Study On The Key Technique Of Cyclobalanopsis Glauca Container Seedling

Cyclobalanopsis glauca, a Fagaceae plant, is one of the dominant tree species of humid subtropical eastern evergreen broad-leaved forest in China and also the main afforestation species in the region. The present paper provided a theoretical basis for nursery technology of container seedlings of C. glauca by the experiments of matrix formulation, fertilization, and shading and plant density, and also provided technological reference for tending of young C. glauca plants. The main results showed that:1. Significant differences on the plant height, root collar diameter, biomass per plant, quality index (QI) of container seedlings were observed among the 15 kinds of media. Quality of seedlings increased with the increase of proportion of peat soil. Substrate bulk density, available nitrogen and phosphorus were the key factors influencing seedling quality of C. glauca. The substrate formula [peat soil (0.46)+ perlite (0.27)+rice husk (0.27)] and [peat soil (0.46)+saw dust (0.27)+rice husk (0.27)] were considered the best, according to the multi-objective comprehensive evaluation on physical and chemical properties of matrix, container seedling quality and production cost.2. Nitrogen effect on the growth of C. glauca was significantly different during the different growth periods. The differences on the container seedling height, root collar diameter, biomass and QI were significant between the nitrogen treatments. The parameters showed a quadratic curve trend with increase of nitrogen fertilizer. The parameters increased to the peak when the nitrogen content to a certain level then decreased when continued to increase the quantity of nitrogen. The nitrogen content of 99.5 mg/plant was the best for the evaluation parameters. Quality of container seedlings grown in different levels of potassium can meet the quality requirements, and the container seedlings were best with the potassium supply of 100 mg per plant. The poorest quality container seedlings of C. glauca were observed in the treatment of no P fertilizer supply, whereas all container seedlings were in line with seedling quality standards but seedlings quality declined with the increase of P fertilizer supply. As a result, the quality of container seedlings was best when plants grown in the treatments with P fertilizer of 40 mg P2O5 per plant. Fertilizer effect on the growth of container seedlings of C. glauca was in the sequence of N> P> K. Time effect of fertilization on seedling quality was significant difference between treatments with the best time in the seedling fertilization should be before transplantation. The comprehensive results of matrix formulation and fertilization experiment showed that the substrate formula [peat soil (0.46)+perlite (0.27)+rice husk (0.27)] and fertilizer combination [N (99.5 mg)+ K2O(100 mg)+P2O5(40 mg)/per plant were the excellent light-media for container seedlings nursery of C. glauca. 3. Moderate shade (60% light transmission rate) benefit for the growth of seedlings of C. glauca during the period between transplantation to September 1, simultaneously reduced significantly the water consumption of container seedlings. Then seedlings should be cultivated with no shading. The height, root collar diameter, biomass and QI of container seedling were significantly affected by shading. These parameters decreased with the increase in shading intensity, ranking from high to low were 100%, 60%,40%,20%, and 5% transmittance, whereas the height of seedlings in 60% transmittance was close to the treatment of all light cultivation. The ratios of Chla/Chlb, Car/Chl and root weight ratio increased but the contents of Chla,Chlb and Car, specific leaf area, and leaf weight ratio decreased with the increase of light transmittance. PSII electron transport efficiency in leaves of seedlings grown in treatments of 20% and 5% transmittance was higher than other treatment, suggesting that C. glauca can improve light use efficiency demonstrating an adaptation strategy for low-light conditions. Cyclobalanopsis glauca is a heliophile species but has a strong shade tolerance.4.Both high and low density was not conducive to the growth of container seedlings of C. glauca. The differentiation of seedling quality grades increased and average biomass per plant and QI decreased with the increase of container seedling density. The root collar diameter of seedlings increased with the decrease of density, but the height and biomass per plant decreased, moreover, water consumption increased significantly. The optimal planting density of container seedlings of C. glauca is 337 individuals per square meter.