Effect of temperature on the growth of broccoli (brassica oleracea l. var. italica plenck) cv. fiesta

Three-year studies on the influence of temperature on vegetative growth and growth of broccoli heads (Brassica oleracea var. italica cv. Fiesta) were carried out at the Experimental Station “Marcelin” of Poznań University of Life Sciences in Poland. The relationship between temperature sum day-degree, number and area of leaves as well as head diameter was estimated. Likewise relationship between number and area of leaves and head diameter was established. The correlations were described using linear, curvilinear and segment linear regression. The relationship between temperature sum day-degree and number of leaves was linear, whereas the correlation between temperature and area of leaves and head diameter was curves function. On the basis of segment linear regression it was found that in the period when slow growth of heads was observed (the size of up to about 1.5 cm), the area of leaves increased the fastest. It occurred between the 24^th and 27^th day after planting. The fastest growth of broccoli heads was noted, when the plant had about 18 leaves and area 4900 cm². In the period of rapid head growth, the increase of sum temperature of 100 day-degree resulted in head diameter increase by 3.5 cm.