THERMAL VARIATION FOR GROWTH OF ZOOSPORES OF Albugo spp.

The objective of this work was to identify the time of the thermal shock that promotes the greater release of zoospores/sporangia. The experiments were carried out with five treatments, varying the thermal variation time (20', 30', 40', 50' and 60') of sporangia suspension of 7.10 5 sporangia mL -1 under 5 °C temperature. The incidence of sporangia germinated by 20 times whose It was evaluated100 units at random, using an optical microscope at 40 times magnification. The F and Tukey test were used to compare the means. The sexual phase (presence of oospores) was identified in the isolate derived from purslane. In purslane leaves (infected by Albugo portulacae ) the time of 20-30' promoted a greater number of zoospores released, whereas for the isolate from amarantus (infected by A. bliti ) the time of 30’ promoted statistically the highest release of zoospores; for the isolate from leaves of “jetirana” (infected by A. ipomoeae-panduratae ) the time of 30-50’ promoted greater release of zoospores; and finally the isolate from “onze-horas” leaves (infected by A. portulacae ) the time of 30-40’ statistically promoted the highest percentage of release of zoospores, It was demonstrating a differential behavior per host in the release of zoospores. The thermal shock time that promoted the highest amount of released zoospores (38 %) was observed for the purslane- Albugo portulacae and “onze horas”- A. portulacae pathosystem.