Effects of Ambient Storage Temperature and Seed Moisture Content on Seed Longevity of Lettuce (Lactuca sativa)

This study was conducted to test changes in seed storage longevity of lettuce seeds at ambient monthly mean temperatures mimicked in five different regions of Turkey, for 28 months and moisture contents of 7, 9 and 11±0.1%. Hermetically stored samples were removed from storage every four months and normal seed germination was tested. Survival curves were constructed and probit analyses were conducted. Differences in longevity were compared by changes in P50, the time germination reduced to 50% and σ, the time germination reduced 1 probit value (i.e. 85% to 50%). The means of three moisture contents revealed that the highest (P50=19.5 months) and lowest (P50=5.5 months) seed longevity was obtained from Black Sea and South East regions, respectively. In all regions, shorter longevity values were recorded in seeds of high moisture content. Results indicated that high ambient moisture and temperature storage conditions can adversely affect lettuce seed longevity. Thus lower seed moisture content is necessary to maintain seed viability.