The reason why the survival rate ofpaeonairockii grafted with herbaceous peonyis high is mainly based on the combined effect of botanical characteristics, physiological adaptability and horticultural practice experience. The following is a detailed analysis from the perspective of scientific principles and practical applications:
I. Botanical kinship and rootstock affinity
- Kinship advantages of different genera in the same family
(Paeonia rockii) and Paeonia lactiflora belong to the Paeoniaceae family. Although they belong to the peony group (Section Moutan) and the peony group (Section Paeonia), they are closely related. The vascular bundle structure and cambium activity of the rootstock (peony root) and the scion (purple-spotted peony branch) are highly matched, and it is easier to heal after grafting. - Physiological advantages of the rootstock
Peony has a well-developed root system, grows fast, and has a strong ability to absorb water and fertilizer. It can provide sufficient nutrients and water for the scion, making up for the weak self-root system of peony (peony is a woody stem with slow root growth). At the same time, the stress resistance of peony roots (cold resistance, drought resistance, and salt-alkali resistance) can significantly enhance the adaptability of Paeonia rockii in harsh environments. - Improved stress resistance and adaptability
- Cold and drought resistance
The cold resistance limit of peony roots can reach below -30℃* (peony self-rooting can only withstand -15℃). After grafting, the ability of Paeonia rockii to survive the winter in the open air in cold areas is significantly enhanced. At the same time, the root depth of peony can reach more than 1.5 meters, which can absorb deep soil moisture and improve drought resistance. - Disease and insect resistance advantages
Peony roots are highly resistant to soil-borne diseases (such as root rot and nematodes). After grafting, the risk of underground diseases of purple peony can be reduced. - Economic Benefits and Horticultural Practice Verification
- Shorten the Growth Cycle
The flowering time of purple-spotted peonies grafted with peony rootstocks is 2 to 3 years earlier (seedlings need 5 to 7 years to bloom, while grafted seedlings only need 3 to 4 years), which significantly reduces the planting cost. - Feasibility of Large-Scale Production
Peony root propagation is easy (can be quickly propagated by division or cuttings) and low cost. For example, our company’s peony base uses peony rootstock grafting technology, and the grafting survival rate is stable at 85% to 90%, while the survival rate of peony root grafting is only 60% to 70%.
- Precautions
- Rootstock selection: give priority to 2 to 3-year-old strong peony roots with a diameter of more than 1.5 cm to ensure sufficient nutrient reserves.
- Grafting time: The best time is late August to early September (north) or mid-September to early October (south), when the cambium activity of the rootstock and scion is the highest.
- Post-graft management: Avoid water accumulation after grafting, cover and keep warm in winter, and cut the rootstock in time in the spring of the following year (remove peony buds).
Summary
The core advantage of choosing Paeonia lactiflora root grafting for Paeonia rockii is that the rootstock and scion have strong affinity, improved stress resistance, and significant economic benefits. This technology not only continues the ornamental and medicinal value of purple peony, but also provides a reliable solution for its large-scale planting in extreme environments.