Background and aims <p>The differentiation of flower buds, powered by leaf photosynthesis, is a critical phase in a plant’s lifecycle. The transition of leaf color from green to red in ‘Nanguo’ pears symbolizes a redistribution of nutrients, which can significantly affect the quality of the buds. This research delves into the physiological, biochemical, and molecular underpinnings of this color transition, aiming to uncover its relationship with bud quality.</p> Methods <p>This study performs a comparative analysis of the pigment composition, antioxidant enzyme activity, photosynthetic capacity, chlorophyll fluorescence traits, and soil physicochemical characteristics in both red and green leaves of ‘Nanguo’ pears. It also utilizes transcriptomic sequencing to examine the leaves. Moreover, the research delves into the sugar, mineral, and hormone concentrations within the axillary flower buds at the corresponding nodes, uncovering the physiological relationships that link leaf color transitions to the quality of flower buds.</p> Results <p>Red leaves had higher anthocyanin, hydrogen peroxide, malondialdehyde, and peroxidase activity than green leaves. However, green leaves displayed higher chlorophyll, photosynthetic rate, and stomatal conductance. Soil analysis under red leaves showed lower pH, phosphorus, potassium, and alkali-hydrolyzable nitrogen content. Transcriptomic data linked leaf color change to secondary metabolite pathways and plant hormone signaling. Flower buds adjacent to red leaves had reduced sugar, mineral, and hormone levels compared to those near green leaves.</p> Conclusions <p>Enhancing red leaf photosynthesis and antioxidant defenses through soil nutrient management, hormone signaling, and secondary metabolite pathway regulation could improve ‘Nanguo’ pear bud development, fruit quality and yield.</p>