PACKAGING MATERIALS AND SEED VIABILITY - EFFECT OF FORMALDEHYDE AND OTHER TOXIC VOLATILES

Formaldehyde and other volatile substances originating from printing i nk, paper, or glue of seed packages may cause a rapid decrease of seed germinability. Lettuce (Lactuca sativa L.) seeds appear particularly sensitive. At 20-degrees-C and 75% relative humidity of the air (RH), lettuce seeds lost germinability within one month when stored in a des iccator together with five recently printed paper bags as a source of toxic volatiles. In the absence of toxic volatiles, germination capaci ty had not decreased after a storage period of 12 months under the sam e conditions of temperature and relative humidity. Various packaging m aterials tested maintained seed germinability for a period of four mon ths in the presence of toxic volatiles, but after eight months germina tion capacity started to decrease. At 30-degrees-C/75% RH, the packagi ng materials tested protected seeds for only a few weeks against deter ioration due to toxic volatiles. Seed species differ considerably with respect to sensitivity to formaldehyde. In some species, low formalde hyde concentrations appear to have a dormancy breaking action. Sensiti vity of lettuce seeds to formaldehyde and other toxic volatiles is lar gely dependent on their moisture content. With increasing moisture con tent, the effect of toxic volatiles compounds dramatically increases. Therefore, besides a protective effect of packaging materials due to s low penetration of toxic volatiles, their ability to maintain a low se ed moisture content is particularly important.