Abstract:

This study aims to enhance the overwintering capacity of rose plants by conducting summer-autumn pruning to regulate the density of new shoots, improve growth conditions, and coordinate the synergistic development of above-ground and under-ground organs, thereby providing technical support for successful rose cultivation in arid desert regions. Using ‘Desert Rose’ in Dunhuang of the Hexi Corridor as experimental material, winter pruning was performed in mid-March 2023 to remove branches above grade 3. After the first flowering in spring-summer, retraction pruning and thinning were conducted to control the density of grade 4 branches at 80-100 (CK), 75, 70, 65, 60, 55, 50, 45 and 40 branches/m² (T1-T8). Physiological and growth indicators were measured by stratified sampling from the canopy edge inward (0-20, 20-40, 40-60 cm). After overwintering, the frost mortality rate of grade 3 branches in CK and T1 exceeded 5%. When branch density was reduced below 70 branches/m² (T2), frost mortality decreased to 2%-4%. The LT₅₀ (lethal temperature for 50% tissue damage) of T3 (65 branches) to T8 (40 branches) was significantly lower than CK, with T6 showing the lowest LT₅₀ (-35.58℃), indicating markedly improved cold resistance. In the following year, bud burst rate and diameter of grade 4 branches significantly increased from T3 to T8. However, the branch diameter in the inner 40-60 cm layer decreased by 13.68% and 4.28% compared to the 0-20 and 20-40 cm layers, respectively, confirming light limitation on inner branch growth. Root length density in T3-T8 decreased significantly compared to CK, while root activity initially increased and then declined across treatments, peaking in T₃-T₅. In Dunhuang and similar ecological regions, controlling summer new shoot density at 55-60 branches/m² under routine winter pruning can effectively improve overwintering survival rates while maintaining higher bud burst rates, branch diameter, and root activity in the subsequent growing season.

Key words: arid desert region, Rosa rugosa, summer pruning, branch density, overwintering, semi-lethal temperature, root activity, stress physiology