Fruit economic characteristics and yields of 40 superior Camellia oleifera Abel plants in the low-hot valley area of Guizhou Province, China.

In this study, we assessed 26 economic characteristics and yields of the mature fruit of 40 superior Camellia oleifera Abel plants grown at the C. oleifera germplasm resource nursery in the low-hot valley area of Southwest Zuizhou, China, using principal component analysis (PCA). Correlations among the characteristics and the variability of the plants in these characteristics were also analyzed. Out of the 26 characteristics, 16 primary economic characteristics were selected for comprehensive assessment, based on the results of which the plants were ordered to obtain excellent C. oleifera germplasms. The data were subjected to PCA, and the 16 characteristics were integrated into 6 independent comprehensive indices, which included PV1 (single-fruit weight), PV2 (pericarp thickness), PV3 (seed rate), PV4 (total unsaturated fatty acids), PV5 (iodine value) and PV6 (dry seed rate). Then, the sum of the products of the contribution rates of the components and components scores was taken as the comprehensive score of each superior plant. In C. oleifera grown in the low-hot valley area, the oil yield exhibited very significant positive correlations with the dry seed rate and kernel rate but a very significant negative correlation with the 100-seed weight. The dry seed rate exhibited very significant negative correlations with the fruit diameter and fresh seed rate. Among the 26 characteristics, the variations of the acid value, peroxide value, number of fertile seeds, 100-seed weight and single-fruit weight were great; those of the fruit diameter, fruit height, kernel yield, oleic acid and total unsaturated fatty acid were small, showing strong genetic stability. According to the obtained comprehensive scores, the top 10 plants were ordered as follows: CY-6 > CY-13 > CY-31 > CY-11 > CY-16 > CY-22 > CY-28 > CY-23 > CY-24 > CY-29. This result was basically consistent with the ranking result according to the average yield per unit crown width within five years. In the low-hot valley area of Guizhou, C. oleifera exhibits excellent performance in single-fruit weight, total unsaturated fatty acids and kernel rate, 6 characteristics, i.e., acid value, peroxide value, single-fruit weight, the number of fertile seeds, 100-seed weight and α-linolenic acid possess high breeding potentials.

A comparative study on the leaf anatomical structure of Camellia oleifera in a low-hot valley area in Guizhou Province, China.

The leaf serves as an important assimilation organ of plants, and the anatomical structure of leaves can reflect the adaptability of the plant to the environment to a certain extent. The current study aimed to cultivate superior local cultivars, and 35 healthy individual plants were selected from the Camellia oleifera germplasm resource nursery for a comparative study of the leaf structure. In July 2019, the leaves were collected from 35 selected healthy C. oleifera plants, and the leaf structure was observed by using the paraffin section method. Healthy individual plants were screened using variance analysis, correlation analysis and cluster analysis. The representative indices were selected according to the cluster membership, correlation indices and coefficient of variation (C/V) for a comprehensive evaluation of drought resistance via the membership function. There were extremely significant differences in 11 indices of leaf structure for these 35 healthy plants. C18 had the greatest leaf thickness, C7 the largest spongy tissue, and C38 the largest ratio of palisade tissue thickness to spongy tissue thickness (P/S). The clustering results of the healthy individual plants differed significantly. The membership function showed that the drought resistance of 35 C. oleifera plants was divided into five categories. C18 had very strong drought resistance, and C3, C7 and C40 had strong drought resistance. There were significant differences in terms of the upper epidermis, P/S ratio and spongy tissue among the C. oleifera plants. C18, C3, C7 and C40 exhibited satisfactory drought resistance. Although C39 and C26 had moderate drought resistance, their P/S ratios were high, which might be used to cultivate high-yield and drought-resistant C. oleifera varieties. The leaf P/S ratio of C. oleifera from low-hot valley areas was high. Among various leaf structures, spongy tissue, upper epidermis, P/S ratio and cuticle constitute the drought resistance evaluation indices for C. oleifera grown in low-hot valley areas.

New perspective for evaluating the main Camellia oleifera cultivars in China.

To assess the adaptability of Camellia oleifera for introduction in new growth locations, this study evaluated 10 representative C. oleifera cultivars from the main areas in China where this oil-producing evergreen crop is grown. Cluster analysis, correlation analysis, and membership function analysis were used to evaluate various indices of the selected C. oleifera cultivars, including flowering phenology, cold tolerance, leaf structure, pollen characteristics, and pollen viability. The correlation analysis identified the full blossoming time, leaf palisade and spongy tissue thickness, pollen deformity rate, and pollen activity as key indices for determining the adaptability of the cultivars to new areas. The membership function analysis of the 10 C. oleifera cultivars revealed the following order of adaptability: 'XLC25' > 'Changlin4hao' > 'Ganzhouyou8hao' > 'Ganzhouyou6hao' > 'Tiechengyihao' > 'Eyou465' > 'XLC10' > 'Changlin3hao' > 'Changlin18hao' > 'QY235.' When introducing C. oleifera cultivars to new regions, the higher-ranked cultivars are more likely to be successful. The results of this study may provide a new direction for the comprehensive assessment of plant introduction and domestication potential, i.e., the assessment of the vegetative and reproductive growth, adversity resistance, and blossoming time of plants.