Three prevalent aliphatic polyamines (PAs) include putrescine, spermidine, and spermine; they are low-molecular-mass polycations involved in many physiological processes in plants, especially, under stressful conditions. In this experiment, three bean (Phaseolus vulgaris L.) genotypes were subjected to well-watered conditions and two moderate and severe water-stressed conditions with and without spermidine foliar application. Water stress reduced leaf relative water content (RWC), chlorophyll contents, stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate, maximal quantum yield of PSII (Fv/Fm), net photosynthetic rate (PN), and finally grain yield of bean plants. However, spermidine application elevated RWC, gs, Ci, Fv/Fm, and PN, which caused an increase in the grain yield and harvest index of bean plants under water stress. Overall, exogenous spermidine could be utilized to alleviate water stress through protection of photosynthetic pigments, increase of proline and carotenoid contents, and reduction of malondialdehyde content., S. Torabian, M. R. Shakiba, A. Dabbagh Mohammadi Nasab, M. Toorchi., and Obsahuje bibliografii
Species of the Theobroma genus are primarily known by their commercially valuable seeds, especially, T. cacao is one of the most important tropical perennial crops. Beside T. grandiflorum, T. bicolor, and T. angustifolium, T. cacao is the only species of the genus that has been better studied to obtain physiologically relevant information. The main objective of this work was to evaluate the leaf gas exchange in seedlings of seven species of the Theobroma genus, seeking to identify characteristics that could be used in T. cacao breeding programmes. The study was realized under greenhouse conditions using six-month-old seedlings, in which net photosynthetic rate (PN), stomatal conductance (gs), transpiration (E), as well as parameters derived from light curves (PN vs. photosynthetically active radiation) were evaluated. T. cacao, along with T. microcarpum, showed the lowest values of PN, gs, and E, while the highest values were presented by T. speciosum, which showed higher saturation irradiance and lower intrinsic and instantaneous water-use efficiencies, being considered the species less conservative in water use. Therefore, the parameters shown by the different evaluated species could serve to design T. cacao genotypes, through introgression of genes for specific environments such as the cabruca system widespread in southern Bahia, Brazil., A.-A. F. Almeida, F. P. Gomes, R. P. Araujo, R. C. Santos, R. R. Valle., and Obsahuje bibliografii
Growth and physiological responses of cotton (Gossypium hirsutum L.) cultivars with different phosphorus (P) efficiencies under variable P environment are poorly known. Therefore, this study explored effects of normal P [P+, 70 kg(P2O5) ha-1] and without P (P-, 0 kg ha-1) on yield, growth, and physiology of different P-efficient cultivars [low-efficient Xinluzao 13 (L1) and Xinluzao 26 (L2); medium-efficient Xinluzao 10 (M1) and Xinluzao 24 (M2);
high-efficient Zhongmiansuo 42 (H1) and Xinluzao19 (H2)]. Cotton growth and yield was higher in H1 and H2 cultivars under P+ compare to P-. Leaf photosynthesis, intercellular CO2 concentration, stomatal conductance, and net assimilation rate increased under P+ and in high-efficient cultivars. Greater Rubisco activity and higher soluble sugar content further promoted P uptake and utilization efficiency which resulted in a higher yield under normal P+ than that at P- treatment. High-P-efficient cultivars have the potential to increase the yield by improving cotton growth and physiological attributes under P+., J. Wang, Y. Chen, P. Wang, Y. S. Li, G. Wang, P. Liu, A. Khan., and Obsahuje bibliografii
The effects of water stress on leaf surface morphology (stomatal density, size, and trichome density of both adaxial and abaxial surfaces) and leaf ultrastructure (chloroplasts, mitochondria, and cell nuclei) of eggplant (Solanum melongena L.) were investigated in this study. Higher stomata and trichome densities were observed on abaxial surface compared with the adaxial surface. Compared with well watered (WW) plants, the stomata and trichome density of the abaxial surface increased by 20.39% and 26.23% under water-stress condition, respectively. The number of chloroplasts per cell profile was lesser, the chloroplasts became round in a shape with more damaged structure of membranes, the number of osmiophilic granules increased, and the number of starch grains decreased. The cristae in mitochondria were disintegrated. The cell nuclei were smaller and the agglomerated nucleoli were bigger than those of WW plants. Our results indicated that the morphological and anatomical responses enhanced the capability of plants to survive and grow during stress periods., Q. S. Fu ... [et al.]., and Obsahuje bibliografii
The objective of this study was to evaluate the response of the giant reed (Arundo donax L.) to drought stress at early stages, as well as to determine the effects of limited soil water availability on plant growth, gas exchange, and water-use efficiency. Plantlets of a commercial clone were grown in a greenhouse under two water treatments: at 100% of field capacity and progressive drought for 66 days (until 20% of field capacity). Soil water content, leaf elongation rate, plant water consumption, and gas-exchange parameters were measured throughout the experiment. Total plant biomass, leaf water, and osmotic potential were determined at the end of the experiment. Plant growth and leaf gas-exchange parameters were significantly affected by soil water availability, but only when it was below 40% of field capacity. At early stages, Arundo donax showed drought stress acclimation due to leaf plasticity, stomatal regulation, and osmotic adjustment., A. Romero-Munar, E. Baraza, J. Cifre, C. Achir, J. Gulías., and Obsahuje bibliografii
Nondestructive methods to estimate individual leaf area (LA) accurately, by leaf length (L) and/or width (W), is helpful for the in situ and successive LA measurements. However, leaf shape and size may covary with environment and thus alter the coefficients of LA estimation models. To test such hypothesis, we carried out an experiment by measuring Saussurea stoliczkai C. B. Clarke leaves along an altitudinal transect in Damxung county, central Tibet. In July 2011, we selected seven sites at about every 150 m in altitude from 4,350 m to 5,250 m a.s.l. A total of 1,389 leaves (182 to 203 leaves for each site) were measured. For each site, models developed by two leaf dimensions [LA = a (L×W) + b] could estimate LA more accurately than those by single dimension. L, W, LA and leaf shape index (L:W ratio) all decreased with increasing altitude, leading to significant differences in coefficients of two-dimension model between almost every two sites. Accordingly, a common
two-dimension model is unlikely to occur for S. stoliczkai across the whole altitudinal transect, indicating that the varying leaf shape may alter the coefficient of LA estimation models., Z. Wang, L. Zhang., and Obsahuje bibliografii
Tropical rainforest trees adjust leaf traits during ontogeny to cope with changes in the physical environment and maximize their carbon uptake. The aim of this study was to determine the plasticity index (PI) of leaf traits in understory and canopy leaves of six Amazonian tree species. In four of the six species the PI of leaf traits varied within species, and in four of the ten leaf traits assessed, the PI differed between species. The greatest PI values were found for stomatal density (Ds) and CO2-saturated photosynthesis, and the lowest ones were found for stomatal size, and leaf thickness. Despite the differences in PI values within species, the mean PI was similar in all the six species. As the saplings grow toward the canopy, the strategy to increase carbon uptake involves increasing Ds and leaf nitrogen and reducing stomatal size., R. A. Marenco, M. A. B. Camargo, S. A. Antezana-Vera, M. F. Oliveira., and Obsahuje seznam literatury
Global climate change may act as a potent agent of natural selection within species with Mediterranean mountain ecosystems being particularly vulnerable. The aim of this research was to analyze whether the phenotypic plasticity of Sesleria nitida Ten. could be indicative of its future adaptive capability to global warming. Morphological, anatomical, and physiological leaf traits of two populations of S. nitida growing at different altitudes on Mount Terminillo (Italy) were analyzed. The results showed that leaf mass per unit leaf area, leaf tissue density, and total leaf thickness were 19, 3, and 31% higher in leaves from the population growing at 1,895 m a.s.l. (B site) than in leaves from the population growing at 1,100 m a.s.l. (A site), respectively. Net photosynthetic rate (PN) and respiration rate (RD) peaked in June in both A and B leaves [9.4 +- 1.3 μmol(CO2) m-2 s-1 and 2.9 +- 0.9 μmol(CO2) m-2 s-1, respectively] when mean air temperature was 16 +- 2°C. R D/P N was higher in B than in A leaves (0.35 +- 0.07 and 0.21 +- 0.03, respectively, mean of the study period). The mean plasticity index (PI = 0.24, mean of morphological, anatomical, and physiological leaf traits) reflected S. nitida adaptability to the environmental stress conditions at different altitudes on Mount Terminillo. Moreover, the leaf key traits of the two populations can be used to monitor wild populations over a long term in response to global change., L. Gratani, M. F. Crescente, V. D’Amato, C. Ricotta, A. R. Frattaroli, G. Puglielli., and Obsahuje bibliografii
Using measures of gas exchange and photosynthetic chain activity, we found some differences between grapevine inflorescence and leaf in terms of photosynthetic activity and photosynthesis regulations. Generally, the leaf showed the higher net photosynthesis (PN) and lower dark respiration than that of the inflorescence until the beginning of the flowering process. The lower (and negative) PN indicated prevailing respiration over photosynthesis and could result from a higher metabolic activity rather than from a lower activity of the photosynthetic apparatus. Considerable differences were observed between both organs in the functioning and regulation of PSI and PSII. Indeed, in our conditions, the quantum yield efficiency and electron transport rate of PSI and PSII were higher in the inflorescence compared to that of the leaf; nevertheless, protective regulatory mechanisms of the photosynthetic chain were clearly more efficient in the leaf. This was in accordance with the major function of this organ in grapevine, but it highlighted also that inflorescence seems to be implied in the whole carbon balance of plant. During inflorescence development, the global PSII activity decreased and PSI regulation tended to be similar to the leaf, where photosynthetic activity and regulations remained more stable. Finally, during flowering, cyclic electron flow (CEF) around PSI was activated in parallel to the decline in the thylakoid linear electron flow. Inflorescence CEF was double compared to the leaf; it might contribute to photoprotection, could promote ATP synthesis and the recovery of PSII., M. Sawicki, B. Courteaux, F. Rabenoelina, F. Baillieul, C. Clement, E. Ait Barka, C. Jacquard, N. Vaillant-Gaveau., and Obsahuje bibliografii
Tropical canopy tree species can be classified into two types by their heterobaric and homobaric leaves. We studied the relation between both leaf types and their water use, together with the morphological characteristics of leaves and xylem, in 23 canopy species in a tropical rain forest. The maximum rates of photosynthesis and transpiration were significantly higher in heterobaric leaf species, which also underwent larger diurnal variations of leaf water potential compared to homobaric leaf species. The vessel diameter was significantly larger and the stomatal pore index (SPI) was significantly higher in heterobaric than that in homobaric leaf species. There was a significant positive correlation between the vessel diameter, SPI, and maximum transpiration rates in all the studied species of both leaf types. However, there was no significant difference in other properties, such as leaf water-use efficiency, leaf mass per area, leaf nitrogen content, and leaf δ13C between heterobaric and homobaric leaf species. Our results indicate that leaf and xylem morphological differences between heterobaric and homobaric leaf species are closely related to leaf water-use characteristics, even in the same habitat: heterobaric leaf species achieved a high carbon gain with large water use under strong light conditions, whereas homobaric leaf species can maintain a high leaf water potential even at midday as a result of low water use in the canopy environment., Y. Inoue, T. Kenzo, A. Tanaka-Oda, A. Yoneyama, T. Ichie., and Obsahuje bibliografii