Plant physiology

About: Plant physiology is a research topic. Over the lifetime, 1537 publications have been published within this topic receiving 72038 citations.

Effects of enhanced UV-B radiation on plant physiology and growth on the Tibetan Plateau: a meta-analysis

Abstract: Uncertainties about the response of plant physiology and growth to enhanced UV-B radiation cause uncertainty to predict how plant production will vary under future radiation change on the Tibetan Plateau. Here, we used a meta-analysis approach to test the influence of UV-B radiation on plant physiology and growth. This hypothesis was tested by investigating the response of plants, which was expressed by some measurable variables. Enhanced UV-B radiation decreased plant biomass, plant height, basal diameter, leaf area index, maximal PSII efficiency, and Chl a+b, but increased intercellular CO2 concentration, malondialdehyde (MDA), hydrogen peroxide, superoxide anion radical, peroxidase, ascorbate peroxidase, proline and UV-B absorbing compounds. The effect of enhanced UV-B radiation on net photosynthesis rate (P n ) increased with mean annual precipitation and experimental duration. The effect of enhanced UV-B radiation on MDA decreased with experimental duration. The effect of enhanced UV-B radiation on superoxide dismutase (SOD) increased with the magnitude of enhanced UV-B radiation. Forests rather than grasslands exhibited a positive response of SOD and a negative response of P n to enhanced UV-B radiation. Therefore, the effect of enhanced UV-B radiation on alpine plants varied with ecosystem types. Local climate conditions may regulate effects of enhanced UV-B radiation on alpine plants.

Daily Temperature Amplitude Affects the Vegetative Growth and Carbon Metabolism of Orange Trees in a Rootstock-Dependent Manner

Abstract: Both instantaneous and average growth temperatures affect plant metabolism, and the physiological importance of daily variations in temperature is frequently underestimated. To improve our understanding of the environmental regulation of citrus trees, we hypothesized that vegetative growth would be stimulated in orange plants subjected to large daily temperature variations, even without changes in the average daily air temperature or the amount of energy given by degree-days. This hypothesis was tested with orange plants grafted onto Rangpur lime or Swingle citrumelo rootstocks and grown for 20 days under thermal regimes (day/night) of 25/25°C or 32.5/17.5°C. Such regimes imposed growth conditions with daily temperature variations of 0 and 15°C. Plant growth, photosynthesis, respiration, and carbohydrate availability in leaves, stems, and roots were measured under both thermal conditions. The daily temperature variation affected the carbon metabolism of young citrus trees; plants grown under daily variation of 15°C used more of the carbon stored in mature leaves and roots and the energy generated by respiration for the biosynthesis of vegetative structures, such as leaves and branches. Thus, there was a significant increase in the leaf area of plants subjected to high daily temperature variation. Current photosynthesis was similar in the two thermal regimes; however, the photosynthetic rates increased under the 15°C variation when measurements were normalized to 25°C. In addition to the stimulatory effect of the source–sink relationship on photosynthesis, we suggest a probable involvement of hormonal regulation of plant growth through gibberellin metabolism. The rootstock affected the response of the canopy to daily temperature amplitude, with the Rangpur lime improving plant growth through higher carbohydrate availability in roots. This is the first report that highlights the importance of daily temperature variations for citrus growth and physiology under nonlimiting conditions.

Plastid and seedling development in SAN-9789 [4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridasinone]-treated etiolated bean seedlings

Abstract: SAN 9789[4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridasinone] inhibits carotenoid synthesis at the level of phytoene in Phaseolus vulgaris L. Although carotenoids are greatly reduced in the primary leaves, prolamellar bodies and thylakoid membranes are formed containing phototransformable protochlorophyll(ide). SAN 9789 also produces developmental effects similar to those of red light since seedlings treated in darkness are short, show plumular unhooking, formation of adventitious roots, expansion of primary leaves and full expansion of the first trifoliate leaf and first internode. The effect is not directly on phytochrome since far red light does not reverse the effect of SAN. If abscisic acid (ABA) is indeed formed from carotenoids, we may be observing the consequences of reduced levels of ABA leading to reduced ethylene production as occurs with red light. The first trifoliate leaf of SAN-treated plants contains practically no carotenoids (0.2%) compared with untreated 7-day-old, ...