Increase in salinity is predicted to affect plant growth and survival in most arid and semiarid regions worldwide. Mitragyna parvifolia (Roxb.) Korth. is an important medicinal tree species distributed throughout the semiarid regions of India; however, it is facing a threat of its extinction in its natural habitat. We examined the effects of increasing NaCl salinity on two-month-old M. parvifolia seedlings grown in an environment-controlled chamber and exposed to soils of different electrical conductivity (EC) caused by NaCl [0-5 (control), 5-10, 10-15, 15-20, and 20-25 dS m-1)] for 85 days. Seedlings transferred to soil of EC >15 dS m-¹ did not survive beyond 1 week. Increase in the Na+ concentration negatively correlated with their height and positively correlated with their water-use efficiency (WUE). However, leaf area, net photosynthetic rate (PN), stomatal conductance, and transpiration rate showed varying correlations and an overall decrease in these parameters compared with the control. At EC of 10-15 dS m-1, the seedling height was reduced by 37% and PN was lowered by 50% compared with those of the control. An increase in the Na+/K+ ratio was observed with increasing salinity. The maximum quantum efficiency of PSII significantly decreased with increasing salinity compared with the control. Our results suggest that the increase in salinity reduced the overall performance of the M. parvifolia seedlings. However, the maintenance of WUE and maximum quantum efficiency of PSII might help M. parvifolia to tolerate NaCl salinity of 15 dS m-1., A. Bidalia, M. Hanief, K. S. Rao., and Obsahuje bibliografii
Clinical and experimental studies have repeatedly indicated that overloaded hearts have a higher vulnerability to ischemia/reperfusion injury. The aim of the present study was to answer the question whether the degree of tolerance to oxygen deprivation in hearts of spontaneously hypertensive rats (SHR) may be sex-dependent. For this purpose, adult SHR and their normotensive control Wistar Kyoto (WKY) rats were used. The isolated hearts were perfused according to Langendorff at constant pressure (proportionally adjusted to the blood pressure in vivo). Recovery of contractile parameters (left ventricular systolic, diastolic and developed pressure as well as the peak rate of developed pressure) was measured during reperfusion after 20 min of global no-flow ischemia in 5 min intervals. Mean arterial blood pressure was measured by direct puncture of carotid artery under light ether anesthesia in a separate group of animals. The degree of hypertension was comparable in both sexes of SHR. The recovery of contractile functions in SHR males and females was significantly lower than in WKY rats during the whole investigated period. There was no sex difference in the recovery of WKY animals; on the other hand, the recovery was significantly better in SHR females than in SHR males. It may be concluded that the hearts of female SHR are more resistant to ischemia/reperfusion injury as compared with male SHR. This fact could have important clinical implications for the treatment of cardiovascular disease in women., J. Bešík, O. Szárszoi, J. Kuneš, I. Netuka, J. Malý, F. Kolář, J. Pirk, B. Ošťádal., and Obsahuje bibliografii a bibliografické odkazy
This study investigated whether gas exchange and the present content of antioxidant compounds can contribute to the survival of Euterpe oleracea plants in environments of frequent waterlogging. A factorial randomised, experimental design included two distinct water conditions (waterlogging and control) and five evaluation times (0, 6, 12, 18, and 24 d). Gasexchange parameters, leaf temperature, electrolyte leakage, and contents of antioxidant compounds were measured. Waterlogging did not promote significant alterations in net photosynthetic rate and transpiration, and stomatal conductance was reduced only after 18 d. Malondialdehyde and glutathione contents did not significantly change during waterlogging. Additionally, electrolyte leakage was significant only after 18 d of waterlogging. Thus, this study revealed that maintenance in gas exchange and antioxidant compounds might contribute to the survival of E. oleracea plants in environments exposed to waterlogging., T. S. Pereira, A. K. S. Lobato, G.A.R. Alves, R.N. Ferreira, O.N. Silva, A. P. Martins Filho, E.S. Pereira, L.S. Sampaio., and Obsahuje bibliografii
Intercropping is a sustainable agricultural practice used worldwide for highly efficient utilization of resources. However, short crops often grow under the shade of the canopy of tall crops in intercropping systems. Plants evolved two main strategies to deal with shade: avoidance and tolerance. Soybean (Glycine max), a legume crop, is often planted in intercropping. But little is known about a strategy that soybean may employ to deal with shade at seedling stage. Therefore, we determined morphological and physiological traits related to shade tolerance and shade avoidance in seedlings of two varieties. Generally, both varieties showed similar shade tolerance traits, such as increased specific leaf area and chlorophyll (Chl) content, and reduced photosynthetic capacity and the Chl a/b ratio. The light-limiting environment eliminated the benefits of shade tolerance traits for the carbon gain, which led to similar real-time photosynthesis and biomass in intercropping. By contrast, two varieties expressed different changes in shade avoidance traits. The variety Guixia 3 exhibited clear preference of shade avoidance that resulted in a high main stem, hypocotyl elongation, and biomass allocation towards the stem. The variety Gongxuan 1 showed those traits less. We suggested that the genetic variation occurs within soybean, thus the shade avoidance related traits might be important for variety selection for intercropping. Hence, the evaluation of performance should focus on shade avoidance in soybean genotypes in future experiments., W. Z. Gong, C. D. Jiang, Y. S. Wu, H. H. Chen, W. Y. Liu, W. Y. Yang., and Obsahuje bibliografii