Natural Far Red Irradiation and Weed Seed Persistence in the Soil

Abstract

It may be assumed that seed reactions to light are an indication of adaptation to environmental conditions. Thus, it is necessary to accept the fact that these reactions can be fully observed only in natural conditions. The results presented concerning the germination of seeds of different photoblastic types were obtained in experiments carried out in natural son conditions. The aim of the experiments was to describe the role of the secondary seed dormancy enforced by far red irradiation on seed persistence in the soil. Seed dormancy was enforced by placing Petri dishes with seeds under a canopy of Parthenocissus quinquefolia leaves. After inducing dormancy by natural far red, the seeds were transferred under a cover of rhubarb leaves and placed in prepared rows in the soil, where they were buried. These operations were performed on cloudy days in the afternoon. The following plants were sown in such a way: Amaranthus retroflexus, Apera spica-vehti, Crepis capillaris, Lactuca serriola, Verbascumlychnitis, Oenothera biennis. After periods of 1 to 24 months the upper layer of the soil was removed. The seedlings that emerged from far red inhibited and control seeds were counted after several months. Many more seedlings were obtained from inhibited seeds; the differences for 5 species were statistically significant. Similar results were obtained with seeds buried in nylon bags.