外源褪黑素对干旱胁迫下多年生黑麦草幼苗生理特性的影响

Effects of exogenous melatonin on physiological characteristics of Lolium perenne seedlings under drought stress

为了研究外源褪黑素(MT)对干旱胁迫下多年生黑麦草幼苗生长的影响,试验以多年生黑麦草为材料,先以叶片喷施法施加外源MT,再采用控水法进行干旱胁迫,共设置6个处理,即CK(干旱+喷施纯化水)、T1(干旱+喷施50μmol/L MT)、T2(干旱+喷施100μmol/L MT)、T3(干旱+喷施150μmol/L MT)、T4(干旱+喷施200μmol/L MT)、T5(干旱+喷施250μmol/L MT),在干旱胁迫第0,3,6,9,12天取样,测定叶绿素a、叶绿素b、游离脯氨酸(Pro)、可溶性糖、丙二醛(MDA)含量,以及过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性。结果表明:在干旱胁迫第3,6,9,12天,T1、T2、T3处理的叶绿素a(除第9天T2处理外)和叶绿素b(除第3,6,9天T1处理外)含量均显著高于CK处理(P<0.05),其中T3处理的叶绿素a、叶绿素b含量均最高;在干旱胁迫第6,9,12天,T3处理的MDA含量显著低于其他处理(P<0.05);在干旱胁迫第12天时,T3处理的Pro含量和T4处理的可溶性糖含量均显著高于其他处理(P<0.05),相较于CK处理增加了31.7%和50.4%;干旱胁迫第9天时,T3处理的POD和CAT活性均显著高于其他处理(P<0.05),相较于CK处理分别提高了41.4%和21.3%;干旱胁迫第12天时,T3处理的SOD活性显著高于其他处理(P<0.05)。说明添加外源MT有助于减轻干旱胁迫下多年生黑麦草幼苗的膜质损伤,提高叶绿素及有机渗透调节物质的含量,缓解植物失水带来的损伤,从而增强多年生黑麦草对干旱胁迫的耐受性。在本试验条件下,喷施150μmol/L MT溶液的效果最好。

In order to study the effects of exogenous melatonin(MT) on the growth of perennial ryegrass seedlings under drought stress,perennial ryegrass was used as material in the experiment,and exogenous MT was first applied by leaf spraying method,followed by water control method for drought stress.A total of six treatments were set up,namely CK(drought + spray of purified water),T1(drought + spray of 50 μmol/L MT),T2(drought + spray of 100 μmol/L MT),T3(drought + spray of 150 μmol/L MT),T4(drought + spray of 200 μmol/L MT),and T5(drought + spray of 250 μmol/L MT).The contents of chlorophyll a,chlorophyll b,free proline(Pro),soluble sugar,malondialdehyde(MDA),and the activities of peroxidase(POD),superoxide dismutase(SOD) and catalase(CAT) were determined by sampling at the 0,3,6,9 and 12 days of drought stress.The results showed that on days 3,6,9,12 of drought stress,the contents of chlorophyll a(except T2 treatment on day 9) and chlorophyll b(except T1 treatment on day 3,6,9) in the T1,T2 and T3 treatments were significantly higher than those in the CK treatment,(P<0.05),and the contents of chlorophyll a and chlorophyll b in the T3 treatment were the highest.At the 6th,9th and 12th days of drought stress,MDA content in the T3 treatment was significantly lower than that in other treatments(P<0.05).On the 12th day of drought stress,the Pro content in the T3 treatment and the soluble sugar content in the T4 treatment were significantly higher than those in other treatments(P<0.05),and were increased by 31.7% and 50.4% compared with CK treatment.On the 9th day of drought stress;the POD and CAT activities in the T3 treatment were significantly higher than those in other treatments(P<0.05),and were increased by 41.4% and 21.3% compared with CK treatment,respectively.On the 12th day of drought stress,the SOD activity in the T3 treatment was significantly higher than that in other treatments(P<0.05).These results indicated that the addition of exogenous MT could help reduce membrane damage of perennial ryegrass seedlings under drought stress,increase the content of chlorophyll and organic osmotic regulatory substances,alleviate the damage caused by water loss,and enhance the tolerance of perennial ryegrass to drought stress.Under the test conditions,spraying 150 μmol/L MT solution had the best effect.