ASSESSMENT OF SEEDLING EMERGENCE, GROWTH TRAITS AND PHYSIOLOGICAL INDICES OF A MEDICINAL PLANT CALOTROPIS GIGANTEA (L.) AITON f. UNDER NaCl INDUCED SALINITY STRESS

Calotropis gigantea (L.) Aiton f. giant milkweed or Aakanda (in Bengali) is a branched large shrub, spreading in many countries all over the world and has important medicinal and fiber production values. With this research, we evaluate the effects of NaCl salinity stress on the seedling emergence, growth and physiological traits of Calotropis gigantea. Following a randomized complete block design with artificial four levels of saline soils viz. 6, 8, 10 and 12 dS m(-1) alongside with control (0 dS m(-1)) were studied with three replications. Calotropis gigantea seeds were tested in varying concentrations of artificial saline soil for 45 days. Analysis of variance showed that seedling emergence, growth and physiological attributes revealed to be severely impacted due to salt stress. Mean emergence time and proline content rose along with a rise in salinity level, but other characteristics declined with the upsurge of saline stress. Reduction of total chlorophyll content was more in 12 dS m(-1) salinity treatment compared to control condition. Principal component analysis showed that first principal component contributed 87% of the total variation and noticeably distinguished Calotropis gigantea genotype for seedling emergence, growth and physiological traits under all salinity treatments (6, 8, 10 and 12 dS m(-1)) from control condition (0 dS m(-1)). Correlation study exhibited that mean emergence time and proline content had positive correlation but both were negatively correlated with other studied traits. Overall, our present investigation brought a new output for cultivating the wild shrub Calotropis gigantea in saline prone soil, especially in the coastal regions of the world.