Contemporary landscape architecture studies have paid close attention to the interactions between public aesthetic preferences and the landscape environment. Scenic beauty has become an important evaluation indicator of landscape quality. The quality of the plant color landscape is an important factor affecting scenic beauty. Exploring the relationship between the composition rules and internal properties of autumn plant color landscapes in urban parks and public aesthetic preferences can provide new ideas for the evaluation and design of plant community color landscapes. Taking 12 parks in Changsha City, Hunan Province, China, as the study area and 85 plant communities as the sample plots, scenic beauty estimation (SBE) was used to evaluate the autumn plant color landscape of urban parks. ColorImpact software was used to extract the color values of each plant community. Fifteen original color element indicators were determined, and the data were statistically analyzed by principal component analysis (PCA), one-way ANOVA, multiple comparison analysis and systematic cluster analysis. Four principal components were extracted to construct the characteristic indices and a comprehensive model of the color landscape quality of autumn plant communities. The four characteristic indices showed significant or extremely significant differences among the five SBE grades. From the overall trend, the SBE grades showed a positive correlation with PC1 (primary and adjunctive color index), PC2 (color structure and property index) and PC3 (autumn-color-leafed index) and a negative correlation with PC4 (intersperse color index). R_PH (ratio of primary hue), R_P (ratio of primary color), R_C (color-leafed index), R_WC (ratio of warm and cool colors), and N_C (number of colors) were the key factors affecting the SBE grade. Overall, R_PH, R_P, R_C, and R_WC positively influenced the SBE values, while N_C negatively influenced the SBE values, and five to seven colors were more moderate. The quality of the color landscape can be improved by creating plant communities with three types of color composition: warm-toned dominant type, warm- and cold-toned contrast type, and multicolor harmonic type. The results provide a reference for the evaluation, design and construction of autumn plant color landscapes in urban parks.

In nature, Orchidaceae seeds establish a relationship with orchid mycorrhizal fungi to obtain essential nutrients for germination. The orchids, Cymbidium mannii and Epidendrum radicans, have significant ornamental and economic value. We isolated and cultured mycorrhizal fungi from C. mannii, E. radicans, and C. goeringii roots. Three strains of fungi, Tulasnella calospora (Tca), T. asymmetrica (Tas), and T. bifrons (Tbi), were identified using ITS-rDNA sequencing. Their mycorrhizal compatibility, germination-promoting effects, and symbiosis with the seeds of C. mannii and E. radicans were studied in vitro using various concentrations of oatmeal agar (OA) medium. Tca exhibited significant seed-germination-promoting effects on C. mannii (92.1%) and E. radicans (84.7%) on 2.0 and 4.0 g/L OA, respectively. For Tbi and Tas, the highest germination percentages were observed on 4.0 g/L OA in E. radicans (73.60% and 76.49%, respectively). Seed germination in C. mannii was enhanced by high oatmeal concentrations (8.0 and 12.0 g/L) during symbiosis with Tas, whereas Tbi had no effect regardless of OA concentration. Tca exhibited high compatibility with C. mannii and E. radicans, and the oatmeal concentration of the medium affected this compatibility. The findings of this study will aid in the propagation of endangered orchid species for conservation and commercial purposes using mycorrhizal technology.

Dendrobium officinale Kimura et Migo, a highly valued Chinese herbal medicine, is on the verge of extinction in the wild, and is not cultivated efficiently. In this study, we explored the possibility that orchid mycorrhizal fungi (OMF) might improve the growth and cultivation of D. officinale. Serendipita sp., Tulasnella calospora and Tulasnella asymmetrica isolated from three different orchids were co-cultured with sterile seedlings of D. officinale. The seedlings were found to stably coexist with fungi after 60 days of co-culture. The co-culture of T. calospora with plants upregulated the activity of antioxidant enzymes, stimulated the production of osmoregulatory substances and reduced electrical conductivity. Plants with T. calospora had longer roots (141.2%), thicker leaves (58.3%), increased root number (71.4%) and leaf number (11.1%), and increased weight (155.2%) and photosynthetic pigment content (99.6%), relative to controls. The content of total medicinal polysaccharides increased by 42.69 % due to the addition of T. calospora. T. asymmetrica was less effective, followed by Serendipita sp. When T. calospora established a symbiotic relationship with D. officinale, resistance indicators increased. The content of functional components was significantly increased. This study contributes to the protection and commercial reproduction of endangered orchid plants with mycorrhizal technology.

Light quality is a vital environmental signal used to trigger growth and to develop structural differentiation in plants, and it influences morphological, physiological, and biochemical metabolites. In previous studies, different light qualities were found to regulate the synthesis of anthocyanin. However, the mechanism of the synthesis and accumulation of anthocyanins in leaves in response to light quality remains unclear. In this study, the Loropetalum chinense var. rubrum “Xiangnong Fendai” plant was treated with white light (WL), blue light (BL), ultraviolet-A light (UL), and blue light plus ultraviolet-A light (BL + UL), respectively. Under BL, the leaves were described as increasing in redness from “olive green” to “reddish-brown”. The chlorophyll, carotenoid, anthocyanin, and total flavonoid content were significantly higher at 7 d than at 0 d. In addition, BL treatment also significantly increased the accumulation of soluble sugar and soluble protein. In contrast to BL, ultraviolet-A light increased the malondialdehyde (MDA) content and the activities of three antioxidant enzymes in the leaves, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), in varying degrees over time. Moreover, we also found that the CRY-like gene, HY5-like gene, BBX-like gene, MYB-like gene, CHS-like gene, DFR-like gene, ANS-like gene, and UFGT-like gene were significantly upregulated. Furthermore, the SOD-like, POD-like, and CAT-like gene expressions related to antioxidase synthesis were found under ultraviolet-A light conditions. In summary, BL is more conducive to reddening the leaves of “Xiangnong Fendai” and will not lead to excessive photooxidation. This provides an effective ecological strategy for light-induced leaf-color changes, thereby promoting the ornamental and economic value of L. chinense var. rubrum.

Loropetalum chinense var. rubrum is a common landscape plant. Because of the preference for the ‘red leaf’ trait, the ‘flower color’ trait was ignored in breeding, and the genetic diversity of L. chinense var. rubrum was replaced by a few genotypes. Therefore, the potential value of flower color traits was affected, and the genetic diversity was not fully exploited. In this study, we utilized a cultivar with mosaic-colored flowers and leaves and observed 15 phenotypic traits in its flower organs and its progeny, as well as a total of 60 different flower color materials. We analyzed the variation characteristics and diversity of flower colors, and qualitatively described and preliminarily classified flower colors using the ISCC-NBS and CIELab systems to explore the correlation with the flower color phenotype from the distribution and content of anthocyanins. The phenotypic diversity of the flower organs was enriched, and genetic differences in flower color were significant for the L.chinense var. rubrum, with most of the 15 phenotypic traits showing significant positive correlations, and the most critical phenotypes are sepal, petal and nectary color, as well as petal length. According to the CIELab color system and anthocyanin content and distribution characteristics, it is considered more accurate and convenient to classify the color phenotypes of L. chinense var. rubrum flowers into five categories. In this study, for the first time, the flower organ phenotype of L. chinense var. rubrum has been systematically analyzed, and it is explored as a reference method for breeding new cultivars of a diverse range of colors in L. chinense var. rubrum.

The friability of callus is closely associated with its genetic transformation efficiency, and optimizing induction and transformation conditions is essential for establishing an efficient transformation system. In this study, we developed a high-efficiency friable callus induction and Agrobacterium-mediated transformation system for Chrysanthemum ‘Jimba’. Three plant growth regulator (PGR) combinations—6-Benzylaminopurine (6-BA) + Naphthaleneacetic Acid (NAA), 6-BA + 2,4-Dichlorophenoxyacetic Acid (2,4-D), and Thidiazuron (TDZ) + 2,4-D—were evaluated for their effects on callus morphology, proliferation, and transformation efficiency. The optimal PGR combination was identified as 1.0 mg/L 6-BA + 0.4 mg/L NAA, which produced highly friable calli with a loose structure, rapid proliferation, and the highest nuclear-to-cytoplasmic ratio. The optimal subculture time for maintaining friability and high proliferation was the 7th week, while the best Agrobacterium infection conditions were OD600 = 0.5 with a 10 min infection period, which achieved a transformation efficiency of 91%. This optimized protocol provides an efficient and rapid transformation method for future gene function studies using callus transformation.