Dynamics of fruit growth and oil quality of sunflower (Helianthus annuus L.) exposed to brief intervals of high temperature during grain filling

摘要: Abstract Brief periods of high temperature have been shown to reduce grain weight and quality in temperate cereals but the nature sunflower growth oil responses exposure are unknown. We examined these issues by exposing capitulae plants cv. HA89 growing at 25 °C temperatures ca. 35, 37 40 °C for seven consecutive days each three different intervals during filling. Final was reduced (−40%, on average) >35 °C early development due a reduction duration growth. Oil percentage also (−30%) >35 °C, largely through an increase pericarp:embryo ratio, although with extreme embryo observed. composition proved be sensitive timing heat stress. The fatty acid pattern strongly modified stress final only altered period from 19 26 after anthesis (daa). Early allowed partial recovery oleate desaturase (ODS) activity post-stress period, this did not occur when ending took place close accumulation process. conclude that 12 19 daa showed greatest sensitivity regarding responses, whereas 26 daa. A clear step-change response found, indicating threshold 35 °C. produced lower weight, greater pericarp, content composition, hence, commercial quality.