作 者：
黄红荣;李建明;胡晓辉;张军;张中典;崔万军
关键词：
黄瓜;亚低温胁迫;镁浓度;根系生长;钾吸收
摘 要：
【目的】我国北方地区冬春季栽培黄瓜经常遭受亚低温(15℃/8℃)胁迫,用标准营养液育苗常会造成黄瓜植株矮小、叶片发黄等问题。研究调整营养液中镁和钾离子浓度,以便达到缓解亚低温对黄瓜幼苗伤害作用的目的。【方法】选用‘博耐3000'黄瓜幼苗为试材,利用人工气候箱,以常温(25℃/18℃)下黄瓜山崎标准营养液配方(K+6 mmol/L、Mg~(2+) 2 mmol/L)为对照,在标准营养液其他元素保持不变的基础上,设置两个钾离子水平(K+6、12 mmol/L),4个镁离子水平(Mg~(2+)2、4、6、8 mmol/L),在亚低温(15℃/8℃)下栽培黄瓜幼苗,于处理后幼苗生长的0、7、14、21 d调查了不同镁钾水平营养液栽培的黄瓜幼苗的根系形态、干物质积累和分配以及对钾和镁元素吸收。【结果】1)亚低温下适当增加营养液中的Mg~(2+) 浓度,能显著提高黄瓜幼苗的壮苗指数,当营养液中Mg~(2+) 和K+均为6 mmol/L时,壮苗指数达到最大值0.17;2)镁和钾对根系形态影响不同,K+浓度与根长和根系总表面积成正相关,且主要影响直径范围为0~0.5 mm的根系,Mg~(2+) 与根系平均直径正相关且主要影响>1.0 mm的根系;较高的K/Mg比例有利于黄瓜0~0.5 mm根系的生长,根系总长和总体积的增加,但显著抑制了0.5~1.0 mm和>1.0 mm根系的生长。3)亚低温下,茎叶中干物质量降低而根中升高,在K1(6mmol/L)水平时,随Mg~(2+) 浓度升高,根和茎中干物质量升高,叶中干物质表现为先升高后下降,且营养液中高浓度的Mg~(2+) 有利于干物质向叶中分配。4)营养液中镁离子浓度小于6 mmol/L时,一定程度地提高Mg~(2+) 浓度能促进对K的吸收,营养液中的Mg~(2+) 和K+在镁钾吸收上表现为协同作用,当Mg~(2+) 大于6 mmol/L时,镁和钾表现为显著的拮抗作用;亚低温下,根茎叶的镁吸收量相比CK分别下降25%、72%和58%,而营养液中K+和Mg~(2+) 均为6 mmol/L时,有利于缓解这一阻碍效果。【结论】冬春季黄瓜育苗时,山崎黄瓜配方营养液中的Mg~(2+) 和K+均为6 mmol/L而其他元素浓度保持不变时,黄瓜幼苗的壮苗指数、根系形态、干物质积累和钾镁元素综合效应表现较好,能有效地抵御亚低温对黄瓜幼苗的伤害。
译 名：
Increasing magnesium level in hydroponic solution will relieve suboptimal temperature stress to cucumber seedlings
作 者：
HUANG Hong-rong;LI Jian-ming;HU Xiao-hui;ZHANG Jun;ZHANG Zhong-dian;CUI Wan-jun;College of Horticulture, Northwest A&F University;
关键词：
cucumber;;suboptimal temperature stress;;magnesium level;;root development;;potassium absorption
摘 要：
【Objectives】In northern China, cucumber seedlings are often subjected to suboptimal temperature(15℃/8℃) stress during spring or winter season. Under such environment, the hydroponic cucumber seedlings using standard nutrient solution are weak and their leaves become yellow in color. A study was conducted aiming to relieve the adverse effects of suboptimal temperature stress by adjusting magnesium(Mg) and potassium(K)concentrations in the nutrient solution.【Methods】Hydroponic experiment was conducted inside a climatic chamber with cucumber ‘Bo Nai 3000' as materials. The day/night culture temperature was 25℃/18℃ for control and 15℃/8℃ for treatment. On the base of a standard Yamazaki cucumber nutrient solution in the control,two levels of K~+(6 and 12 mmol/L) and four Mg~(2+) (2, 4, 6 and 8 mmol/L) were set for the treatments under suboptimal temperature. The root morphology, dry matter accumulation and distribution as well as K and Mg absorption in cucumber seedlings were investigated every 7 days since the cultivation, and 4 investigations were did in total.【Results】1) Appropriate increasing of the Mg~(2+) concentration in the culture solution significantly improved healthy seedling index under suboptimal temperature. When the Mg~(2+) and K+ concentrations were all 6mmol/L, the seedling index reached the maximum value of 0.17. 2) The effects of Mg~(2+) and K+ on root morphology were different. K+ concentration was positively correlated with the total root length and root surface area, the effect was mainly on roots of 0–0.5 mm in diameter; Mg~(2+) was positively correlated with the average diameter of the root system, the effect was mainly on roots of >1.0 mm in diameter; higher K/Mg ratio was beneficial to the increase of total length and volume of roots of 0–0.5 mm in diameter, but not for those of roots of 0.5–1.0 mm and >1.0 mm in diameter. 3) Compared to normal temperature, the dry biomass of stems and leaves were decreased while the root dry biomass increased under suboptimal temperature. Under K+concentration of 6 mmol/L, root and stem dry biomass were increased with enhanced Mg~(2+) concentration. The high Mg~(2+) concentration of nutrient solution contributed to the distribution of dry matter to leaf. 4) When Mg~(2+) was less than 6 mmol/L, interaction effect existed between Mg~(2+) and K+, while significant antagonism effect existed when Mg~(2+) was higher than 6 mmol/L. The absorptive amount of Mg under suboptimal temperature decreased by25%, 72% and 58% in root, stem and leaf respectively, compared to CK.【Conclusions】Under suboptimal temperature, 6 mmol/L Mg~(2+) and K+ in Yamasaki cucumber nutrient solution improved the seedling index of cucumber seedlings, root morphology and dry matter accumulation. It can effectively resist the adverse effects of suboptimal temperature on cucumber seedlings.
