Hydraulically based stomatal oscillations and stomatal patchiness in Gossypium hirsutum

Abstract

Slow stomatal oscillations (70–95 min), associated with feedback within the plant hydraulic systems, were studied in cotton (Gossypium hirsutum L.). Oscillations were only evident when the whole plant was exposed to light, and were not influenced by reductions in intercellular CO2 concentrations (Ci) in intact, attached leaves. Oscillations were synchronised among different leaves of the same plant, even when the leaf-to-air vapour pressure difference (VPD) was reduced in a cuvette enclosing one of the leaves. In the trough phase of stomatal oscillations the apparent Ci was higher than expected from the combination of the observed assimilation rate and the A(Ci) relationship measured in the absence of oscillations. Using chlorophyll fluorescence imaging we found evidence of stomatal heterogeneity in this phase. Finally, we found that stomatal oscillations appeared to be correlated with xylem embolism, with more vessels filled with gas at the peak than at the troughs of stomatal oscillations.

Partitioning hydraulic resistance in Sorghum bicolor leaves reveals unique correlations with stomatal conductance during drought

“…Hydraulic resistance through the xylem changes on a diurnal basis as vessel elements cavitate and refill in response to changes in leaf hydration status (Marenco et al 2006) and has recently been shown to correlate closely with changes in r * Leaf (Johnson et al 2012). The leaf water potential of the genotypes in our study did not change significantly in response to the drought treatment (Table 2); instead g s decreased keeping the leaf water potential relatively constant during our experiment.…”

“…Leaf hydraulic resistance responds to leaf water status through, at least, two mechanisms: reduced conductance due to xylem dysfunction (Trifilò et al 2003;Cochard et al 2004a;Marenco et al 2006), or changes in aquaporin transport as water moves through the leaf mesophyll (Kim and …”

Fotossíntese, condutância estomática e potencial hídrico foliar em árvores jovens de andiroba (Carapa guianensis)

“…A baixa correlação entre A e g s e entre g s e Ψ confirma que tanto a fotossíntese como a condutância estomática são parâmetros da planta que respondem simultaneamente a um conjunto de fatores que interagem de forma coordenada, mas altamente complexa. Enquanto, a baixa concentração de CO 2 e a alta irradiância estimulam diretamente a abertura dos estômatos, a baixa umidade e a transpiração excessiva causam diminuição no potencial hídrico foliar, o que pode levar ao fechamento dos estômatos (Hsiao, 1973;Marenco et al, 2006). Desse modo, não é surpreendente encontrar uma baixa correlação entre A e g s em condições naturais de luminosidade e umidade do ar.…”

“…Desse modo, não é surpreendente encontrar uma baixa correlação entre A e g s em condições naturais de luminosidade e umidade do ar. Além disso, uma pobre correlação entre fotossíntese e condutância estomática pode indicar ausência de uniformidade na abertura dos estômatos na superfície da folha (manchas estomáticas), conforme mostrado por Marenco et al (2006), tornando complexa e não linear a relação entre fotossíntese e condutância estomática (Pospisilová & Santrucek, 1994).…”

Growth, leaf and stomatal traits of crabwood (Carapa guianensis Aubl.) in central Amazonia

“…Excessive water loss by transpiration as a result of a high leaf to air vapour pressure difference (VPD) may induce stomatal closure (REIS et al, 1988;MARENCO et al, 2006). In isohydric plants, stomata exhibit a strong control of transpiration so that Ψ L of droughted and watered plants remains constant during the day, whereas in anysohydric plants larger oscillations in Ψ L can be observed during the day, as a result of low stomatal sensitivity to evaporative demand and leaf water content (TARDIEU; SIMONNEAU, 1998).…”