外源硅调控滇润楠幼苗对干旱胁迫的生理响应

Regulation of Exogenous Silicon in Physiological Response of Machilus yunnanensis Seedlings under Drought Stress

为探究不同浓度外源硅(Si)条件下滇润楠(Machilus yunnanensis)幼苗对干旱胁迫的生理响应。采用盆栽控水法,设置对照(CK,良好水分处理)、单独干旱处理(D)、干旱+1 g/L硅处理(M1)、干旱+2 g/L硅处理(M2)、干旱+3 g/L硅处理(M3)、干旱+4 g/L硅处理(M4)和干旱+5 g/L硅处理(M5)7个处理,分析各处理植株生物量及生理指标的变化。结果表明:干旱胁迫抑制了滇润楠幼苗的生物量积累和光合能力,对其造成氧化伤害,施硅处理可缓解干旱胁迫对滇润楠幼苗造成的伤害,且存在明显的浓度效应。主要表现为M4处理下,滇润楠的生物量、净光合速率、最大光化学效率、实际光化学效率、电子传递速率及叶绿素含量、脯氨酸及可溶性蛋白含量、抗氧化酶SOD、POD和CAT的活性显著高于单独干旱处理组(D);而膜脂过氧化产物丙二醛含量显著低于单独干旱处理组(D)。综上可知,4 g/L的硅酸钠能更好地促进干旱胁迫下滇润楠叶片渗透调节物质的积累及抗氧化酶活性的提高、增加生物膜的稳定性,从而减轻干旱胁迫对其造成的伤害,提高了干旱下植株的光合能力及生物量积累。

To investigate the physiological response of Machilus yunnanensis seedlings to drought stress under different concentrations of exogenous silicon(Si)condition.Seven treatment groups were set using the potting water control method.These group included control(CK,well-watered treatment),drought stress alone(D),drought+(1 g/L)silicon treatment(M1),drought+(2 g/L)silicon treatment(M2),drought+(3 g/L)silicon treatment(M3),drought+(4 g/L)silicon treatment(M4)and drought+(5 g/L)silicon treatment(M5).The changes in plant biomass and physiological indexes were determined and compared among the different treatment groups.The results showed that drought stress inhibited the biomass accumulation and photosynthetic capacity of Machilus yunnanensis seedlings and caused oxidative damage.However,silicon application treatment alleviated this damage caused by drought stress to Machilus yunnanensis seedlings,and there was an obvious concentration effect of silicon.In the 4 g/L silicon treatment(M4),the biomass,net photosynthetic rate,maximum photochemical efficiency,actual photochemical efficiency,electron transport rate,chlorophyll contents,proline and soluble protein content,as well as activities of antioxidant enzymes SOD,POD and CAT of Machilus yunnanensis,were significantly higher compared to seedlings subjected to drought stress alone(D),while the content of malondialdehyde,a membrane peroxidation product was significantly lower in M4 treatment than under drought stress alone(D).In conclusion,the 4 g/L sodium silicate better promotes the accumulation of osmotic regulatory substances and the improves the antioxidant enzyme activity in the leaves of Machilus yunnanensis,increases the stability of the biofilm,reduces the damage caused by drought stress,and improves the photosynthetic capacity and biomass accumulation of plants under drought stress.