不同钾肥用量对莴笋产量和品质的效应

Effect of different Potassium Fertilizer Amount on Yield and Quality of Lettuce

莴笋是中国南北地区广泛栽培和食用的叶类蔬菜之一, 其对氮、磷、钾三要素的吸收量中以钾最大，氮次之，磷最小。钾素作为作为“品质元素”，对莴笋品质形成至关重要。为寻求大田条件下合适的钾肥用量，在田间试验研究了不同钾肥施用量（K1、K2、K3、K4）对莴笋产量和品质的影响。结果表明：不同施肥处理间莴笋产量有显著差异。不同施肥处理提高莴笋产量2.0%～18.5％，增产幅度以K2＞K1＞K3＞K4，增施钾肥处理的增产效率则以K1＞K2＞K3＞K4。与CK1相比，不同施肥处理提高莴笋茎和叶片硝酸盐含量12.9%～140%；增施钾肥降低莴笋茎和叶片硝酸盐含量12.2%～43.8%和20.6%～35.0%，且茎、叶片硝酸盐含量与钾肥用量呈显著的二次回归关系。与CK1处理相比，不同施肥处理对莴笋Vc和可溶性糖含量茎中以负效应为主，叶片中以正效应为主；低K 处理（K1和K2处理）对Vc和可溶性糖含量正效应较大。不同施肥处理对莴笋茎和叶片氨基酸含量的效应以降低作用为主。综合莴笋产量和品质来看，以K2处理（即K2O 150kg/km2）为莴笋高产优质的最佳处理。

Lettuce with rich nutrients is broadly cultivated around the whole years in both north and south of China. Among the three nutrient factors （N, P, K）, the most amount absorbed for lettuce was K, then N and the least P. The nutrient limiting factors for lettuce growth was N and K. As a quality nutrient, the proper use of potassium fertilizer was beneficial to promote its growth, yield and quality. A field experiment was carried out to study the effect of different potassium fertilizer amount （K1, K2, K3, and K4） on yield and quality of lettuce. The results indicated that there were significant differences between the yields of lettuce. The yield of lettuce was increased by 2.0%-18.5% and the effect was in the order of K2〉K1 〉 K3〉K4 and the increase efficiency of yield by potassium fertilizer in the＇ order of K~〉K2〉K3〉K4.Comapred to CK~, the nitrate concentration in lettuce leaf and stem were increased by 12.9%-140%, but application potassium fertilizer reduced the nitrate concentration in lettuce stem and leaf by 12.2%-43.8% and 20.6%-35.0% .The relationship of nitrate concentration in lettuce stem, leaf and potassium fertilizer could be well described with quadratic regression equations. Comapred to CK~, different treatments mainly had negative effects on Vc and soluble sugar in lettuce stem, but the contrary effect were showed in leaf .The K~ and K2 treatments had positive effects on Vc and soluble sugar of lettuce. The amino acid concentration in lettuce leaf and stem were mainly decreased under different treatments. K2treatment （I（20 150kg/km2）was best treatment for higher yield and quality of lettuce.