INFLUENCE OF SALT STRESS ON SOME PHYSIOLOGICAL AND BIOCHEMICAL ATTRIBUTES AND OIL COMPOSITION OF A POTENTIAL OILSEED CROP SAFFLOWER (Carthamus tinctorius L.).

Abstract

The principal objectives of the present investigation were to assess inter- cultivar variation for salt tolerance in safflower, draw relationships of various physiological and biochemical attributes to salt tolerance of safflower, identify selection criteria for further improvement in salt tolerance of safflower through specific breeding programs and to appraise whether or not salt stress alters the composition and quality of safflower oil. Different experiments were carried out to assess variation in salt tolerance in 10 accessions (Safflower-31, Safflower-32, Safflower-33, Safflower-34, Safflower-35, Safflower-36, Safflower-37, Safflower-38, Safflower-39, Safflower-78) of safflower (Carthamus tinctorius L.) at varying levels of salt (NaCl) at different growth stages, germination, seedling and adult stages. The results of the germination experiment showed that salt stress had an inhibitory effect on germination percentage and seedling biomass of all 10 accessions. A significant variation in the accessions was observed at the two higher salt levels (180 and 240 mM). While ranking the accessions on the basis of their potential for germination and producing seedling biomass at 240 mM NaCl, lines Safflower- 31 and Safflower-35 were found to be tolerant, Safflower-33, Safflower-37, Safflower-38 and Safflower-78 salt sensitive, and Safflower-32, Safflower- 34, Safflower-36 and Safflower-39 moderately tolerant. To further evaluate safflower lines for their performance at later growth stages, an experiment was conducted using two salt levels (0 control, 150 mM NaCl). Salt stress caused a marked reduction in biomass production, photosynthetic pigments, leaf water relations, gas exchange characteristics, proline content, mineral nutrients, activities of some key antioxidant enzymes, different fatty acids, tocopherol contents and yield attributes. A significant inter-cultivar variation was found in the set of 10 diverse safflower accessions at the adult stage. Although variation for salt tolerance was found at all growth stages, that found at the germination and seedling stage was not maintained at the vegetative or adult growth stages. On the basis of shoot biomass production at the vegetative stage, accession Safflower-37 was ranked as tolerant, while Safflower-31, Safflower-32, Safflower-34, Safflower-39, and Safflower-78 as salt sensitive. In contrast, in terms of seed yield, accessions Safflower- 32, Safflower-34, and Safflower-39 were ranked as tolerant, while Safflower-31, Safflower-33, Safflower-35, Safflower-36, and Safflower-38 as salt sensitive. A positiveassociation of net photosynthetic rate (A) with growth and seed yield was observed in the 10 diverse safflower lines under saline conditions, and thus it could be used as an effective selection criterion for salinity 2 tolerance in safflower.