Effect of temperature on biomass allocation in seedlings of two contrasting genotypes of the oilseed crop Ricinus communis created by Paulo R. Ribeiro a b , Rafael F. Zanotti a c , Carole Deflers a , Luzimar G. Fernandez b , Renato D. de Castro b , Wilco Ligterink a , Henk W.M. Hilhorst a

Ricinus communis is becoming an important crop for oil production, and studying the physiological and biochemical aspects of seedling development may aid in the improvement of crop quality and yield. The objective of this study was to assess the effect of temperature on biomass allocation in two R. communis genotypes. Biomass allocation was assessed by measuring dry weight of roots, stems, and cotyledons of seedlings grown at three different temperatures. Root length of each seedling was measured. Biomass allocation was strongly affected by temperature. Seedlings grown at 25 °C and 35 °C showed greater biomass than seedlings grown at 20 °C. Cotyledon and stem dry weight increased for both genotypes with increasing temperature, whereas root biomass allocation showed a genotype-dependent behavior. Genotype MPA11 showed a continuous increase in root dry weight with increasing temperature, while genotype IAC80 was not able to sustain further root growth at higher temperatures. Based on metabolite and gene expression profiles, genotype MPA11 increases its level of osmoprotectant molecules and transcripts of genes encoding for antioxidant enzymes and heat shock proteins to a higher extent than genotype IAC80. This might be causal for the ability to maintain homeostasis and support root growth at elevated temperatures in genotype MPA11.