Constant temperatures and the rate of seed germination in maize (Zea mays L.) of contrasting endosperm

Abstract

The germination of quality protein maize (QPM) cultivar, Obatanpa, was compared to normal endosperm (NEM) cultivar, Okomasa, on a temperature gradient plate at constant temperatures ranging from 15-45 oC. Germination occurred at all temperatures except at 42.5 oC for the QPM cultivar and 45 oC for the NEM cultivar. The rate of germination of the NEM cultivar was faster than that of the QPM cultivar at all temperatures. The thermal times for median germination were 46 for QPM and 40.7 oCd for the NEM cultivar. The cardinal temperatures (base, Tb, optimum, To and ceiling, Tc) for the NEM cultivar were Tb: 7, To: 30 and Tc: 48.2 oC. The corresponding values for the QPM cultivar were Tb: 7.6, To: 27.5 and Tc: 43.4 oC. The base and optimal temperatures were not significantly different but the ceiling temperature for the QPM was significantly lower(P<0.05). For each cultivar, a positive linear relationship was established between temperature and rate of germination from the base temperature, Tb, at which germination rate was zero to the optimum temperature, To, at which germination rate was maximal. Above To, negative linear relationships were established between temperature and rate of germination to the respective ceiling temperatures, Tc, at which germination rate was again zero.


(Ghana Journal of Agricultural Science, 1996, 29(2): 33-38)