Testing method of pre-harvest sprouting and genealogical pedigree of pre-harvest sprouting resistant cultivars in wheat [Triticum aestivum]

Sprouting damage in wheat usually occurs at the ripening stage which coincides with the rainy season in Japan. The attempts to test a great breeding lines for sprouting resistance have not been successful. The objectives of our studies were to develop effective testing methods for the selection of lines with pre-harvest sprouting resistance and analyze the genealogical pedigree of resistant cultivars in wheat. In the first part of the study, the sprouting percentage immediately after sampling was found to be high at 35 and 55 days after heading (DAH), and low at 45 DAH (near maturity) except for Saitama 27, while the sprouting percentage one month after sampling increased with the number of days after heading (Fig. 1). The sprouting percentage depending on the storge conditions among 19 cultivars increased in proportion to the storage ternperature, namely, in the order of -16°C0°C16°CRoom. The sprouting differences observed immediately after sampling were significantly correlated with the 0°C (r=0.691**), 16°C (r=0.489*), room (r=0.550*) storage conditions for 1 month and room storage conditions for 2 months (r=0.628**), but were not correlated with the O°C and 16°C for 2 months among 19 cultivars. The sproutng performance at different ripening stages under constant ternperature testing conditions (17°C) and alternating temperature testing conditions (25°C in day time for 12 hrs. and 15°C at night for 12 hrs.) was very similar but the sprouting percentage under the constant temperature testing conditions was higher than that under the alternating ones (Fig. 2). The sprouting differences among cultivars immediately after sampling were observed at 14 days after simulated rain treatment, while at 6 days after simulated rain treatment in stored spikes (Fig. 3). A significant correlation was observed between sprouting immediately after sampling and sprouting of spikes wrapped with wetted filter paper (filter paper wrapping method) under different testing temperatures (16°C, 21°C, 26°C, 31°C, 26°C+16°C).