THE INFLUENCE OF TEMPERATURE ON SEED-GERMINATION IN CULTIVARS OF COMMON BEAN

Common bean (Phaseolus vulgaris L.) is grown over a wide range of environments, including sites with low or high soil temperatures at sowing time. To describe the temperature response of seed germination, 20 bean genotypes were evaluated using a rolled paper towel system with 11 constant temperatures ranging from 12 to 34 degrees C. Germination response was characterized by fitting cumulative counts using a maximum-likelihood analysis. Rate of germination increased from a base temperature (T-b) typically near 8 degrees C to an optimal development temperature (T-0) of 29 to 34 degrees C. T-b did not differ among common bean genotypes. Mesoamerican germplasm showed slightly higher T-0 than Andean germplasm, but there was large variation in T-0 within each of the two gene pools. The single accession of tepary bean (P. acutifolius) evaluated appeared to be the most tolerant to high germination temperatures.