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162. Lantana camara L.: a weed with great light-acclimation capacity

Creator:
Carrión-Tacuri, J., Rubio-Casal, A. E., de Cires, A., Figueroa, M. E., and Castillo, J. M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, chlorophyll fluorescence, gas exchange, leaf growth rate, light acclimation, photosynthetic pigments, and trade-off
Language:
Multiple languages
Description:
Plant invasions may be limited by low radiation levels in ecosystems such as forests. Lantana camara has been classified among the world's 10 worst weeds since it is invading many different habitats all around the planet. Morphological and physiological responses to different light fluxes were analyzed. L. camara was able to acclimate to moderately shaded environments, showing a high phenotypic plasticity. Morphological acclimation to low light fluxes was typified by increasing leaf size, leaf biomass, leaf area index and plant height and by reduced stomatal density and leaf thickness. Plants in full sunlight produced many more inflorescences than in shaded conditions. Physiological acclimation to low radiation levels was shown to be higher stomatal conductance, higher net photosynthetic rates and higher efficiency of photosystem II (PSII). L. camara behaves as a facultative shade-tolerant plant, being able to grow in moderately sheltered environments, however its invasion could be limited in very shady habitats. Control efforts in patchy environments should be mainly directed against individuals in open areas since that is where the production of seeds would be higher and the progress of the invasion would be faster. and J. Carrión-Tacuri ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

163. Leaf area expansion and net photosynthetic rate of three bromegrass (Bromus) species

Creator:
Biligetu, B. and Coulman, B.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, bromegrass, forage, and regrowth
Language:
Multiple languages
Description:
This study measured individual leaf area expansion rate and leaf net photosynthetic rate (PN) of meadow bromegrass (Bromus riparius Rehm.), smooth bromegrass (Bromus inermis Leyss.) and hybrid bromegrass (B. riparius × B. inermis). Smooth bromegrass expanded individual leaf area 1.5 times faster than meadow bromegrass and hybrid bromegrass. PN was highest in smooth bromegrass, intermediate in hybrid bromegrass, and lowest in meadow bromegrass. Rapid growth of meadow bromegrass following defoliation compared to smooth bromegrass and hybrid bromegrass could not be explained by higher rates of these measured characteristics. and B. Biligetu, B. Coulman
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

164. Leaf area prediction for corn (Zea mays L.) cultivars with multiregression analysis

Creator:
Oner, F., Odabas, M. S., Sezer, I., and Odabas, F.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, leaf area, multiregression analysis, and Zea mays L.
Language:
Multiple languages
Description:
Leaf area is one of the most important parameter for plant growth. Reliable equations were offered to predict leaf area for Zea mays L. cultivars. All equations produced for leaf area were derived as affected by leaf length and leaf width. As a result of ANOVA and multiregression analysis, it was found that there was a close relationship between actual and predicted growth parameters. The produced leaf-area prediction model in the present study is LA = a + b L + c W + d LZ where LA is leaf area, L is leaf length, W is maximum leaf width, LZ is leaf zone and a, b, c, d are coefficients. R2 values were between 0.88-0.97 and standard errors were found to be significant at the p<0.001 significance level. and F. Oner ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

165. Leaf cuticular waxes and physiological parameters in alfalfa leaves as influenced by drought

Creator:
Ni, Y., Guo, Y. J., Han, L., Tang, H., and Conyers, M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, drought resistance, lucerne, photosynthesis, stomatal conductance, 2, and 58
Language:
Multiple languages
Description:
Drought significantly constrains higher yield of alfalfa (Medicago sativa L.) in arid and semiarid areas all over the world. This study evaluated the responses of leaf cuticular wax constituents to drought treatment and their relations to gas-exchange indexes across six alfalfa cultivars widely grown in China. Water deficit was imposed by withholding water for 12 d during branching stage. Cuticular waxes on alfalfa leaves were dominated by primary alcohols (41.7-54.2%), alkanes (13.2-26.9%) and terpenes (17.5-28.9%), with small amount of aldehydes (1.4-3.4%) and unknown constituents (4.5-18.4%). Compared to total wax contents, the wax constituents were more sensitive to drought treatment. Drought decreased the contents of primary alcohol and increased alkanes in all cultivars. Alkane homologs, C25, C27, and C29, were all negatively correlated with photosynthetic rate, transpiration rate, stomatal conductance, and leaf water potential. Under drought conditions, both stomatal and nonstomatal factors were involved in controlling water loss from alfalfa leaves. No direct relationship was observed between wax contents and drought resistance among alfalfa cultivars. An increase in alkane content might be more important in improving drought tolerance of alfalfa under water deficit, which might be used as an index for selecting and breeding drought resistant cultivars of alfalfa., Y. Ni ... [et al.]., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

166. Leaf development, gas exchange characteristics, and photorespiratory activity in maize seedlings

Creator:
Kutschera, U., Pieruschka, R., and Berry, J. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, leaf development, maize seedlings, photorespiration, and photosynthesis
Language:
Multiple languages
Description:
Five decades ago, a novel mode of CO2 assimilation that was later described as C4-photosynthesis was discovered on mature leaves of maize (Zea mays L.) plants. Here we show that 3- to 5-day-old developing maize leaves recapitulate the evolutionary advance from the ancient, inefficient C3 mode of photosynthesis to the C4 pathway, a mechanism for overcoming the wasteful process of photorespiration. Chlorophyll fluorescence measurements documented that photorespiration was high in 3-day-old juvenile primary leaves with non-specialized C3-like leaf anatomy and low in 5-day-old organs with the typical "Kranz-anatomy" of C4 leaves. Photosynthetic gas (CO2)-exchange measurements on 5-day-old leaves revealed the characteristic features of C4 photosynthesis, with a CO2 compensation point close to zero and little inhibition of photosynthesis by the normal oxygen concentration in the air. This indicates a very low photorespiratory activity in contrast to control experiments conducted with mature C3 sunflower (Helianthus annuus L.) leaves, which display a high rate of photorespiration. and U. Kutschera ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

167. Leaf morphological and ultrastructural performance of eggplant (Solanum melongena L.) in response to water stress

Creator:
Fu, Q. S., Yang, R. C., Wang, H. S., Zhao, B., Zhou, C. L., Ren, S. X., and Guo, Y.-D.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, eggplant, stomata, trichome, ultrastructure, water stress, 2, and 58
Language:
Multiple languages
Description:
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
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

168. Leaf shape alters the coefficients of leaf area estimation models for Saussurea stoliczkai in central Tibet

Creator:
Wang, Z. and Zhang, L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, alpine grassland, altitude, leaf area, leaf length and width, nondestructive methods, 2, and 58
Language:
Multiple languages
Description:
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
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

169. Light acclimation at the end of the growing season in two broadleaved oak species

Creator:
Cano, F. J., Sánchez-Gómez, D., Gascó, A., Rodríguez-Calcerrada, J., Gil, L., Warren, C. R., and Aranda, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, hydraulic conductivity, internal conductance, light acclimation, mature leaves, Quercus petraea, and Quercus pyrenaica
Language:
Multiple languages
Description:
The ability of plants to increase their net CO2 assimilation rate in response to increased irradiance is due to morphological and physiological changes, which might be related to their shade tolerance and leaf ontogeny, but few studies have considered morphology and physiology. Two sympatric oak species (the shade-tolerant Q. petraea and the comparatively shade-intolerant Q. pyrenaica) were grown in hydroponic solution in low-light (LL) and high-light (HL) conditions. 5 months after leaf expansion under these conditions, half of the LL plants were transferred to high light (TLH). Transfer of Q. pyrenaica, from low- to high light led to photoinhibition and after 21 days in higher light there was little acclimation of the maximum rate of carboxylation (VCmax) or the maximum rate of electron transport (Jmax). Q. pyrenaica TLH plants showed lower stomatal conductance at all times compared to plants growing in LL. Stomatal closure was the main limitation to photosynthesis after transfer in Q. pyrenaica. The increase in evaporative demand upon TLH did not affect hydraulic conductivity of Q. pyrenaica. In contrast, the more shade-tolerant Q. petraea showed a greater degree of acclimation of gas exchange in TLH than Q. pyrenaica and two weeks after transfer gas-exchange rates were as high as in LL plants. In Q. petraea, the most important changes occurred at the level of leaf biochemistry with significant increase in VCmax that decreased the Jmax/VCmax ratio below values recorded in HL plants. However, this potential increase in photosynthesis was at least partially hamstrung by a decrease in internal conductance, which highlights the importance of internal conductance in acclimation to higher light in mature leaves. Neither oak species reached the photosynthetic rates of HL plants; however a trend towards leaf acclimation was observed in Q. petraea while the transfer was harmful to the leaves of Q. pyrenaica developed in the shade. and F. J. Cano ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

170. Light distribution in leaf chambers and its consequences for photosynthesis measurements

Creator:
Hogewoning, S. W., Trouwborst, G., Harbinson, J., and van Ieperen, W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, gas exchange, heterogeneity, leaf chamber, light distribution, photosynthesis, and photosynthetic quantum yield
Language:
Multiple languages
Description:
The impact of a heterogeneous distribution of actinic light within a leaf chamber for photosynthetic measurements by gas exchange on the photosynthesis-irradiance relationship was investigated. High-resolution light distributions were measured over the area of a commercially available clamp-on leaf chamber equipped with build-in red and blue LEDs, as well as over the area of a custom-made leaf chamber with external light source, using a low-cost digital camera and freely available software. The impact of the measured heterogeneity on the photosynthesis-irradiance response curve was calculated for two realistic scenarios. When the average light intensity over the leaf chamber area was estimated accurately, heterogeneity had minor effects on the photosynthesis-irradiance response curve. However, when the irradiance was measured in the chamber centre, which is common practice, and assumed to be homogeneous, for both leaf chambers the photosynthesis-irradiance response curve was subject to considerable error and led to serious underestimation of the light-limited quantum yield of photosynthesis. Additionally, mixed light sources with different heterogeneity patterns per light source, such as in the clamp-on leaf chamber, potentially increase errors due to heterogeneous physiological responses to light spectrum. High-resolution quantification of the leaf-chamber light distribution enables calculation of the correct average light intensity and already resolves the most pressing problems associated with heterogeneity. To exclude any light-distribution related errors in gas-exchange measurements a leaf chamber and actinic irradiance source design with a homogeneous light distribution is an absolute requirement. and S. W. Hogewoning ...[et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public