Applied powdered leaf-biomass of alien weed Hyptis suaveolens (L.) Poit. in soil adversely impacts germination, growth, and yield of crop Lens culinaris Medik. despite enhancing soil fertility

Abstract

Hyptis suaveolens L. (family Lamiaceae), an exotic fast-spreading invasive weed in Indian dry-tropics, was investigated for the allelopathic impact of its powdered leaf-biomass on the seed germination, growth, yield, photosynthetic-pigments and biochemical parameters (protein, proline and phenolic content) of the crop Lens culinaris. Soil characteristics (organic carbon, total nitrogen, available phosphorous and phenolic content) of soils amended with powdered leaf-biomass were also examined in this study. Soils were amended with differing doses (1g, 2g, 4g and 8g kg− 1 soil) of powered leaf-biomass of the investigated weed. Lentil seed germination distinctly declined in soils amended with higher doses of powdered leaf-biomass. Crop growth, including its yield, significantly declined with increasing dose of powdered leaf-biomass. Compared to control, chlorophylls (a and b), carotenoids and protein content decreased significantly at varying growth stages of lentil with increasing dose. In contrast, proline and phenolic content in lentil crop significantly increased with increasing doses. The allelopathic index and synthesis effect of powdered leaf-biomass increased with increasing doses and it was significantly higher at the higher dose (8g kg− 1 soil). Thirty-five chemical compounds were GCMS-identified from the leaf extract of this weed. The identified compounds were mainly alkaloids, terpene, phenolics and fatty acids. Organic carbon, total nitrogen and phenolic content of the variously amended-soils increased significantly with increasing applied powdered leaf-biomass. In conclusion, powdered leaf-biomass of the Hyptis suaveolens, despite improving soil fertility, adversely impacted crop growth and its biochemical attributes, ostensibly through the release of allelochemicals, implying its immense invasibility in diverse ecosystems of India.