Temperature-Dependent Effects of Beauveria bassiana on Germination and Early Growth of Allium cepa Seedlings
DOI:
https://doi.org/10.31098/cset.v5i1.1167Keywords:
Allium Cepa, Entomopathogenic Fungus, Heat Stress, Plant Growth Promotion, Seedling EstablishmentAbstract
The entomopathogenic fungus Beauveria bassiana can associate with plants and promote growth, but these effects may vary with temperature. This study evaluated the effects of B. bassiana on germination and early growth of red onion (Allium cepa L.) at 22, 28, and 34 °C. Bulbs were soaked for 3 h in 10^8 conidia/mL or sterile water before planting. Fungal treatments were reinforced by soil drenching at 3, 6, and 9 days after planting (DAP) and foliar spraying at 6, 9, and 12 DAP. Germination, plant height, and leaf number were monitored for 12 days. Temperature significantly affected mean germination time (F₂,₁₀ = 51.49, p < 0.001), increasing from 2.98 days at 22 °C to 3.43 days at 28 °C and 4.58 days at 34 °C, whereas B. bassiana had no significant effect (p = 0.339). At 12 DAP, B. bassiana-treated seedlings were significantly taller than controls (18.73 vs. 18.16 cm; F₁,₁₀ = 11.75, p = 0.006). Temperature, B. bassiana, and their interaction significantly affected area under the plant-height growth curve (F₂,₁₀ = 4.99, p = 0.031). Growth promotion occurred at 22 and 28 °C but was negligible at 34 °C. Leaf number was markedly reduced at 34 °C, while B. bassiana had no significant overall effect. Thus, the early growth-promoting effect of B. bassiana was temperature-dependent and substantially attenuated under continuous high temperature.
