低钾配施纳米氢氧化镁对白菜的营养效应研究

【目的】 探讨低量施钾条件下配施纳米氢氧化镁对白菜营养效应的影响和提高钾素利用效率的作用。【方法】 采用酸性紫色土在西南大学进行了大白菜盆栽试验。在所有处理均施N 200 mg/kg和P₂O₅ 100 mg/kg的基础上，试验设不施钾，低钾量（K₂O 75 mg/kg土），适量钾（K₂O 105 mg/kg土），低量钾配施纳米氢氧化镁1.13、1.88 mg/kg土，共5个处理。在大白菜生长68天后收获，测定了白菜产量、叶绿素含量、抗氧化能力、养分吸收量及钾素利用效率、营养品质等指标。【结果】 低量钾配施纳米氢氧化镁对白菜增产作用极显著，配施氮磷钾肥总量的0.3%（1.13mg/kg土）时白菜产量增加21.5%；配施纳米氢氧化镁使白菜叶绿素a含量、叶绿素b含量、叶绿素总量和叶绿素a/b值分别提高5.3%~10.3%、4.0%~6.1%、4.8%~8.9%和4.3%~8.7%。提高白菜抗氧化能力，使白菜胡萝卜素、总酚和类黄酮等非酶类抗氧化物质含量分别提高7.6%、6.2%和6.8%~20.0%，超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）等酶类抗氧化物质含量分别提高9.8%~18.8%、10.7%~11.2%和7.4%~9.9%。配施纳米氢氧化镁促进白菜养分吸收，白菜磷、镁含量分别提高3.8%~16.9%、11.1%~24.9%，氮、磷、钾和镁吸收量分别提高9.1%~10.2%、13.2%~32.3%、8.4%~14.4%、26.6%~39.7%，钾素偏生产力、钾素农学效率、钾素生理效率和钾素利用率分别提高20.6%~23.7%、74.5%~77.6%、27.4%~36.5%和14.6%~25.0%。低钾与纳米氢氧化镁配施的效果以配施氮磷钾肥总量的0.3%好于配施0.5%（1.88 mg/kg土）。配施纳米氢氧化镁对白菜可溶性糖含量影响不大，对氨基酸含量有一定的降低作用，但显著降低硝酸盐含量11.5%~12.9%，有利于改善白菜卫生品质。【结论】 综合白菜产量、叶绿素含量、抗氧化能力、养分含量和吸收量、钾素利用效率和营养品质，以配施氮磷钾肥总量0.3%的纳米氢氧化镁处理综合效应最佳。

Effect of combined application of low-level potassium fertilizer with nano-Mg(OH)2 on Chinese cabbage quality

Objectives] To evaluate the effect of low-level potassium fertilizer and nano-Mg(OH)2 combination application on growth and K use efficiency of Chinese cabbage.Methods] A pot experiment was conducted using purple soil and Chinese cabbage as test materials in Southwest University.At the base of applying N 200 mg/kg and P2O5 100 mg/kg soil,five treatments were set as:low K (K2O 75 mg/kg soil),proper K (K2O 105 mg/kg soil),low K plus 1.13 and 1.88 mg/kg of nano-Mg(OH)2,and no K control.After 68 days growth,the Chinese cabbages were harvested and the yield,chlorophyll content,antioxidant resistance,nutrients uptake were analyzed,the nutrient use efficiency was calculated.Results] The combined application of low K and nano-Mg(OH)2 significantly increased the yield of Chinese cabbage,with the highest yield-increasing of 21.5％ in treatment of addition of Mg(OH)2 0.3％ (1.13 mg/kg).With the two addition dosages of Mg(OH)2,the contents of chlorophyll a,chlorophyll b,chlorophyll and chlorophyll a/b were increased by 5.3％-10.3％,4.0％-6.1％,4.8％-8.9％ and 4.3％-8.7％;the contents of carotenoid,total phenol and lavonoid were increased by 7.6％,6.2％ and 6.8％-20.0％,the nitrogen uptake,phosphorus,potassium and magnesium uptakes were significantly increased by 9.1％-10.2％,13.2％-32.3％,8.4％-14.4％,26.6％-39.7％;the partial factor productivity of K,agronomy efficiency of K,K physiology efficiency and utilization efficiency were increased by 20.6％-23.7％,74.5％-77.6％,27.4％-36.5％ and 14.6％-25.0％.The highest potassium fertilizer use efficiency was observed in the treatment of low K plus 0.3％ of Mg(OH)2.The contents of nitrate were reduced by 11.5％-12.9％,the content of soluble sugar was little affected by the addition of nano-Mg(OH)2.Conclusions] The yield,chlorophyll content,antioxidant resistance,nutrients uptake,K use efficiency of Chinese cabbage were significantly increased with low-level potassium fertilizer and nano-Mg(OH)2 combination application.The added nano-Mg(OH)2 treatment with the 0.3％ dosage of NPK was perfect treatment for combined effect.