Growth and development characteristics of fruit and vegetative bud outgrowth of Prunus sibirica L. in relation to physiological fruit drop.

BACKGROUND

Prunus sibirica L. is one of the most pivotal eco-economic tree species in China's arid and semi-arid areas. The phenomenon of physiological fruit drop in P. sibirica L. is severe, and understanding fruit growth patterns and drop characteristics is crucial for high-quality cultivar production. However, there are few reports on P. sibirica fruit development and physiological fruit drop.

RESULTS

In this study, we investigated the characteristics of fruit development, vegetative bud outgrowth, and fruit abscission, and explored the dynamic features of sugar metabolism in different tissues during physiological fruit drop and its relationship with fruit drop. The results showed that the fruit and vegetative bud outgrowth of the "Shanxing No. 1" variety exhibited an S-shaped growth pattern with three physiological stages. The flower and fruit drop of "Shanxing No. 1" lasted for about 70 days with an 89.73% total drop rate and three abscission peaks, which could be divided into the flower abscission stage mainly caused by pistil abortion, rapid fruitlet abscission stage, mainly caused by carbohydrate competition between the fruit and vegetative bud outgrowth; and slow fruit abscission stage mostly related to seed abortion. The perspective of the vegetative buds removal experiment further proved the competition between fruitlet and vegetative bud outgrowth simultaneously. During physiological fruit drop, the sugar contents and activities of sucrose metabolism enzymes in different tissues showed regular changes, corresponding to the dynamic law of fruit drop. Sucrose metabolism was mainly dominated by decomposition, and the enzymes involved in sucrose decomposition played a significant role. Acid invertase and sucrose synthase (decomposition direction) were the key enzymes regulating fruit abscission in P. sibirica L.

CONCLUSIONS

These results laid a foundation for revealing the physiological characteristics and physiological mechanism of P. sibirica L. fruit development, and also provided a theoretical basis for high-quality and high-yield cultivation of P. sibirica L.