Effect of water stress and accelerated ageing on some physiological characteristics of Pinus brutia Ten. seeds

The research was carried out for considering the effect of water stress and accelerated ageing on several physiological characteristics of pinus brutia seeds including germination percent, mean germination time, germination speed, germination energy and vigor index. Seeds were arranged in petri dishes with 4 replications in completely randomized design with five levels of water potential and five levels of accelerated ageing factor. Water potentials of the germination substrates (0, -2, -4, -6 and -8 bars) were produced using PEG-6000 solutions and seeds involving accelerated ageing treatment were exposed to 40 °C and relative humidity of 100 percent for zero, 24, 48, 72 and 96 hours. Then seeds were kept for 37 days in germinator (16 h photoperiod at 1000 lux and at 20 ± 0.5°C). For measuring Electrical Conductivity (EC) test, seeds selected from all of accelerated age treatments exposed to 25 °C in incubator for 24 hours. The results indicated that water stress and accelerated ageing had significant effect on seed physiological characteristics. Decreasing water absorption potential from 0 to -8 bars and increasing ageing period significantly reduced most of the seed physiological characteristics. The EC values were the least and highest in control samples and accelerated ageing treatments, respectively. Vigor index was more affecting water stress and accelerated ageing than germination percent.