Effects of seed aging on subsequent seed reserve utilization and seedling growth in soybean

Reduced seedling growth is a consequence of seed deterioration. The heterotrophic seedling growth can be considered as the product of three components: (1) initial seed weight, (2) the fraction of seed reserves which are mobilized, and (3) the conversion efficiency of mobilized seed reserves to seedling tissues. It is not clear which of these component (s) is affected by seed deterioration. To study this subject, germination characteristics and seedling growth from deteriorated soybean (Glycine max) seeds were studied; seeds were incubated at two different temperatures of 34 ºC and 40 ºC for varying times. The results indicated that seed deterioration results in decreased percentage and rate of germination and decreased percentage of normal seedlings. Seedling growth and the fraction of seed reserve mobilization indicated a significant decrease with the advance of deterioration. However, the effect of seed deterioration on the conversion efficiency of mobilized reserves to seedling tissues was not significant. Thus efforts to improve seedling germination and growth in plant breeding programs should focus on improvement of fraction of mobilized seed reserves.