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Evaluation of the pressure chamber technique for measurement of leaf water potential in cassava (Manihot species)

By: Contributor(s): Material type: ArticleArticleLanguage: English Description: 56:1638-1641Subject(s): LOC classification:
  • 4920
 In: Canadian Journal of BotanySummary: Se evaluo la tecnica de la camara de presion como metodo para estimar el potencial hidrico de la hoja en la yuca. Se compararon los potenciales de presion xilematica (psi p) medidos con la camara de presion, y el potencial hidrico de la hoja (psi L) obtenido para la misma hoja con un higrometro para medir el punto de rocio in situ. En ambas variedades, estudiadas, psi p y psi L se relacionaron linealmente (r2 = 0,87 y 0,98 para CMC9 y CMC40, respectivamente). El largo del peciolo expuesto fuera de la camara afecta la relacion psi L/psi P y deberia mantenerse entre 1-3 cm para una mejor concordancia. En CMC40, psi P fue consistentemente mas bajo (mas seco) que psi L, aprox. 1,0 bar (1 bar = 100 kPa), en el rango entero de potenciales hidricos estudiado, pero no en el caso de CMC9. El motivo de esta diferencia no esta claro, pero es posible que los tejidos distintos al xilematico se hayan llenado durante la medicion de psi P en CMC40. Los potenciales osmoticos promedio del xilema (psi S) fueron bajos (-1,0 mas o menos 0,2 bares y -1,0 mas o menos 0,4 bares para CMC9 y CMC40, resp.). Por lo tanto, es innecesario corregir a psi S cuando se usa la camara de presion para estimar los potenciales hidricos de la hoja en la yuca. (RA-CIAT)Summary: The pressure chamber technique was evaluated as a method for estimating leaf water potential in cassava. Xylem pressure potentials (psi (p)) measured with the pressure chamber were compared with leaf water potential (psi (L)) obtained for the same leaf with the in situ dew-point hygrometer. In both var. studied, psi (L) and psi (p) were linearly related ((r)2 = 0.87 and 0,98 for CMC9 and CMC40, respectively). The length of petiole exposed outside the chamber affects the psi(L)/psi (p) relation and should be kept at between 1-3 cm for better agreement. In CMC40, psi (p) was consistently lower (drier) than psi (L) by about 1.0 bar (1 bar = 100 kPa) in the entire range of water potential studied, but was not the case in CMC9. The reason for this difference is unclear but may be due to a filling of tissues other than xylem tissue during the measurement of psi (p) in CMC40. Av xylem osmotic potentials (psi (s)) were low (-1.0 plus or minus 0.2 barsand -1.0 plus or minus 0.4 bars for CMC9 and CMC40, respectively). It is therefore unnecessary to correct for psi (s) when using the pressure chamber to estimate leaf water potentials in cassava. (AS)
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Se evaluo la tecnica de la camara de presion como metodo para estimar el potencial hidrico de la hoja en la yuca. Se compararon los potenciales de presion xilematica (psi p) medidos con la camara de presion, y el potencial hidrico de la hoja (psi L) obtenido para la misma hoja con un higrometro para medir el punto de rocio in situ. En ambas variedades, estudiadas, psi p y psi L se relacionaron linealmente (r2 = 0,87 y 0,98 para CMC9 y CMC40, respectivamente). El largo del peciolo expuesto fuera de la camara afecta la relacion psi L/psi P y deberia mantenerse entre 1-3 cm para una mejor concordancia. En CMC40, psi P fue consistentemente mas bajo (mas seco) que psi L, aprox. 1,0 bar (1 bar = 100 kPa), en el rango entero de potenciales hidricos estudiado, pero no en el caso de CMC9. El motivo de esta diferencia no esta claro, pero es posible que los tejidos distintos al xilematico se hayan llenado durante la medicion de psi P en CMC40. Los potenciales osmoticos promedio del xilema (psi S) fueron bajos (-1,0 mas o menos 0,2 bares y -1,0 mas o menos 0,4 bares para CMC9 y CMC40, resp.). Por lo tanto, es innecesario corregir a psi S cuando se usa la camara de presion para estimar los potenciales hidricos de la hoja en la yuca. (RA-CIAT) spa

The pressure chamber technique was evaluated as a method for estimating leaf water potential in cassava. Xylem pressure potentials (psi (p)) measured with the pressure chamber were compared with leaf water potential (psi (L)) obtained for the same leaf with the in situ dew-point hygrometer. In both var. studied, psi (L) and psi (p) were linearly related ((r)2 = 0.87 and 0,98 for CMC9 and CMC40, respectively). The length of petiole exposed outside the chamber affects the psi(L)/psi (p) relation and should be kept at between 1-3 cm for better agreement. In CMC40, psi (p) was consistently lower (drier) than psi (L) by about 1.0 bar (1 bar = 100 kPa) in the entire range of water potential studied, but was not the case in CMC9. The reason for this difference is unclear but may be due to a filling of tissues other than xylem tissue during the measurement of psi (p) in CMC40. Av xylem osmotic potentials (psi (s)) were low (-1.0 plus or minus 0.2 barsand -1.0 plus or minus 0.4 bars for CMC9 and CMC40, respectively). It is therefore unnecessary to correct for psi (s) when using the pressure chamber to estimate leaf water potentials in cassava. (AS) eng

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