SEEDS OF KOSTELETZKYA-VIRGINICA (MALVACEAE) - THEIR STRUCTURE, GERMINATION, AND SALT TOLERANCE .1. SEED STRUCTURE AND GERMINATION

Dormancy of Kosteletzkya virginica (L.) Presl. seeds is primarily due to the impermeability of the seed coat to water. The impermeable struc ture is assumed to be, in other Malvaceae, the palisade layer of the s eed coat. The percentage of seeds capable of imbibition and germinatio n increased with increasing time of storage at low temperatures, but t he release from dormancy was not accompanied by decreased seed coat re sistance to pressure. Under natural conditions, mechanical damage to t he seed coat due to changes in temperature and/or abrasion may render the seeds water permeable. It is not clear what causes water permeabil ity during storage under laboratory conditions. During seed maturation and drying, the inner epidermis of the tegmen partly separates from t he rest of the seed coat and an air space, which makes the seed buoyan t, is formed around the region of the chalazal cleft. The optimal temp erature for germination of K. virginica seeds is between 28 and 30 C i n light or darkness.