Phenological development and productivity of wild chamomile and calendula officinalis depending on the sowing time in Transbaikalia

The article presents the results of a study on the formation of agrophytocenoses of valuable medicinal plants – wild chamomile ( Matricaria chamomilla ) and calendula officinalis ( Calendula officinalis L.) – at different sowing times in the forest-steppe zone of the Trans-Baikal Territory, based on three years (2020–2022) of field experiments and laboratory research. The study was conducted on the experimental field of the Scientific Research Institute of Veterinary Science of Eastern Siberia. The soil of the experimental plot was meadow-chernozem floury-carbonate, light loam in granulometric composition. The purpose of the work was to study the effect of the sowing dates (second ten days of May, second ten days of June, second ten days of July) on the duration of interphase periods of plant development, linear growth, foliage, field germination, plant survival, and yield of medicinal raw materials. The obtained data indicate that, thanks to different sowing times depending on the soil and climatic conditions of the region, it is possible to obtain different yields of the studied medicinal crops. The highest yield of medicinal raw materials was achieved when sowing on May 15 and June 15: the yield of the raw mass of wild chamomile was 8.20–9.60 t/ha, dry mass – 1.37–1.49 t/ha, seeds – 0.15–0.16 t/ha, and for calendula officinalis – 9.80–10.30; 1.80–1.87; 0.40–0.41 t/ha, respectively. By the harvest time, the wild chamomile plants reached 89–95 cm in height, with a foliage coverage of 57–58%, while the calendula officinalis plants reached 82–84 cm and 52–55%, respectively. These medicinal plants were noted to be free of diseases and pests, and their crops were resistant to lodging and drought in the conditions of Transbaikalia.