LOGISTIC FUNCTION-ANALYSIS OF GERMINATION BEHAVIOR OF AGED FENNEL SEEDS

Fennel seeds (Foeniculum vulgare Mill. cv. amargo) collected from cultivated plants grown in experimental fields were germinated in darkness at 20, 25 and 30°C after 1, 3 and 5 years of seed storage at room temperature. Logistic function G = A[1 + exp (β - kt)]-1 was used to analyse cumulative germination curves over time. In addition to determining the function parameters (A, β and k), other derived quantities including germination percentage at the point of inflexion (A/2), time to reach 50% of final germination (β/k), maximum germination rate (Ak/4), onset of germination (Gt10) and mean cumulative relative germination rate (k/2) were also calculated. Through the use of these variables, the behaviour of aged fennel seeds was studied in terms of their germination success. The most relevant aspects were: (1) the main source of variation was the age of seeds; (2) the onset of germination was highly dependent on age of seeds; and (3) there was no significant influence of germination temperature on A. Statistical differences were found between younger and older seeds for A, Gt10, β/k and Ak/4. There were no significant differences between older seeds for all germination variables considered. Statistical differences were also found between seeds germinated at 20 and 30°C for both Gt10 and β/k, and between seeds germinated at 25 and 30°C for both Ak/4 and k/2. In addition to this biometric evaluation, a factor analysis by principal components method was performed. The first component is more correlated with Gt10, β/k and A, and may be interpreted as a "temporal factor". However, the second component is more correlated with k/2, Ak/4 and β, and may be partially interpreted as an "environmental factor". © 1990.