钾肥减量分期施用对莴笋产量和品质的效应研究

通过大田试验研究了紫色菜园土壤钾肥减量分期施用对莴笋产量和品质的影响。结果表明：两个试验点钾肥减量10%~30%分期施用对莴笋产量有提高作用，各处理以K2（钾肥减量10%分期等量追施）效应最好，增产最大（4.2%和4.5%）、施肥利润最高（84923元/hm²和72075元/hm²）。两个试验点莴笋叶维生素C含量均呈下降趋势，K2处理较常规施肥(CK)处理均显著降低莴笋叶维生素C含量（8.0%和8.7%）；而莴笋茎维生素C含量变化规律不一致。钾肥减量分期施用降低两个试验点莴笋叶和茎硝酸盐含量，以K4处理（钾肥减量30%分期等量追施）降低作用最大；从莴笋叶和茎糖组分的均衡性看，以K3处理最好。钾肥减量分期施用对两个试验点莴笋叶必需氨基酸含量有显著增加作用，改善叶氨基酸品质性状，但降低莴笋茎必需氨基酸含量和品质性状；莴笋氨基酸品质性状以K4处理为最优，其次是K2处理。综合考虑莴笋产量和品质，紫色菜园土壤以K2处理（钾肥减量10%分期等量追施）最优。

Effects of Potassium Fertilizer Reduction and Split Application on Yield and Quality of Lettuce

The field experiment was conducted to study the effects of different levels potassium fertilizer reduction application by stages on yield and quality of lettuce in purple garden soils. The results showed that the potash fertilizer reduction of 10% - 30% application by stages did not influenced lettuce yields at two experiment sites, the K2 treatment (reduction of K 10% amount of topdressing) had best effects included in the maximum yield (the increase of 4.2% and 4.5%) and the optimum economic profit (84923 yuan/hm₂ and 72075 yuan/hm₂). Vitamin C content of lettuce leaves showed a downward trend in potassium fertilizer reduction application by stages at two experiment sites, compared with the conventional fertilization (CK) the K2 treatment were significantly decreased vitamin C content of lettuce leaf (8.0% and 8.7%), but the changes of vitamin C content in lettuce stem was different. Potassium fertilizer reduction application by stages reduced nitrate content of lettuce leaves and stems at two experiment sites, the role of K4 treatment (minus the amount of potassium 30% equivalent to topdressing) was the maximum. Considering the balance of sugars in lettuce leaves and stems, K3 treatment was best. Essential amino acid content of lettuce leaves were increased significantly in potassium fertilizer reduction application by stages at two experiment sites but essential amino acid contents of lettuce stem were decreased. Amino acids quality traits of lettuce is the best in K4 and the second was K2. Comprehensive consideration of yield and quality of lettuce, the K2 treatment (reduction 10% potassium fertilizer application by stages) was the best in two purple vegetable soil.