温度与水分胁迫下玉米的交叉适应机制研究

Studies on Cross Adaptation Mechanism of Maize under Temperature and Moisture Stress

为了揭示高、低温及干旱交替对玉米植株生长及渗透调节物质的影响机制,以会单2号幼苗为试材,分别经高温(36℃、40℃)、低温(4℃、8℃)、室温(25℃,CK)预处理72 h,然后进行无土栽培,待苗长至50 cm左右时在营养液中加入15%聚乙二醇(PEG-6000)进行模拟干旱处理。结果表明,高、低温预处理对玉米苗的生长影响较大,其中高温预处理抑制玉米苗在干旱胁迫前的生长,降低生物量积累,但干旱胁迫后高温(36℃、40℃)预处理的玉米苗保持较快的生长速率,株高较干旱胁迫前分别增长了46.7、44.0 cm,生物量分别增长了41.0、37.4 g;而低温预处理却显著促进了玉米苗在干旱胁迫前的生长和生物量积累,但在干旱胁迫过程中表现不明显。高、低温预处理可显著减小玉米根、茎、叶相对含水率和总相对含水量的降幅,显著增加游离脯氨酸、可溶性糖、可溶性蛋白、总氮、钾的含量。干旱胁迫结束时,40℃预处理的玉米植株游离脯氨酸、可溶性糖、可溶性蛋白、总氮、钾含量分别达到1 286.31μg/g、75.76 mg/g、11.43 mg/g、32.80 mg/g、12.19 mg/g,显著高于低温处理和CK。因此,低温预处理可促进玉米苗的生长,而高温预处理则抑制其生长,这种作用在干旱胁迫下则逆转。高、低温预处理可诱导玉米植株对干旱胁迫的交叉适应性,这种适应性与渗透调节能力的增强密切相关。

In order to reveal the action mechanism of alternate treatments with high-low temperature /drought on plant growth and osmoregulation of maize,the seedlings of ‘Huidan 2 ＇were used as experimental materials,which were pretreated under high temperature（36 ℃,40 ℃） and low temperature（4 ℃,8 ℃） for 72 h,taking room temperature（25 ℃） as control.Thereafter the soilless culture of the seedlings was conducted.When the seedlings grew to 50 cm high,15% polyethylene glycol（PEG-6000）was added into the nutrient solution to simulate the drought treatment.The results showed that the high and low temperature pretreatment had a large effect on the growth of maize seedlings.Among them,the high temperature pretreatment inhibited the growth of maize seedlings and decreased the biomass accumulation before the drought stress.However,after the drought stress,the maize seedlings pretreated with high temperature（36 ℃,40 ℃） remained rapid growth,of which the plant height increased by 46.7 cm and44.0 cm respectively,while the biomass increased by 41.0 g and 37.4 g respectively.Low temperaturepretreatment significantly promoted the growth and biomass accumulation of maize seedlings before the drought stress,but it gradually became not obvious after the drought stress.High and low temperature pretreatment significantly decreased the relative water contents of roots,stems and leaves of maize,while significantly increased the contents of proline,soluble sugar,soluble protein,total nitrogen and K＋.At the end of the drought stress,the contents of proline,soluble sugar,soluble protein and K＋in maize with 40 ℃pretreatment reached 1 286.31 g / g,75.76 mg / g,11.43 mg / g,32.80 mg / g,12.19 mg / g respectively,significantly higher than other treatments and CK.The results suggested that the low temperature pretreatment could promote the growth of maize seedlings,and the high temperature pretreatment inhibited the growth,but these effects could be reversed under drought stress.High and low temperature pretreatment could induce the cross adaptation of maize seedlings to drought,and the adaptation might be related to the observed enhance in osmoregulation capability.