Thermal requirements for germination, production and distribution model of Brassica napus L.

Abstract

Canola (Brassica napus) occupies the second position in the oil production ranking among oilseeds. However, it is a crop highly influenced by climatic variations and there are still few studies related to its thermal thresholds and the expansion potential of this species. This study aimed to determine a climate suitability model for canola in the world and the thermal thresholds for germination and production of canola in a tropical environment. The potential distribution model was developed in the CLIMEX software version 4.0 using canola biological data from scientific publications, to define the parameters of temperature, humidity and heat stress, drought and wet stress indices for calculating the Ecoclimatic Index (EI). The model was validated using the species' geographic distribution map. Canola biological data published in the literature are generally from winter cultivars, as a result, in this study experiments were also carried out with a spring cultivar, in which a germination test was carried out at constant temperatures of 3, 6, 10, 15, 25, 30, 35, 40 and 45 oC following the criteria established by the Seed Analysis Rules (RAS). In addition, spring canola was cultivated at different sowing times in regions with a predominantly tropical climate and determined the temporal influence on the production of seeds and canola oil, in addition to determining the influence of the planting time on the quality of the oil of canola. The modeled results indicate medium to high climate suitability for canola cultivation in several countries around the world, including in territories where the species still occurs, thus increasing the species' expansion potential. With the experiments carried out, it was possible to verify different thermal threshold values from thresholds published in the literature, which can serve as data for other distribution modeling studies for spring canola cultivars.