Seedling Age and Cold Treatment Effects on Induction of Panicle Production in Reed Canarygrass 1

The objective of this investigation was to determine plant age and environmental factors influencing panicle emergence and production in reed canarygrass ( Phalarls arundinacea L.). Seedlings of ‘Rise’ and ‘Vantage’ grown in the glasshouse at 27/19 C (day/night, warm) temperatures and a 16‐hour photoperiod for seven periods ranging from 1 to 13 weeks of growth after emergence, were exposed to cold treatments at 6 ± 1 C in a growth chamber for an 8‐ or 16‐hour photoperiod. About 75% of 4‐week or older seedlings were vernalized effectively with 12 to 15 weeks of cold treatment, and flowered 3 weeks after being returned to warm, 16‐hour days. Twenty‐two percent of the seedlings that received cold treatment starting 3 weeks after emergence produced panicles, but 1‐ and 2‐week‐old seedlings did not. Four‐week old seed. lings required at least 9 weeks of cold treatment before some panicles were produced. Panicle production per plant after 12 weeks of cold treatment was greater for 13‐ than for 4‐week‐old seedlings. Percentage of plants with emerged panicles and panicle production were greater with the 8‐ than with the 16‐ hour photoperiod during cold treatment. When 60% of the herbage was ronoved immediately before onset of the cold treatments, percentage of plants with panicles, duration of panicle emergence, and panicles produced per plant were reduced as compared to those left uncut. Eighty.eight percent of the panicles produced in Vantage arose from tillers that emerged from the soil during cold treatment. The 12‐week cold treatment in a controlled environment was also effective in causing panicle formation on 22 diverse reed canarygrass clones. The procedure will enable plant breeders to reduce intergeneration time and to make crosses in reed canarygrass within 5 months after seeding or vegetative propagation of parent material.