Cardinal temperatures and thermal time requirements for germination of forage brassicas
2012
Andreucci, Mariana | Black, Alistair | Moot, Derrick
Cardinal temperatures, base (Tb), optimum (Topt) and maximum (Tm), and thermal time (Tt) requirements were defined for germination of nine forage brassica cultivars. Seeds were germinated at nine constant temperatures. Germination rate was described using linear and broken stick development models. Germination rate responses to temperature were more dependent on species than cultivars. Turnip (Brassica rapa) cultivars required 17°C days above a Tb of 3.6°C until 10°C, and 14°C days from 10°C until a Topt of 31°C. Rape (B. napus) required 26.5°C days above a Tb of 3.3°C, and „Aparima Gold‟ swedes required 34°C days above a Tb of -0.6°C, until a Topt of 33°C. Kale and Raphanobrassica (B. oleracea) cultivars required 60°C days above a Tb of 0°C until a Topt of 27°C. Estimates of Tm were 48°C for B. rapa, 38°C for B. napus and 35°C for B. oleracea. These cardinal temperatures were used to describe the daily Tt response to temperature of each species.
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