不同钾肥对甘蓝产量、品质和营养元素形态的影响

EFFECTS OF POTASSIUM FERTILIZER ON YIELD,QUALITY AND NUTRIENTS OF CABBAGE RELATIVE TO FORMULA OF THE FERTILIZER

选择重庆地区适宜栽培的甘蓝品种，采用田间小区试验，研究不同种类和用量钾肥对甘蓝产量、品质和营养元素形态的影响，为无公害甘蓝生产确定合理的施钾技术提供科学依据。结果表明，不同施钾处理甘蓝生物产量和商品产量均显著提高（增量为4.3%~20.2%），两种钾肥均以中量水平（K2）增产最显著，但相同用量下钾肥种类间增产效果无显著差异，从肥料成本看以氯化钾更优。各处理均提高甘蓝氨基酸含量，以低量硫酸钾最优，增幅达56.9%；除中量氯化钾提高甘蓝维生素C含量6.8%外，其余处理均降低维生素C含量；各处理对甘蓝硝酸盐含量以降低为主，以高量硫酸钾降幅最大达12.3%；钾肥对甘蓝还原糖含量表现为提高，且以低量氯化钾最优。各处理均在一定程度上提高甘蓝矿质元素含量（Zn除外）。甘蓝各营养元素形态中，均以非蛋白态为主。不同钾肥处理蛋白氮含量与氨基酸含量呈极显著负相关（相关系数r=-0.820），蛋白磷与氨基酸含量呈显著正相关，而非蛋白磷含量与维生素C含量呈显著正相关；与氮、磷素形态相比，不同钾素形态与甘蓝品质间关系更为密切，其中全钾、蛋白钾含量与维生素C含量均呈显著正相关。综合各指标效应看，甘蓝适宜钾肥种类为氯化钾，且以中量施钾水平最优。

A field experiment was carried out using a cultivar of cabbage that suits the area of Chongqing for cultivation, to study effects of SOP and MOP on yield, quality and nutrients of cabbage, so as to provide a scientific basis for designing a reasonable K fertilizer application technique for production of hazard free cabbage. Results show that application of K fertilizer increased the yield, either biomass or commodity, of cabbage significantly by 4.32%~14.6%. The effects were the most significant in treatments moderate （K2） in K application rate, regardless of forms of potash, and the effects did not differ much between treatments the same in application rate, but different in potash form. But in terms of cost, potassium chloride was superior. K application increased the content of amino acids in cabbage in all the treatments, especially in Treatment K1（S）, by 56.9%;decreased VC content in cabbage in all the treatments except for Treatment K2（Cl）, which increased the content by 6.8%; reduced nitrate content in cabbage in all the treatments, particularly in Treatment K3（S）, by as much as 12.3%; increased reduced sugar content in cabbage in all the treatments with Treatment K1（Cl） in particular; and mineral nutrients, except for Zn, in cabbage to a certain extent in all the treatments. The nutrients in the cabbage were mostly dominated with non-protein forms. Protein-N was significantly and negatively related with amino acid in content in cabbage in all the K treatments, while protein-P was reversely with amino acid, and non-protein-P was significantly and positively related with VC content. Compared with N and P, K, regardless of its form, was more closely related to the quality of cabbage. Total-K and protein-K was in a significantly positive relationship with VC content, but in a negative one with nitrate in the cabbage. To sum up, potassium chloride is a kind of K fertilizer more suitable for cabbage cultivation, preferably at 225 kg hm-2.