Search Results

You are looking at 31 - 40 of 91 items for :

  • "growth substance" x
  • Refine by Access: All x
Clear All
Free access

Yong Yang, Xueyong Liu, Yuanli Jiang, Zuoxiang Xiang, Qingguo Xu, Na Zhao, and Bichao Shu

adjustments to adapt/tolerate salinity stress, which include the changes of free amino acids and carbohydrates metabolism. Free amino acids are fundamental compositions in the processes of protein and other growth substances synthesis, which are vital for

Free access

M.H. Aboul-Nasr and M.A. Ahmed

This experiment was performed at the Tissue Culture Laboratory of the Horticulture Dept. of the Faculty of Agriculture at Assiut Univ., Egypt. After several attempts to determine the proper stage of buds for collection of pollen, we determined that the tetrad stage was most suitable. The pollen was cultured on either MS or B5 liquid or solid media (7% agar). Both media were used as basic salts or supplemented with growth regulators. The four growth substances were BA, NAA, K, and 2,4-D. Each growth substance was added to the medium separately as follow: BA, NAA at 15, 10, or 5 ppm; K at 0.1, 1, 2, or 5 ppm; and 2,4-D at 0.5, 1, or 5 ppm. The solidified medium was superior to the liquid medium at all the treatments that were used for callus formation. Using B5 medium did not result in any callus. The highest value of callus formation was obtained when MS medium supplemented with BA at 5 ppm. Moreover, the callus that was grown on the MS medium that had BA at 5 or 10 ppm developed a merstim tip. The control treatment produced calluses but did not develop any meristem tips. This process can be used to develop haploid plants.

Open access

Jung M. Lee and N. E. Looney

Abstract

Regrowth of decapitated seedlings of apple (Malus domestica Borkh.) of a compact phenotype revealed stronger apical dominance and narrower branching angle than normal seedlings. Normal and compact seedlings were also found to differ in their phyllotaxy at lower nodes. Spraying with 2,3,5-triiodobenzoic acid (TIBA) before and/or after decapitation increased apparent apical dominance in compact seedlings; reduced shoot thickness in normal seedlings; and reduced shoot length and increased branching angle of both phenotypes. Gibberellic acid (GA3) increased shoot length and reversed the TIBA effect on branch angle in the compact seedlings. These differing growth regulator effects are thought to relate to differences in endogenous growth substance levels. Shoot tips of normal seedlings were higher in abscisic acid (ABA) but the dwarf pea bioassay indicated the presence of another acidic inhibitor present only in the compact seedlings. Normal seedlings exhibited higher levels of gibberellin-like growth promoters.

Open access

A. H. Hatch and L. E. Powell

Abstract

Indoleacetic acid (IAA), gibberellins A4 + A7 (GA4&7) and benzyladenine (BA) were applied to apple seedlings to determine their influence on movement or translocation of 14C-sorbitol, 14C-glycine, 14C-naphthaleneacetic acid (14C-NAA), 3H-gibberellin A1 (3H-GA), and 14C-kinetin. The materials mobilized 14C-sorbitol in an acropetal direction, but only after root competition had been eliminated by steam girdling. A mixture of the 3 growth substances brought about mobilization of 14C-glycine acropetally that was greatly enhanced after root competition had been eliminated. 14C-NAA was not mobilized acropetally or basipetally by GA4&7, and/or BA. BA mobilized 3H-GA1 acropetally and mobilization was enhanced by the addition of IAA. A mixture of IAA and BA also mobilized 3H-GA1 basipetally. An acropetal movement of 14C-kinetin was induced only with a mixture of GA4&7 and IAA.

Free access

Gerson R. de L. Fortes, Nilvane T.G. Müller, Janine T.C. Faria, Luciana B. Andrade, and Marisa de F. Oliveira

Asparagus is a vegetable that presents an increase in yield when propagated by meristem culture. On the order hand, the rooting phase in asparagus is greatly affected by the previous phase, i.e,. multiplication. This species presents a better rooting performance when callus is formed at the shoot base. So, the aim of this work was to evaluate treatments during the multiplication phase, which also leads to callus formation at the shoot base. The initial explants came from shoots being cultivated in vitro. It was tested kinetin at: (0.0, 0.5, 1.0, 1.5, and 2.0) μM; ancymidol at (0.0 and 0.5) μM and NAA at (0.0 and 0.5) μM for both genotypes, which were cultured in a MS medium added to sucrose (30 g·L–1), agar (6.0 g·L–1) and myo-inositol (100.0 m g·L–1). Shoots bearing two buds were inoculated in 10-ml test tubes and placed in a growth room for 30 days when they were evaluated. The addition of kinetin significantly improved the number of buds and at 1.3 μM this growth substance presented the best results as number of shoots is concerned. NAA application promoted a negative effect on spear bearing. The addition of ancymidol in this phase did not improve the bud multiplication. It was shown that clone M14 performed better than the hybrid cv. Deco as multiplication is concerned.

Free access

Rodomiro Ortiz and Dirk R. Vuylsteke

Apical dominance, i.e., the inhibition of lateral bud growth due to growth substances released by the terminal bud, has been considered as a limiting factor for the perennial productivity of plantains (Musa spp., AAB group). Segregation ratios in F1 and F2 plantain-banana hybrids suggest that inheritance of apical dominance is controlled by a major recessive gene, ad. The dominant Ad allele improved the suckering of plantain-banana hybrids, as measured by the height of the tallest sucker at flowering and harvest. At harvest, the ratoon crop of the diploid and tetraploid hybrids had completed 70% to 100% of its vegetative development, whereas the ratoon of the plantain parents, due to high apical dominance, was only at 50% of total pseudostem growth. Sucker growth rates are generally the result of gibberellic acid (GA3) levels, and it is suggested that the Ad gene regulates GA3 production. However, the Ad gene has incomplete penetrance, genetic specificity, and variable expressivity. Increased frequency of the Ad gene and a commensurate improvement in the suckering behavior of the diploid populations may be achieved by phenotypic recurrent selection.

Open access

S. Y. Wang and A. N. Roberts

Abstract

The physiology of dormancy in Lilium longiflorum ‘Ace’ was studied by determining the relationships between plant growth and composition and treatments such as bulb scale removal, cold treatment, field soil heating and chemical stimuli. Initiatory activity was continuous in the daughter bulb until its anthesis, but elongation of daughter axis leaves and internodes were normally inhibited until autumn. Inhibition of the daughter axis was high during the spring prior to anthesis of the mother, but progressively decreased following anthesis and disappeared completely by autumn. Balances of inhibitor-promoter growth substances were found in the bulb scales. Daughter scales were found to be the principal source of inhibitors. Treatments conducive to breaking dormancy included 40°F storage, GA3 treatment and field soil heating in early spring. Dormancy-breaking cold treatments were followed by changes in nitrogenous substances characteristic of dormancy removal in other species. The period of dormancy in the daughter portion of the lily bulb is of the correlated type and involves scale inhibition of axis elongation rather than initiatory activity in the apex.

Open access

Walter J. Kender and Jean-Claude Desrochers

Abstract

Lowbush blueberry fruit, exhibiting the characteristic double sigmoid growth pattern, were analyzed for endogenous gibberellin-like substances, auxins, and inhibitors on 10 sampling dates throughout their ontogeny. During the initial berry enlargement period (stage I) from 0 to 26 days after anthesis, gibberellin content was high and auxin and inhibitor contents low. Gibberellin-like substances reached a peak of 2.1 GA3 equivalents (ug/g dry weight) 26 days after anthesis. At the onset of growth stage II, gibberellin activity declined sharply and remained at a low level throughout the developmental period. During the stage of retarded berry growth, 26 to 48 days after anthesis, auxin activity increased markedly followed by a decrease prior to the start of growth stage III.

All 3 growth substances were at non-active levels during the ripening period. However, inhibitor activity increased sharply as berries developed blue coloration, 61 and 69 days after anthesis. The growth promoting substances were associated with the premature phases of blueberry fruit development and the inhibiting substances with senescence. Auxins and inhibitors were low in flower buds and open flowers while gibberellin-like substances exhibited slight activity in these tissues.

Free access

Sheila A. Blackman and Eric E. Roos

The low quality of some seed lots received by germplasm repositories such as the National Seed Storage Laboratory can thwart efforts to regenerate seed for storage. This germplasm is in danger of irretrievable loss. The aim of this work is to promote the germination, and hence regeneration, of such low quality seeds through sterile culture of the isolated embryos. Hybrid (B73×LH51) maize seeds were aged 5 y at 32°C and 0.037 g H2O g-1 dry wt. Vigor - but not viability -declined under these conditions. The effects of four factors on growth and germination were systematically examined. These were: seed pretreatments; antibiotics and fungicides; nutrients; and growth substances. Amongst the pretreatments, none surpassed partial hydration of seeds for 24 hr to 0.55 g H2O g-1 dry wt at 25°C prior to embryo dissection. Thiram (2.4 mg mL-1) and kanamycin (50 ug ml1) effectively controlled bacterial and fungal growth with no deleterious effects on growth during culture of the isolated embryos. Exogenous sucrose (optimum 5 % wt/vol) significantly stimulated radicle growth in both deteriorated and non-deteriorated embryos. No other organic or inorganic nutrient stimulated growth. Naphthalene acetic acid did not affect growth while kinetin reduced radicle growth and stimulated coleoptile growth. Gibberellic acid (GA3 at 10-5M) significantly stimulated radicle growth in deteriorated embryos, whereas it promoted coleoptile growth in both deteriorated and non-deteriorated embryos. These data suggest GA or a GA-stimulated process may limit the growth of aged embryos.

Free access

Khalid M. Ahmad, Syed M. A. Zobayed, Praveen K. Saxena, and David M. Hunter

Dionaeamuscipula Ellis commonly known as Venus fly trap is an important carnivorous plant with medicinal importance. It contains certain secondary metabolites like naphthoquinones and is used in anti-aid and anti-cancer drugs and other medicines like Cornivora. Increasing interest and use as an ornamental and medicinal plant, and dietary supplement have put it in an endangered state. Development of in vitro techniques for the preservation of germplasm that is on the brink of extinction is highly demanded. A regeneration protocol for the multiplication and micropropagation of Dionaeamuscipla Ellis was established. In vitro regeneration potential of leaf explants in different concentrations and combinations of plant growth substances was investigated in this study. Seeds were grown and leaf disc explants were excised and cultured under aseptic conditions on nutritional medium containing half strength Murashige and Skoog (MS) mix with combinations of 1.0–20.0 μm BA, 2.5.0 μm IBA, 1.0–10.0 μm 2iP and 0.1–0.5μm TDZ. The cultures were kept in growth cabinet with cool white light (40–60 μmol·m-2·s-1) under 16-h photoperiod. Regeneration was recorded after 60 days with the intervals of 15 days based on the degree of shoot organogenesis and somatic embryogenesis. 1/2 MS + 0.1 TDZ appeared to be efficient for somatic embryogenesis and simple MS for direct shoot organogenesis. 1/2 MS combined with 2iP appeared to be efficient for regeneration either by direct shoot organogenesis or by somatic embryogenesis. Plants were rooted well in Cape Cundew medium. These investigations will aid in the development of a model system for clonal mass propagation and in vitro regeneration of Dionaeamuscipla Ellis.