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When lettuce seeds are sown in soil temperature above 30℃ germination can be erratic or completely inhibited and crop or transplant production is thereby limited.Thus lettuce seed germination is strongly temperature dependent.As temperature rises even 2 or 3(℃) above the optimum (usually 15-22(℃)) lettuce germination can sharply decline from nearly 100% to near 0%.Relief of such dormancy can be obtained by a number of methods,seed priming can shorten the period from sowing to seedling establishment and reduce the risk of seeds being exposed to adverse environmental and biotic factors.Priming initiates several physiological and biochemical changes in lettuce.