GERMINATION OF PRIMED, PELLETED, AND FILM-COATED LETTUCE SEEDS BEFORE AND AFTER STORAGE

摘要

Under high temperatures, lettuce {Lactuca sativa L.) germination can be erratic or completely inhibited in commercial cultivars. However, priming seeds circumvents thermo-dormancy, facilitating germination at higher temperatures. 'Green Towers' and 'Desert Storm' were primed, pelleted, or film-coated by four different seed treatment companies to determine the effects of treatment on germination at 20 and 30°Cbefore and after storage for 9 months. Most of the seeds, regardless of treatment, germinated above 90% at 20°C before and after storage. At 30°C nonprimed seeds of 'Desert Storm' germinated at 57% and 'Green Towers' at 67%, while primed seeds germinated above 96% regardless of company treatment. After 9 months storage, germination at 30°C of control seeds was as low as 2% for 'Green Towers', while germination of primed seeds was near 100%. Although there were some variations among the seed companies' techniques for priming, pelleting and film-coating, germination at 20°C was similar among treatments to the control. Pelleting and film-coating resulted in reduced germination at 30°C, especially after storage. Pelleted-primed seeds of 'Desert Storm'however germinated at the same rate as primed seeds after 9 months storage at 30°C. Vigor, measured as germination rate, and radicle length were similarly negatively affected by pelleting and film-coating. Seed priming, regardless of company, did not affect seed viability or seed vigor after 9 months storage of both lettuce genotypes, but germination at 30°C of pelleted and film-coated seeds lacking the priming treatment was reduced before and after 9 months storage. Under conditions of high temperature during germination, use of film-coated seeds or pelleted seeds without priming should be avoided.