SEASONAL GROWTH AND DEVELOPMENT OF ASPARAGUS (ASPARAGUS-OFFICINALIS L.) - II - INFLUENCE OF DROUGHT ON CROWN ACTIVITY

In order to investigate effects of drought periods on activity/dormanc y of Asparagus officinalis L. pot experiments were performed in fields , greenhouses, and growth chambers. A high temperature during growth a nd ''ripening'' of the ferns during July - August reduced or even prev ented the sprouting ability of the crowns (SA, measured as cumulative spear number and spear weight), which after fern cutting were kept at incubation temperatures of 15 degrees and 20 degrees C. Drought period s (3 to 8 weeks) had a similar, but weaker effect, which was more evid ent in combination with a high growth/''ripening'' temperature and a l ow incubation temperature of 15 degrees C. For plants with drought per iods in July only a small or no reaction was indicated. A cold period (2 degrees C for 3 weeks) after fern cutting stimulated SA, but was no t able to eliminate the temperature and drought effects. Physiological interpretation and final conclusions will be presented on the basis o f chemical analyses and further experiments in the following reports.