Effects of seed priming on catalase activity and storage reservoirs of aged milk thistle seeds (Silybum marianum (L.) Gaertn)

In order to study effects of seed priming on storage reservoirs and element contents of aged milk thistle seeds a factorial experiment was conducted based on complete randomized design (CRD) with three replications. Treatments were hydropriming (using distilled water), halopriming (0, 1.5, 3, 4.5 and 6% KNO 3 ) and accelerated aging (0, 48, 96 and 144 hours under 45 °C and 100% relative humidity). Investigated parameters were germination percentage, mean time germination, seedling length, seedling dry weight, seed reservoirs usage rate (SRUR), seed reservoirs usage efficiency (SRUE), fraction of utilized seed reservoirs (FUSR), catalase activity (CAT), content of sodium, potassium, calcium and sodium to potassium ratio in seedling and cotyledons. The result showed that priming could increase germination percentage, seedling length, and dry weight and reduce mean time of seed germination, while under aging conditions all these traits were decreased except mean time of germination. Priming with concentrations of 3% and 1.5% KNO 3 showed the highest germination percentage, seedling length, dry weight and least mean time germination. Catalase activity deceased at ageing treatment and priming seeds with 3% KNO 3 exhibited the highest value of catalase activity. Aging treatment led to increase of SRUR and in contrast it decreased SRUE and FUSR. The highest SRUR appointed to hydropriming, whereas the highest amount of SRUE and FUSR belonged to 3% KNO 3 treatment. Aging increased Na + content and Na + /K + ration while, it deceased K + and Ca 2+ in seedling and cotyledon. In general priming increased germination percent and improved seedling growth, performance of reserves and as well as increased catalase activity and reduced elements leakage from the cells under the aging.