As对谷子萌发、幼苗生长及抗氧化酶系统的影响

Effect of As Stress on Millet Germination,Seedling Growth and Antioxidant System

为探究As对谷子苗期生长的影响及谷子生长的临界浓度,设置As浓度梯度分别为0,2,4,8,10mg/kg,以石英砂为基质,通过培养试验,分析探讨不同浓度As对谷子萌发、苗期生长与抗氧化酶系统的影响。研究表明:低浓度的As(<4mg/kg)促进谷子萌发,高浓度的As(≥4mg/kg)抑制谷子萌发。当As浓度为2 mg/kg时,谷子的发芽势、发芽率和发芽指数在所有处理中最高,其值分别为18.67%,32.00%和19.00%。低浓度的As对谷子幼苗生长有促进作用,高浓度对其有抑制作用,当As浓度为2mg/kg,谷子的株高、根长和地上部鲜重与地下部鲜重都达到最大值,分别为15.46,7.34cm和0.64,0.16g,随着As浓度梯度增加,地下部鲜重/地上部鲜重先增加后降低,As对根系的促进与抑制作用大于地上部,谷子幼苗根部的As含量均明显高于地上部,且TF值逐渐减小;当As浓度<4mg/kg时,As能促进谷子叶绿素的合成,在As浓度为2 mg/kg时,谷子的叶绿素a、叶绿素b和叶绿素总量显著高于对照28.38%,51.60%,37.06%,As浓度高于4mg/kg时,谷子的叶绿素合成受到抑制;随着As浓度梯度的增加,谷子幼苗的SOD活性不断增强,POD与CAT活性呈先增加后减小的趋势,但均高于对照,As浓度>4mg/kg后,CAT活性开始减小;As浓度>8mg/kg后,谷子幼苗的POD活性开始减小,表明低浓度的As(<4mg/kg)对谷子萌发及幼苗生长有促进作用,高浓度的As(≥4mg/kg)抑制谷子萌发和幼苗生长,且根系对As胁迫的反应更为敏感,抗氧化酶系统(POD和CAT)活性降低。研究可为谷子的抗污染栽培和无公害生产提供科学依据。

To investigate the effect of arsenic on the growth of millet seedlings and the critical concentration of millet stress,the As concentrations were set to0,2,4,8,10mg/kg for quartz sand.Substrates,through cultivation and pot experiments,analyzed the effect mechanism of As on the germination,seedling growth and antioxidant enzyme system of millet.Studies have shown that:Low concentrations of As(<4mg/kg)can promote millet germination,high concentrations of As(<4mg/kg)inhibit millet germination,when the As concentration of2mg/kg,the millet germination potential,germination rate and germination index in all treatments the highest value.They were18.67%,32.00%,and19.00%,respectively.The low concentration of As promoted the growth of millet seedlings,and the high concentration had an inhibitory effect.When the As concentration was2mg/kg,the plant height,root length,fresh shoot weight,and under ground fresh weight of millet were all reached.The maximum values were15.46cm,7.34cm,0.64g,and0.16g,respectively.As the concentration gradient of As increased,the fresh weight of the under ground layer increased first and then decreased,and the promotion and inhibition of the root system was greater than that of the shoot.The content of As in the roots of millet seedlings was significantly higher than in the shoots,and the TF value gradually dccreased.When As concentration was less than4mg/kg,As could promote the synthesis of chlorophyll in millet.When As concentration was2mg/kg,the total amount of chlorophyll a,chlorophyll b and chlorophyll in millet was significantly higher than that of the control28.38%,51.60%and37.06%,when the concentration of As was higher than4mg/kg,the chlorophyll synthesis of Millet was inhibited;with the increase of As concentration gradient,the SOD activity of millet seedlings continued to increase,and the activities of POD and CAT increased first and then decreased,but higher than the contro.When the As concentration exceeded8mg/kg,the POD activity of the millet seedlings began to decrease.After the As concentration exceeded4mg/kg,the CAT activity began to decrease.After As concentration higher than8mg/kg,the POD actibvity of millet seedlings began to decrease.The results showed that low concentration of As(<4mg/kg)promoted the germination and seedling growth of millet,and the high concentration of As(≥4mg/kg)inhibited the germination and seedling growth of millet,and the root system was more sensitive to As stress,and the activity of antioxidant enzyme system(POD,CAT)was reduced.The research can provide a scientific basis for the anti-pollution cultivation and pollution-free production of millet.