Logistic function analysis of germination behaviour of aged fennel seeds

Abstract 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 ( Gt 10) 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 , Gt 10, 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 Gt 10 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 Gt 10, 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”.