Heat stress resistance in Camelina sativa: morphological, physiological, yield and seed quality responses

Barbara Alberghini¹Federica Zanetti^1*Federico Ferioli¹Richard P Haslam²Susana Silvestre²Andrea Monti¹

• ¹DISTAL (Dept. of Agricultural and Food Sciences) Alma Mater Studiorum - Università di Bologna, Bologna, Italy
• ²Rothamsted Research, Harpenden, United Kingdom

Cultivated crops are increasingly facing episodes of extreme heat. Crops grown in the Mediterranean basin are often subjected to heat stress during spring or summer, when flowering and seed ripening phases occur. Latterly Camelina sativa has emerged as an alternative oilseed crop of interest by virtue of its resistance to abiotic stresses. To investigate possible mechanisms behind the ability of camelina to cope with heat stress and to evaluate the role of tocopherols, two different camelina spring varieties (Cypress and Omega) were tested in two controlled environment experiments: heat was imposed for five consecutive days both from the end of flowering (EXP1) and from the silique final dimension stage (EXP2). Early imposition of heat stress (EXP1) had the greatest impact on camelina morphological parameters during growth cycle. At harvest, in EXP1 only genotype had a significant effect on plant height and seed yield, with Omega having taller plants and increased seed yield (0.83 g per plant) compared with Cypress (0.70 g per plant). In EXP2, cultivar only had an effect on straw weight, which was higher in Omega. Nonetheless, Cypress had the highest 1000-seed weight in both experiments (1.36 g in EXP1 and 1.34 g in EXP2). Seed oil content was reduced by heat stress (-9.89% in EXP1 and -11.6% in EXP2, respectively). Fatty acid composition in EXP1 was mainly influenced by the cultivar, except for C18:1, while in EXP2, heat stress predominantly effected 18 carbon fatty acids. Measured total tocopherol content was mainly under genetic control, and despite α-tocopherol is associated with abiotic stress responses, it was increased only by the later stress imposition (+75.8% in the stressed plants). Notwithstanding the high tocopherol content of camelina, it appeared to play a role in plant stress resistance only when heat was imposed at a later stage of seed maturation.