3.1 Plant development, head development, yield and product appearance
During the first 8 experimental weeks, no differences in plant height and number of leaves were detected. At the beginning of head development, when plants had an average of twelve leaves, the leaf color changed from green to violet, and chlorosis of medium-aged and young leaves was observed at about one fifth of the plants receiving an insufficient S supply. On some plants, young leaves exhibited spoon-like deforma- tions. The color changes of the leaves resulted from the unspecific chlorosis of younger plant tissues. This observa- tion was described by Deloch and Bussler (1965) as a typical symptom of S deficiency for oil radish, mustard, and colza, caused by an irregular degradation of plastid proteins due to the slow motility of the organically bound S in the plant.
Plants with an insufficient N supply having the same number of leaves exhibited lower growth and had lighter colored