Drought-induced photosynthetic inhibition and autumn recovery in two Mediterranean oak species (Quercus ilex and Quercus suber)

Responses of leaf water relations and photosynthesis to summer drought and autumn rewetting were studied in two evergreen Mediterranean oak species, Quercus ilex spp. rotundifolia and Quercus suber. The predawn leaf water potential (ΨlPD), stomatal conductance (gs) and photosynthetic rate (A) at ambient conditions were measured seasonally over a 3-year period. We also measured the photosynthetic response to light and to intercellular CO2 (A/PPFD and A/ Ci response curves) under water stress (summer) and after recovery due to autumn rainfall. Photosynthetic parameters, Vcmax, Jmax and triose phosphate utilization (TPU) rate, were estimated using the Farquhar model. RuBisCo activity, leaf chlorophyll, leaf nitrogen concentration and leaf carbohydrate concentration were also measured. All measurements were performed in the spring leaves of the current year. In both species, the predawn leaf water potential, stomatal conductance and photosynthetic rate peaked in spring, progressively declined throughout the summer and recovered upon autumn rainfall. During the drought period, Q. ilex maintained a higher predawn leaf water potential and stomatal conductance than Q. suber. During this period, we found that photosynthesis was not only limited by stomatal closure, but was also downregulated as a consequence of a decrease in the maximum carboxylation rate (Vcmax) and the light-saturated rate of photosynthetic electron transport (Jmax) in both species. The Vcmax and Jmax increased after the first autumnal rains and this increase was related to RuBisCo activity, leaf nitrogen concentration and chlorophyll concentration. In addition, an increase in the TPU rate and in soluble leaf sugar concentration was observed in this period. The results obtained indicate a high resilience of the photosynthetic apparatus to summer drought as well as good recovery in the following autumn rains of these evergreen oak species

Acclimation to short-term low temperatures in two Eucalyptus globulus clones with contrasting drought resistance

We tested the hypothesis that Eucalyptus globulus Labill. genotypes that are more resistant to dry environments might also exhibit higher cold tolerances than drought-sensitive plants. The effect of low temperatures was evaluated in acclimated and unacclimated ramets of a drought-resistant clone (CN5) and a drought-sensitive clone (ST51) of E. globulus. We studied the plants’ response via leaf gas exchanges, leaf water and osmotic potentials, concentrations of soluble sugars, several antioxidant enzymes and leaf electrolyte leakage. Progressively lowering air temperatures (from 24/16 to 10/ 2 C, day/night) led to acclimation of both clones. Acclimated ramets exhibited higher photosynthetic rates, stomatal conductances and lower membrane relative injuries when compared to unacclimated ramets. Moreover, low temperatures led to significant increases of soluble sugars and antioxidant enzymes activity (glutathione reductase, ascorbate peroxidase and superoxide dismutases) of both clones in comparison to plants grown at control temperature (24/16 C). On the other hand, none of the clones, either acclimated or not, exhibited signs of photoinhibition under low temperatures and moderate light. The main differences in the responses to low temperatures between the two clones resulted mainly from differences in carbon metabolism, including a higher accumulation of soluble sugars in the drought-resistant clone CN5 as well as a higher capacity for osmotic regulation, as compared to the droughtsensitive clone ST51. Although membrane injury data suggested that both clones had the same inherent freezing tolerance before and after cold acclimation, the results also support the hypothesis that the droughtresistant clone had a greater cold tolerance at intermediate levels of acclimation than the drought-sensitive clone. A higher capacity to acclimate in a short period can allow a clone to maintain an undamaged leaf surface area along sudden frost events, increasing growt

Yoga for Vital Capacity

The purpose of this study was to ascertain the effect of yogic exercises and pranayam on the vital capacity adolescent school going boys. In total 60 numbers of school students (boys only) were taken as subjects and were divided equally (30 each) into two groups namely Experimental and Control groups. Pre tests on Vital Capacity was conducted prior to Yogic exercises and pranayam treatment to the experimental group and post test was made after a 12 week treatment and comparisons were made between and within the groups using descriptive statistics and Factorial ANOVA. It was concluded that Yoga Training Group (Experimental Group) improves Vital Capacity of adolescent student

Evaluation of the oxidative profile in leukocytes of jiu jtisu athletes

Oxidative stress is a process where there is an increase in reactive species, both oxygen and nitrogen. This can happen at both systemic and mitochondrial levels. One of the physiological conditions currently associated with oxidative stress is high-performance physical activity. In this way, it is possible to relate that this problem impacts on sports competitions, especially in Jiu-Jitsu, a growing sport in the world and which demands intense physical effort. Thus, the objective was to evaluate the level of mitochondrial and systemic oxidation in leukocytes of jiu-jitsu athletes. 20 adult men were selected for the control group and 13 athletes for the experimental group. A blood collection was performed to perform MTT and chemiluminescence assays for an analysis of mitochondrial and systemic oxidation, respectively. In addition, two reactive nitrogen species were measured: nitric oxide and peroxynitrite. The evaluation of the leukocyte reducing capacity by MTT showed that the athletes presented a greater reducing environment compared to the control. On the other hand, the chemiluminescence evaluation showed that the athletes' leukocytes showed greater systemic oxidation. There was an increase in both reactive nitrogen species in alteta leukocytes. Given this, it was possible to notice that the athletes presented greater systemic oxidative stress, but with mitochondria with better adaptive capacity to the cell's metabolic demands