Effect of temperature and photoperiod on the phenological development of wild mustard (Sinapis arvensis L.)

The development of mechanistic weed models focuses on determining the outco me of weed-crop interference. Phenological development is a major factor de termining the outcome of weed and crop competition. The influence of temper ature and photoperiod on phenological development of wild mustard (Sinapis arvensis L.) was studied in growth cabinets. The life cycle of wild mustard was defined in terms of biological days (Bd: chronological days at the opt imum photoperiod and temperature). Wild mustard was a long-day species adap ted to a wide temperature range of 1.5-48 degreesC. Four phases of developm ent of wild mustard were described: (1) a juvenile phase of 12.7 Bd; (2) a photoperiod-sensitive inductive phase of 6.2 Bd; (3) a photoperiod-sensitiv e post-inductive phase of 12.8 Bd; (4) a photoperiod-insensitive phase of 3 3.9 Bd. When effects of photoperiod on rate of development were normalized across phases of development, photoperiod sensitivity did not vary among ph ases of development. Interpretation of constant sensitivity to photoperiod will simplify simulation of weed phenology in mechanistic models. (C) 2001 Published by Elsevier Science B.V.