Effect of increasing the daylight period and applying growth stimulants on reducing the growing season of spring rapeseed in a climatic chamber

Spring rapeseed (Brassica napus L. subsp. oleifera (DC.) Metzg.) is one of the most important oil crops in agriculture worldwide, having significant economic and agronomic value. Under modern conditions of a greenhouse cultivation, its full growing season lasts about 70–120 days. This creates some research limitations for accelerated breeding. Reducing the growing season opens up new opportunities to intensify the entire breeding process, reducing the time and money required to conduct research and obtain new rapeseed genotypes. Of particular interest is reducing the production cycle when growing under the controlled conditions of a climatic chamber, where it is possible to increase the number of generations received from the traditional two–three to four per year. This article examines the effect of a gradual increase in daylight hours and treatment with the Epin and Zircon growth stimulants on the growing season of spring rapeseed. The experiment showed that a controlled increase in photoperiod and the use of growth stimulants accelerated the transition of plants to the flowering stage by 18.1 days (32.8%) when treated with the Epin stimulant and by 17.3 days (31.3%) with the Zircon stimulant. The treatments with the Epin and Zircon stimulants shortened the growing season by 18.7 days (20.2%) and by 18.1 days (19.6%), respectively.