Temperature and solar radiation during grain filling are the main drivers of grain weight and composition in several crops. While significant progress has been done on the effect of solar radiation intercepted by the plants (ISR) on grain weight (GW, mg) and oil content (OC, mg grain⁻¹) of sunflower (Helianthus Annus L.), the effects of temperature on these traits are far from clear. As temperature affects the rate of plant development, increasing temperature would shorten grain filling duration and so, the critical period for ISR effect on GW and OC (indirect effect of temperature). However, direct effects of temperature non-mediated by ISR accumulation could also affect these traits. The objectives of this work were a) to characterize the responses of grain weight and oil content to mean temperature during grain filling in two traditional sunflower hybrids and b) to determine whether these responses can be exclusively explained by changes in ISR or any direct effect of temperature should also be considered. Two experimental approaches have been used to address these objectives: i) temperature manipulation at constant incident radiation in growth chambers; ii) modification of radiation interception in the field in different locations and years (different mean temperatures). Growth chamber experiments showed that GW and OC respond to temperature in a plateau lineal shape. At low incident radiation such as that of growth chambers, temperature effects on GW can be exclusively explained by reductions in ISR, while both direct and indirect effects of MT are evident on OC. Results obtained in field experiments confirmed this behavior at low radiation. Both GW and OC exponentially increased up to a maximum with ISR disregarding MT. Mathematical models were established to describe the responses of GW and OC to MT and ISR. These models consider MT x ISR interactive effects on GW; and MT - ISR additive effects on OC. The combination of growth chamber and field experiments observations allowed to unravel different mechanisms underlying the responses of GW and OC to temperature: at low incident radiation intensity, increasing temperature decreased GW exclusively by reducing ISR accumulation (indirect effects) while at higher radiation, temperature displays both direct (non-mediated by ISR) and indirect (ISR mediated) effects on GW. OC is affected by temperature in both direct and indirect way disregarding ISR. This work constitutes an important contribution towards understanding the effect of temperature during grain filling on sunflower yield and its relationship to solar radiation effects.

谷物填充过程中的温度和太阳辐射是几种作物谷物重量和组成的主要驱动因素。虽然植物（ISR）截获的太阳辐射对向日葵的粒重（GW，mg）和含油量（OC，mg谷物^-1）的影响已经取得了显着进展，但向日葵（Helianthus Annus L.），温度对这些性状的影响尚不清楚。由于温度影响植物的生长速度，温度升高会缩短籽粒充实时间，因此，ISR对GW和OC（温度的间接影响）的关键时期。但是，不受ISR积累影响的温度的直接影响也可能影响这些性状。这项工作的目的是：a）表征两种传统向日葵杂交种在灌浆过程中谷物重量和含油量对平均温度的响应； b）确定这些响应是否可以由ISR的变化或ISR的任何直接影响来专门解释。温度也应予以考虑。已经使用两种实验方法来解决这些目标：i）在生长室中恒定入射辐射下的温度控制；ii）修改不同位置和年份（平均温度不同）的野外辐射拦截。生长室实验表明，GW和OC以高原线性形状响应温度。在低入射辐射（例如生长室的辐射）下，对GW的温度影响可以完全通过降低ISR来解释，而MT对OC的直接和间接影响都是显而易见的。在现场实验中获得的结果证实了这种低辐射下的行为。ISR不考虑MT的情况下，GW和OC均呈指数增长。建立了数学模型来描述GW和OC对MT和ISR的响应。这些模型考虑了MT x ISR对GW的交互作用；和MT-ISR对OC的累加效应。生长室和野外实验观察的结合允许揭示GW和OC对温度响应的不同机制：在低入射辐射强度下，增加温度仅通过减少ISR积累（间接影响）降低GW，而在较高辐射下，温度显示对GW的直接影响（非ISR介导）和间接影响（ISR介导）。OC不受ISR的直接和间接影响。这项工作为理解籽粒灌浆期间温度对向日葵产量的影响及其与太阳辐射影响的关系做出了重要贡献。升高温度仅通过减少ISR积累（间接作用）而降低了GW，而在较高的辐射下，温度对GW既表现出直接作用（不受ISR介导）又表现出间接作用（ISR介导）。OC不受ISR的直接和间接影响。这项工作为理解籽粒灌浆期间温度对向日葵产量的影响及其与太阳辐射影响的关系做出了重要贡献。升高温度仅通过减少ISR积累（间接作用）而降低了GW，而在较高的辐射下，温度对GW既表现出直接作用（不受ISR介导）又表现出间接作用（ISR介导）。OC不受ISR的直接和间接影响。这项工作为理解籽粒灌浆期间温度对向日葵产量的影响及其与太阳辐射影响的关系做出了重要贡献。