两种外源物在寒潮下对美花红千层的影响

Effects of Two Exogenous Substances on Callistemon rigidus Under Cold Wave

寒潮引起的温度骤降是常见的低温胁迫之一。探明外源脯氨酸和褪黑素在寒潮下对美花红千层(Callistemon rigidus)适应能力的提升效果,初步解释其气孔密度、长度与光合能力的相互关系。通过设置500 ml双蒸水对照组(CK)、100μmol/L褪黑素(M)、100 mg/L脯氨酸(P)、100 mg/L脯氨酸+100μmol/L褪黑素(MP)4个组,在2022年第一次寒潮入侵时进行气孔结构和生理、光合指标的观测。研究结果为:(1)寒潮使美花红千层气孔长度(SL)下降,气孔密度(SD)上升,叶片净光合速率(Pn)和PSⅡ中最大光化学效率(Fv/Fm)降低,丙二醛(MDA)含量和叶片伤害度(Ⅱ)增加;(2)SD与气孔导度(Cond)为显著负相关,与叶绿素(Chl)含量有着显著正相关,SL与光化学淬灭系数(qP)呈极显著正相关、与脯氨酸(Pro)含量呈正相关,SD和SL呈极显著负相关;(3)施加外源物可以维持气孔形态,提高Pn和F_(v)/F_(m),降低MDA含量和Ⅱ,施加效果为MP>P>M。施加褪黑素可以提升Pn、Chl含量,施加脯氨酸提高叶片内Pro含量以维持细胞渗透压平衡。100 mg/L脯氨酸+100μmol/L褪黑素联合施加能够更全面地提高植物抗逆性,维持气孔结构稳定,减少细胞膜结构损伤,提高光合作用。

The sudden drop in temperature caused by cold waves is a common form of low-temperature stress.This study aims to investigate the effect of exogenous proline and melatonin on enhancing the adaptive capacity of Callistemon rigidus under cold wave conditions and to preliminarily explain the relationship between stomatal density,length,and photosynthetic capacity.Four groups were set up with the application of 500 ml of double-distilled water control group(CK),100μmol/Lmelatonin(M),100 mg/L proline(P),and 100 mg/L proline+100μmol/L melatonin(MP),and an open fi eld experiment was conducted at the onset of the fi rst cold spell in 2022.Results show that:(1)The cold wave caused a decrease in stomatal length(SL)and an increase in stomatal density(SD)of Callistemon rigidus,with a reduction in leaf net photosynthetic rate(Pn)and PSⅡmaximum photochemical effi ciency(Fv/Fm),and an increase in malondialdehyde(MDA)content and leaf damage degree(Ⅱ).(2)SD was signifi cantly negatively correlated with stomatal conductance(Cond)and signifi cantly positively correlated with chlorophyll content,while SL was signifi cantly positively correlated with photochemical quenching coeffi cient(qP)and proline content.There was a signifi cant negative correlation between SD and SL.(3)The application of exogenous substances maintained stomatal morphology,increased Pn and F_(v)/F_(m),and reduced MDA content andⅡ,with the effectiveness ranked as MP>P>M.The application of proline and melatonin maintained the stomatal structure of Callistemon rigidus,increased the photosynthetic rate,reduced MDA accumulation,and enhanced plant stress resistance;among them,the combination of 100 mg/L proline+100μmol/L had the optimal effect.