Showing papers on "Gibberellic acid published in 1995"

Effects of temperature, light and gibberellic acid on the germination of seeds of 43 species native to Western Australia

Abstract: Species native to the southwest of Western Aus- tralia, representing a range of plant families, life-history strat- egies, fire-response syndromes, seed-store types and seed weights, were tested for viability using tetrazolium chloride and for germination under combinations of constant tempera- tures of 15 ?C or 23 ?C, constantly dark or 12 h diurnal white- light conditions, and with, or without, addition of gibberellic acid (GA3, 50 mg/1). Species previously known to require a heat-shock treatment to overcome dormancy due to an imper- vious testa were pre-treated prior to imposition of tempera- ture, light and GA3 conditions. The test environmental condi- tions related to differences between winter and autumn tem-

The Effect of Temperature, Light and Gibberellic Acid (Ga3) on the Germination of Australian Everlasting Daisies (Asteraceae, Tribe Inuleae)

Abstract: Australian everlasting daisies have considerable potential as bedding plants, but little is known about their germination requirements. In ten taxa of everlasting daisies (Asteraceae, Tribe Inuleae) examined, germination in petri dishes was optimum over the temperature range 10-20°C with little or no germination at more extreme temperatures (5 and 30°C). Light stimulated germination in seven of the ten tare; Erymophyllum ramosum (A. Gray) Wilson, Craspedia sp., Leucochrysum fitzgibbonii (F. Muell.) Wilson, Waitzia suaveolens var. flava Wilson, Rhodanthe chlorocephala subsp. rosea (Hook.) Wilson, R. chlorocephala subsp. splendida (Hemsley) Wilson and R. floribunda (DC.) Wilson. In the dark, gibberellic acid (GA3, 50 mg L-1) stimulated germination to similar levels observed in light-treated seed. Schoenia filifolia subsp. subulifolia and S. cassiniana were not affected by light regime, but in both taxa germination was improved by the addition of GA3. By contrast, germination in Rhodanthe humboldtiana, which also had no response to light, was inhibited by GA3. In most species, germination in the dark was similar over the GA3 concentration range 1-100 mg L-1, but 500 mg L-1 was often inhibitory. Germination was optimised under temperature and light conditions related to maximising survival of seedlings which germinate near the soil surface during winter in the arid interior habitat of central Australia.

Spectral Filters and Growing Season Influence Growth and Carbohydrate Status of Chrysanthemum

Abstract: Additional index words. Dendranthema × grandiflorum, photomorphogenesis, light quality, plant growth regulation Abstract. The interactions of light quality and growing season on growth and carbohydrate content of chrysanthemum (Dendranthema × grandiflorum (Ramat.) Kitamura) plants were evaluated using 6% CuSO4and water (control) as spectral filters. Light transmitted through the CUSO4 filter significantly reduced plant height and internode length compared to control plants regardless of the season. However, the degree of response varied with growing season. Light transmitted through CUSO4 filters delayed flowering. Total number of flowers was not affected by spectral filter, but plants grown under CUSO4 filter had smaller flowers than those grown under the control filter. Light transmitted through CuSO 4 filter resulted in reduced leaf and stem soluble sugar (sucrose, glucose, and fructose) and starch concentrations regardless of the growing season. However, the magnitude of reduction was greater in spring- than in fall-grown plants. Stems of fall- grown plants had more starch deposition than spring-grown plants under both filters. Filters with specific spectral characteristics can be used as alternative means of producing compact plants in the greenhouses, however, the delay in flowering and smaller flowers could limit their use for growth control of plants intended for flower production. A wide range of nonchemical methods for growth regulation of ornamental crops has received much attention in recent years (Heins and Erwin, 1990; Latimer et al., 1991; McMahon and Kelly, 1990; Mortensen and Stromme, 1987). Our research focusing on manipulation of greenhouse light quality as a nonchemical alterna- ative indicated that light transmitted through CUSO 4 filters reduced plant height similar to chemical growth regulators and produced compact plants in a range of horticultural crops (McMahon and Kelly, 1990; Rajapakse and Kelly, 1992). Our results with minia- ture roses indicated that light transmitted through CUSO 4 filters interacted with growing season and altered flower development (Rajapakse and Kelly, 1994). Alteration of light quality in the greenhouse for plant growth regulation may be feasible with the use of electric light sources with various spectral qualities, by appropriate fluid roof greenhouses, and/or by developing green- house construction material with specific spectral properties. How- ever, further research is needed to enhance our knowledge of light quality as a nonchemical alternative. Although the light transmitted through CUSO4 filters reduced plant height and internode length, the mechanism of height control by CuSO4 filters is not well understood. In our previous experiments, we observed that the reduction of plant height and internode length by light transmitted through CUSO4 spectral filters could be reversed by weekly application of gibberellic acid (GA 3) or by exposure to end- of-day far-red (FR) light, suggesting that GA and phytochrome may be involved in the growth regulation under CuSO4 filters (Rajapakse and Kelly, 199 1; Rajapakse et al., 1993). Gibberellic acid increases soluble sugar and starch content in soybean (Glycine max L.) and Phalaenopsis amabilis leaves and promotes sink activity in the apical meristem (Cheikh and Brenner, 1992; Chen et al., 1994). Gibberellic acid also increases the activity of two key enzymes in sucrose metabolism, sucrose phosphate synthase activity (SPS) of soybean

Controlling Cropping in 'Loadel' Cling Peach Using Gibberellin: Effects on Flower Density, Fruit Distribution, Fruit Firmness, Fruit Thinning, and Yield

Abstract: Whole-tree sprays of Release LC (predominantly gibberellic acid) (GA,) were applied in a commercial peach (Prunus perisca (L.) Batsch.) orchard in the California Central Valley on three dates from mid-June (about 90 days after

Cell wall hydrolytic enzyme activity during development of nonclimacteric sweet cherry (Prunus avium L.) fruit

Abstract: SummaryThe cell wall hydrolytic enzyme activities of polygalacturonase (PG, EC 3.2.1.15), pectinmethylesterase (PME, EC 3.1.1.11) and carboxymethylcellulase (Cx-cellulase, EC 3.2.1.4) were detected during development of nonclimacteric sweet cherry (Prunus avium L. ‘Bing’) fruit in 1992. Peak specific activity of all three hydrolytic enzymes occurred when fruit was red, 65 d after anthesis. Total protein content of fruit decreased from the earliest green coloured stage, 34 d after anthesis, until the later red-coloured stage, then increased to a maximum in mature, dark-red fruit, 74 d after anthesis. Thus, the highest enzyme activities on a tissue fresh weight basis occurred in dark-red fruit. Fruit firmness declined significantly after endocarp lignification (‘pit hardening’), 45 d after anthesis, and, therefore, was inversely related with increases in PG, PME and Cx-cellulase activities. Two in situ applications of 20 mg 1−1 gibberellic acid (GA3) decreased the activities of PG and PME and increased frui...

α-Amylase production and leaf protein synthesis in a gibberellin-responsive dwarf mutant of ‘Himalaya’ barley (Hordeum vulgare L.)

Abstract: A dwarf mutant, M117, was isolated following sodium-azide mutagenesis of barley (Hordeum vulgare L. ‘Himalaya’). Treatment of the mutant with gibberellic acid (GA3) restored growth to levels of the tall parent, α-Amylase production was examined in germinated grains of the dwarf mutant and in Himalaya plants treated with gibberellin (GA) biosynthesis inhibitors. The mutant showed reduced α-amylase activity relative to the parent when grains were germinated on water, but activities were equivalent to the parent following germination on GA3 solution. Germination of normal or mutant grains in the presence of GA biosynthesis inhibitors led to reduced α-amylase activity levels, but normal levels were restored if GA3 was included in the inhibitor solution. These data are consistent with a model in which α-amylase production in the germinated grain is regulated by the supply of active GAs. Treatment of M117 with GA3 increased the length, fresh weight, dry weight, volume, cell number, and protein content of the first leaf. Proteins being synthesized in the first leaf were labelled with [35S]methionine and fractionated by two-dimensional electrophoresis. No reproducible qualitative or quantitative differences in protein profiles were detected in response to GA3 treatment. In contrast, first leaves from seedlings exposed to dehydration stress had profiles clearly distinguishable from those of control seedlings. Stem sections from dwarf plants maintained on 10 μM GA3 in the presence of sucrose elongated significantly more than controls without GA3, but two-dimensional analysis of the [35S]methionine-labelled radioactive polypeptides again revealed no GA3-induced differences. It was concluded that enhanced elongation rates of leaves or stem segments were not associated with major changes in gene expression.

Effect of the Rht3 dwarfing gene on dynamics of cell extension in wheat leaves, and its modification by gibberellic acid and paclobutrazol

Abstract: The second leaf of wheat was used as a model system to examine the effects of the Rht3 dwarfing gene on leaf growth. Compared to the rht3 wild type, the Rht3 allele decreased final leaf length, surface area and dry mass by reducing the maximum growth rates, but without affecting growth duration. Gibberellic acid (GA 3 ) increased final leaf length and maximum growth rate in the rht3 wild type, but was without effect on the Rht3 mutant, which is generally regarded as being non-responsive to gibberellin (GA). Paclobutrazol, an inhibitor of GA biosynthesis, decreased final leaf length and maximum growth rate in the rht3 wild type to values similar to those in the untreated Rht3 mutant. Neither GA 3 nor paclobutrazol affected the duration of leaf growth. The decrease in leaf length was produced by reduction of cell length rather than cell number. The maximum relative elemental growth rate (REGR) for cell extension was essentially the same in all treatments, as was the time between the cells leaving the meristem and achieving maximum extension rate. The differences between the genotypes and treatments were all almost entirely due to differences in the time taken from the attainment of maximum REGR of cell extension to the cessation of extension. This was reflected in the length of the extension zone, which was approximately 6-8 per cent of final leaf length. The effects of the Rht3 allele, GA 3 and paclobutrazol all appear to be on the processes which promote the cessation of cell elongation.

Performance of bread wheat (Triticum aestivum) seed primed with growth-regulators and inorganic salts

Abstract: An experiment was conducted during 1991-92 and 1992-93 to study the effect of priming the seed of bread wheat (Triticum aestivum L. emend. Fiori & Paol.) with growth-regulators and inorganic salts on its performance. Seeds of ‘HD 2380’ and 'VL 616' were primed for different durations of 1-24 hr at 20°C in dark, with growth hormones [indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), gibberellic acid (GA 3 ) and abscisic acid] and inorganic salts (potassium, calcium and triadimefon). In general seed priming with most of the treatments significantly improved the seed performance in laboratory in terms of germination (%), germination time and seedling growth (length and dry matter). Varietal response was specific to each priming treatment. In 'HD 2380' maximum germination was observed with GA 3 (20 ppm), KNO 3 (50 ppm) and CaS0 4 (75 ppm), whereas in 'VL 16', auxins (IAA and IBA) and potassium salts (KH 2 P0 4 and KN0 3 ) were most effective for germination and mean germination time. The seedling growth was highest with KNO 3 (100 ppm) in 'HD 2380', whereas CaCl 2 (50 and 100 ppm), indole-3.butyric acid (20 ppm) and triadimefon (20 ppm) were more effective in 'VL 616'.

Genotype-Dependent morphogenetic potentiality of various explants of a food legume, the pigeon pea (Cajanus cajan L.)

Abstract: The morphogenetic response of various explants of seven different cultivars of a food legume, the pigeon pea (Cajanus cajan L.), has been studied. The stimulation and elongation of shoot buds into shoots derived from the mature embryo axis and intact seed on Murashige and Skoog’s medium supplemented with 2.32µM kinetin and 22.2µM benzyladenine was found to be optimum in Murashige and Skoog’s medium supplemented with 0.46µM kinetin, 0.53µM naphthalene acetic acid, and 0.29µM gibberellic acid. Even though the response of these two explants for formation of shoot buds in all the genotypes is 30–100% depending on media composition, subsequent growth and elongation of these shoot buds into plants is genotype dependent and is restricted to two genotypes. Cotyledon and epicotyl explants of pigeon pea cultivars on the other hand differentiated directly into four to eight and two to four shoots, respectively, depending on the media composition and genotype. In vitro rhizogenesis of regenerated shoots was 80% and the survival of these plantlets in the field was 70–80%.

Effects of three plant growth regulators on growth, morphology, water relations, and frost resistance in lemonwood (Pittosporum eugenioides A.Cunn)

Abstract: Pittosporum eugenioides is a native ornamental species with a wide distribution throughout New Zealand. The effects of the application of two plant hormones (gibberellic acid and abscisic acid) and a gibberellin biosynthesis inhibitor (paclobutrazol) on the growth and development, frost resistance, and water loss on two-year old seedlings of P. eugenioides were studied. Gibberellic acid increased plant growth, stem diameter, and shoot succulence, while also inducing leaf hyponasty and vegetative bud break of apices. Abscisic acid induced growth suppression while being effective in promoting leaf epinasty and inhibiting bud break. Paclobutrazol induced growth suppression, promoted epinasty, decreased shoot succulence, inhibited bud break in apices, and increased foliar frost resistance. The effects of paclobutrazol were also overcome by the addition of gibberellic acid. The results are compared with those gained from species not native to New Zealand, and indicate the potential for the application...

Enhancement of somatic embryogenesis frequency by gibberellic acid in fennel

Abstract: The effect of GA3 on somatic embryogenesis from petiole fragments excised from micropropagated fennel plantlets was studied. Explants were maintained for 4 weeks on an induction medium containing, 2,4-d and kinetin and were then transferred to a medium devoid of these growth regulators to allow embryo development. The addition of autoclaved or filter-sterilized GA3 to the induction medium or to the embryo development medium increased the number of embryogenic explants. No positive effect was observed when GA3 was added to the micropropagation medium of the mother plantlets. Gibberellic acid also counteracted the inhibiting effect of continuous light on the number of embryogenic explants. Moreover, the embryogenic frequency of petiole explants from several genotypes previously considered as poorly reacting was highly enhanced by GA3.

Plant hormones in fungi and bacteria from malting barley

Abstract: 40 Fungi and 16 strains of bacteria, isolated from the grains of three cultivars of malting-grade barley (Kymppi, Pokko and Kustaa, of 1990 harvest), were screened for the production of the plant hormones gibberellic acid (GA 3 ), abscisic acid (ABA) and indole-3-acetic acid (IAA). Four fungal strains were found capable of GA 3 production and four of ABA production. IAA production was common among both fungi (58% of strains active) and bacteria (88% of strains active). To get an estimate of the physiological significance of the presence of plant hormone producing microbes, the plant hormone production per microbial unit in the liquid growth media of the cultured organisms was weighed against the microbial counts and the endogenous hormone concentrations of barley grains. It was concluded that bacterial IAA production could be of significance in imbibed grains. This presupposes, however, that the conditions be ideal for the propagation of the active species and also, for the production of IAA by those same species and lastly, that similar production occurs in vivo as well as in vitro. Microbial GA 3 and ABA production, on the other hand, were estimated to occur in negligent amounts.

The effects of hormones and saccharides on growth and flowering of green and herbicides-treatedChenopodium rubrum L. plants

Abstract: The medium forin vitro culture of green and SANDOZ herbicides-treatedChenopodium rubrum L. plants contained saccharides and hormones in different concentrations. Five days after sowing, the plants were exposed to non-inductive (15 long days—LD) or inductive (6 short days—SD + 9 LD) photoperiodic conditions. The length of hypocotyl and cotyledon blade were measured and percentage of flowering was scored. Gibberellic acid (GA3) stimulated hypocotyl growth of green and photobleached plants under SD and inhibited under LD conditions. Indole-3-acetic acid (IAA) slightly stimulated hypocotyl growth of green plants only under LD conditions. Benzylaminopurine (BAP) inhibited hypocotyl growth regardless of photoperiodic regime. The optimal concentration of glucose or saccharose for flowering in green and SANDOZ-treated plants was 5%. In green SAN 9785-treated plants exogenous saccharides compensated lack of photosynthates to bring about full flowering, but SAN 9789-treated plants needed in addition GA3.

Gibberellic Acid-induced Fruit Set of Rabbiteye Blueberry following Freeze and Physical Injury

Abstract: In a series of experiments, gibberellic acid (GA 3 ) was applied to rabbiteye blueberries (Vaccinium ashei Reade) under field and greenhouse conditions to determine if fruit set could be improved following physical or freeze injury to flowers. In field experiments, physically damaged flowers (i.e., corollas and styles removed, styles only removed, or ovaries lanced) of'Climax' and 'Tifblue' treated with GA 3 (4% ProGib at 250 mg.liter -1 ) set substantially more fruit than nontreated, damaged flowers. Under greenhouse conditions, GA 3 applied postfreeze to 'Tifblue' and 'Brightwell' resulted in increased fruit set compared to unsprayed control plants of the same cultivars. Freeze-damaged plants had substantially reduced fruit set overall but to a much lesser extent for GA 3 -treated plants than for those not treated with GA 3 . Individual fruit weight was reduced by GA 3 applications, as was berry seediness. Results from these greenhouse and field trials suggest that GA 3 can be used to salvage a blueberry crop following a moderate freeze durine bloom.

Plant genes affecting gibberellic acid biosynthesis

Abstract: Genes controllong gibberellic biosynthesis are used in genetic engineering to alter plant development. Alterations in the nature or quantity of products of the genes affects plant development. A family of An genes in monocots encodes a cyclase involved in the early steps of gibberellic acid (GA) biosynthesis. Members of the family are identified in wheat, barley, sorghum and maize. Two members of the family, the genes An1 and An2, are identified in maize. The An1 gene is cloned and the function of the gene is characterized. An2 is isolated and identified by homology to An1. Using recombinant genetic technology, GA levels are manipulated. Changes in GA levels alter monocot plant phenotypes, for example, increasing or decreasing height and fertility.

Effect of light and gibberellic acid on chromosome endoreduplication in leaf epidermis ofTriticum durum Desf.

Abstract: The first foliage leaf ofTriticum durum Desf., cvs. Capelli and Creso, was studied for the action of light and gibberellic acid on different aspects of plant growth. Creso is a short-strawed cultivar carrying theRht 1 gene, that influences both plant height and sensitivity to applied gibberellins. In this study, a cytophotometric analysis of chromosome endoreduplication in bulliform cells of the leaf epidermis was undertaken. The bulliform cells are arranged in long rows and comprise 4C, 8C, and 16C cells. The relative percentage of these cells was recorded under different light regimes and in the presence or absence of gibberellic acid (GA3). Our data indicate that light strongly affects the occurrence of chromosome endoreduplication. Although cvs. Cappelli and Creso show the same frequency of endo-reduplicated cells in the dark, all light treatments induce lower endo-polyploidy in cv. Creso whereas, in cv. Cappelli, a reduction in endo-polyploidy is observed when plants are irradiated with blue-lacking lights. This indicates that the action of a blue-light responsive photo-receptor determines high endopolyploidy. With respect to GA3 treatment, cv. Creso is again shown to be insensitive to hormone application, whereas in cv. Cappelli, gibberellic acid influences endopolyploidy level in the dark, causing very high frequencies of 8C cells and relatively high frequencies of 16C cells.

A fed-batch culture model for improved production of gibberellic acid from a waste medium

Abstract: The kinetics of the production of gibberellic acid (GA3) in conventional batch culture was compared with that obtained in fed-batch cultures at three different feeding regimes with media containing protein N, one of which was calculated to maintain a constant biomass, and two others able to promote linear growth. It was found that the production of GA3 improves substantially in the latter two cases, and that the general model applicable to the formation of a secondary metabolite correctly predicts the results if one dispenses with the assumption of avoiding the increase in the biomass during the production phase.

Germination of Musa velutina seeds: Comparison of in vivo and in vitro systems

Abstract: In the genusMusa, germination is extremely variable and relatively difficult Even more difficulties are faced when producing hybrids The seed yield of hybrids in breeding programs is usually low and often, to ensure the viability and survival of seeds, it is necessary to attempt to germinate a large excess of these seeds In this context,in vitro embryo culture might be an invaluable tool for obtaining desirable hybrid plants in a short time Seeds ofMusa velutina were sown in seed trays in a peat-based mixture Thein vivo seed germination reached 78% but only after 9 mo Because of this delayed and intermittent germination, embryos were excised from seeds and inoculated onto half-strength Murashige and Skoog (1962) medium, with or without supplementation with various concentrations of gibberellic acid Light and dark conditions were also used to test their effect on embryo germination After 2 wk, 82% of embryos germinated in the dark on medium containing 01 µM gibberellic acid Addition of gibberellic acid increased the shoot length and root number over the gibberellic acid-free treatment Similarly, dark conditions gave a significant increase over light conditions for all the parameters except root number where light or dark conditions did not make any difference Thus, the present study highlights the importance of various components of thein vitro culture ofMusa embryos and the advantage over direct use of greenhouse-sown seeds both in terms of the time taken to germinate and the final percentage

Germination of Lomandra sonderi (Dasypogonaceae) Promoted by Pericarp Removal and Chemical-Stimulation of the Embryo

Abstract: Lomandra Labill. is a common genus in the understorey of the jarrah (Eucalyptus marginata Sm.) forest of Western Australia. Species in this genus are difficult to propagate by seed and do not readily re establish following mining. Limiting factors for germination success were explored and identified. Lomandra sonderii (F.Muell.) Ewart set very few seed (seeds per flower = 0.122). Tetrazolium tests indicated that seed viability was relatively high (50%). Germination was inhibited (0%) by the inner pericarp tissues which surround the seed and are part of the diaspore. Manual removal of the inner pericarp or leaching overcame this inhibition with a fifth of seeds subsequently germinating. Similar treatments improved germination of L. drummondii (F. Muell. ex Benth.) Ewart from 40% to 80%. Soaking L. sonderi seeds in gibberellic acid (GA3, 50 mg L-1) further improved germination (28%). Ants (Camponotus sp. and Iridomyrmex sp.) collected and dispersed L. sonderi seed and are likely to improve germination in the forest by removing and consuming the inner pericarp. Only half of the Viable excised embryos of L. sonderi grew in vitro, indicating the presence of embryo dormancy. Embryo dormancy was overcome by GA3 (0.5 mM) and zeatin (0.5 mM) in the liquid culture medium. In vitro culture may be a practical means of propagating Lomandra if seed is scarce.

Comparison of silverleaf whitefly-induced and chlormequat chloride-induced leaf silvering in Cucurbita pepo

Abstract: Whitefly-mediated squash silverleaf is induced by the feeding of nymphs of the silverleaf whitefly, Bemisia argentifolii, but the mechanism involved in symptom expression is unknown. Several plant biochemical regulators were tested to determine whether they could mitigate expression of squash silverleaf in Cucurbita pepo. Application of chlormequat chloride, a gibberellic acid biosynthesis inhibitor, induced leaf silvering symptoms similar to those induced by the silverleaf whitefly in squash plants, cvs. Senator and Dixie, but not in cv. Small Sugar Pumpkin. Chlormequat chloride-induced silvering never extended over more than 80% of the upper leaf surface, compared with 100% for whitefly-induced silverleaf. Paclobutrazol, but not Alar, also produced leaf silvering symptoms. Chlormequat chloride treatment also resulted in internodal stem shortening, increased chlorophyll levels, and increased root and stem weight in Small Sugar Pumpkin and Senator but not in Dixie. Chlormequat chloride did not produce detectable double-stranded RNAs (dsRNAs) or changes in intercellular fluid proteins in any of the C. pepo cultivars tested. Silvered leaves from whitefly-infested plants, in contrast, had 15 to 40% lower chlorophyll levels, two induced intercellular leaf proteins, and some reductions in foliar and root biomass. No dsRNAs were detected in whitefly-silvered tissues or plants. Gibberellic acid applied after chlormequat chloride or paclobutrazol treatment resulted in less internodal shortening and decreased both chemical- and whitefly-induced leaf silvering. Chlormequat chloride-treated plants attracted greater whitefly oviposition and had more nymphs than untreated controls in greenhouse tests. These data suggest that leaf silvering induced by gibberellic acid biosynthesis inhibitors and by the silverleaf whitefly results from hormonally mediated alterations in the plant's physiology. Because the silverleaf whitefly also induces discoloration disorders in plants other than squash, hormonal inhibition may be a general component of whitefly phytotoxicity.

In vitro high frequency plant regeneration from hypocotyl and root segments of spinach by organogenesis

Abstract: An efficient protocol for spinach (Spinacia oleracea L.) plant regeneration from hypocotyl and root segments was established. When the sub-apical hypocotyl and tip-free root segments were cultured on Murashige & Skoog (1962)-based medium containing high concentrations of indole-3-acetic acid (85.62 μM) and gibberellic acid (100 μM), more than 75% and 90% of the hypocotyl and root explants, respectively, formed shoots. After elongation, more than 92% of the shoots rooted on medium supplemented with 2.85–5.71 μM of indole-3-acetic acid. More than 70% of rooted plantlets survived in soil and were fertile. Significant interactions between growth regulator combinations, explant types and environmental conditions on shoot initiation, development and rooting were discussed.

Hormones-induced modifications in the response of wheat flag leaf to NaCl

Abstract: A field experiment was carried out to investigate the effects of presoaking the wheat grains (Triticum aestivum L.) in 33 or 66 mM NaCl and indolyl-3-acetic acid (IAA at 50 g m−3), gibberellic acid (GA3 at 100 g m−3) or kinetin (100 g m−3) on some tolerance criteria in wheat flag leaf at different stages of development. At various stages of flag leaf development pretreatment with 33 or 66 mM NaCl decreased degree of succulence (particularly 66 mM), relative growth rate, net assimilation rate, relative water content, K+ content and K+/Na+ ratio and at the same time induced accumulation of abscisic acid and Na+. In the majority of cases grain pretreatment with GA3 or kinetin and to a lesser extent with IAA alleviated either partially or completely the deleterious effect of salinity on the above mentioned parameters.

Influence of culture conditions on embryo formation and maturation in auxin-induced embryogenic cultures of Digitalis obscura.

Abstract: Somatic embryogenesis was induced in hypocotyls of Digitalis obscura using indoleacetic acid or 2,4-dichlorophenoxyacetic acid with different culture and subculture conditions. Indoleacetic acid-induced embryogenic cultures were used to investigate the effects of amino acids, polyamines and growth regulators on embryo differentiation and maturation. Supplementation of the media with amino acids, polyamines or abscisic acid did not influence or had an adverse effect on embryogenic response. Gibberellic acid at 1.4 μM in either culture (30 days) or subculture medium was effective in promoting both differentiation and normal embryo development. The efficiency of somatic embryogenesis was greatly enhanced when isolated indoleacetic acid-induced proembryogenic masses were subcultured in liquid medium with reduced auxin content.