Comparative Study of Morphological Characteristics of Phytopathogenic Fungi Fusarium oxysporum from Allium sativum at Two Different Temperatures

Abstract

Aims: It is of great importance to better understand plant pathogenic fungi, to clarify host–pathogen relationships, and to select the most effective disease control strategies. Since temperature is one of the most influential environmental factors shaping host–pathogen interactions and fungal development, this study aimed to evaluate the morphological and developmental differences of Fusarium oxysporum isolated from garlic (Allium sativum) at different temperatures. Materials and Methods: Fusarium oxysporum isolates obtained from garlic were cultured at 20°C and 27°C. Morphological and developmental traits such as colony diameter, mycelial growth rate, mycelium width, conidial size, and colony color were examined and compared between the two temperature conditions. Statistical analyses were performed using ANOVA to determine significant differences between parameters, with significance set at P < 0.05. Results: All traits studied, except microconidia length, differed significantly between the two temperatures. Colony diameter, final mycelial growth rate, and mycelium width were greater at 27°C, whereas macroconidia length and width were higher at 20°C. Microconidia width increased at 27°C, while microconidia length showed no significant difference. Colony color darkened progressively at both temperatures, but at 27°C it developed into a very dark bordeaux when viewed from both the front and reverse sides of Petri dishes. Overall, colony growth at 27°C was approximately 22% higher than at 20°C, highlighting the temperature-dependent developmental differences. Conclusion: The results demonstrate that classical species identification should be based on colonies developed at different temperatures, as morphological traits vary significantly. Inoculum sources responsible for contamination and spread may differ between summer and winter crops. Furthermore, these findings contribute to explaining why certain diseases emerge earlier or later, highlighting the importance of temperature in host–pathogen interactions.