基质栽培番茄营养液中氮、钾最佳浓度研究

Optimum levels of nitrogen and potassium in the irrigation water for best growth and quality of tomato in soilless culture

【目的】合理的氮、钾养分供给是提高番茄生长及果实品质的重要措施,本文研究了滴灌营养液中不同的氮、钾养分供给水平对基质栽培番茄生长及果实品质的影响,为优化基质栽培番茄的营养液配方,确定最佳的氮、钾养分浓度,实现养分供给的精量化管理提供科学依据。【方法】以沙∶珍珠岩比例为1∶2配置栽培基质,用于温室中番茄栽培,以番茄‘A20’为试材,进行了水培试验。采用2因素(氮、钾)5水平响应面中心复合设计,滴灌营养液中氮浓度的基础值为244 mg/L,试验设计步长为120 mg/L;钾浓度的基础值为313mg/L,试验设计步长为150 mg/L。调查了番茄叶片叶绿素含量、净光合速率、单株产量、果实可溶性糖含量、可滴定酸含量、糖酸比、维生素C含量和番茄红素含量。【结果】随着滴管液中氮浓度从74 mg/L增加到414mg/L,番茄产量、叶片叶绿素含量、叶片净光合速率、果实可溶性糖含量、糖酸比、番茄红素含量和果实维生素C含量均呈先增后减的趋势。随着营养液中钾浓度从101 mg/L增加到525 mg/L,果实可溶性糖含量、糖酸比和维生素C含量持续增加,番茄产量、叶绿素含量、净光合速率、番茄红素含量均先增后减。此外,通过建立各指标与氮钾二因子的二次回归方程发现,氮素是叶绿素含量、净光合速率和单株产量的主要影响因子,钾素是果实可溶性糖、可滴定酸、糖酸比、维生素C和番茄红素含量的主要影响因子。氮、钾互作显著影响番茄产量和叶片叶绿素含量;充足的钾营养供给可以促进植株对氮素的吸收与同化,提高叶片叶绿素含量,利于产量提高;适量的氮素供应有利于钾素的吸收与利用,促进产量的进一步提高。采用主成分分析方法对8种配施方案下番茄产量和品质的综合性能进行评价,结果显示营养液中氮、钾浓度分别为N 378 mg/L、K 391 mg/L时为最优配方方案,且番茄叶片净光合速率达到最大值。【结论】在沙子和珍珠岩1∶2(v∶v)为基质的番茄无土栽培条件下,滴灌营养液中氮、钾浓度分别为N 378 mg/L和K 391 mg/L时,番茄产量和品质的综合性能达到最优,该方案可在生产实践中为基质栽培番茄营养液精确管理提供一定的借鉴意义。

【Objectives】Reasonable N and K nutrition supplementation is an important strategy to improve tomato growth and fruit quality.In this study,we attempted to optimize N and K supplement levels for tomato precision management in substrate cultivation system.【Methods】In greenhouse,a soilless culture experiment was conducted using sand and pearlite mixture in ratio of 1∶2 in volume as growth substrates,and potato cultivar A20 as tested materials,the irrigation treatments were composed of two factors(N and K)and five levels.The basic levels of N and K in irrigation water were 244 and 313 mg/L respectively,and the designed steps were 120 mg/L for N and 150 mg/L for K,respectively.The yield,chlorophyll content and net photosynthetic rate in leaves,the soluble sugar and titratable acid contents,the sugar/acid ratio,vitamin C,and lycopene contents in fruits were measured.【Results】Within the N levels of 74-414 mg/L in the irrigation water,both the yield and chlorophyll content increased first and then decreased.Within the K supply levels of 101-525 mg/L,the net photosynthetic rate in leaves,lycopene contents in fruits increased first and then decreased,the soluble sugar content,sugar/acid ratio and Vc content in fruit kept increasing.N supplying levels mainly affected yield,chlorophyll content and net photosynthetic rate,while K supplying levels mainly affected soluble sugar,titratable acid,sugar/acid ratio,Vc and lycopene contents.There were significant interaction between N and K levels on yield and chlorophyll content.Adequate K supplement promoted the uptake and assimilation of N nutrition and increased the leaf chlorophyll content and yield.Appropriate N supplement was conducive to K uptake and utilization.According to the principal component analysis,the comprehensive performance of tomato yield and quality reached the optimum at the N 378 mg/L and K 391 mg/L with the highest net photosynthetic rate in tomato leaves.【Conclusions】Using sand and pearlite as growth substrate,the optimum N and K supplying levels in irrigation water for tomato production are 378 and 391 mg/L,respectively,and the comprehensive performance of tomato yield and quality reached optimum level.The fertilization strategy may serve as reference for the precise management of nutrient solution for tomato cultivation in production practice.