Investigating high throughput phenotyping based morpho-physiological and biochemical adaptations of indian pennywort (Centella asiatica L. urban) in response to different irrigation regimes.

Indian pennywort (Centella asiatica L. Urban; Apiaceae) is a herbaceous plant used as traditional medicine in several regions worldwide. An adequate supply of fresh water in accordance with crop requirements is an important tool for maintaining the productivity and quality of medicinal plants. The objective of this study was to find a suitable irrigation schedule for improving the morphological and physiological characteristics, and crop productivity of Indian pennywort using high-throughput phenotyping. Four treatments were considered based on irrigation schedules (100, 75, 50, and 25% of field capacity denoted by I [control], I, I, and I, respectively). The number of leaves, plant perimeter, plant volume, and shoot dry weight were sustained in I irrigated plants, whereas adverse effects on plant growth parameters were observed when plants were subjected to I irrigation for 21 days. Leaf temperature (T) was also retained in I irrigated plants, when compared with control. An increase of 2.0 °C temperature was detected in the T of plants under I irrigation treatment when compared with control. The increase in T was attributed to a decreased transpiration rate (R = 0.93), leading to an elevated crop water stress index. Green reflectance and leaf greenness remained unchanged in plants under I irrigation, while significantly decreased under I and I irrigation. These decreases were attributed to declined leaf osmotic potential, increased non-photochemical quenching, and inhibition of net photosynthetic rate (P). The asiatic acid and total centellosides in the leaf tissues, and centellosides yield of plants under I irrigation were retained when compared with control, while these parameters were regulated to maximal when exposed to I irrigation. Based on the results, I irrigation treatment was identified as the optimum irrigation schedule for Indian pennywort in terms of sustained biomass and a stable total centellosides. However, further validation in the field trials at multiple locations and involving different crop rotations is recommended to confirm these findings.