长期施肥红壤钾有效性研究

目的探讨不同钾肥水平对盆栽现蕾期海法白三叶(Trifolium repens L.cv.Haifa)光合特性、生物量及根系形态的影响。方法设置0、60、120、180、240和300 kg/hm² (以K₂SO₄计算) 6个施钾水平处理的盆栽试验，测定海法白三叶植株的光合参数及根系形态指标。结果(1)施钾60 kg/hm²可显著提高植株叶片的叶绿素含量(P< 0.05)，比对照增加11.56%；施钾肥120 kg/hm²可显著提高植株叶片的净光合速率、气孔导度和蒸腾速率(P< 0.05)，分别比对照增加29.04%、45.03%和77.17%，且可有效降低植株叶片的胞间CO₂浓度(P< 0.05)，比对照减少2.24%。(2)施钾120 kg/hm²可明显提高植株的根干重、地上部干重和根冠比(P< 0.05)，分别比对照增加25.55%、17.31%和7.25%。(3)施钾60 kg/hm²可显著提高植株的总根长及根系活力(P< 0.05)，分别比对照增加13.10%和29.82%；施钾120 kg/hm²可明显提高植株的总根表面积、总根体积和根系可溶性糖含量(P< 0.05)，分别比对照增加33.10%、20.00%和31.00%，但施钾对白三叶根系平均直径的影响不显著(P>0.05)。结论在中钾酸性土壤中，种植海法白三叶推荐施钾量为60~120 kg/hm²。

Effects of Potassium Fertilizer on the Photosynthesis and Root Morphology of Trifolium repens L.cv.Haifa in Squaring Stage

PurposeTo study the effects of different potassium fertilizer levels on the photosynthesis, biomass and root morphology of Trifolium repens L.cv.Haifa in potted squaring stage.MethodPot experiments of six potassium levels were carried out with 0, 60, 120, 180, 240, 300 kg/hm² (calculated as K₂SO₄) using T. repens L.cv.Haifa as the test material, and the photosynthetic parameters and root morphological indexes of the plants were measured.Result(1) Potassium fertilizer application of 60 kg/hm² significantly increased the chlorophyll content of leaves (P< 0.05), which was 11.56% higher than the control, the application of potassium fertilizer was 120 kg/hm² significantly increased the photosynthetic rate, stomatal conductance and transpiration rate of the leaves (P< 0.05), which increased by 29.04%, 45.03% and 77.17%, respectively, compared with the control, and the intercellular carbon dioxide concentration of plant leaves was effectively reduced (P< 0.05), with a decrease of 2.24% compared with the control. (2) The application of potassium fertilizer 120 kg/hm² could significantly increase the root dry weight, shoot dry weight and root shoot ratio of the plants (P< 0.05), which increased by 25.55%, 17.31% and 7.25%, respectively, compared with the control. (3) Potassium application of 60 kg/hm² significantly increased the total root length and root activity of the plants (P< 0.05), which were 13.10% and 29.82% higher than the control, respectively; potassium fertilizer application of 120 kg/hm² could significantly increase the total root surface area, total root volume and soluble sugar content of root (P<0.05), respectively increasing by 33.10%, 20.00% and 31.00% compared with the control, but the influence of potassium fertilizer application on the average root diameter of T. repens L.cv.Haifa was not significant (P>0.05).ConclusionIn the medium-potassium acidic soil, the recommended potassium fertilizer application level of the T. repens L.cv.Haifa is 60-120 kg/hm².