ADAPTABILITY POTENTIAL OF JUSTICIA ADHATODA L. TO XERIC ENVIRONMENTS THROUGH ROOT MORPHO-PHYSIOLOGICAL AND ARCHITECTURAL MODULATIONS

Abstract

Justicia adhatoda colonizes tropical and subtropical areas of the world. Populations of Justicia adhatoda were collected from different environments in Punjab, Pakistan. The habitats were classified into least dry habitats , moderately dry habitats, and severely dry habitats based on Budekyo lettu dryness ratio. These ecotypes of Justicia adhatoda were evaluated for adaptability potential under drought stress in relation to soil physico-chemical and environmental attributes. Root fresh weight, root dry weight and root length was significantly increased at severely dry habitats. Among root ionic contents Na + content was the maximum at severely dry habitats. Root Ca, K, P and Mg contents were high at Barakhu (BAR) and Khewra (KHW) sites. Among anatomical attributes, root epidermal thicknesses, epidermal cell area, root endodermal thickness and cell area, the cortical cell area, root metaxylem and protoxylem area and root pith area were significantly increased while cortical region thickness, metaxylem cell area and root radius reduced in ecotypes of Justicia adhatoda of severely dry habitats. It was concluded adaptability of Justicia adhatoda under drought stress was directly linked to the plasticity in root morpho-physiological and anatomical traits such as sclerification in roots epidermis, cortex and endodermis and vascular bundle that also help to conserve water and provided mechanical strength for adaptability against environmental conditions.