Hybrid vigor induced by cross-breeding enhances canopy photosynthesis and fruit yield of Japanese sweet pepper

The effect of hybrid vigor on the fruit yield in Japanese sweet pepper (Capsicum annuum L.) was investigated by comparing dry matter production, canopy light-intercepting characteristics and canopy photosynthesis of F₁ cultivars to those of their parent lines. The greater yields in the F₁ cultivars were caused by both higher dry matter partitioning rate into fruits and total dry matter production. There was no difference in the leaf photosynthetic capacity between the F₁ cultivars and their parent lines. The canopy photosynthetic rate, total dry matter production, and yield showed significantly positive correlations with the photosynthetic photon flux absorbed within the plant canopy. The hybrid vigor caused higher plant statures with richer foliage, which led to more effective vertical profiles of leaf area, light absorption, and photosynthesis within the respective canopies. These factors caused a sufficiently higher canopy photosynthesis to produce greater dry matter production and maintain a higher dry matter partitioning rate into fruits, which resulted in higher yields. These results suggest that the vertical profiles of light-intercepting characteristics and photosynthesis within the canopies, which are evaluated by agro-meteorological methodology, are effective selection indices for breeding plants with higher yields.