Effects of hydropriming and osmopriming in germinability and storability of 'Bang Chang' pepper (Capsicum annuum L.) seeds

Commercial seedling production of ‘Bang Chang’ pepper often has problems with delayed and non-uniform germination. This study investigated the effects of hydropriming and osmopriming on germinability and storability of pepper seeds on germination uniformity. Initial seed qualities were: 7.6% seed moisture content, 52.0±2.7% germination, and 13.37±1.6 days of mean germination time (MGT). A completely randomized design with 4 replicates was used. Treatments were non-primed seeds (control), hydropriming (soaked seeds in reverse osmosis water for 8 h plus non-incubation or incubation at 20±2°C and 100% RH for 24 h), osmopriming (soaked seeds in 3% KNO₃ or -1.5 MPa polyethylene glycol (PEG) 6000 for 8 h plus non-incubation or incubation for 24 h). Seeds were then dried to 7% moisture content. A standard germination test was carried out immediately after priming treatments. Seeds were kept in aluminium foil zip-lock bags at 20±2°C for 6 months in order to determine seed longevity. Germination percentage and MGT were recorded at two-month intervals for 6 months. Seeds osmoprimed with 3% KNO₃ plus incubation before storage had the highest germination (83.0±1.1%), the fastest and uniform MGT (9.34±0.2 days) and highest seedling growth (plant height, stem diameter, dry weight of shoot and root) at 28 days after sowing comparing with seeds primed by other methods and control seeds (52.0±2.7%). Primed seeds maintained quality for 4 months. Seeds osmoprimed with 3% KNO₃ and -1.5 MPa PEG 6000 plus incubation had germination of 78.5±1.2 and 68.0±1.4%, respectively, when compared with control seeds (48.0±2.3%). In addition, MGT of seeds osmoprimed with 3% KNO₃ was faster than that of seeds osmoprimed with -1.5 MPa PEG 6000 (10.02±0.5 and 10.81±0.4 days, respectively). Thus, osmopriming with 3% KNO₃ plus incubation was the best technique for improving germination, speed of germination and uniformity of ‘Bang Chang’ pepper seeds.