The effect of moisture in grape leaf litter holding overwintering Plasmopara viticola oospores was investigated. Oospores were incubated under different regimes of water activity (a(W) 0.991 to 0.123) for 2 to 15 days and their ability to germinate and cause infection was determined using a sensitive leaf disk assay. Reduction of a(W) caused a significant shift in the infection dynamics, with maximum effect when a(W) <= 0.56. Dynamics of a(W) in the leaf litter under natural conditions were estimated from moisture data using a Chen-Clayton equation. Daily patterns of leaf litter moisture (M in % weight) were determined in non rainy periods between mid February and mid June, while the Chen-Clayton equation was calculated using data of a(W) and M measured in both sorption and desorption conditions, at different temperatures. Water activity was highest at 08.00 hours, decreased progressively until 14.00 hours, and then increased. Water activity was favourable for oospores to develop in about 25% of the measurements, all made between 18.00 hours and 08.00 hours. A close relationship was found between vapour pressure deficit (VPD in hPa) and a(W) of the leaf litter, so that when VPD is lower than 2.13 hPa there is sufficient water for oospores to develop. Results showed that leaf litter moisture due to water from the atmosphere makes oospore development possible during non rainy periods.

Rossi, V., Caffi, T., Effect of water on germination of Plasmopara viticola oospores, <<PLANT PATHOLOGY>>, 2007; 2007 (Settembre): 957-966. [doi:10.1111/j.1365-3059.2007.01685.x] [http://hdl.handle.net/10807/37829]

Effect of water on germination of Plasmopara viticola oospores

Rossi, Vittorio;Caffi, Tito
2007

Abstract

The effect of moisture in grape leaf litter holding overwintering Plasmopara viticola oospores was investigated. Oospores were incubated under different regimes of water activity (a(W) 0.991 to 0.123) for 2 to 15 days and their ability to germinate and cause infection was determined using a sensitive leaf disk assay. Reduction of a(W) caused a significant shift in the infection dynamics, with maximum effect when a(W) <= 0.56. Dynamics of a(W) in the leaf litter under natural conditions were estimated from moisture data using a Chen-Clayton equation. Daily patterns of leaf litter moisture (M in % weight) were determined in non rainy periods between mid February and mid June, while the Chen-Clayton equation was calculated using data of a(W) and M measured in both sorption and desorption conditions, at different temperatures. Water activity was highest at 08.00 hours, decreased progressively until 14.00 hours, and then increased. Water activity was favourable for oospores to develop in about 25% of the measurements, all made between 18.00 hours and 08.00 hours. A close relationship was found between vapour pressure deficit (VPD in hPa) and a(W) of the leaf litter, so that when VPD is lower than 2.13 hPa there is sufficient water for oospores to develop. Results showed that leaf litter moisture due to water from the atmosphere makes oospore development possible during non rainy periods.
Inglese
Rossi, V., Caffi, T., Effect of water on germination of Plasmopara viticola oospores, <<PLANT PATHOLOGY>>, 2007; 2007 (Settembre): 957-966. [doi:10.1111/j.1365-3059.2007.01685.x] [http://hdl.handle.net/10807/37829]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10807/37829
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 23
  • ???jsp.display-item.citation.isi??? 23
social impact