Bacterial Bio-fertilizer Increases Vegetative Growth and Leaf Oil Yield in Cinnamomum verum J. Presl Variety Sri Gemunu.

Abstract

Sri Lankan cinnamon (Cinnamomum verum J. Presl) is the most economically significant spice in Sri Lanka’s export market, generating substantial income. However, Cinnamon cultivation relies heavily on chemical fertilizers contributing to elevated production costs and posing significant environmental and health hazards due to overuse. Despite the global demand for eco-friendly agricultural practices, alternative fertilizers for cinnamon remain underexplored. The objective of this research was to determine the effect of two locally isolated Bacillus spp. as a soil amendment and foliar spray on vegetative growth and leaf oil yield of widely grown cinnamon variety Sri Gemunu (SG) in comparison to commonly used organic alternatives. A completely randomized pot experiment was conducted with five replicates for vegetative data and two replicates for oil yield, using four-month-old SG plants grown in a potting mixture of loamy topsoil, cow dung, coir dust, and soil in a 1:1:1:1 ratio. The treatments included a negative control of topsoil (NC), recommended inorganic fertilizer (F), compost (C), Gliricidia leaves (G), strain 1 foliar spray (1F), strain 2 foliar spray (2F), strain 1 to soil (1S), strain 2 to soil (2S), strain 1 to soil with Gliricidia leaves (1G) and strain 2 to soil with Gliricidia leaves (2G). Vegetative growth parameters and leaf oil yield were measured after 12 months of pot establishment. Vegetative growth parameters of plant height, root length, and leaf number were the highest (101.20 ± 7.36 cm, 118.40 ± 6.81 cm and 191.60 ± 14.80 respectively) in 1S, while 2S recorded the highest stem circumference (3.60 ± 0.59 cm) and SPAD value (56.83 ± 4.48). Inorganic fertilizer supported root growth (118.20 ± 15.22 cm) but showed reduced overall vegetative performance compared to Bacillus treatments. The highest leaf oil yield was produced from 1G (21.34 ± 0.82 μL/g). These findings underscore the potential of Bacillus-based biofertilizers as a sustainable alternative for improving vegetative growth and oil yield in the Sri Lankan cinnamon industry, reducing reliance on chemical inputs.