The role of hull in germination and salinity tolerance in some sunflower (Helianthus annuus L.) cultivars

Six different NaCl levels (0, 5, 10, 20, 30 and 40 dS m(-1)) and two seed types (hulled and dehulled) of sunflower seeds of Opal, Shelly (Confectionary) and Pactol (Oily) were tested to determine the effects of the hull on salinity tolerance during germination. Germination percentage (%), mean germination time (day), root and shoot length (cm) were investigated. Kernel type seeds exhibited higher germination percentage, longer root and shoot length and lower mean germination time compared to the achene type seeds at all NaCl levels. Both achene and kernel type seeds of cv. Pactol gave the highest germination percentage, root and shoot length. Hull was responsible for delaying germination and water uptake by seeds while it had no role in lowering the toxic effects of NaCl during germination. Therefore, it was concluded that inhibition in germination at all levels of NaCl was mainly due to osmotic barriers created by the presence of hulls rather than salt toxicity.