Viability of Stored Maize Seed Exposed to Different Periods of High Temperature During the Artificial Drying
A plan for drying seed artificially is necessary, during the inadequate field drying conditions to avoid the lost of large volumes of high quality maize seed. This work aimed to examine effects of the exposure to high drying temperature at different periods on maize seed quality soon after drying, after 3 and 6 months from storage. The obtained ears of hybrid single cross 10 (Sc.10) was grown at the Agricultural Research Station Farm in Gemmiza, Garbia Governorate, Agricultural Research Center, Egypt, during 2013 season. Cobs were harvested to obtain seed with moisture percentage ranges from 30-33% and exposure to different high drying temperature periods and then completed drying at 38°C until reach to 12% seed moisture content (50°C for 28 h, 50°C for 24 h+38°C for 5.50 h, 50°C for 20 h+38°C for 12.00 h, 50°C for 16 h+38°C for 17.30 h, 50°C for 12 h+38°C for 22.50 h, 50°C for 8 h+38°C for 29.00 h, 50°C for 4 h+38°C for 34.45 h and 38°C for 40.00 h). Dried seed was stored during 2013 and 2014 seasons at the laboratory natural conditions of Seed Technology Research Unit in Mansoura, Dakahlia Governorate, Field Crops Research Institute, Agricultural Research Center, Egypt. Laboratory seed quality tests (fast green test, standard germination, abnormal seedlings, speed of germination, cold test, electrical conductivity, shoot length, root length and seedling dry weight) were conducted soon after drying, after 3 and 6 months from storage. The drying temperature can be raised to 50°C for seed harvested at a moisture range (30-33%) with maintaining adequate levels of seed and seedling vigor. The best combination treatment maintains standard germination above 90% soon after drying was drying at 50°C for 20 h before completed drying at 38°C until obtain 12% seed moisture content. But after 6 months storage, the best one was 50°C for 16 h before completed drying at 38°C which maintains standard germination above 88%. These combinations can be saving about 21 and 16.25% drying time, respectively with maintaining adequate levels of seed and seedling vigor.