German chamomile performance after stubble catch crops and response to nitrogen fertilization

Pharmaceutical companies have a growing demand for herb raw material, including German chamomile (Chamomilla recutita (L.) Rauschert), produced according to the rules of Good Agricultural Practices (GAP) for medicinal plants. These rules, among others, require limitation of the application of mineral fertilizers and pesticides. Catch crops can improve soil fertility and reduce weed infestation for subsequent crops. The aim of this study was to evaluate the effect of stubble catch crops and different nitrogen doses on anthodia and herb yield, and content and yield of essential oil from a diploid and tetraploid cultivar of German chamomile. In the 3-year experiment, two chamomile cultivars were grown - Mastar (2n) and Dukat (4n). They were sown after ploughing legume mixture or buckwheat (Fagopyrum esculentum Moench) stubble catch crops; nitrogen fertilization rates were 0, 30, 60, and 90 kg N ha−1. It was found that fertilization with 60 and 90 kg N ha−1 reduced chamomile weed infestation to a greater extent than the use of catch crops. The highest yield of anthodia was obtained after the application of the highest nitrogen rate. The herb and oil yield from herb were highest after the application of 60 kg N ha−1. Cultivation of Dukat after a legume catch crop allowed for a reduction in nitrogen fertilizer rate from 90 to 60 kg N ha−1 without a decrease in anthodium yield. Buckwheat catch crop inhibited the growth of chamomile. A higher yield of anthodia was collected from the cultivar Dukat, but the essential oil content was higher in anthodia of Mastar. The content of chamazulen in essential oil from anthodia was 17.7 and 17.2%, α-bisabolol 23.0 and 21.1%, respectively, from Mastar and Dukat. The essential oil from herb contained mainly farnesene and en-in-dicycloether. The requirements of Good Agricultural Practices in chamomile cultivation can be met by the application of legume stubble catch crops, choice of suitable cultivar, and by adopting the nitrogen rate appropriate for the aim of cultivation.