SEED PERSISTENCE - A CORRELATION BETWEEN SEED LONGEVITY IN THE SOIL AND ORTHO-DIHYDROXYPHENOL CONCENTRATION

1. Ortho-dihydroxyphenol and cyanoglycoside concentrations were determ ined in seeds of over 80 species, drawn largely from the native Britis h flora but including a number of weeds and other species of agricultu ral significance. 2. All seeds examined contained at least trace amoun ts of hydroxyphenols and three-quarters released hydrogen cyanide on h ydrolysis. A highly significant correlation was found between (a) seed persistance in the soil and ortho-dihydroxyphenol concentration and ( b) between protein content, as a measure of the nutritional value of t he seed, and ortho-dihydroxyphenol content. No such relation was found with cyanoglycosides. 3. Particularly high concentrations of ortho-di hydroxyphenols were found throughout species within the order Myrtales (Onagraceae and relatives), all with little or no seed endosperm. 4. From this broad survey we conclude that ortho-dihydroxyphenols, as a c lass, play an important role in maintaining seed persistence in the so il, probably by deferring or decreasing the rate of decomposition by m icrobes as well as by defending against herbivory, and that this is on e important mechanism, along with morphological adaptations, which con fers longevity and persistence on seeds buried in cool temperature and relatively moist soil conditions.