To clarify the impact of fertilization methods on the nutrients and economic characteristics of Camellia oleifera, explore the relationship between nutrients and fruit economic characteristics, and to identify suitable fertilization methods for Camellia oleifera forests.

Using ‘Ganxing 48’@@@ Camellia oleifera as the material, three fertilization treatments were set up: hole fertilization (D), furrow fertilization (G), and no fertilization (CK). The nutrient content and fruit economic characteristics of Camellia oleifera leaves, fruits, roots, and flower buds were investigated, and a partial least squares path model was constructed to analyze the relationship between tree nutrients and fruit economic characteristics as well as the influence of fertilization methods on tree nutrients and fruit economic characteristics.

Compared with CK, the fruit shape index of the hole application treatment is closer to 1, and the quality of fresh fruits increased by 21.51% and 9.00%, respectively. The oil yield of fresh fruits increased by 22.21% and 24.67% respectively, and the oil production per plant increased by 33.12% and 41.23% respectively; With the extension of growth time, N and K nutrients gradually accumulate as a whole; P nutrients gradually transfer from leaves, fruits, and roots to flower buds. The soluble sugars in roots and flower buds gradually transfer to the fruit; The overall trend of soluble starch content is decreasing and increasing. Fertilization can promote the accumulation of N, K and soluble starch in various organs, increase P content in roots, leaves, and fruits during the growth period of spring shoots, promote the accumulation of soluble sugars in leaves and fruits, and alleviate the consumption of soluble sugars in roots and flower buds. The results of the PLS-PM show that G mainly increases fruit nutrients and reduces leaf nutrients during the oil conversion period, while D mainly reduces leaf nutrients during the rapid growth period of spring shoots and increases root nutrients during the peak fruit growth period, thereby improving fruit economic traits. The results of PCA showed that 5 fruit quality indicators, 2 moisture content indicators, fruit shape index, fresh fruit oil content, dry seed oil content, and oil production were the main indicators for evaluating the fertilization effect, with a cumulative contribution rate of 88.79%. The comprehensive score from high to low was D>G>CK.

Hole fertilization is a more suitable fertilization method for Camellia oleifera forests, as it improves fruit economic characteristics by affecting the nutrients of Camellia oleifera at different stages.

Aiming to provide precise guidance for elite cultivar breeding and pollination configuration, the flowering and pollination biological characteristics of 10 main cultivated Camellia oleifera varieties in Jiangxi Province were studied for two consecutive years.

Ten cultivars—‘CL4’ ‘CL40’ ‘CL53’ ‘CL18’ ‘CL3’ ‘GS83-4’ ‘GW2’ ‘GX48’ ‘GW1’ ‘GS84-8’ were evaluated for flowering phenology, floral morphology, and to examine pollen viability, stigma receptivity, and pollen germination dynamics on stigmas.

Flowering duration in most cultivars correlated with annual climatic conditions: high temperatures delayed flowering onset and increased the proportion of peak flowering relative to the total flowering period. Some cultivars exhibited significant inter-annual fluctuations in total flowering duration, whereas ‘CL53’ demonstrated stable flowering timing and duration across both years. Except for ‘GX48’, whose stigma protruded, all cultivars had stigmas enclosed within the stamen cluster. ‘CL53’ showed the largest height difference between pistils and stamens. All cultivars exhibited outcrossing breeding systems, relying predominantly on cross-pollination. ‘GW1’ produced significantly higher pollen quantities per flower than other cultivars. ‘CL4’ displayed frequent anther abortion under climatic stress, drastically reducing pollen germination rates. ‘CL53’ and ‘GW2’ exhibited superior stigma receptivity intensity and duration. Pollen tube growth depended on maternal genotypes: ‘GW2’ as the maternal parent maintained high pollen germination rates, whereas most hybrid combinations with ‘CL40’ as the maternal parent failed to develop pollen tubes to the stylar base.

Integrated analysis of flowering stability, synchronized peak flowering periods, floral architecture, pollen viability, and stigma compatibility identified two optimal configuration models: The optimal pollination cultivars for ‘CL53’ is ‘CL3’, followed by ‘CL40’; The best pollination cultivars for ‘GW2’ is ‘GW1’, followed by ‘GS84-8’; The best pollination cultivars for ‘GX48’ is ‘GW1’, followed by ‘GS84-8’ and ‘GS83-4’; Among self-pollination combinations, ‘CL53’ and ‘GX48’ exhibited relatively high pollen germination rates on their own stigmas, potentially offering fruit setting assurance under unfavorable pollination weather conditions.

To explore the effects of rootstocks on leaf structure and physiology of grafted Camellia oleifera at the early fruit stage, reveal the law of rootstocks on the aboveground parts, and analyze the relationship between leaf structure and physiology, the study laid a theoretical foundation for the selection of rootstock for Camellia oleifera bud seedling grafting.

‘GW2’ ‘GS83-1’ and ‘G8’ were used as rootstocks for ‘GW2’ panicle grafting to develop different rootstock combinations with the same panicle, the anatomical structure, resistance physiology, photosynthetic characteristics and chlorophyll fluorescence characteristics of the grafted plants were investigated at the age of 5 years, the differences of different stock combinations and the relationship between leaf structure and physiology of grafted Camellia oleifera were analyzed.

1) There were significant differences in leaf anatomical structure among different stock combinations with the same panicle, the ‘GW2’ rootstock combination had significantly higher leaf thickness (330.15 μm), palisade tissue thickness (180.97 μm) and sponge tissue thickness (149.19 μm) than other combinations, and lowest gate/sea ratio (1.22), the content of chlorophyll (12.61 mg·g^-1) was significantly lower than that of other combinations; 2) the effect of rootstock varieties on soluble protein content of 5-year-old grafted leaves was significant, but the effect on soluble sugar content was not significant. The soluble protein content of ‘G8’ was also the highest (3.51 mg·g^-1), and ‘G8’ as rootstock was the highest (1.28) in palisade/sea ratio, indicating that ‘G8’ had the most remarkable drought resistance; 3) Rootstock had no significant effect on the activities of four antioxidant enzymes (SOD, POD, CAT, MDA), which may be due to the fact that the sampling time was in the less stress 5 months, and the antioxidant enzymes had not started the protective procedure. 4) There were no significant effects on F_o, F_m, F_v/F_m, q_P, q_N of leaves, but significant effects on intercellular CO₂ concentration, stomatal conductance and Y (II) value and ETR value of chlorophyll fluorescence characteristics of leaves, the actual photochemical quantum efficiency and apparent electron transfer efficiency of photosystem II of ‘GW2’ rootstock combination are both at a high level, which may be due to the high affinity of the rootstock combination.

There are differences in leaf structure and physiological characteristics between five-year-old and five-year-old grafted plants on different rootstocks with the same panicle, ‘G8’ as rootstock had the highest tissue thickness and soluble protein content in palisade/sponge, and had stronger drought resistance. ‘GW2’ rootstock had significantly lower chlorophyll content than other combinations, the gate/sea ratio was positively correlated with chlorophyll, and the soluble sugar content was the highest. The actual photochemical quantum efficiency and apparent electron transfer efficiency of photosystem II were stronger, and the adaptability was stronger.