Induce Plant Growth Research Articles

The effects of elevated CO2 and nitrogen availability supersedes the need for nodulation in peas grown under controlled environmental conditions

The effect of elevated CO 2 (1 000μmol mol − 1 ) on the growth and leaf development of nodulating and non-nodulating Pisum sativum L. var. Greenfeast was studied under both nitrogen (6mM) and nitrogen-free nutrient solution supply. Plants were sown and kept under ambient and elevated CO 2 throughout their growth period. Studies were based on the use of the plastochron index as a measure of plant growth. Results show that short-term exposure to elevated CO 2 induced plant growth, irrespective of treatment. Long-term elevated CO 2 treatment did not affect rate of leaf appearance (RLA) in nodulated plants irrespective of mineral N supply but induced RLA in non-nodulating plants supplied with mineral N. Supplied N induced leaflet elongation rate significantly under both ambient and elevated CO 2 in nodulated and non-nodulated plants. Leaflet elongation rate was not significantly affected by nodulation but was increased by high CO 2 . The results reported here, show that a CO 2 level of as high as 1 000μmol mol − 1 may not significantly affect the growth of nodulating P. sativum L. Our data suggest that elevated CO 2 will enhance canopy size, provided adequate soil N is available. In addition, canopy size will be significantly increased under elevated CO 2 in non-nodulating plants, provided adequate soil N is applied.

The phytochrome-interacting transcription factor, PIF3, acts early, selectively, and positively in light-induced chloroplast development

The phytochrome (phy) family of sensory photoreceptors transduce informational light signals to selected nuclear genes, inducing plant growth and developmental responses appropriate to the environment. Existing data suggest that one signaling pathway by which this occurs involves direct, intranuclear interaction of the photoactivated phy molecule with PIF3, a basic helix-loop-helix transcription factor. Here, we provide evidence from recently identified pif3 mutant alleles that PIF3 is necessary for early chloroplast greening and rapid phy-induced expression of nuclear genes encoding chloroplast components upon first exposure of seedlings to light. Therefore, these data indicate that PIF3 functions to transduce phy signals to genes involved in a critical facet of the early seedling deetiolation process, the generation of a functional photosynthetic apparatus. When transgenically expressed GUS:PIF3 fusion protein constructs were used, we found that PIF3 protein levels are rapidly and reversibly modulated by the photoreceptor over diurnal cycles in Arabidopsis seedlings. The PIF3 protein declines rapidly to a basal steady-state level upon initial light exposure, but reaccumulates to preirradiation levels in darkness during the subsequent night period. These data suggest that PIF3 may function in early phy signaling at the dark-to-light transition, not only during initial seedling deetiolation, but daily at dawn under diurnal light-dark cycles.

Effects of agricultural runoff on vegetation composition of a priority conservation wetland, Vermont, USA.

This study examined the effects of agricultural runoff on the vegetation structure of Franklin Bog, a priority conservation area located in a rapidly developing region of northwestern Vermont. Forested and agricultural runoff from the mixed land use watershed created differential vegetation patterns in the wetland, including weedy species introductions. Concentrations of nitrogen and phosphorus were measured in the stream runoff from four forested subwatersheds and two agricultural subwatersheds. Nutrient concentrations were significantly higher for agricultural vs. forested runoff for all measured parameters. Nitrate and total phosphorus concentrations in agricultural runoff ranged from 0.62 to 1.35 mg L(-1) and 0.07 to 0.37 mg L(-1), respectively. Forested runoff values were less than 0.37 mg L(-1) nitrate and 0.09 mg L(-1) total phosphorus. Significantly higher proportions of weedy species occurred at impacted vs. reference sites (46 +/- 5% vs. 23 +/- 4%). Furthermore, significantly higher total percent vegetated cover occurred at impacted vs. reference sites (116 +/- 11% vs. 77 +/- 9%) suggesting nutrient induced plant growth. Of the nine frequently occurring species categorized as bog species, only one was found within impacted sites while all nine were found at the reference sites. This suggests that the wetland's distinctive native flora is being replaced by widespread, vigorous species enhanced by agricultural nonpoint pollution in the watershed of Franklin Bog. Protection of wetlands requires attention to conservation measures throughout the entire watershed.

Potential for improving pea production by co-inoculation with fluorescent Pseudomonas and Rhizobium

Seed bacterization with five plant growth promoting fluorescent Pseudomonas strains isolated from Indian and Swedish soils and three Rhizobium leguminosarumbiovar viceae strains isolated from Swedish soils were shown to promote plant growth in Pisum sativum L. cv. Capella. Co-inoculation of the fluorescent pseudomonads and Rhizobium improved plant growth in terms of shoot height, root length and dry weight. Both the fluorescent pseudomonads and Rhizobium were shown to exhibit a wide range of antifungal activity against pathogens specific to pea. Seed bacterization with plant growth promoting strains alone and together with a rhizobial isolate, R 361-27 reduced the number of infected peas grown in Fusarium oxysporum infested soils. We found that the introduced organisms were able to colonize the roots, which was confirmed using immunofluorescence staining and drug resistant mutant strains. In a synthetic culture medium, all the plant growth promoting fluorescent pseudomonads strains produced siderophores, which shown to express antifungal and antibacterial activity. Our results suggest the potential use of these bacteria to induce plant growth and disease suppression in sustainable agriculture production systems.

Formation of raphanusanins depends on extraction procedure and solvent

Formation of raphanusanins, which had been reported as light induced plant growth regulators in radish plant, was examined using different extraction procedures and solvents including MeOH- d 4 . Formation of raphanusanin, 3-[α-methoxy-(α-methylthio)methyl]-2-thioxopyrrolidine, which had been reported as a light-induced plant growth inhibitor in roots and seedlings of radish, was examined using different extraction procedures and solvents including methanol- d 4 . Both (3 R *,6 R *)- and (3 R *,6 S *)-isomers of the compound were detected in the methanol extract of autolysed radish roots, but not in the acetone nor in the water extracts. When autolysed radish seedlings were extracted with methanol- d 4 , raphanusanin- d 3 having a CD 3 group was formed instead of raphanusanin. In the case of blanched seedlings and roots, raphanusanins were detected only in the methanol extract of myrosinase-treated homogenates. These results demonstrate that raphantin or raphanusanin is an artifact formed during extraction of radish with methanol, and therefore it may not be involved in phototropism of radish.

A Highly efficient preparation of lunularic acid and some biological activities of stilbene and dihydrostilbene derivatives

Lunularic acid, an acid possessing dormancy inducing, antifungal, thromboxane synthetase and hyaluronidase inhibitory and plant growth inhibitory activities, was obtained quantitatively from hydrangenol by reduction using sodium borohydride-palladium chloride. Some stilbene and dihydrostilbene derivatives prepared from hydrangenol and its glucoside also showed plant growth inhibitory, hyaluronidase inhibitory and piscicidal activities.

Lime Induced Plant Growth Depression in an Alluvial Entisol from Costa Rica

AbstractPoor plant growth in field experiments following clearing of a forested virgin Entisol in eastern Costa Rica and the subsequent detrimental effect of lime on growth of warm‐season grasses were studied in greenhouse and laboratory experiments. Greenhouse experiments were carried out with pangolagrass (Digitaria decumbens Stent) by sterilizing a virgin surface soil, limed with 0, 4, and 8 meq/100 g of CaCO3, with heat and gamma radiation. Incubation experiments in the laboratory were conducted with a differentially limed surface soil that had been in pasture for 8 years and its subsoil. Every 2 weeks, for 10 weeks, samples from the incubating soils were extracted with water. Calcium, Mg, K, Na, NO3, SO4, P, and Cl were determined in the water extracts. Electrical conductivity in the soil was measured before and after water extractions. After 10 weeks of incubation, electrical conductivity was measured in saturated soil extracts. Soil organic matter was determined before and after incubation.The negative effect of lime persisted in the sterilized soils; however, water leaching of unlimed and limed virgin soils markedly improved pangolagrass growth. Laboratory studies showed considerable increases in water‐extractable Ca, NO3, and SO4 ions with increasing lime rates and incubation time in the pasture surface soil and its subsoil. Electrolytes reached a maximum at 2 weeks of incubation. Conductivity measurements higher than 4 mmhos/cm in saturated soil extracts after 10 weeks of incubation indicated harmful concentrations of electrolytes which were apparently derived from lime and biological decomposition of soil organic matter.

Peach Thinning with Ethylene1

Abstract A resurgence of interest has been focused on the search for a chemical which would evolve ethylene after foliar application and thus induce plant growth responses. One such compound, 2-chloroethylphosphonic acid (Ethrel), has been under study as a peach thinner at the University of California orchards at Davis. It has been assumed that the peach thinning induced by Ethrel was caused by the ethylene gas which is released after application2. As an adjunct to the work with Ethrel, we were interested in the thinning action of ethylene gas and the resultant gross effects on the treated tree parts.

Peach Thinning with Ethylene1

Abstract A resurgence of interest has been focused on the search for a chemical which would evolve ethylene after foliar application and thus induce plant growth responses. One such compound, 2-chloroethylphosphonic acid (Ethrel), has been under study as a peach thinner at the University of California orchards at Davis. It has been assumed that the peach thinning induced by Ethrel was caused by the ethylene gas which is released after application2. As an adjunct to the work with Ethrel, we were interested in the thinning action of ethylene gas and the resultant gross effects on the treated tree parts.

RELATIONS OF RESPIRATION AND GROWTH IN THE AVENA COLEOPTILE

THE AVENA coleoptile is a classical obj ect for the study of the effect of auxin in inducing plant growth. A particularly simple system for the study of the auxin response is constituted by excised sections of the coleoptile which when floated on aqueous solutions containing an active auxin, are capable of extensive and rapid growth (Bonner, 1933). It is known that there is a relation between the auxin induced growth of such sections and their respiration. Thus response to auxin does not occur in an 02 free atmosphere (Bonner, 1933), while HCN, which inhibits respiration of the coleoptile, inhibits response to auxin in a parallel manner (Bonner, 1933, 1936). As a preliminary step in the elucidation of the relation of auxin to respiration, the respiratory systems of the coleoptile have been reviewed and reported in a previous paper (Bonner, 1948). The oxygen uptake of the coleoptile is mediated by the cytochrome-cytochrome oxidase system. Hexose is converted to fructose diphosphate through a series of reactions involving ATP and evidence that pyruvate is the product of initial hexose breakdown has been presented (Bonner, 1948). Pyruvate in turn is metabolized through a system involving succinic dehydrogenase and resembling in general terms the cycle of Krebs. Thus the Avena coleoptile possesses so far as present information goes what might be termed an orthodox respiratory mechanism, one resembling that of animal tissues. The previous paper in this series (Bonner, 1949) has dealt with the influence of several factors including respiratory substrates and inhibitors on the auxin induced growth of A4vena coleoptile sections. This paper deals with experiments which bear on the relation of auxin to respiration. MATERIALS AND METHODS.-A4vena seedlings (var. Siegeshafer) were grown from intact fruits (glumes not removed) in flats in vermiculite and incubated under occasional orange light at 260C. for 5 days before use. At this time the plants were approximately 2 cm. tall and were identical with those used for growth measurements in the preceding paper. For the respiration measurements, tips 2-3 mm. long were removed from the coleoptile and one 5 mm. section cut from each hollow coleoptile cylinder with a double bladed cutting tool. The segments were thoroughly randomized and dispensed into Warburg vessels, twenty per vessel. At the same time one lot of twenty sections was weighed directly in the fresh condition and all respiratory rates are calculated to the basis of 100 mg. fresh wt., twenty sections weighing in general 75-85 mg. Measure1 Received for publication August 28, 1948. Report of work supported in part by the Herman Frasch Foundation. ments of respiration were made in single side-arm conical Warburg vessels of approximately 16 cc. capacity and provided with a central well which contained 5 per cent KOH where oxygen uptake was to be determined. A bath temperature of 30?C. was used throughout. M/100 KH2PO4, pH 4.5,