Thermal Adaptation of Pennisetum: Seedling Development

Abstract

Germination, establishment, dry weight accumulation and leaf development of seedlings of two Pennisetum typhoides cultivars and a P. typhoides × P. purpureum biotype were studied at four temperatures from 33/28 to 15/10°C (day/night) under natural irradiances.

Percentage seedling germination was independent of temperature. However, rate of germination and emergence were fastest, the spread in populations of time to germination least, and seedling survival highest, at the temperature at which rates of leaf area expansion and dry weight accumulation were greatest, i.e. 33/28°C. Rates of dry weight accumulation differed between the three pennisetums, the ranking in early growth at temperatures below 33/28°C being the same as that for seed size, and in later growth at all temperatures being in the order interspecific hybrid > intra-specific hybrid > selected strain.