Seasonal variation in gas exchange by plants of Erythroxylum simonis Plowman

Abstract

Erythroxylum simonis is an understory species found in Northeast Brazil. Due to its shaded habitat, E. simonis is subjected to seasonal oscillations of the environment, to which it must respond ecophysiologically. Th e objective of this study was to evaluate the eff ects of seasonality on the ecophysiology of E. simonis in a fragment of Seasonal Semideciduous Forest. Leaf area index, visible sky fraction and photosynthetically active radiation were measured for 10 individuals during the dry and rainy seasons. Soil moisture, temperature and monthly precipitation were measured, as well as photosynthetic rate, stomatal conductance, internal CO 2 concentration, transpiration, instantaneous water use effi ciency, instantaneous carboxylation effi ciency and chlorophyll content. Ecophysiological variables were correlated with environmental variables, with a greater association of rainfall and soil moisture with stomatal conductance, transpiration and photosynthetic rate, indicating that water availability has an eff ect on the ecophysiology of E. simonis. With the exception of instantaneous carboxylation effi ciency, gas exchange exhibited signifi cant diff erences among the months studied, with the highest values being for months with greater water availability, thus showing that the ecophysiology of the species responds to seasonal changes throughout the year.

Leaf Area Estimate of Erythroxylum simonis Plowman by Linear Dimensions

“…This study was developed in Mata do Pau-Ferro State Park, located 5 km west of the center of the city of Areia-PB, Northeast of Brazil, at a latitude of 6°58'12" S and longitude 35°42'15" W, totaling an approximate area of 608 ha (Figure 1). The region presents an altitude that varies between 400 and 600 m, an annual average temperature of 22°C (Ribeiro et al, 2018), and a tropical climate classified, according to Köppen (1936), as As.…”

Anatophysiology of Vouacapoua americana Aubl. in the juvenile phase: A species included in the IUCN red list of threatened species

“…Stomatal conductance (gs) also exhibited significant differences among months, with lowest values in the dry season, varying from 0.02 mol m-2s-1 (September) to 0.127 mol m-2s-1 (May). On the other hand, with water stress during the dry season the species exhibited distinct physiological responses, with lower photosynthetic rates due to the closure of stomata as a physiological strategy to avoid excessive water loss (Ribeiro et al, 2018).…”

Maize (Zea mays) Cultivated in Concrectionary Petric Plinthosol

“…In the maize cultivated in soil without ironstone concretions, at 04:00 p.m. photosynthesis was greater, as well as transpiration, which reflected in WUE and showed a statistical difference. Ribeiro, Barbosa, Lopes, Pereira, and Albuquerque (2018) commented that the relationship between photosynthesis and transpiration determines the instantaneous efficiency in the use of water, meaning, the amount of carbon that the plant fixes, for each unit of water it loses. Magalhães et al (2009) in a work of characterization of contrasting maize lineages regarding the resistance to drought, perceived higher value in maize with water deficiency.…”