施钾水平对纽荷尔脐橙养分、产量和品质的影响

【目的】通过不同施钾水平对纽荷尔脐橙树体养分吸收、产量和品质的影响研究,提出纽荷尔脐橙适宜施钾量,为纽荷尔脐橙钾肥的科学合理施用提供理论依据。【方法】以7年生枳(壳)砧纽荷尔脐橙为试材,设置0(K0)、0.38(K1)、0.64(K2)、0.89(K3)、1.28(K4)和1.40 kg/株K2O(K5)6个施钾水平,研究施钾水平对树体枝梢干物质积累量、枝叶和果实养分吸收、果实产量和品质、土壤理化性质与环境的影响。【结果】不同施钾水平处理后,各时期叶片和枝条干物质量变化趋势相似,均表现为随着施钾量的增加呈先增加后降低的趋势。不同时期的枝叶干物质量均表现为春梢大于秋梢,叶片干物质量大于枝条。春梢的氮、磷、钾吸收量均随施钾量的增加呈显著增加趋势,其中以K2处理的吸收量最大。秋梢的氮、磷、钾吸收量变化趋势与春梢相似,但K5处理的氮、磷、钾吸收量低于K0。各处理间的果实氮、磷、钾含量差异均不显著;果实氮带走量以K3处理为最高,磷、钾养分带走量以K2处理为最高,果实带走的养分量大小顺序为氮≈钾>磷。果实产量和单果重均随着施钾量的增加呈先增加后降低的趋势,但差异不显著,K2处理产量最高,且较...

Effects of Potassium Application Levels on Nutrient,Yield and Quality of Newhall Navel Orange

【Objective】This study investigated the effects of different potassium application levels on nutrient absorption, fruit yield and quality and determined the appropriate amount of potassium application, which provided a theoretical basis for the scientific application of potassium fertilizer for Newhall navel orange.【Method】Six different potassium application levels, including K0 (0 K₂O), K1 (0.38 kg/plant), K2 (0.64 kg/plant), K3 (0.89 kg/plant), K4 (1.28 kg/plant) and K5 (1.40 kg/plant), were performed to study its effects on nutrient absorption of branches, leaves and fruit, fruit quality and yield by using 7-year-old Newhall navel orange grafted on Poncirus trifoliata (L.) .【Result】The dry matter accumulation of leaves and branches of Newhall navel orange in different periods were similar among different groups, while spring shoots were higher than autumn shoots as well as leaves higher than branches. Dry matter quality of leaves and branches were increased first and then decreased with the increased potassium level. The nitrogen fertilizer enhanced the nutrient absorption of nitrogen, phosphorus and potassium in spring shoots with a peak level under K2 treatment, and it also similarly increased the absorption of nitrogen, phosphorus and potassium in autumn shoot with lower level in K5 group than that in K0 group. Potassium had no significant effect on nitrogen, phosphorus and potassium content of fruit. Maximum nitrogen removal was found under K3 treatment, and then phosphorus and potassium were found under K2 treatment. The amount of fruit nutrient removal was nitrogen ≈ potassium > phosphorus. Potassium application first enhanced the yield and single fruit weight, and then decreased, and the highest level of yield under K2 treatment was higher than that under K0 treatment. Potassium application made the fruit redder with the best effect under K3 treatment. Potassium application first thinned the pericarp and then thickened with the thinnest level under K2 treatment. Potassium application first enhanced the vitamin C content, and then decreased with the highest level under K3 treatment. The maximum soluble sugar content was found under K3 treatment, and the minimum titratable acid content was found under K2 treatment. Potassium application first enhanced the soil organic matter and available N, and then decreased at the highest level under K1 and K3 treatment, respectively. Potassium application first decreased the soil available P, and then enhanced at the highest level under K4 treatment, and then decreased. Potassium application under K4 treatment could maximize the content of available potassium in the soil, and the most of the available potassium was distributed in the surface soil (0-20 cm) and tended to accumulate in the deep soil (60—80 cm). Correlation analysis showed that the potassium content in spring leaves was significantly positively corrected with the total nitrogen and potassium content of fruit and was significantly negatively correlated with fruit firmness. The potassium content in autumn shoots was significantly positively correlated with yield and TSS content, and the potassium content in autumn twigs was significantly negatively correlated with the thickness of peel. The soil available K content was significantly negatively correlated with the total nitrogen and potassium content of fruit, and was significantly negatively correlated with fruit hardness.【Conclusion】These results indicated that the pure potassium oxide application rate was 0.64 to 0.89 kg/plant to ensure high level of yield and fruit quality, and to facilitate nutrient absorption and utilization of Newhall navel orange tree while maintaining high soil fertility. At the same time, the risk of soil potassium accumulation and pollution was reduced.