Growth temperature and the response of stomata to drought and ABA.

 

 

Effect of growth temperature on the response of lupin stomata to drought and abscisic acid.

by Osório M. L., Rodrigues M. L., Chaves M. M., Correia M. J., (1999)

M. Leonor Osório, M. Lucília Rodrigues, M. Manuela Chaves, Maria João Correia,

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in Austral. J. Plant Physiol. 26(6): 549-559 – https://doi.org/10.1071/PP99053

http://www.publish.csiro.au/FP/PP99053

Abstract

To assess how growth temperature affects stomatal responses to xylem-transported abscisic acid (ABA), leaf conductance (g), the concentrations of ABA and calcium ions, and the pH of the xylem sap were measured in well-watered and water-stressed Lupinus albusL. plants grown under two thermal regimes: 10/15°C and 20/25°C, night/day temperature. Moderate water deficit was imposed, at the same thermal time, and induced a significant reduction in g regardless of temperature. In the morning, g was higher in plants grown at 20/25°C than in cooler conditions, and these differences could not be explained by dissimilarities in shoot water status or xylem ABA concentration. At midday, the apparent stomatal sensitivity to xylem-carried ABA was increased and the effect of temperature on the relationship between g and xylem ABA was no longer observed. A positive effect of higher temperature on stomatal aperture was also evident when artificial sap containing ABA was fed to leaves of well-watered plants. In response to exogenous ABA, stomata closed to the same extent as observed in the morning in water-stressed plants. However, exogenous ABA feeding could not mimic the relationship between g and xylem ABA determined at midday in intact plants. The pH and the concentration of calcium in xylem were not affected by temperature. At midday, however, the calcium concentrations were higher in water-stressed than in well-watered plants. These changes in the concentrations of calcium or other xylem components, such as ABA conjugates, together with possible changes in the ability of the leaves to degrade and/or to compartmentalise ABA, may partly explain the midday increase in the apparent stomatal sensitivity to xylem ABA.

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Hydraulic and chemical signalling in the regulation of stomatal conductance

 

Photo credit: Google

Vitis vinifera

Hydraulic and chemical signalling in the regulation of stomatal conductance and plant water use in field grapevines growing under deficit irrigation

by Rodrigues M.L., Santos T.P., Rodrigues A.P., de Souza C.R., Lopes C.M., Maroco J.P., Pereira J.S., Chaves M.M. (2008)

M. Lucília Rodrigues A D , Tiago P. Santos A , Ana P. Rodrigues A B , Claudia R. de Souza B , Carlos M. Lopes A , João P. Maroco B C , João S. Pereira A, M. Manuela Chaves A B

A Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.

B Laboratório de Ecofisiologia Molecular, Instituto de Tecnologia Química e Biológica, Apartado 127, 2780-901 Oeiras, Portugal.

C Instituto Superior de Psicologia Aplicada. Rua Jardim do Tabaco, 34, 1149-047 Lisboa, Portugal.

 

in Funct. Plant Biol. 35: 565–579 – https://doi.org/10.1071/FP08004 –

Google Scholar CrossRef

http://www.publish.csiro.au/fp/FP08004

Abstract

Effects of irrigation strategies on stomata and plant water use were studied in field-grown grapevines (Vitis vinifera L.).

We assessed the importance of root-derived chemical signals vs. hydraulic signalling in stomatal regulation. The experiment included two treatments with the same water added to the soil (50% ETc) applied either to the whole root system (DI) or to half of the roots, alternating irrigation side every 15 days (PRD). Well-watered plants (FI) (100% ETc) and non-irrigated grapevines (NI) were also studied.

Partial stomata closure occurred in both PRD and DI plants. [ABA] of xylem sap remained constant during the day and was maintained throughout the season, with higher values in NI plants. Xylem sap pH was not affected by soil water availability.

A positive correlation between ψpd and maximum g s was found, indicating that grapevine stomata strongly respond to plant water status.

In contrast, ABA did not explain stomatal control at veraison. At mid-ripening g s was significantly correlated with ABA, apparently interacting with the rise in xylem sap pH.

Therefore, our data suggest that hydraulic feedback and feed-forward root-to-shoot chemical signalling mechanisms might be involved in the control of stomata in response to decreased soil water availability, hydraulic signals playing the dominant role.