Seed vigor and ion toxicity in safflower (Carthamus tinctorius L.) seedlings produced by various seed sizes under NaCl stress

Abstract

Safflower is an important oilseed crop and is largely grown for edible oil production in low moisture or saltaffected soils of Turkey. The objective of the study was to find out the quality of seeds with different sized seeds, and the effects of seed size (3, 4 and 5 mm) and NaCl stresses at electrical conductivities of 5, 10, 20 and 30 dS m-1 on the germination and early seedling growth of the safflower cultivar Din?er. Our results show that heavier one-thousand-seed weight (70.5 g) and higher hull percentage (52.9 %) were obtained from large seeds while the oil content and water uptake of small seeds was higher than that of medium or large seeds. Germination percentage, germination time, root length, shoot length, and seedling fresh and dry weight showed size-dependent responses of the seeds to salt stress. In general, medium-sized (4 mm) seeds germinated more rapidly compared to small and large seeds against all levels of salt stress; however, the highest germination percentage and most vigorous seedling growth was recorded from large seeds after 10 days incubation. The inhibitory effect of NaCl levels was exhibited a drastic effect on seedling growth. Increased NaCl resulted in an increase in the Na+ and Cl- content of the seedlings produced by all seed sizes, while the K+ content was not changed. However, the seedlings from small seeds had the highest Na+ and Cl- content of all measured NaCl levels. It was concluded that large seeds produced vigorous seedling growth due to a lower ion accumulation under NaCl stress. Consequently, large seeds could be used for successful stand establishment in contrast to their slow germination performance if the cultivation of safflower on saline soils is required.