THE INFLUENCE OF BURIAL AND DRY‐STORAGE UPON CYCLIC CHANGES IN DORMANCY, GERMINATION AND RESPONSE TO LIGHT IN SEEDS OF VARIOUS ARABLE WEEDS

Abstract

SummarySeeds of Alopecurus myosuroides, Bromus sterilis, Capsella bursa‐pastoris, Papaver rhoeas, Stellaria media, Veronica arvensis, Veronica persica and Viola arvensis were sown in soil at depths of 0, 25 and 150 mm. Seeds buried at 150 mm were exhumed at intervals of 3, 6, 12 and 15 months and incubated at an alternating temperature regime of 10/20 °C (16/8 h) or irradiated with light of various wavelengths prior to incubation.In general, shallow burial (25 mm) reduced seedling emergence except in the case of B. sterilis, which also germinated at a depth of 150 mm but failed to emerge.Cyclic changes in dormancy of buried seeds were observed. Although sensitivity to light was enchanced by burial, germination and response to light quality varied between seasons. Dormancy of most species, including the winter annuals A. myosuroides, Veronica persica and Viola arvensis, was least in autumn and most in summer. Papaver rhoeas was least dormant in spring and S. media was least dormant in summer. Generally, red light promoted germination whereas far‐red light or darkness was not stimulatory. However, A. myosuroides was more sensitive to far‐red light in autumn than at other times of the year.Natural day‐light promoted germination of A. myosuroides, S. media and Veronica arvensis. Germination of B. sterilis was delayed in natural daylight. Transfer of A. myosuroides, Papaver rhoeas, Veronica arvensis and Viola arvensis from darkness to daylight increased germination above that obtained under natural daylight.Germination of freshly collected seeds of Alopecurus myosuroides, Arrhenatherum elatius, Poa annua, Poa trivialis, Plantago major and Viola arvensis was promoted by short irradiations of red light. Dry‐storage did not affect germination of Alopecurus myosuroides, Poa annua, Plantago major or Viola arvensis, but did affect dormancy and light requirement of Poa trivialis. Burial of seeds of Alopecurus myosuroides, Poa trivialis and Plantago major increased their sensitivity to far‐red light.It is concluded that cyclic changes in seed dormancy and associated light sensitivity are determined seasonally and result from changing environmental factors and that they are of adaptive importance for survival.