Morphological and Physio-biochemical Changes of in Vitro Cactus (Echinopsis calochlora) in Responses to Salt Stress

Na+ content in the plantlets was increased upon exogenous NaCl in the culture medium whereas the potassium ion (K+) decreased. Free proline content in salt stressed cactus plantlets was also enriched and peaked when plantlets were subjected to 200 mM NaCl. Na+ in salt stressed plantlets was negatively correlated to chlorophyll a content. Photosynthetic pigments, i.e., chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids, declined significantly in plantlets exposed to 100 mM NaCl, resulting in reduced net photosynthetic rate and inhibition of overall growth characters. Number of cladode budding, root length, number of roots, and fresh and dry weight of cactus plantlets was significantly declined when cactus plantlets expose to 50 mM NaCl. In addition, the number of roots of in vitro cactus plantlets was a good indicator for salt sensitivity, which were absent in plantlets subjected to 200 mM NaCl for 28 days.