The objective of this study was to evaluate the effect of different storage methods on the viability of the urediniospores of P. pachyrhizi. Urediniospores were collected and stored in five different conditions: detached dry leaves (24°C), desiccator (10°C) + liquid nitrogen (-196°C) after 60 days, refrigerator (4°C), deep-freezer (from -60°C to 80°C) and liquid nitrogen (-196°C). The percentage of germination from stored urediniospores was evaluated every thirty days in water-agar medium. Urediniospores stored in liquid nitrogen presented the highest germination percentage after 270 days of storage. In desiccator, the germination was zero at ninety days of evaluation, and when urediniospores were transferred to and kept in liquid nitrogen, the germination was up to 30%. The urediniospores stored under others conditions presented a decline in germination at sixty days and at the ninety days the germination declined to zero. Based on these results, the most efficient way of storing urediniospores of P. pachyrhizi was using liquid nitrogen.
liquid nitrogen; rust soybean; inoculum storage
