Effect of temperature, light on germination and morphological characteristics of Bipolaris sorokiniana

Wheat is one of the most nutritious, proteinaceous and basic stable food crop is attacked by several factors. Among the biotic factors, the most notorious disease of wheat is spot blotch caused by Bipolaris sorokiniana. The behaviour of the pathogen with different combinations of weather regimes were studied in-vitro, in the dark at different temperatures. Maximum conidial germination (92.04%) was observed at 30 °C followed by 91.69% at 25 °C temperature after 4 h of incubation. Lowest germination was recorded at 10 °C. Maximum length of unipolar germ tube (26.28 µm) was recorded at 15 °C which was statistically superior than other treatments. Whereas, maximum width of unipolar germinated germ tube (4.49 µm) was observed at 25 °C followed by 15 °C. The length and width of germ tubes of the two poles of bipolar germinated B. sorokiniana spores were 19.74, 22.61 and 3.92, 4.11 µm, respectively at 15 °C followed by 20 °C temperature. Significantly lowest time required for secondary conidiophore formation (25 h) and conidia formation (39 h) was recorded at 25 °C. Highest time required for formation of secondary conidiophore (35 h) at 20 °C, conidia at 30 °C (80 h) but at 10 and 35 °C temperature secondary conidiophore and conidia formation was not observed within 80 h of incubation. Higher mycelial growth and no sporulation were observed under continuous light condition. © 2018, Indian Phytopathological Society.