Objective  A new high-quality, high-yield, heat- and cold-tolerant Azolla with broad-adaptability was bred.

  Method   Minyu 1 was bred by interspecies crossing male parent A. filiculoides 1001 and female parent A. microphylla 4018.

  Result   After being screened at the variety comparison test and the regional and field trials conducted from 2001 to 2015, Minyu 1 was registered by the Chinese Herbage Cultivar Registration Board in 2015. It demonstrated an average hay yield of 88 209 kg·hm⁻², which was significantly 158.3% higher than 34 146 kg·hm⁻² exhibited by the reference variety, A. imbricata 500, 30.9% significantly higher than that of the parent, A. filiculoides 1001, at 67 398 kg·hm⁻², and 30.9% significantly higher than that of the parent, A. microphylla 4018, at 71 738 kg·hm⁻² (P＜0.01). It was also stable in maintaining the high yield performance. The nutritional content (dry matters) of Minyu 1 included 26.3% of crude protein, 16.0% of crude fat, 11.2% of crude fiber, 13.6% of crude ash, 36.9% of acidic detergent fiber, and 50.3% of neutral detergent fiber.

  Conclusion  Minyu 1 had a short generation cycle, high yield, and strong cold- and heat-resistance suitable for cultivation in the country. The optimal temperature for its growth was 10-30 ℃. It could be used as green forage for raising fish, cattle, pigs, chickens, ducks, geese, and other animals, or as an aquatic green fertilizer in paddy fields as well.