Overnight rainfall inducing rapid changes in photosynthetic behaviour in a cerrado woody species during a dry spell amidst the rainy season

2002 ◽  
Vol 50 (2) ◽  
pp. 241 ◽  
Author(s):  
Eduardo A. de Mattos ◽  
Patrícia C. Lobo ◽  
Carlos A. Joly
Keyword(s):  
Gas Exchange ◽  
Rainy Season ◽  
Woody Species ◽  
Co2 Uptake ◽  
Brazilian Cerrado ◽  
Wet Season ◽  
Midday Depression ◽  
Dry Spell ◽  
Rapid Changes ◽  
Net Co2 Uptake

We examined the effects of a short rainfall during a dry spell amidst the rainy season on CO2 and H2O gas exchange and chlorophyll a fluorescence in leaves of Miconia albicans (Sw.) Tr. (Melastomataceae), a common shrub of the Brazilian cerrado. A strong midday depression of gas exchange was observed at the end of the dry spell. Nevertheless, during the day after a rainfall, net CO2 uptake (JCO2), stomatal conductance to water vapour (gs), transpiration rates (JH2O) and the actual photosystem II (PSII) efficiency (ΔF/F´m) increased, whereas the fraction of light absorbed in the PSII antennae that is dissipated directly within the antennae (1 – F´v/F´m) and the degree of PSII closure (1 – qP) decreased. Although CO2 and H2O gas exchange were very sensitive to the rain-free event in the wet season, the occurrence of a small rainfall was enough to elicit rapid changes in gs, JH2O and JCO2. We hypothesise that the strong effect of the dry spell during the wet season on gas exchange may be due to the highest leaf area available for transpiration at this time and a lower hydraulic limit for catastrophic embolism to occur.

scholarly journals Cambial activity in dry and rainy season on branches from woody species growing in Brazilian Cerrado

Flora ◽  
2016 ◽  
Vol 223 ◽  
pp. 1-10 ◽  
Author(s):  
Carmen R. Marcati ◽  
Silvia R. Machado ◽  
Diego Sotto Podadera ◽  
Natalia O. Totti de Lara ◽  
Fabio Bosio ◽  
...  
Keyword(s):  
Rainy Season ◽  
Woody Species ◽  
Cambial Activity ◽  
Brazilian Cerrado

Facultative crassulacean acid metabolism (CAM) in four small C3 and C4 leaf-succulents

2017 ◽  
Vol 65 (2) ◽  
pp. 103 ◽  
Author(s):  
Klaus Winter ◽  
Joseph A. M. Holtum
Keyword(s):  
Gas Exchange ◽  
Crassulacean Acid Metabolism ◽  
Native Species ◽  
Acid Metabolism ◽  
Titratable Acidity ◽  
Co2 Uptake ◽  
Drought Treatment ◽  
Whole Plant ◽  
Type Pattern ◽  
Net Co2 Uptake

Measurements of whole-plant gas exchange and titratable acidity demonstrate that the Australian native species Anacampseros australiana J.M.Black (Anacampserotaceae), Crassula sieberiana (Schult. & Schult.f.) Druce (Crassulaceae) and Portulaca australis Endl. (Portulacaceae) and the widespread naturalised tropical exotic, Portulaca pilosa L., exhibit facultative crassulacean acid metabolism (CAM). In well-watered plants, net CO2 uptake was restricted to the daylight hours and occurred via the C3 pathway (A. australiana and C. sieberiana) or the C4 pathway (P. australis and P. pilosa). Leaves of well-watered plants did not accumulate titratable acidity during the night. Following drought treatment, CO2 uptake in the light by shoots decreased markedly, nocturnal gas-exchange shifted from net CO2 loss to a CAM-type pattern that included net CO2 uptake, and leaves acidified at night. Nocturnal CO2 uptake by shoots and leaf acidification were most pronounced in A. australiana and least so in C. sieberiana. The induction of dark CO2 uptake and tissue acidification was fully reversible in all four species: upon rewatering, nocturnal CO2 uptake and acidification ceased and the rates of CO2 incorporation in the light were restored. We suggest that, hitherto considered relatively exceptional globally, facultative CAM may be more common than previously suspected, particularly among the generally small ephemeral leaf-succulents that characterise Australia’s succulent flora.

Historical aspects and net CO2 uptake for cultivated Crassulacean acid metabolism plants in Mexico

2002 ◽  
Vol 140 (2) ◽  
pp. 133-142 ◽  
Author(s):  
PARK S NOBEL ◽  
EULOGIO PIMIENTA-BARRIOS ◽  
JULIA ZANUDO HERNANDEZ ◽  
BLANCA C RAMIREZ-HERNANDEZ
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Co2 Uptake ◽  
Historical Aspects ◽  
Net Co2 Uptake

Temporal partitioning of reproductive activity in a neotropical anuran community

2004 ◽  
Vol 20 (3) ◽  
pp. 271-280 ◽  
Author(s):  
Brigitte Gottsberger ◽  
Edith Gruber
Keyword(s):  
Water Level ◽  
Rainy Season ◽  
Abiotic Factors ◽  
Reproductive Mode ◽  
Reproductive Activity ◽  
Active Species ◽  
South American ◽  
Wet Season ◽  
Breeding Sites ◽  
Calling Activity

The phenology of calling activity and reproduction of a neotropical anuran community in French Guiana was studied during one rainy season. We investigated the correlation between calling activity, rainfall, temperature and water level in two ponds and recorded the occurrence of tadpoles of pond-breeding species. The study site contained 31 calling frog species, which were divided into groups according to reproductive mode. Increased rainfall was associated with increased reproductive activity in all groups, but temporal patterns in calling activity varied significantly between groups. Species with aquatic oviposition exhibited sporadic acoustic activity, aggregating into explosive breeding events following heavy rainfall. Species laying eggs in foam nests had the peak of calling activity at the start of the rainy season. Taxa with embryonic development on vegetation called mainly from middle to late wet season, being the only group which showed a significant correlation of calling with increasing water level. Dendrobatids with terrestrial oviposition and subsequent parental tadpole transportation were continuously active. Species with direct development or with non-feeding larvae were mainly active at the beginning of the rainy season. It is concluded that phenologies of calling activity in South American tropical anuran species are strongly influenced by abiotic factors like rainfall and availability of breeding sites. The temporal limitation of the rainy season forces species to adjust calling and reproductive activity according to their reproductive modes.

scholarly journals Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

2019 ◽  
pp. 1-11
Author(s):  
Adekunle Titus Adediji ◽  
Joseph Babatunde Dada ◽  
Moses Oludare Ajewole
Keyword(s):  
Rainy Season ◽  
Annual Variation ◽  
Ground Surface ◽  
Local Effect ◽  
Dry Season ◽  
Radio Link ◽  
Wet Season ◽  
Annual Variations ◽  
Microwave Radio

In this study, four years in-situ measurements of atmospheric parameters (pressure, temperature and relative humidity) were carried out. The measurement was by placing an automatic weather station at five different heights: ground surface, 50, 100, 150 and 200 m respectively on a 220 m Nigeria Television Authority TV tower in Akure, South Western Nigeria. The four years Data collected (January 2007 to December 2009 and January to December 2011) were used to compute radio refractivity and its gradient. The local effect of a location/ region cannot but looked into when designing effective radio link, hence the diurnal, seasonal and annual variations of the radio refractivity gradient were studied. Results showed that refractivity gradient steadily increases inthe hour of 8:30 and 9:30 to 18:00 during dry season throughout the years investigated, and decreases two hours in the rainy season than the dry season. The record shows that at 50 m altitude, the maximum and minimum values are 158 N-unit/km around 14:30 and - 286 N-unit/km around 13:30 to 14:00 hrs, LT during the dry and rainy season respectively. Seasonally, refractivity gradient is steeper with greater variability in the dry season months than in the wet season months.

Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns

1999 ◽  
Vol 26 (8) ◽  
pp. 749 ◽  
Author(s):  
Joseph A.M. Holtum ◽  
Klaus Winter
Keyword(s):  
Carbon Isotope ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Dark Period ◽  
Titratable Acidity ◽  
Isotope Ratios ◽  
Light Period ◽  
Co2 Uptake ◽  
Carbon Isotope Ratios ◽  
Net Co2 Uptake

Crassulacean acid metabolism (CAM) was observed in three species of tropical ferns, the epiphytes Microsorium punctatum and Polypodium crassifolium and the lithophyte Platycerium veitchii. Polypodium crassifolium and P. veitchii exhibited characteristics of weak CAM. Although no net nocturnal CO2 uptake was observed, the presence of CAM was inferred from nocturnal increases in titratable acidity of 4.7 and 4.1 µequiv (g fr wt)–1 respectively, a reduction in the rates of net CO2 evolution during the first half of the dark period, and the presence of a CAM-like decrease in net CO2 uptake during the early light period. In M. punctatum net CO2 uptake during the first half of the dark period was accompanied by an increase in titratable acidity of 39.2 µequiv (g fr wt)–1 and a pronounced reduction in net CO2 uptake during the early light period. When water was withheld from P. crassifolium and M. punctatum, net CO2 uptake during the light was reduced markedly but there was no change in the extent or patterns of CO2 exhange in the dark. As a consequence, the proportion of carbon gained due to CO2 fixation in the dark increased from 2.8 and 10% to 63.5 and 49.3%, respectively (100% being net CO2 uptake during the light plus the estimated CO2 uptake during the dark). After 9 days without added water, dark CO2 uptake was responsible for the maintenance of a net 24 h carbon gain in P. crassifolium. Platycerium veitchii, P. crassifolium and M. punctatum exhibited carbon isotope ratios of between –25.9 and –22.6‰ indicating that carbon isotope ratios may not, by themselves, be sufficient for the identification of weak CAM. We suggest that CAM may be more prevalent in tropical epiphytic and lithophytic ferns than currently envisaged.

Reproductive biology of two sympatric colubrid snakes, Chironius flavolineatus and Chironius quadricarinatus, from the Brazilian Cerrado domain

2010 ◽  
Vol 31 (4) ◽  
pp. 463-473 ◽  
Author(s):  
Roberta Richard Pinto ◽  
Otavio Augusto Vuolo Marques ◽  
Ronaldo Fernandes
Keyword(s):  
Reproductive Biology ◽  
Sexual Maturity ◽  
Egg Production ◽  
Sympatric Species ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Brazilian Cerrado ◽  
Wet Season ◽  
Reproductive Cycles ◽  
First Time

AbstractThe reproductive biology of Chironius flavolineatus and C. quadricarinatus from the Brazilian Cerrado domain is described, including sexual maturity, female fecundity, and reproductive cycles of males and females. Egg-laying is recorded here for the first time for C. quadricarinatus. Males of both species attain sexual maturity with a smaller snout-vent length than females. Females of C. flavolineatus have an extended reproductive cycle with egg production during the wet season, whereas males exhibit year-round sperm production. Chironius quadricarinatus has continuous reproductive cycles in both sexes. Differences in reproductive pattern between these two sympatric species are probably related to phylogenetic constraints on intrageneric lineages of Chironius.

scholarly journals Impacts of the dry season on the gas exchange of oil palm (Elaeis guineensis) and interspecific hybrid (Elaeis oleífera x Elaeis guineensis) progenies under field conditions in eastern Colombia

2016 ◽  
Vol 34 (3) ◽  
pp. 329-335 ◽  
Author(s):  
Cristihian Jarri Bayona-Rodríguez ◽  
Iván Ochoa-Cadavid ◽  
Hernán Mauricio Romero
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Water Potential ◽  
Oil Palm ◽  
Interspecific Hybrid ◽  
Elaeis Guineensis ◽  
Dry Season ◽  
Wet Season ◽  
Elaeis Oleifera ◽  
Photosyn Thesis

Elaeis guineensis palms and its interspecific hybrid (E. oleifera x E. guineensis) were planted in 2004 in the Cuernavaca farm of Unipalma S.A., located in the municipality of Paratebueno (Cundinamarca, Colombia). The palms were planted in two fields: Mecasaragua and Aurora. The first field has never been irrigated, and the second one (Aurora) has always been flood-irrigated during the dry season according to the parameters of the plantation. In this study, physiological parameters (gas exchange and water potential) were assessed in three seasons of the year 2013 (dry season, dry-to-wet transition season and wet season). Significant gas exchange differences were found among the seasons in the field with no irrigation (Mecasaragua). Likewise, differences between the genetic materials were observed during the dry season. For example, the photosyn thesis decreased by 75% compared with the palms planted in the irrigated field. No differences among seasons or materials were found in the irrigated field (Aurora). E. guineensis palms were more sensitive to water stress compared with the OxG interspecific hybrid. Both genetic materials responded rapidly to the first rains by leveling their photosynthetic rates and demonstrated an excellent capacity to recover from water stress.

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