Constant temperatures and the rate of seed germination in maize (Zea mays L.) of contrasting endosperm
1996
Aflapui, G.K.S., Crops Research Institute, Council for Scientific and Industrial Research P. 0. Box 3785, Kumasi,Ghana
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 "C. Germination occurred at all temperatures except at 42.5 "C for the QPM cultivar and 45 "C 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 "Cd for the NEM cultivar. The cardinal temperatures (base, Tb, optimum, T" and ceiling, T) for the NEM cultivar were T.: 7, T,,:.30 and T,: 48.2 "c. The corresponding values for theQPM cultivar were Tb: 7.6, T,,: 27.5 and T,: 43.4 "c. Thebase and optimal temperatures were not significantly different but the ceiling temperature for the QPM was significantly lower (P0.05). For each cultivar, a positive linear relationship was established between temperature and rate of germ ination from the base temperature, T., at which germination rate was' zero to the optimum temperature,T , at which germination rate was maximal. AboveT , neg~tive linear relationships were established between~~perature and rate of germination to the respective ceiling temperatures, T" at which germination rate was again zero. Original scientific paper. Received 22 Jan 96; revised 10 Ju196.
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