Resilience of rapeseed to cope with heat and light stress during post flowering

RIVELLI, GONZALO M.; CALDERINI, DANIEL F.; ABELEDO, GABRIELA L.; MIRALLES, DANIEL J.; RONDANINI, DÉBORAH P.

CABA, Buenos Aires

Simposio; Frontiers in Bioscience 4; 2023

High temperatures combined with cloudiness during a few days are frequent during the post-flowering period of temperate crops in the Southern Cone of South America. Several studies evaluated the effect of either high temperature or shading on rapeseed productivity, but little is known about combined stresses. Recent results show that the effects of combined stresses are well described by photothermal quotient, and there is evidence for high reproductive plasticity in rapeseed and compensatory mechanisms between grain weight (GW) and grain number (GN). Whether these compensatory mechanisms in rapeseed are a general response or only operate in high-yielding environments is unknown. To quantify the effects of combined abiotic stresses such as high temperature and low radiation during post-flowering on grain yield, irrigated crops were grown in environments of high (Valdivia, Chile) and medium (Buenos Aires, Argentina) productivity. The treatments were applied to a hybrid spring rapeseed (Solar CL) using portable chambers placed 14 days after the start of flowering, for 10 days: unstressed (control), shading (-60% incident solar radiation), high temperature (+5ºC) for 5 hours at midday, and combined stress of shading and high temperature, in a RCB with 4 replicates. Moderate background temperatures and higher radiation levels caused a higher photothermal quotient during the critical period of rapeseed in the Valdivia control compared to Buenos Aires, with grain yields in controls of 9.3 and 4.5 tn/ha, respectively. These grain yields were reduced by 39% by the combined stress in Buenos Aires (p