Biomass and centellosides production in two elite Centella asiatica germplasms from India in response to seasonal variation

In the present study two selected germplasm accessions of Indian Centella asiatica have been compared for biomass accumulation and centellosides production when grown at Indo-Gangetic plains and southern plateau region of India. Significant variation in plant growth and content of four major centellosides, namely asiaticoside, madecassoside, asiatic acid and madecassic acid was evident in different seasons at both the locations. Under northern Indian climate at Lucknow, maximum plant growth in both the accessions occurred in hot and humid season (July-September; average rainfall 181-314 mm month−1; max:min temperature being 34:24 °C) during which biomass yield of 4.687-5.962 Mg (Mega gram) fresh weight ha−1 and 6.264-7.618 Mg fresh weight ha−1 could be realized in accession A and M, respectively. The maximum biomass productivity under southern climate at Bengaluru location in these two accessions (4.862 and 3.822 Mg fresh weight ha−1) was recorded in the month of April when max:min temperature ranged between 35 and 22 °C with very low (Average rainfall 18.0 mm/month) rainfall. The pooled ANOVA of the obtained data suggested significant (p < 0.01) genotype × location, accession × harvest and location × harvest interactions. The accumulation profiles of centellosides in the two accessions at two locations also showed interesting trends. Accession M consistently registered more total centellosides content (7.5-80.1 mg g−1 dry weight) than accession A (6.5-64.6 mg g−1 dry weight) during round the year cropping cycle under Lucknow climate whereas, both the accessions performed at par under Bengaluru climate. The bulk of the accumulated centellosides in accession M and A during high biomass accumulation phase at Lucknow was contributed by the two saponin constituents i.e., 52.1 and 32.7 mg g−1 dry weight asiaticoside and 25.6 and 13.7 mg g−1 dry weight madecassoside, respectively. However, both the accessions tend to accumulate more of madecassoside (59.1 and 64.4 mg g−1 dry weight) than asiaticoside (24.9 and 27.4 mg g−1 dry weight) during corresponding growth phase at Bengaluru. Interestingly, when crop under Lucknow climate was allowed to grow in the field for one full year, accessions A and M accumulated more of the two sapogenins (16.7 and 21.7 mg g−1 dry weight asiatic acid and 44.0 and 9.4 mg g−1 dry weight madecassic acid) than the saponin constituents before the onset of succeeding rainy season in the month of July. This study thus, suggests that different crop duration cycles and harvesting schedules in C. asiatica can be followed at two studied locations for ensuring round the year supply of this herb.