Substitution of winter chilling by spring forcing for flowering using sweet cherry as model crop

摘要

Many horticultural crops such as apple, pear, plum, cherry, strawberry and Asparagus require a cold period in winter (chilling) with a subsequent warm period (forcing) for flowering. The objective of the present work was to investigate the effects of more forcing due to projected diminishing available chill as a result of climate change and elaborate the possibility of substitution of chilling by forcing, using cherry as the most affected crop. Therefore, 160 potted sweet cherry trees were exposed to different chilling in four consecutive winters at Klein Altendorf, near Bonn (50 degrees N), Germany. Three cherry cultivars with a wide range of chilling requirement (3-fold) were employed in eight scenarios per variety per year, ranging from - 50% less/insufficient chill for warm temperature zone winters to + 50% more or excess chill for cold winter fruit growing regions: