喷施硅肥对茶树生长及硅素分布的影响

【目的】研究喷施硅肥对茶树生长和茶叶品质的影响，以及硅在茶树中的累积和分布，为优质安全茶叶生产提供依据。【方法】采用室内盆栽与田间试验相结合的方法，供试硅肥为硅酸钠(Na2SiO3·9H2O)。室内盆栽试验设置7个硅喷施浓度：0、50、150、300、500、750、1500 mg/L，每7天喷施一次，共喷施3次。通过测定茶苗生物量、SPAD值、叶绿素荧光特性、植保素含量及气孔特性，以确定最佳喷施硅肥浓度。然后，以该最佳喷施浓度进行室内茶苗盆栽和田间试验，在室内试验中测定了茶苗不同部位和组织的硅含量，在田间试验中测定了茶园春、夏、秋季茶叶产量及新梢品质成分。【结果】喷施硅300、500 mg/L处理的茶苗地上部和根部生物量高于其他处理，幼苗叶绿素含量、叶片光化学猝灭系数(qP)、非光化学荧光淬灭系数(qNP)、表观电子传递速率(ETR)及植保素含量也高于Si0和其他处理，综合茶苗生长和生理指标结果，选用500 mg/L作为最佳硅喷施浓度。第一次喷施硅肥7天后，硅主要积累在叶部，从顶芽往下数的不同叶位硅含量分布为第3叶>第5叶>第1叶；第三次喷施7天后，第5叶硅含量显著高于第...

Effects of silicon fertilizer on the growth and silicon partitioning in tea plant parts

  【Objective】  The experiment was conducted to determine the effects of Si foliar application on the growth and tea quality, and accumulation of Si in tea plant parts for the safe use of Si fertilizer.  【Methods】  Pot and field experiments were used in this research, sodium silicate (Na₂SiO₃·9H₂O) was used as the silicon fertilizer. First, seven spraying concentrations of Si (0, 50, 150, 300, 500, 750, and 1500 mg/L) were set up in the indoor pot experiment, sprayed three times in total and once every 7 days. On the seventh day after the third spraying, the chlorophyll content (SPAD), the chlorophyll fluorescence characteristics, and the stomatal characteristics were measured. The biomass of shoot and root was weighed, the phytoalexin content of tea seedlings was measured, and the optimal Si spray concentration was proposed. The second indoor experiment was then conducted using the optimum Si spray concentration as treatment and distilled water as control. The Si concentration in the top 1, 3, and 5 leaves, in stem and root of tea seedlings were measured after the first, second, and third spray treatments, respectively. At the same time, field experiment was conducted in a tea garden located in Shandong Province, taking the same treatment as in the pot experiment. The tea yield and active component contents related to tea quality were investigated in spring, summer and autumn, respectively.  【Results】  Si300 and Si500 exhibited higher leaf SPAD, qNP, and electron transport rate (ETR) values than other treatments, and contained significantly higher phytoalexin content than Si0. Si500 also elicited the highest bud density and 100-bud weight, thus it was the optimum spraying concentration. The concentration was used as Si treatment and distilled water as control in the following pot and field experiment. After the first spray treatment in the pot experiment, silicon content was found to be higher in leaves than in stems and roots, and the silicon content in different leaves was in order: the top third leaf > the top fifth leaf > the top first leaf. After the third spray treatments, the top fifth leaf had higher silicon content than the top first and third leaves; and root had the highest Si content in tea plants. In the field experiment, Si spray increased the 100-bud weight and budding density of tea plants significantly in all the three seasons. The content of free amino acids in spring tea, summer tea, and autumn tea increased by 17.49%, 94.48%, and 15.06%, respectively; soluble sugar content increased by 2.72%, 91.69%, and 3.33%, while caffeine decreased significantly by 7.07%, 32.91%, and 16.59%, respectively.  【Conclusions】  Foliar spraying of 500 mg/L silicon is beneficial to the growth of tea seedlings. Spraying silicon fertilizer before picking is beneficial to improve the yield and quality of tea, especially summer tea. After spraying silicon fertilizer, silicon is mainly accumulated in the roots and mature leaves of tea.