A low cost apparatus for measuring the xylem hydraulic conductance in plants

Abstract

Plant yield and resistance to drought are directly related to the efficiency of the xylem hydraulic conductance and the ability of this system to avoid interrupting the flow of water. In this paper we described in detail the assembling of an apparatus proposed by Tyree et al. (2002), and its calibration, as well as low cost adaptations that make the equipment accessible for everyone working in this research area. The apparatus allows measuring the conductance in parts of roots or shoots (root ramifications or branches), or in the whole system, in the case of small plants or seedlings. The apparatus can also be used to measure the reduction of conductance by embolism of the xylem vessels. Data on the hydraulic conductance of eucalyptus seedlings obtained here and other reports in the literature confirm the applicability of the apparatus in physiological studies on the relationship between productivity and water stress.Key words: water, conductivity, cavitation, embolism. Um aparato de baixo custo para medição da condutância hidráulica do xilema em plantasResumo A produtividade das plantas e a capacidade de resistência à seca estão diretamente relacionadas com a eficiência da condutância hidráulica do xilema e a capacidade desse sistema em evitar a interrupção do fluxo de água. No presente trabalho, detalha-se a montagem de um aparato proposto por Tyree et al. (2002), e sua calibração, bem como adaptações com peças de menor custo que tornam o aparelho acessível a qualquer um trabalhando nesta linha de pesquisa. Esse aparato possibilita medir a condutância de partes do sistema radicular ou da parte aérea (ramificações radiculares ou ramos), ou em todo o sistema, no caso de plantas de porte pequeno ou plântulas. O aparato também pode ser usado para medir a redução da condutância pela embolização dos vasos do xilema. Medições de condutância hidráulica feitas em plântulas de eucalipto e outros trabalhos encontrados na literatura confirmaram a aplicabilidade desse aparato em estudos fisiológicos de produtividade relacionada ao estresse hídrico.

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

“…For the hydraulic method, we used an ultralow flow meter to measure PLC (Pereira & Mazzafera, ). Here, five segments of the base of dehydrated branches with c .…”

“…For the hydraulic method, we used an ultralow flow meter to measure PLC (Pereira & Mazzafera, 2012). Here, five segments of the base of dehydrated branches with c. 4-6 cm length and 3-5 mm diameters length were cut under water, trimmed with a razor blade and attached to the flow meter.…”

Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long‐term drought

“…All samples used for hydraulic measurements were: first-or second-order branches, between 30-55 mm in length and 3-5 mm in diameter and recut underwater with a sharp razor blade before connecting to the apparatus, to ensure all vessels were open at both ends. We measured flow using the pressure drop over a capillary method in an hydraulic apparatus (Espino & Schenk, 2011;Pereira & Mazzafera, 2012;Sperry, Donnelly, & Tyree, 1988), where a capillary of known conductance is connected in series with the sample, and the samples were flushed to remove emboli and estimate maximum conductance (Martin-StPaul et al, 2014). We calculated PLC nat as the ratio of K snat to K s multiplied by 100.…”

Plant pneumatics: stem air flow is related to embolism – new perspectives on methods in plant hydraulics

“…The hydraulic vulnerability curves were produced for 10 species by the bench dehydration method , using an ultra-low flow meter as previously described by Pereira & Mazzafera (2012) (see Methods S1 for the detailed procedure).…”