Assessing suitability of Andrographis paniculata genotypes for rain-fed conditions in semi-arid climates

Medicinal plants are generally suggested for degraded land or areas having low rain-fall. Andrographis paniculata is an important medicinal plant known for its diterpene lactone i.e. andrographolide. We exposed 26 genotypes of A. paniculata to rain-fed condition during early-season rain-fed (ESRF) and mid-season rain-fed (MSRF) conditions and compared with the control to assess their suitability in semi-arid climate region of Gujarat, India. The study was performed during two consecutive years 2016–2017 in split plot design with rain-fed conditions as main-plot treatment and genotypes as sub-plot treatment in three replications. The gaseous exchange parameters taken at 85∼100 days after transplanting exhibited mean photosynthesis rate was 20.5 μmol CO2 m−2 s−1 ranging between 15.9 μmol CO2 m−2 s−1 and 24.0 μmol CO2 m−2 s−1. Exceeding 7% decrease in stomatal conductance was recorded compared to the control plants under imposed rain-fed condition. The mean value of transpiration rate was 4.8 mmol H2O m−2 s−1. The mean value of water use efficiency was 4.6. MSRF condition decreased leaf water potential from −0.517 to −1.189 Mpa. The dry herbage decreased by 29.2% due to MSRF condition as compared the control. The andrographolide yield per plant suffered significantly and under ESRF condition it reduced mainly due to reduction in andrographolide content. Reduced andrographolide yield per plant in MSRF condition was mainly due to reduction in herbage yield. Results revealed that ESRF and MSRF condition characterized by erratic rainfall pattern and dry spell is not beneficial for quality production in A. paniculata. Based on the least decrease in andrographolide, yield two genotypes viz., AP 6 and AP 12 identified to be suitable for ESRF condition and two genotypes viz., AP 19 and AP 6 suitable for MSRF condition. Overall, four genotypes, AP 35, AP 39, AP 61 and AP 24 were suitable as the promising genotypes having high andrographolide yield.