten) führte die K?lteperiode nicht zu einem früheren Keimungsbeginn, aber die Zahl der wachsenden Keime stieg an und dadurch die Gesamtkeiml?nge pro Knolle. In diesen Sorten wurde die L?nge des l?ngsten keims pro Knolle durch eine K?lteperiode verringert (Tabellen 1 und 2). Bei den übrigen Sorten hatte die K?lteperiode weder einen Einfluss auf den Keimungsbeginn noch auf die Keiml?ngen am Ende der Lagerung.

---

Résumé Dans deux essais sont comparés les effets d’un entreposage à basse température (3 C) suivi d’une mise en germoir, d’une part, et les effets d’une conservation uniquement en germoir, d’autre part, sur la croissance des germes de 13 variétés de pomme de terre. Pour quatre variétés. Désirée, Majestic (demitardives). Pentland Meteor et Vanessa (hatives) le passage au froid induit un départ de germination plus précoce qu’un stockage continu dans les conditions ambiantes (fig. 1). Pour ces variétés, la longueur des germes, totale et individuelle, est augmentée en fin de germination (tableaux 1 et 2). Pour Civa, Craig’s Alliance, Dunluce, Home Guard, Arran Comet et Ulster Sceptre (variétés hatives) le passage au froid ne hate pas le départ de la germination mais augmente de fa?on marquée le nombre de germes et donc la longuer totale de germe par tubercule. Dans ces variétés, la longueur du plus long germe par tubercule est réduite par le passage à basse température (tableaux 1 et 2). Pour les variétés restantes, le froid n’a pas d’effet ni sur le départ de germination, ni sur la longueur des germes à la fin du stockage.

     

马铃薯晚疫病种薯带菌的分子检测

从马铃薯块茎上分离纯化得到晚疫病菌、银腐病菌、癌肿病菌、红腐病菌、黑点病菌和镰刀菌等并提取它们的全基因组DNA,用引物08-3和08-4对这些真菌的DNA进行PCR扩增,以检验该引物扩增晚疫病菌DNA的特异性。取马铃薯种薯的芽眼、芽及其他不同部位并用NaOH法提取晚疫病菌DNA,再用引物08-3和08-4进行特异性扩增以检验种薯是否带晚疫病菌。结果表明:(1)引物08-3和08-4有很强的特异性,只能扩增出大小为257bp的马铃薯晚疫病菌DNA片段;(2)用该引物能扩增出种薯芽眼组织中大小为257bp的晚疫病菌DNA,说明通过PCR特异扩增,能直接检测出马铃薯种薯中潜伏的晚疫病菌。(3)本次检测的本地感病品种米拉有10%的种薯带晚疫病菌。该研究为种薯传播晚疫病菌的分子检测提供了依据和方法。     

The use of hormonal and osmotic growth retardants in media used for the storage of potato germplasm in-vitro

Summary Cultures of 23 potato cultivars were examined for their responses to hormonal and osmotic growth inhibitors incorporated in media used for storage in-vitro. Cultivars differed in their tolerance of inhibitors and also in their growth on a Murashige and Skoog medium with 3% sucrose. Both osmotic and hormonal growth retardants restricted the development of shoot tips but there were significant cultivar x treatment interactions, indicating that the ranking of cultivars will vary with the media used. Such interactions may complicate the establishment of facilities for storage in-vitro. However, addition to the basal medium of 5 mg l⁻¹ abscisic acid reduced both the overall mean scores and, more importantly, the between cultivar variance; its use in conjunction with low temperature shows promise as a method for conserving potato germplasm in-vitro.