Higher Concentrations Of NAA Research Articles

Chemical regulation of growth, yield, and digestibility of alfalfa and smooth bromegrass

In addition to enabling manipulation of plant growth and development, growth regulators have potential for increasing forage digestibility. This study focuses on the use of gibberellic acid (GA3), α-naphthalene acetic acid (NAA), 6-benzylaminopurine (BA), o-benzylhydroxylamine (OBHA), and monocetyl phosphate (C16P) to alter growth, dry weight (DW) yield, and in vitro digestible dry matter (IVDDM) of forage grasses and legumes grown in a greenhouse. Screening experiments revealed that GA3, NAA, and OBHA at rates of 1.6, 160, and 0.51 g a.i. ha−1, respectively, were more effective in altering regrowth of potted alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) compared with other treatments. Subsequent experiments with increasing dosages of GA3, NAA, and OBHA on alfalfa and smooth bromegrass (Bromus inermis Leyss.) confirmed that these regulators can be used to manipulate forage growth. Increasing concentrations of GA3 increased growth and DW yield but decreased IVDDM, whereas high concentrations of NAA decreased growth and DW yield but increased IVDDM. OBHA treatments resulted in little or negative change in IVDDM. Results generally showed that plant growth regulators can be used to manipulate forage growth, but that there is a trade-off between herbage yield and digestibility of forage tissues.

Effects of some growth regulators on in vitro tuberization in Dioscorea alata L. ?Brazo fuerte? and D. abyssinica Hoch.

Nodal cuttings of Dioscorea alata L. 'Brazo fuerte' and D. abyssinica Hoch. were cultured in vitro to assess the influence of NAA on the production of microtubers. In D. alata, high concentrations of NAA (27 and 54 μM) favored the production of large microtubers, whereas the highest number of microtubers was obtained with 2.7 μM. D. abyssinica was found to be more sensitive to NAA since concentrations higher than 0.27 μM promoted the growth of callus on the root system. In this species, the production of the largest microtubers was obtained at 2.7 μM whereas the number of microtubers was not affected by any concentration tested. In D. alata, the effects of ABA and BAP were also evaluated. The weight of the microtubers increased with increasing concentrations of ABA. This effect, however, was observed only on expiants cultured under 8 h photoperiod, but not on those cultured under 16 h. Finally the presence of BAP at concentrations as low as 0.22 μM adversely affected the survival of the explants.

Micropropagation of a terrestrial Cymbidium species using rhizomes developed from seeds and pseudobulbs

Growth of Cymbidium kanran rhizome was enhanced by higher NAA:BAP ratios in modified Murashige & Skoog (MS) media. Only vegetative shoots resulted from rhizomes cultured in vitro when lower NAA:BAP ratios were used. The rhizomes were induced from the axils of leaves when shoots were explanted to medium containing higher concentrations of NAA. Root formation of C. kanran was inhibited by the addition of either auxin or cytokinin to the culture media. Differentiation of the rhizomes into plantlets occurred when the concentrations of ammonium nitrate and potassium nitrate in MS medium wewe reduced. The modified MS medium containing lesser amounts of potassium nitrate and ammonium nitrate than those of the original MS media, and was optimal for the production of plantlets from rhizomes of C. kanran without addition of auxin and cytokinin.

Auxin Effect on the Transmembrane Potential Difference of Wild-Type and Mutant Tobacco Protoplasts Exhibiting a Differential Sensitiity to Auxin

The effects of 1-naphthaleneacetic acid (NAA) and other auxin analogs on the transmembrane potential difference (Em) were compared on tobacco protoplasts isolated from two genotypes differing in their sensitivity to auxins. For both types, NAA modifies Em by inducing at low doses a hyperpolarization, the amplitude of which increased with auxin concentration. Above an optimal concentration this hyperpolarization was reduced and even nullified. However, for the mutant type, this electrical response was shifted toward higher NAA concentrations, as its growth response. In the presence of structural analogs of auxin which have been showed to modify the dose-response curve for growth, the Em was altered: the growth-stimulatory molecule (picloram) initiated hyperpolarization, whereas the growth-inhibitory substance (4-bromophenylacetic acid) caused depolarization. These results provide evidence for a specific action of auxin at the membrane level related to its biological activity.

‘Vitrified’ Dianthus—Teratomata in vitro due to Growth Factor Imbalance*

Cultured shoot tips of Dianthus caryophyllus often develop as abnormal, ‘vitrified’ plants that have the characteristics of teratomata: stable, unlimited development with fasciated shoot apices, a bush habit, reduced stem elongation and succulent leaves. High concentrations of NAA in the culture medium increased and benzylaminopurine decreased the proportion of shoot-tips that developed as abnormal plants. The requirements of abnormal and normal plants for continued development differed. During the initial stages of development abnormal plants did not require auxin and they were able to continue their growth in the absence of roots. It is suggested that the abnormal plants are teratomata, similar to those induced by Crown Gall bacteria, and their induction and abnormal traits could be due to imbalance of auxins and cytokinins.

リンゴ茎頂の生長に及ぼす生長調節物質及び糖の影響

In order to clarify the mechanism of the growth of an apple shoot, the authors aseptically cultured shoot apices (about 0.5mm in length) on an agar medium con taining Murashige and Skoog′s inorganic and organic substances. The effect of growth regulators and sucrose on the growth of the shoot apex was investigated. The results are summarized as follows.1. The effect of α-Naphthaleneacetic acid (NAA) was not observed in the differ entiation and elongation of leaves, and the growth of the shoot apex was inhibited by high concentration of NAA.2. The differentiation and elongation of leaves was enhanced on a culture medi um with N6-benzyladenine(BA), whereas the length and number of leaves increased according to the increase in BA concentrations within a range of 0.01 to 10μM. The apical shoots cultured on a medium with BA continued growing for six weeks. The number of leaves differentiating at 10μM BA was three fold, and the length of the longest leaf was seven fold as large as those of control respectively.3. Gibberellic acid (GA) had no effect on the internode elongation, but enhanced the differentiation and elongation of leaves. However the effectiveness of GA became stronger with the increase in concentration within a range of 0.01 to 0.1μM, and was observed slightly at above 0.1μM. But the differentiation and elongation of leaves was not enhanced by prolonging the culture period beyond four weeks. Therefore, it seemed that GA affects the growth of shoot apices within four weeks.4. In treatment of BA combined with NAA, the effectiveness of BA on the differentiation and elongation of leaves was observed at higher concentrations of NAA, suggesting that the effect of NAA was antagonistic to that of BA.5. No callus formation was obtained on a media containing NAA, BA or GA alone, but under treatment of both BA and NAA callus formation was observed remarkably. The induction and growth of callus increased with the increase of concentrations of both NAA and BA.6. The differentiation and elongation of leaves was inhibited by decreasing the sucrose concentration regardless of BA concentration. It is considered that sucrose is a limiting factor of the differentiation and elongation of leaves.

ユリの遠縁種間交雑に関する研究

1) The embryo culture technique was applied to the immature hybrid embryos for the purpose of enhancing their growth. The embryos used as materials were from 2 crosses between distantly related species or hybrids: L. longiflorum X L. 'Sugehime'and L.'Shikayama'X L. henryi.2) The Murashige & Skoog medium was recognized as the most suitable among the three basic media for the culture of immature embryos when it was adjusted at pH 5.0 and supplemented with 20-40g/l sucrose. Higher sucrose concentrations than the above mentioned generally enhanced root growth and inhibited shoot growth.3) The addition of 10-4-10-2mg/l NAA to the basic media was effective for the direct germination of immature embryos and the addition of BA tended to lead them to calluses in some degree. Higher NAA concentrations than the above mentioned promoted root growth and inhibited normal shoot growth, while the higher BA concentrations sometimes gave the reverse result to NAA.

Propagation of hyacinths by tissue culture

Sterile tissue from most parts of the hyacinth will regenerate plantlets in vitro. Bulbscale and basal plate tissue require no added growth substances but leaf, stem and ovary tissue respond to low concentrations of the auxins indolyl-3-acetic acid (IAA) and 1-napthylacetic acid (NAA). At higher concentrations of NAA, plantlets are replaced by callus from which plantlets may be regenerated. In vitro plantlets may be split into two halves each of which regenerates a whole plantlet on sub-culture; this process may be repeated at intervals of 8–12 weeks throughout the year. The efficiency of in vitro propagation compared with conventional methods is discussed.

Growth Hormones and Propagation of Cymbidium in vitro

AbstractProtocorms of Cymbidium (Orchidaceae) were grown on solid or liquid medium with macro‐nutrients according to Wimber (van Raalte 1967) and iron, micro‐nutrients and vitamins according to Nitsch (1968) the medium also contained 2% sucrose. The effects of 1) the auxins; indol‐3yl‐acetic acid (IAA), α‐naphthaleneacetic acid (NAA) and 2,4‐dichlorophenoxyacetic acid (2,4‐D); 2) the cytokinins; 6‐furfurylaminopurine (kinetin) and benzyladenine (BA) and 3) the gibberellin; gibberellic acid (GA) were examined alone or in combinations.IAA had no effect alone. NAA resulted in optimal fresh weight at 10 μM and the protocorms were vigorous, but lighter green than usual. 2,4‐D caused a high weight increase at 1 μM, but the protocorms were abnormal. Higher concentrations of NAA and 2,4‐D inhibited chlorophyll synthesis. On solid medium kinetin (100 μM) induced a growth of many small shoots, but had no effect on the fresh weight. In liquid medium, kinetin promoted a callus formation and fresh weight increase. BA had effects similar to kinetin, but at lower concentrations. GA alone promoted shoot and leaf growth.Combinations of kinetin and NAA resulted in a maximal fresh weight increase at kinetin concentrations one tenth of the NAA concentrations. The optimal growth and the best development occurred at 10 μM NAA and 1 μM kinetin. NAA and kinetin together could limit the shoot and leaf growth induced by GA.

Characterization of cytokinin action on enzyme formation during the development of the photosynthetic apparatus in rye seedlings

The action of cytokinin on the formation of photosynthetic enzymes in rye seedlings, which was described earlier, is further characterized by studying the interactions of kinetin with specific inhibitors of protein synthesis and with auxins. The combined action of cytokinin and auxin simultaneously affects enzymes of the oxidative pentose phosphate cycle which show a definite relationship to the appearance of the photosynthetic apparatus. 1. The formation of the photosynthetic enzyme carboxydismutase (EC 4.1.1.39) in rye seedlings can be almost completely prevented by chloramphenicol, but is also strongly inhibited by cycloheximide. These effects of chloramphenicol and cycloheximide cannot be overcome by the application of kinetin. 2. Plastid growth as well as the formation of photosynthetic enzymes (carboxydismutase; NADP-dependent glyceraldehydephosphate dehydrogenase, EC 1.2.1.9) are selectively curtailed in dark- or light-grown rye seedlings by treatment with relatively high concentrations of auxins like 3-indoleacetic acid, α-naphthalene-acetic acid (NAA) or 2,4-dichlorophenoxyacetic acid. 3. The inhibition of plastid growth and enzyme formation can be overcome to an increasing extent by applying increasing amounts of kinetin to young seedlings simultaneously with the NAA. Conversely, the promoting effect of kinetin on the formation of photosynthetic enzymes can be lowered by simultaneous application of NAA. In older seedlings the effect of NAA is no longer reversed by kinetin. An interpretation of the particularly high cytokinin requirement for the synthesis of photosynthetic enzymes in the seedlings is proposed. The appearance of the photosynthetic enzymes in the dark and in the light is accompanied by a decline in the rate of accumulation of key enzymes of the oxidative pentose phosphate cycle, especially glucose-6-phosphate dehydrogenase (EC 1.1.1.49). This effect is not due to a simple insufficiency of nutrients. Moreover, applications of glucose-6-phosphate or 6-phosphogluconate did not suggest an inducing effect of these substrates on their corresponding enzymes. No further increase of glucose-6-phosphate dehydrogenase can be achieved by application of either kinetin or NAA alone. But the formation of this enzyme continues at a high rate and reaches nearly twice the maximal activity of the controls when high concentrations of kinetin and NAA are applied simultaneously. It is concluded that a specific effect of the auxin and the diminished competition of the plastids for the promoting effect of kinetin contribute to the increased formation of glucose-6-phosphate dehydrogenase.The role of cytokinins in the control of the described enzymes is discussed.

Organogenesis in the meristem tissue cultures of cymbidiums. II

Protocorm-Pieces of Cymbidium pumilum ROLFE and rhizome-tips of Cymbidium goeringii REICHB. F. were cultured aseptically in the dark. Chemical control of the organ formation in these cultures was studied. The results obtained were summarized as follows:1) Cymbidium pumilum; On the basal medium (KNUDSON C+NITSCH microelement) shoots were formed in a half of samples after 8 weeks, while no root was formed. Addition of NAA markedly affected their organ formation. Low concentrations of NAA (below 0.1mg/l) promoted shoot formation. With increasing concentration from 0.1 to 0.6mg/l, root arose and the number of shoot decreased. Root formation was most abundant at 0.6mg/l, where root formation scarcely occurred. Still higher concentration suppressed completely both shoot and root formation. Shoot formation was also improved respectively by addition of 0.01mg/l 2, 4-D, 0.01 mg/l gibberellin, 10-3M L-arginine, 10-3M L-aspartic acid and 1mg/l ascorbic acid. Addition of kinetin showed no remarkable effect.2) Cymbidium goeringii; Rhizome-tips of C. goeringii cultured on the basal medium always developed into rhizomes without shoot formation. Addition of 10mg/l kinetin led most of samples to shoot formation. Whereas low concentration of NAA tends to promote the growth of shoot in combination with 10mg/l kintin, high concentration of NAA tends to counteract the stimulating effect of kinetin on the shoot formation. Incorporation of 10-3M L-arginine and L-aspartic acid stimulated shoot formation slightly. Growth of rhizome was improved by addition of 10-3M L-tryptophan and 0.1mg/l biotin to some extent.

THE EFFECT OF GIBBERELLIN AND TEMPERATURE ON THE GERMINATION OF SEED OF BELLS OF IRELAND

Gibberellic acid (GA) at constant temperatures partially replaced the alternate temperatures required to break dormancy of intact seed of Bells of Ireland (Moluccella laevis L.). In the presence of GA optimum germination occurred at 10 °C. and declined to almost nil at 25 °C. When 2-naphthaleneacetic acid (NAA) at 10−5 M. was combined with GA the effect on germination at 20 °C. was synergistic. Higher concentrations of NAA antagonized the stimulatory effect of GA. All excised embryos germinated whether from chilled or unchilled seed. Embryos with attached endosperms from chilled seed showed a marked increase in germination over those from unchilled seed. GA induced 100 per cent germination of embryos with attached endosperms, irrespective of chilling, at 20 °C, but not at 25 °C. The presence of the pericarp completely prevented the germination of untreated seed at constant temperatures. Chilling whole seeds for 6 weeks at 5 °C. greatly enhanced penetration of external solutions to the embryo.

Dormancy of gladiolus corm. (IV)

1) Previous works by the authors showed that many factors affected the dormancy of gladiolus corms. The present work reports three years experiments in 1955_??_1957 on the effects of auxin spary on breaking dormancy. The varieties used were as follows: For auxin spray, Bo Peep and Spot Light in 1955, Atom and Snow Princess in 1956 and Snow Princess and Spot Light in 1957. For tryptophane spary, Hector and Valeria in 1955, White Gold and Spot Light in 1956 and Snow Princess and Spot Light in 1957. As the rule, these corms were planted in early April and dug out in late September or October. 2) Auxin (10, 50 and 100 ppm of NAA) upon the leaf of gladiolus was applied once a week during its growth. After digging, the corms were treated at 35°C for 5 days and then at 0°C for 25 days. As the result, the high concentration of NAA inhibited the sprouting in general. However, NAA spray promoted the sprouting in some cases in the lots of temperature treatment. The higher concentrations of auxin were more effective in the earlier stage of dormancy, while the lower ones in the later stage. The corms which were sprayed with NAA showed abnormal root formation and decreased propagation power. Namely, the weight of corm and number of spawn decreased. 3) Tryptophane which is considered to be the precursor of auxin in plant tissue was sprayed as in the case of NAA. In this case, the temperature treatment and addition of ascorbic acid were under-taken. In most cases, a slight promotion of sprouting was seen by the application of tryptophane. The lower concentrations were more effective in the later stage of dormancy as the case of NAA application. 4) The soaking of corms in the aqueous solution of NAA (10, 50 and 100 ppm) for four hours inhibits the sprouting of corms.