Influence of water potential and osmoticum on growth detection by baiting and germination of Phytophthora cactorum

Nik Masdek Hassan, . (1990) Influence of water potential and osmoticum on growth detection by baiting and germination of Phytophthora cactorum. [Proceedings Paper]

The growth rate of 2 isolates of Phytophthora cactorum on potato dextrose agar PDA and on a basal medium was stimulated by the addition of potassium chloride KCI with maximum growth at -10 to -15 bar. The growth rate gradually declines at lower osmotic potential and growth ceases at about -40 bar on a basal medium. However on PDA some growth still occurs at -50 bar and ceases at -60 bar. Detection of P.cactorum by baiting with apple cotyledons from naturally infested soil was inhibited when the soil was flooded with osmoticum at water potentials lower than -2.0 bar. Flooding of soil with solutions of NH42SO4 NH4Cl each at -0.5 and -1.0 bar KCl NH4NO3 K2SO4 and CaCl1 each at -0.5 bar did not interfere with colonization of baited cotyledons. No colonization of baits occurred when infested soil was flooded with CaNO32 whereas NaCl and polyethylene glycol 3350 at -0.5 -1 -1.5 and -2.0 bar had no inhibitory effect on detection by baiting. Sporangial formation and indirect germination of P.cactorum grown on V-8 agar were influenced by various osmotica. Cultures flooded with NH42SO4 and NH4Cl tended to form fewer sporangia. Indirect gemination did not occur in cultures flooded with NH42SO4 NH4Cl and CaNO32 at any water potentials. Failure of P.cactorum to colonize baits in osmotically adjusted solutions was partially explained by inhibition of indirect gemination of P.cactorum

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Abstract

The growth rate of 2 isolates of Phytophthora cactorum on potato dextrose agar PDA and on a basal medium was stimulated by the addition of potassium chloride KCI with maximum growth at -10 to -15 bar. The growth rate gradually declines at lower osmotic potential and growth ceases at about -40 bar on a basal medium. However on PDA some growth still occurs at -50 bar and ceases at -60 bar. Detection of P.cactorum by baiting with apple cotyledons from naturally infested soil was inhibited when the soil was flooded with osmoticum at water potentials lower than -2.0 bar. Flooding of soil with solutions of NH42SO4 NH4Cl each at -0.5 and -1.0 bar KCl NH4NO3 K2SO4 and CaCl1 each at -0.5 bar did not interfere with colonization of baited cotyledons. No colonization of baits occurred when infested soil was flooded with CaNO32 whereas NaCl and polyethylene glycol 3350 at -0.5 -1 -1.5 and -2.0 bar had no inhibitory effect on detection by baiting. Sporangial formation and indirect germination of P.cactorum grown on V-8 agar were influenced by various osmotica. Cultures flooded with NH42SO4 and NH4Cl tended to form fewer sporangia. Indirect gemination did not occur in cultures flooded with NH42SO4 NH4Cl and CaNO32 at any water potentials. Failure of P.cactorum to colonize baits in osmotically adjusted solutions was partially explained by inhibition of indirect gemination of P.cactorum

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Item Type:	Proceedings Paper
Additional Information:	Summary En
AGROVOC Term:	PHYTOPHTHORA CACTORUM
AGROVOC Term:	PRESION OSMOTICA
AGROVOC Term:	CRECIMIENTO/ GERMINACION
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:26
URI:	http://webagris.upm.edu.my/id/eprint/15316

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