Sand burial is a ubiquitous disturbance that influences the ecological and hydrological properties of moss crusts in many sandy desert areas. There is little available information regarding the effect of sand burial on the water repellency (WR) of moss crusts in desert areas. Therefore, this study evaluated the effects of sand burial (sand depths of 0 (control), 0.5, 1, 2, 4 and 10 mm) followed by three simulated precipitation regimes (through applying 4 and 6 mm, 2 and 3 mm, and 1 and 1.5 mm of distilled water at 8-day intervals in spring and autumn, respectively) on the WR of a widespread moss crust dominated by Bryum argenteum Hedw. in a revegetated area of the Tengger Desert, China. The results showed moss crust WR remained subcritical during the whole experiment, and that it considerably decreased immediately after sand burial, even though the values of WR were significantly higher in autumn than those in spring under the same treatment (p < 0.05). Furthermore, the depth threshold (TD) values for sand burials that reduced WR to zero were 1 and 2 mm in spring and autumn, respectively. After a recovery period of nearly one-season (72 days), the WR of the moss crust significantly increased (p < 0.05). In addition, sand burial had two separate effects on moss crust WR. Specifically, shallower sand burial (burial depth less than 0.5 mm) increased moss crust WR, whereas deeper sand burial (burial depth exceeds 0.5 mm) decreased it. The TD values also significantly increased to 2 and 4 mm in spring and autumn, respectively. These findings about the effects of sand burial on moss crust WR provide additional information that can be used to better understand the influence of sand burial on moss crust colonization and maintenance in arid sandburial- stressed ecosystems, and to help explain why there are some contrasting viewpoints on biocrust WR.
To understand the physiology of rice under seawater salinity, potted rice plants were irrigated with different concentrations of Japan seawater (electrical conductivity 0.9, 5.7, 11.5, or 21.5 mS cm-1) from 10 d after transplanting (DAT) to 35 DAT, and from 75 to 100 DAT. Seawater salinity decreased the net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, leaf water and osmotic potentials, and relative water content, and increased leaf temperature. The contents of chlorophylls, carotenoids, and total sugars significantly decreased in the leaves but content of non-reducing sugars decreased only slightly. With increasing salinity the Na+ concentration increased, while Ca2+, Mn2+, and K+ concentrations decreased. Salinity decreased the contents of sugars and proteins, dry mass, and rate of dry mater accumulation in developing grains. and N. Sultana, T. Ikeda, M. A. Kashem.
Pearl millet (Pennisetum glaucum L. cv. HHB-67) seeds were pre-soaked in sulphydryl compounds (dithiothreitol, thioglycollic acid, thiourea, and cysteine). In plants at 59 and 67 d after sowing (DAS), activities of photosystem (PS) 2 (ferricyanide site) and PS1, both chloroplastic and total superoxide dismutase, glutathione reductase, and glutathione-S-transferase increased after all sulphydryl pre-treatments at both stages of plant development. Also dry matter of plant parts sampled at 55 DAS was higher after thiol-treatments in comparison with control. and N. K. Ramaswamy ... [et al.].
In order to study the mechanisms of Se-mediated growth improvement as related to carbon (C) and nitrogen (N) metabolism, wheat plants were cultivated hydroponically with adequate (4 mM, Na) or low (1 mM, Nd) N supply and treated with 10 and 50 μM Na2SeO4 for six weeks. The Se supplementation enhanced plant biomass; it was significant for shoots of Na plants at 50 μM Se. Chlorophyll fluorescence parameters were significantly lowered under Nd conditions but restored completely by Se addition reaching values of those in Na plants. Net CO2 assimilation rate (PN) decreased only slightly by limited N availability, but it enhanced significantly in both Nd and Na plants equally by 10 and 50 μM Se. Effect of Se on PN in the Na plants occurred mainly due to the stomata opening, while it was related to both stomatal and nonstomatal mechanisms in the Nd plants. The Se treatment resulted in enhancement of nitrate reductase (NR) activity in both Na and Nd plants with an optimal response at 10 μM Se. Negative correlations between nitrate concentration and NR activity indicated a partial nitrate depletion in the roots following by elevated NR activity in Nd plants. In contrast, nitrite concentrations were higher in the Se treated plants. Higher amino acids and protein concentrations in the Se-treated plants might be an indication of a general upregulation of N metabolism. However, in Na plants, the stimulation of N metabolism was not observed at 50 μM Se which could not be attributed to lesser availability of C skeletons because of maintaning higher CO2 fixation under these conditions. It implies the function of some regulatory mechanisms that are responsible for coordination of C and N metabolism in whole plant., R. Hajiboland, N. Sadeghzade., and Obsahuje bibliografii
Freezing of thylakoid membranes in the presence of 0.1 M NaCl and increasing concentrations of serine changed the photochemical actívity of photosystem (PS) 2 with beginning of freezing, while the PSI mediated electron transport was altered after a 24 h storage at -20 °C.
The physiological significance of serotonin released into the intestinal lumen for the regulation of motility is unknown in humans. The aim of this study was to evaluate the effect of serotonin infused into the lumen of the gastric antrum, duodenum or the jejunum, on antro-duodeno-jejunal contractility in healthy human volunteers. Manometric recordings were obtained and the effects of either a standard meal, continuous intravenous infusion of serotonin (20 nmol/kg/min) or intraluminal bolus infusions of graded doses of serotonin (2.5, 25 or 250 nmol) were compared. In addition, platelet-depleted plasma levels of serotonin, blood pressure, heart rate and electrocardiogram were evaluated. All subjects showed similar results. Intravenous serotonin increased migrating motor complex phase III frequency 3-fold and migrating velocity 2-fold. Intraluminal infusion of serotonin did not change contractile activity. Platelet-depleted-plasma levels of serotonin increased 2-fold following both intravenous and high doses of intraluminal infusions of serotonin. All subjects reported minor short-lived adverse effects following intravenous serotonin stimulation, while only half of the subjects reported minor short-lived adverse effects following intraluminal serotonin stimulations. We conclude that exogenous serotonin in the lumen of the upper part of the small intestine does not seem to change antro-duodeno-jejunal contractility significantly in healthy adult volunteers., M. B. Hansen, F. Arif, H. Gregersen, H. Bruusgaard, L. Wallin., and Obsahuje bibliografii a bibliografické odkazy
The effects of 8-days treatment with 17α-estradiol (33.3 μg/kg) and progesterone (1.7 mg/kg) on plasma lipids and fatty acid composition of plasma phospholipids were examined in intact (INT) and bilaterally common carotid arteries occluded (BCO) male Wistar rats. Significant decrease of triglyceride level was found in BCO rats after the estradiol treatment. Both hormones elevated proportion of 18:1n-7 fatty acid in INT, but they failed to have such an effect in BCO. Estradiol increased 22:5n-3 and total n-3 polyunsaturated fatty acids (PUFA) in intact, and decreased 18:2n-6 in BCO rats. Significantly lower level of total n-3 was found in progesterone-treated than in estradiol-treated BCO rats. Given that n-3 PUFA have many beneficial effects on cell and tissue function, while n-6 PUFA have mostly the opposite effects, estradiol, rather than progesterone, was seen to improve plasma lipids and phospholipids FA profiles in INT and BCO animals. Estradiol significantly elevated the estimated activity of Δ9-desaturases and progesterone of Δ5-desaturase in BCO group, with no effects in INT rats., S. Petrović, M. Takić, A. Arsić, V. Vučić, D. Drakulić, M. Milošević, M. Glibetić., and Obsahuje bibliografii
The objective of this study was to investigate a response to low-light environments in hybrids and commercial cultivars of Boehmeria nivea L. Two hybrids (Chuanzhu 11 and Chuanzhu 8) and two commercial cultivars (Chuanzhu 12 and Chuanzhu 6) of ramie were subjected to a shade treatment for 6, 12, and 18 days. The shade treatment led to a significant decrease in some plant traits and fiber yield in four ramie cultivars, whereas their leaf area and plant height increased. In addition, net photosynthesis and stomatal conductance significantly declined in response to shade, while transpiration rate and intercellular CO2 did not significantly change. Moreover, chlorophyll (Chl) and carotenoid (Car) concentration, Chl/Car, and Chl (a+b) per leaf dry mass significantly increased in the response to shade, while the Chl a/b ratio decreased. Furthermore, Chuanzhu 6 and Chuanzhu 11 were more tolerant to shade than Chuanzhu 12 and Chuanzhu 8, thus, they could be potentially used for management practices and breeding programs., C.-J. Huang, G. Wei, Y.-C. Jie, J.-J. Xu, S. A. Anjum, M. Tanveer., and Seznam literatury
Little is known regarding to impact of simulated shading conditions on cotton yield and fiber quality at different fruiting positions. In this 2-year study, our field experiments investigated the effects of shading percentage on the cotton yield, fiber properties, photosynthesis, and carbohydrate concentrations in boll's subtending leaves during various growing stages at different fruiting positions (FP). Net photosynthetic rate and effective quantum yield of PSII photochemistry decreased in response to shading on both FP1 and FP3 of the 7th sympodial branches, respectively. Shading also reduced sucrose and starch contents of leaves at each fruiting position. Shading decreased the number and mass of cotton bolls, the fiber strength and micronaire, while the fiber length increased at both fruiting positions. Our results suggested that shading resulted in the reduction of the cotton yield and fiber quality, which are mainly associated with the changes in boll number and alteration of photosynthesis and carbohydrate concentrations during the boll development., B. L. Chen, H. K. Yang, Y. N. Ma, J. R. Liu, F. J. Lv, J. Chen, Y. L. Meng, Y. H. Wang, Z. G. Zhou., and Obsahuje bibliografii