Dammarane-type triterpenoid saponin-rich elite genotypes of Bacopa monnieri from south India and their edaphic-ecological preferences

Abstract

High domestic and export demands are prompting the uncontrolled collection of the nootropic herb Bacopa monnieri (L.) Wettst. (BM) from its natural habitats in India; therefore, selection and cultivation of elite genotypes is one of the priorities for generating its quality biomass for industrial purposes. Here sixty BM accessions collected from diverse geographical regions of south India were screened for the two major bioactive dammarane-type triterpenoid saponins, bacoside A (BA) and bacopaside I (BI), by HPTLC-densitometry. Among these sixty accessions, BA, BI and (BA+BI) contents ranged from 0.36 ± 0.05 to 5.68 ± 0.18%, 0.00 ± 0.00 to 1.53 ± 0.12% and 0.41 ± 0.13 to 7.17 ± 0.35%, respectively. Industries consider BM accessions with (BA+BI) ≥ 5.5% as elite lines; this study identified eight elite accessions (1/Bm-11, 2/Bm-55, 3/Bm-57, 11/Bm-68, 19/Bm-76, 33/Bm-90, 36/Bm-93, 44/Bm-102) of BM, satisfying this benchmark. In bi-location trials, six BM elite genotypes were cultivated at two geographical locations (plot 1, low altitude and plot 2, high altitude). In Plot 1, highest (BA+BI) contents and biomass yields were observed in 2/Bm-55 (6.60 ± 0.09%) and 19/Bm-76 (4090.28 Kg/ha, fresh wt.), respectively. Elite accession 2/Bm-55 was subjected to agrotechnology standardization trails at Plot 1 with 10 combinations of nitrogen-phosphorous-potassium (N-P-K), cow dung, cocopeat and soil (only) treatments. Two treatments, N:P:K 150:90:90 and soil (only), gave elite contents of BA+BI (≥ 5.5%) (5.89%, 6.62%) and high biomass yields (64152.84 Kg/ha, fresh wt., 63076.45 Kg/ha, fresh wt.). Significantly, five of the eight elite BM accessions identified viz., 1/Bm-11, 3/Bm-57, 44/Bm-102, 36/Bm-93, 19/Bm-76, were collected from ≤ 10 m altitude locations; this study provides experimental evidence to the preference of BM to low altitude, wet and marshy habitats. Briefly, this study reports conservation, sustainable utilization and edaphic-ecological preferences of the natural resources of this high value memory enhancing herb.