Germination of Stored Cassava Seed at Constant and Alternating Temperatures

Abstract

Cassava seed is only capable of germinating over a restricted range of constant temperatures. During storage the optimum constant temperature for germination decreases from about 35 to 30 °C or possibly less. The rate at which the optimum temperature changes during dry storage increases with increase in storage temperature over the range 0 to 40 °C. Some alternating- temperature regimes (16 h at the lower temperature; 8 h at the higher temperature) can provide conditions as favourable for germination as the optimum constant temperatures. Furthermore, it has been shown that temperature alternation itself is stimulatory because when the range of the alternation does not include the optimum constant temperature value, percentage germination is often higher than could be obtained at any constant temperature within the range, though this stimulatory response declines during storage. For these reasons it is provisionally recommended that cassava seed should be germinated at 25/35 °C which is as stimulatory a treatment as any which has so far been investigated and has the advantage of encompassing the range over which the optimum constant temperature changes during storage.