Evaluation of promising brahmi (Bacopa monnieri Linn.) accessions for yield and quality

Abstract

Brahmi (Bacopa monnieri Linn.), belonging to family Plantaginaceae, is a herb of immense pharmaceutical significance owing to the presence of the saponin ‘bacoside’. It is widely distributed in warmer parts of the world and grows in damp or marshy areas near streams or along borders of ponds, being abundant particularly in monsoon. It is also an endangered species due to excessive collection from the wild. This necessitated the identification of varieties of brahmi suitable for commercial cultivation, in order to meet the rising demands. Hence this study was aimed at identifying suitable accessions of brahmi for cultivation, wherein 13 ecotypes selected through the preliminary screening of 52 ecotypes were evaluated for yield and secondary metabolite production. Some of the accessions under our experiment have proven to be promising in terms of high herbage yield and secondary metabolite accumulation. Thirteen promising accessions (ODBm-11, ODBm-30, ODBm-31, ODBm-32, ODBm33, ODBm-34, ODBm-35, ODBm-36, ODBm-37, ODBm-38, ODBm-39, ODBm-42, ODBm-52) identified based on yield index and bacoside content from a preliminary screening of 52 accessions at AMPRS, Odakkali, were evaluated under this study in Randomised Block Design (RBD) with three replications in one square meter plots. Two crops of 60 days duration each were taken in September and December months of 2020. Vegetative parameters were recorded at one month interval. The crop was harvested at sixty days of planting, and fresh and dry herbage yield and quality parameters were compared. Some of the accessions showed significant variation in the vegetative growth parameters of the accessions. Accessions ODBm-31, ODBm-33, ODBm-34, ODBm-36, ODBm-37, ODBm-38 and ODBm-39 showed significantly higher vine length at 1 month after planting in Season II. Accessions ODBm-33, ODBm-34, ODBm-35, ODBm-38, ODBm-39 and ODBm-42 showed higher cumulative number of branches at 1 month after planting. All accessions except ODBm-33, ODBm-35, ODBm-38 and ODBm-52 showed higher number of leaves at 2 months after planting in Season II. In terms of fresh and dry herbage yields, the accessions ODBm-33, ODBm-37 and ODBm-39 were found to be superior compared to other accessions. Direct hexane extracts ranged from 0.49 % in accession 38 to 0.69 % in accession ODBm-39 though there was no significant difference among accessions. Sequential acetone extract from hexane-extracted dry powder residue varied significantly among the accessions and ranged from 3.71 % in accession ODBm-42 to 5.61 % in accession ODBm-38. The yield of direct methanol extractives obtained ranged from 15.01 % in accession ODBm-32 to 20.32 % in accession ODBm-36, whereas sequential methanol extractives yield of dry powder residue after extraction with hexane and acetone in sequence varied from 10.60 % in accession ODBm-42 to 15.64 % in accession ODBm31 and showed a significant difference among the accessions. The bacoside content showed variation from 2.16 % to 3.35 % of dry weight. Total phenol content ranged from 6.24 mg GAE/100 mg to 9.32 mg GAE/100 mg of direct methanol extract on dry weight basis whereas the total phenol content ranged from 96.84 mg GAE/100 g to 160.88 mg GAE/100 g of whole plant dry powder. Total phenol content in direct methanolic extractives of accessions ODBm-11, ODBm-31, ODBm-34, ODBm-39 and ODBm-42 were significantly higher whereas total phenolic content in terms of content in dry powder basis were higher in accessions ODBm-11, ODBm-34, ODBm-38, ODBm-39 and ODBm-42 only. Accessions ODBm-33, ODBm-37, ODBm-39 were found to be superior in fresh and dry yield. But for the purpose of selection of high yielding, high quality accessions for cultivation, consistency in yield and quality are to be further confirmed over a few more years.