Showing papers in "Australian Journal of Plant Physiology in 1976"
TL;DR: Barley plants (cv Prior) were grown in nutrient culture and subjected to a variety of salinity stress treatments when 10-12 days old, and proline accumulation appeared to be controlled by tissue osmotic potential rather than by turgor.
Abstract: Barley plants (cv. Prior) were grown in nutrient culture and subjected to a variety of salinity stress treatments when 10-12 days old. Salinity stress was either imposed abruptly by transferring plants to a solution containing NaCl of - 5.7 or - 10.7 bar osmotic potential, or gradually by transferring plants daily to solutions of successively lower osmotic potential (- 1 bar per day). Prolonged exposure to salinity stress was achieved by holding plants in a - 10.7 bar osmotic potential solution for 6 days. Proline accumulated rapidly in plants subjected to a salinity stress greater than - 5.7 bar osmotic potential. Accumulation appeared to be controlled by tissue osmotic potential rather than by turgor, and continued for 24 h after the saline solution was removed from the root medium. Proline accumulation continued for at least 3 days in plants held at - 10.7 bar osmotic potential, during which time the plants continued to grow slowly. The accumulated proline made only a minor contribution to osmotic regulation in the plant,
106 citations
TL;DR: Flower induction in this long day plant is optimal when phytochrome is mostly in the Pr form early in the night, and in the Pfr form later, a sequence opposite to that required by short day plants such as Pharbitis nil and Chenopodium rubrum.
Abstract: Plants of L. temulentum grown in short days were exposed at various times during one night to mixtures of red (R) and far red (FR) light or to prolonged irradiation on a spectrograph. Irradiation with red light through the latter half of the 16-h night was inductive of flowering, its effect being enhanced by exposure to FR during the first 6 h after the period in daylight. Brief exposure to FR during this initial period was as effective as continuous irradiation with FR, and its effect was reversible by brief subsequent exposure to R, implicating the pigment phytochrome. Brief exposures to mixtures of R + FR at various times during the first 6 h in darkness were used to chart apparent changes in the two forms of phytochrome. To judge from the R + FR mixtures giving null responses, phytochrome reverted from the Pfr to the Pr form progressively over the first 5 h of darkness. There was no evidence of inverse reversion after an initial exposure to FR. Optimum flowering response required most of the phytochrome to be present in the Pfr form in the initial hours after daylight, followed by a rise in the proportion of the Pfr form to that set by R. Reflecting this shift during the night in the optimum proportion of Pfr, the spectrograph experiments indicated peak effectiveness in the far red region of the spectrum for irradiation at the end of the period in daylight, and in the red region (~670 nm) for irradiation during the latter part of the night. Flower induction in this long day plant is optimal when phytochrome is mostly in the Pr form early in the night, and in the Pfr form later, a sequence opposite to that required by short day plants such as Pharbitis nil and Chenopodium rubrum.
32 citations
TL;DR: It is concluded that wilting, characteristic of copper-deficient plants, is due to structural weakness (decreased lignification) and not to the water status of the plants; also, increased leaf diffusive resistance isdue to a specific effect of copper deficiency on guard cells andNot to decreased leaf water potential.
Abstract: Leaf water potential, diffusive resistance, relative water content, weekly water use, yields and head bending were measured on wheat plants subjected to four copper levels (0, 0.4, 0.8 or 4.0 mg Cu per pot) and two water levels (6 or 12% soil water content). Severe copper deficiency (Cu 0) resulted in no grain yield, wilting, increased leaf diffusive resistance and, at the same time, increased leaf water potential relative to plants receiving 4.0 mg Cu (Cu 4.0). Water supply effects were observed but there was no interaction between copper and water treatments. Mild copper deficiency (Cu 0.4, Cu 0.8) resulted in small yield decreases, relative to Cu 4.0, and increased head bending towards maturity. It is concluded that wilting, characteristic of copper-deficient plants, is due to structural weakness (decreased lignification) and not to the water status of the plants; also, increased leaf diffusive resistance is due to a specific effect of copper deficiency on guard cells and not to decreased leaf water potential.
31 citations
TL;DR: Lactate is formed during the initial hours of seed swelling during natural anaerobiosis in maize and ethanol is formed later, at a concentration greater by one order, with 7-day-old seedlings.
Abstract: Lactate is formed during the initial hours of seed swelling during natural anaerobiosis in maize. Ethanol is formed later, at a concentration greater by one order. With 7-day-old seedlings, first lactate and then ethanol are also formed after transfer of the plants to an atmosphere of nitrogen. Lactate and alcohol dehydrogenases are active in the germinating seed. The molecular weight of maize alcohol dehydrogenase (EC 1.1.1.1) is 62 000 ± 5000. Inhibition by chelating agents and 'sulphydryl poisons' indicates the probable presence of metal and -SH groups. The enzyme oxidizes ethanol at an optimum pH of 8.7 with a Km of 1.8 x 10-2 M and reduces acetaldehyde at an optimum pH of 6.7 with a Km of 1.0 x 10-3M. It is inhibited by succinate, malate, lactate and acetate, non-competitively with respect to the substrate. Acetoxime is a competitive inhibitor and butyrylamide, acetamide and cyclohexanone oxime are non-competitive inhibitors.
8 citations