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3062. Leaf gas exchange in species of the Theobroma genus
- Creator:
- Almeida, A.-A. F., Gomes, F. P., Araujo, R. P., Santos, R. C., and Valle, R. R.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, Bahía (Brazílie), Bahía (Brazil), light-response curves, stomatal conductance, transpiration, water-use efficiency, 2, and 581
- Language:
- Multiple languages
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3063. Leaf gas exchange of Pachyrhizus ahipa and P. erosus under water and temperature stress
- Creator:
- Leidi, E. O.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon isotope discrimination, photosynthesis, stomatal conductance, transpiration, water-use efficiency, and yambean
- Language:
- Multiple languages
- Description:
- Gas exchange, water relations, and leaf traits were studied in the tuberous-root producing legumes ahipa (Pachyrhizus ahipa) and yambean (P. erosus) under different environmental conditions. Differences in leaf traits (hairiness, leaf area, areal leaf mass, stomatal density) and paraheliotropism were found between ahipa and yambean. Under sufficient water supply, the increase in air temperature and decrease in air humidity increased stomatal conductance (gs) and net photosynthetic rate (PN) in yambean but reduced them in ahipa. In a drying soil (14 d after irrigation), inter-specific variation in gas exchange was only observed in the early morning, and yambean showed a greater sensitivity to water restriction than ahipa. High gs at low humidity increased PN of P. erosus but resulted in lower water-use efficiency (WUE). However, long-term WUE, estimated by leaf carbon isotope discrimination, showed little variation between species. Daily-irrigated ahipa and yambean grown in the greenhouse did not show significant differences in gas exchange. However, leaf temperature was significantly greater in yambean than in ahipa while a steepper relationship between E and PN and gs was observed in ahipa.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3064. Leaf gas exchange, chlorophyll fluorescence and growth responses of Melaleuca alternifolia seedlings to flooding and subsequent recovery
- Creator:
- Jing, Y. X., Li, G. L., Gu, B. H., Yang, D. J., Xiao, L., Liu, R. X., and Peng, C. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, flooding, leaf gas exchange, Melaleuca alternifolia, and recovery
- Language:
- Multiple languages
- Description:
- Periodic flooding of trees in tropical floodplains and reservoirs where water levels fluctuate is a common phenomenon. The effects of flooding and subsequent recovery on gas exchange, chlorophyll fluorescence and growth responses of Melaleuca alternifolia seedlings, a tall shrub species used in floodplain and reservoir forest restoration in southern China, were studied during a grow season (from March to December in 2007). M. alternifolia seedlings were flooded for 180 days, drained and left to recover for another 60 days. Survival rates of the seedlings were 100% during the 180-day flooding period. Chlorophyll (Chl) content, net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) of the flooded seedlings were all significantly lower than those of the control. Significant reductions of photochemical quenching coefficient (qp) and increases of nonphotochemical quenching (NPQ) in the flooded seedlings were observed. However, there were no significant differences in the maximal quantum yield of PSII photochemistry (Fv/Fm) between treatments. All seedlings survived during the two-month recovery period after the flooded treatment was drained, and the biomass and height of the recovered seedlings approached those of the control at the end of the experiment. During the first-month recovery period, Chl content, PN, gs and E in the recovered seedlings were all obviously low, then increased gradually and rose to the levels similar to the control by the end of the experiment. Quenching analysis revealed significant reductions of qp and increments of NPQ in the recovered seedlings at the beginning of draining, and a nearly complete recovery for both parameters by the end of the experiment. However, Fv/Fm of the recovered seedlings did not differ significantly from the control during the recovery period. Our study demonstrated that M. alternifolia seedlings can survive and grow through 180 days of flooding with a subsequent 60-day recovery period in drained conditions, indicating that seedlings of this species would be suitable for afforestation in areas exposed to intermittent flooding. and Y. X. Ying ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3065. Leaf gas exchange, phosphorus uptake, growth and yield responses of cotton cultivars to different phosphorus rates
- Creator:
- Wang, J., Chen, Y., Wang, P., Li, Y. S., Wang, G., Liu, P., and Khan, A.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- enzymatická aktivita, index listové plochy, fotosyntéza, enzymatic activity, leaf area index, photosynthesis, net assimilation rate, photosynthetic pigments, 2, and 581
- Language:
- Multiple languages
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3066. Leaf longevity, construction, and maintenance costs of three mangrove species under field conditions
- Creator:
- Suárez, N.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Avicennia germinans, heat of combustion, Laguncularia racemosa, leaf age, leaf half lifetime, Rhizophora mangle, and salinity
- Language:
- Multiple languages
- Description:
- This study assessed the effect of leaf age on construction cost (CC) in the mangrove species Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle growing in their natural habitat. Leaf osmolality values were species-specific, the highest in A. germinans (1 693 mmol kg-1) and the lowest in L. racemosa (1 270 mmol kg-1). In the three species, contents of chlorophyll (a+b) (Chla+b) and nitrogen (N) per unit of leaf area were maximal in adult leaves and tended to decline with age. Leaf mass to leaf area ratio (LMA) and ash content increased during leaf ageing. Similarly, as leaves aged, a significant increase in leaf construction cost per leaf area (CCa) was observed, while per leaf mass (CCm) it remained almost constant, suggesting a sustained production of leaf compounds as leaves became older. CC was positively correlated with LMA and heat of combustion (Hc) per leaf area, suggesting differences among species in the quantity and composition of expensive compounds. Leaf half lifetime (t0.5) showed contrasting values in the three mangrove species (60, 111, and 160 d in L. racemosa, R. mangle, and A. germinans, respectively). Overall, L. racemosa was the species with less expensive leaves to construct while leaves of A. germinans and R. mangle had the highest CCm and CCa, respectively. Leaf longevity was positively correlated with the ratio between CC and maximum photosynthetic rate (Pmax), clearly showing the existence of a balance between leaf costs and benefits.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3067. 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
3068. Leaf phosphate status and photosynthesis in vivo: changes in sugar phosphates, adenylates and nicotinamide nucleotides during photosynthetic induction in sugar beet
- Creator:
- Madhusudana Rao, I. and Terry, N.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers. Leaf orthophosphate levels were varied nutritionally. The effect of decreased leaf phosphate (low-P) status was determined on the rate of photosynthesis (PN) and on pool sizes of leaf ribulose-l,5-bisphosphate (RuBP), 3-phosphoglycerate (PGA), triose phosphate (triose-P), fructose-1,6-bisphosphate (FBP), fructose-6-phosphate (F6P), glucose-6-phosphate (G6P), adenylates and nicotinamide nucleotides during photosynthetic induction (measured at 0, 1.5, 5 and 30 min from irradiation). p N reached 50 % of its final value in 4 min in control leaves and 10 min in low-P leaves. Hence the increase in the length of induction period in low-P leaves was most likely due to a slow build-up in RuBP: ATP, NADPH, PGA, and FBP all reached high levels in 5 min at which time RuBP was half and PN 16 % of their eventual values at 30 min. The slow-build-up of RuBP did not appear to be due to insufficient ATP and NADPH for the conversion of PGA to triose-P; rather, low-P seemed to limit photosynthetic induction somewhere in the sequence of reactions between triose-P and RuBP formation.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3069. Leaf photosynthesis and chlorophyll fluorescence in a chlorophyll-deficient soybean mutant
- Creator:
- Xu, D. Q., Chen, X. M., Zhang, L. X., Wang, R. F., and Hesketh, J. D.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- A comparative study of chlorophyll (Chl) fluorescence characteristics was made between a soybean [Glycine max (L.) Merr.] Chl-deficient mutant (light green leaf, LG, Eji^ii), and a nearly isogenic Chl normál biotype (dark green leaf, DG, EnEn) of cultivar Clark, LG had a lower light-saturated net photosynthetic rate (/^n), compared with DG at early stages of growth (before pod filling), but the difference in Ejsi between LG and DG became smaller at later stages of growth. The lower of LG may result from lower Chl content (Chl a and b), lower carboxylation efficiency, and lower photochemical efficiency of photosystem 2. Both LG and DG grown at low iradiance [about 200-300 pmol(photon) m'^ s"’] in a growth cabinet had similar photochemical effíciencies. However, the efficiency was lower in LG than in DG grown in field sunlight in mid summer, especially during the aftemoon on clear days, indicating that LG is more sensitive to photoinhibition.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3070. Leaf photosynthesis is resistant to a mild drought stress
- Creator:
- Cornic, G., Ghashghaie, J., Genty, B., and Briantais, J.-M.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- When a terrestňal plant is subjected to a mild drought stress, the leaf net CO2 uptake declines as a result of the stomatal closure. In contrast to previous beliefs the photosynthetic apparatus is vety resistant to dehydration. Particularly the relations between photochemistry, its regulation and leaf CO2 assimilation (f) are identical when F is changed either by increasing leaf water deficit or by decreasing the ambient CO2 concentration. When the stomata close in a leaf under water deficit the CO2 concentration within the leaf declines. As a result photorespiration is favoured, the photochemical yield of open photosystem 2 (PS 2) centres and the activity of some enzymes dechne (sucrose-phosphate synthase, nitráte reductase). The dechne of photochemical yield of PS 2 is consequential to an increase in thermal dissipation of the excitons trapped by PS 2 units. The dechne in CO2 concentration occurring in a desiccating leaf may trigger an integrated response of leaf metabohsm which still remains to be explored.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public