Plant physiology

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

The rôle of light in the life of plants

Abstract: Relation of light to biological processes . . . . . . . . . . . . . . . . . . . 2 Photosynthesis . . . . . . . . . . . . . . . 6 ChlorophyU formation . . . . . . . . 7 Other pigments . . . . . . . . . . . . . . . 11 Chromatic adaptation . . . . . . . . . 13 Photodynamic action . . . . . . . . . 15 Transpiration . . . . . . . . . . . . . . . . . 16 Absorption and use of solutes . 17 Permeability . . . . . . . . . . . . . . . . . 20 Protoplasmic movement . . . . . . 21 Assimilation . . . . . . . . . . . . . . . . . . 21 Carbohydrate/nitrogen ratio .. 25 Inorganic elements . . . . . . . . . . . . 30 Acidity, stomatal movement, etc. 32 Photoperiodic stimulation . . . . 34 Reduction/oxidation ratio . . . . 38 Enzymes . . . . . . . . . . . . . . . . . . . . . 41 Vitamins . . . . . . . . . . . . . . . . . . . . . 42 Seed germination . . . . . . . . . . . . . 44 Growth-substances . . . . . . . . . . . . 47 Electrical potential . . . . . . . . . . . 49

Effects of light quality on growth and development, photosynthetic characteristics and content of carbohydrates in tobacco (Nicotiana tabacum L.) plants

Abstract: In this study, effects of yellow (Y), purple (P), red (R), blue (B), green (G), and white (W) light on growth and development of tobacco plants were evaluated. We showed that monochromatic light reduced the growth, net photosynthetic rate (P N), stomatal conductance, intercellular CO2, and transpiration rate of tobacco. Such a reduction in P N occurred probably due to the stomatal limitation contrary to plants grown under W. Photochemical quenching coefficient (qP), maximal fluorescence of dark-adapted state, effective quantum yield of PSII photochemistry (ΦPSII), and maximal quantum yield of PSII photochemistry (Fv/Fm) of plants decreased under all monochromatic illuminations. The decline in ΦPSII occurred mostly due to the reduction in qP. The increase in minimal fluorescence of dark-adapted state and the decrease in Fv/Fm indicated the damage or inactivation of the reaction center of PSII under monochromatic light. Plants under Y and G showed the maximal nonphotochemical quenching with minimum P N compared with the W plants. Morphogenesis of plants was also affected by light quality. Under B light, plants exhibited smaller angles between stem and petiole, and the whole plants showed a compact type, while the angles increased under Y, P, R, and G and the plants were of an unconsolidated style. The total soluble sugar content increased significantly under B. The reducing sugar content increased under B but decreased significantly under R and G compared with W. In conclusion, different monochromatic light quality inhibited plants growth by reducing the activity of photosynthetic apparatus in plants. R and B light were more effective to drive photosynthesis and promote the plant growth, while Y and G light showed an suppression effect on plants growth. LEDs could be used as optimal light resources for plant cultivation in a greenhouse.

Nitrogen enrichment of soil and plant byRhizobium phaseoli-Phaseolus vulgaris symbiosis

Abstract: Incubation of 25 and 30 day old nodulated plants ofPhaseolus vulgaris for periods of 24 h and 72 h under 15-dinitrogen atmosphere indicated nitrogen enrichment of soil compared with soil free of plants and with other plants under the same experimental conditions. This indication of release from the root-nodule system is discussed.

Kinetin and Indole Acetic Acid Promote Antioxidant Defense System and Reduce Oxidative Stress in Maize ( Zea mays L.) Plants Grown at Boron Toxicity

Abstract: A study was conducted to assess the influence of boron (B) toxicity on functioning of antioxidant machinery to counteract oxidative stress in maize (Zea mays L.) plants as well as the mitigating effect of kinetin (KIN) and indole acetic acid (IAA) on these phenomena. Plants of maize cv. DK 647 F1 were exposed to 0.05 and 2 mM boron in nutrient solution 8 days after germination, and the plants were grown for a further 7 days in these conditions. After 15 days growth, deionized water (control), 1.0 or 2.0 mM of KIN, or IAA were applied to the leaves of maize plants once each 7 days. After 21 days of these treatments, the plants were harvested to evaluate growth, water relations, and oxidative and antioxidative systems. Boron toxicity significantly reduced dry matter, efficiency of photosystem II (Fv/Fm), and leaf relative water content in the maize plants when compared to those in non-stressed plants, but in contrast, it enhanced electrolyte leakage (EL), hydrogen peroxide (H2O2), free proline, malondialdehyde (MDA) and the activities of peroxidase, superoxide dismutase, and catalase in the maize plants. However, KIN or IAA applied as a foliar spray to maize plants grown at excess B caused a significant improvement in growth attributes, plant water status and the activities of various antioxidant enzymes as well as proline content, but they lowered EL, and H2O2 and MDA contents. Boron toxicity increased leaf B and reduced leaf K+, Ca2+, and P contents when compared to those in the control plants. Foliar applied KIN or IAA to the plant leaves lowered tissue B levels, but in contrast, it resulted in significant increases in Ca2+, K+ and P levels. The results of the study indicated that the spray of KIN and IAA, particularly at 2 mM, can mitigate to a significant extent the adverse effects of B toxicity on maize plants, which was found be associated with reduced content of B, H2O2, MDA as well as EL, and increased activities of key antioxidant enzymes in maize plants.