Effect of alkalinity on growth performance of Jatropha curcas inoculated with PGPR and AM fungi

Abstract

A pot experiment was conducted to assess the effect of soil alkalinity on emergence, growth, leaf relative water content, total soluble sugar and soluble protein of seedlings of Jatropha curcas L. Na₂CO₃ was added to the soil and alkalinity was maintained at 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%. In general increased alkalinity caused reduction in growth.   Hence we designed the experiment to test the efficacy of beneficial microbes (Azotobacter, Microfoss and arbuscular mycorrhizal fungi) individually and in combinations to alleviate the stressful effect of alkaline soil. The data pertaining to the effect of bioinoculants on different parameters of Jatropha curcas under alkaline stress were collected and statistically analyzed. The effect of bioinoculants on percentage seed germination and survival at 0.4% of Na₂CO₃ was found to be in order of; Azotobacter+AMF> AMF>Azotobacter+ Microfoss>Microfoss > Azotobacter >control (no germination) while at 0.5 % Na₂CO₃ germination was almost nil with all treatments. The survival percentages with respect to all treatments were found to be significant at 0.4%, Na₂CO₃ level over control. The combination of AM fungi and Azotobacter increased plant height, shoot diameter, shoot dry weight, leaf relative water content and soluble sugar content and decreased level of soluble protein at 0.4 % of Na₂CO₃ over other treatments. We conclude that the combinations of Azotobacter and AMF performed well up to 0.4 % of Na₂CO₃ in soil.