Thiourea Application Increases Seed and Oil Yields in Camelina Under Heat Stress by Modulating the Plant Water Relations and Antioxidant Defense System

Heat stress is causing serious problems in crop production, leading to catastrophic losses in crop yield worldwide. The study was conducted to evaluate the role of thiourea to ameliorate the negative impact of high-temperature stress on plant growth, seed yield, and seed oil content in camelina. The study comprised of (i) camelina genotypes, Australian and Canadian; (ii) temperature stress, normal (25/18°C) and heat stress (38/25°C); (iii) thiourea supplementation (1000 mg L⁻¹), NA= no application (control), WA₁= water application at vegetative stage-31 DAS, TU₁= thiourea application at vegetative stage, WA₂= water application at the reproductive stage-59 DAS, and TU₂= thiourea application at the reproductive stage. Water application at both growth stages was taken as control. Heat stress caused significant reduction in plant water relations and photosynthetic pigments which suppressed plant growth and yield attributes of camelina genotypes. High-temperature stress reduced the seed yield and seed oil content in the tested camelina genotypes, whereas an increase in seed protein content was noted under heat stress as compared with no stress (control). However, thiourea applications ameliorated the injuries caused by heat stress–induced oxidative damages through increase in antioxidative enzymes activities, osmotic adjustment, and maintenance of tissue water relations which contributed to improving seed yield and seed oil contents over no thiourea application (control). Thiourea application at the reproductive stage was more effective than the vegetative stage. Among the genotypes, the Canadian genotype was more heat-tolerant than the Australian genotype. Moreover, the Canadian camelina was more responsive to thiourea application than the Australian genotype as indicated by improvement in plant physicochemical attributes, seed yield, and seed oil content. Thiourea applications improved the seed and oil yields in camelina genotypes by modulating the plant water relations, regulation of soluble sugars, and the activation of enzymatic antioxidants under heat stress.