Effect of desiccation on germination and vigor of Manna Oak (Quercus brantii Lindl.) acorns

This research is aimed to study the seed moisture content (SMC) and its effects on the germination and vigor of Manna oak (Quercus brantii Lindl.) acorns. Acorns were collected from Manna oak forest habitat, in Mámásáni, Fars province, and subjected to oven-dry (30 °C) at five treatments: no desiccated (control), 24, 48, 72 and 96 hours for decreasing SMC. The SMC of treatments were obtained 47.4 (fresh weight basis or control sample), 46.7, 42.5, 40.7 and 32.2%, respectively. For measuring of germination, the acorns were placed in germinator at 25 °C and 8-16 hours (radiation-darkness). Results in a 30-day period revealed that germination rate, germination speed, root and shoot lengths, dry mass of root, shoot and plant, and vigor index severely decreased with decreasing SMC. Most of the seed characteristics severely decreased when SMC reduced about 7% (reached 40/7%). When the SMC decreased about 15% (reached 32.2%), germination declined about 77%. The SMC had a negative significant correlation with mean germination time (P < 0.05) and had a positive significant correlation (P < 0.05) with other measured characteristics. The results revealed that germination and vigor index of Manna oak acorns are highly dependent on SMC and have a recalcitrant storage behavior. It is needed to keep the SMC of Manna oak from harvesting date to sowing date.