The effect of seed harvesting time on seed viability of some perennial grasses in Yazd province

Seed availability is essential for biological reclamation projects. Proper seed harvesting time is an important factor to ensure maximum seed viability and to avoid collecting immature or dehiscent seeds. This study aimed to investigate the optimal seed harvesting time of three range plants including Cymbopogon olivieri, Stipa parviflora and Stipa barbata in Yazd province during growing season of 2007. Seeds were collected periodically from physiological maturation time to seed shatter stage. At each collected time 400 seeds were dried and were used in 4 replications for viability test. The experiment lasted for 21 days in completely randomized design. Treatments included species and different harvesting times (four times for S. parviflora, six times for C. olivieri and three times for S. barbata). Duncan mean separation test was performed by SAS program to analysis the data. According to the results, different harvesting times in all three species had significant differences (p≤0.01). Seeds of S. parviflora collected on May 24 had highest germination percentage (93%) and the least occurred on June 7 (63%). Seventy percent of C. olivieri seeds collected on May 11 were germinate seven percent seed of collected S. barbata on June 13 were germinated showing highest germination percentage for treatments. Collected seeds of C. olivieri and S. barbata had minimum germination percentage on June 8 (28%) and June 6 (25%), respectively.