Contribution of the nutrient-enriched ant nest debris soil to growth and yield of Kalmegh (Andrographis paniculata) under natural and experimental field conditions

Abstract

Andrographis paniculata, commonly known as Kalmegh, is an important medicinal plant which exhibits a range of pharmacological characteristics. The present study revealed that under natural and experimental field conditions, the debris soil of the ground-nesting ant (Pheidole latinoda) colonies increased soil fertility and yield of this plant. The growth of Kalmegh planted in the debris amended soil was significantly enhanced in a dose-dependent manner. The yield, in terms of number of branches, number of leaves, plant biomass and number of pods plant−1 was consistently higher for plants grown in debris amended treatments as compared with plants grown in control soil. Concentrations of total C, P, available N (NH4-N, NO3-N) and microbial biomass C and P were significantly higher in the various debris amended soil treatments as compared with the control soil. Significant positive correlations were found between the ecophysiological traits of Kalmegh plants, i.e. leaf area, total biomass and number of fruits plant−1, and the soil chemical properties of the soil. Under natural field conditions also the biomass of Kalmegh plants growing within 5 m distance of P. latinoda nests was significantly higher as compared with plants located at a distance >10 m. Overall, the results suggested that the ecosystem engineering activities of P. latinoda colonies have the potential to contribute to soil fertility and thereby promote enhanced growth and yield of this medicinally important plant. Since colonies of ground-nesting ant species, such as P. latinoda, are abundant in annual cropping systems, they can contribute to agricultural sustainability.