Within-row advection and stomatal conductance of an irrigated crop

• Autor(a) principal: Ferreira, Maria Isabel
• Data de Publicação: 2023
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/28015
• topic: leaf water potential; atmospheric stress; edaphic stress; vapour pressure deficit; tomato; potencial foliar; stress atmosférico; stress edáfico; défice de pressão de vapor; tomate

The effects of soil water deficit (edaphic stress) and air vapour-pressure-deficit (atmospheric stress) on stomatal conductance of tomato (Lycopersicon esculentum Mill.) were separately analysed for the range of predawn leaf water potential (Ψp) normally observed in an irrigated crop. Three separate experiments under field conditions were used. In this respect, the main experimental results were: (i) noon stomatal conductance (gs) correlated well with Ψp but poorly with leaf water status expressed via noon leaf water potential; (ii) the scattering sometimes obtained in the relationship between Ψp and gs, for high values of Ψp (above -0.4 MPa) can be explained by a preponderant effect of air vapour-pressure-deficit on stomatal behaviour, compared to the effect of soil water deficit; (iii) the reason for the change on leaf-to-air VPD, responsible for the stomatal closure seems to be the clothesline effect i.e. the positive within-row advection from dry inter-row space. The discussion suggests that the slope of the relationship Ψp - gs can change with the soil cover, the size of the plots and their surrounding conditions. What we observed for this crop and irrigation system is extendable to other crops with important dry soil around, to analyse the implications of the air humidity near the leaves on the stomatal behaviour and water fluxes. This hypothesis can also explain opposite tendencies on the transpiration versus evapotranspiration efficiency.