Studies on NaCl stress in chrysanthemum (Chrysanthemum morifolium Ramat.)

In this study, effect of applied NaCl on plant growth, chlorophyll and mineral ion concentrations of chrysanthemum was investigated. The experiment was undertaken at the Research Farm of Division of Floriculture and Landscaping, IARI, New Delhi during the winter season of 20162017 and 2017–2018. The present study had explored the effect of salinity stress on growth, biochemical content and mineral composition of chrysanthemum varieties which were exposed to 0 mM NaCl (control) and 150 mM NaCl. Varieties selected for the experiment were Garden Beauty, Shanti, Red Stone, Basanti, Yellow Reflex, Arka Ravikiran, Anmol, Mother Teresa, Sweta Singar and Jaya. Changes in morphological and flowering attributes viz., shoot length (cm), number of branches per plant, days taken for flowering, number of flowers per plant, flower yield/m², plant dry weight (g); biochemical attributes, chlorophyll content (mg/g FW), shoot proline concentration (μmol/g FW) and mineral ion uptake viz., shoot Na⁺ (%), shoot K⁺(%) shoot Ca²⁺ (%) and shoot K⁺/Na⁺ (%) concentration were studied for identifying the salinity tolerance. Salt stress significantly affected plant growth, biochemical content and mineral ion uptake. It was observed that except for shoot Na⁺ and proline concentrations, all the parameters studied showed decreased effect when level of NaCl was raised from 0mM to 150 mM. Stress level and variety is dependant of reduction in plant height and number of branches per plant. At 150 mM NaCl, the highest plant height was recorded in Jaya, Vijay Kiran, Sweta Singar and Mother Teresa. Maximum number of branches/plant was recorded in variety Yellow Reflex, Mother Teresa, Shanti and Red Stone. Flowering was delayed and significant decreased in number of flowers/plant was observed when salinity was increased. Highest shoot proline concentration was found in Vijay Kiran, Jaya, Yellow Reflex, Anmol and Shanti. Treatment differed significantly for shoot Na⁺, K⁺ and Ca²⁺ and K⁺/Na⁺ for all the chrysanthemum varieties. At 150 mM NaCl, highest shoot Na⁺ concentration was found in variety Sweta Singar, Basanti and Mother Teresa whereas lowest Na⁺ concentrations was found in Yellow Reflex, Garden Beauty, Anmol and Shanti. Salt-tolerant genotypes have lower shoot concentrations due to their ability to restrict Na⁺ transports to shoots. Significant decreased in shoot K⁺ concentration and Ca²⁺ concentration was observed with increased salinity. At 150 mM NaCl, highest shoot K⁺ was recorded in Vijay Kiran, Yellow Reflex, Anmol and Jaya whereas shoot Ca²⁺ concentration was maximum in Yellow Reflex, Vijay Kiran, Shanti and Jaya. Highest ratios of K⁺/Na⁺ was recorded in Red Stone (1.50%), Jaya (1.07%), Shanti (1.05%), Sweta Singar (0.89%). From the experiment, Vijay Kiran, Shanti, Yellow Reflex and Jaya were found to be more tolerant to salinity owing to their better growth and yield performance, low Na⁺ accumulation and higher K⁺/Na⁺ ratio.