外源脯氨酸对盐胁迫下芹菜生长及光合特性的影响

Effects of Exogenous Proline on Growth and Photosynthetic Characteristics of Celery under Salt Stress

【目的】盐胁迫是影响作物生长及产量的重要非生物胁迫,探究脯氨酸(Proline,Pro)对盐胁迫下芹菜生长及光合特性的影响,并筛选缓解胁迫最适浓度。【方法】以‘美国西芹’为试验材料,以无盐胁迫且不喷施脯氨酸(Pro)为对照1(CK1),在盐胁迫(100 mmol/L NaCl)下,以叶面喷施0 mmol/L Pro为对照2(CK2),以及喷施0.1,0.3,0.9,1.5,3,4.5,6 mmol/L Pro共计9个处理,测定芹菜的生长及光合特性相关指标。【结果】与CK1相比,盐胁迫显著抑制了芹菜的株高、茎粗、根系形态建成及生物量的积累,显著降低了芹菜叶片叶绿素含量及光合电子从初级醌受体QA向次级醌受体QB的传递效率,使快速叶绿素荧光诱导动力学曲线(OJIP)发生明显变形,抑制了光合作用。叶面喷施适宜浓度脯氨酸可有效缓解盐胁迫下芹菜株高、茎粗及叶片叶绿素含量的下降,促进根系形态建成及生物量的积累,恢复OJIP曲线,增强光合作用。0.3 mmol/L Pro处理芹菜叶片的净光合速率Pn、气孔导度Gs、蒸腾速率Tr及光合性能指数PI(_(ABS))较CK2分别提高60.24%、31.90%、22.00%及3.07%,最大光化学效率Fv/Fm、光系统Ⅱ(PSII)实际光化学效率Y(Ⅱ)、光化学淬灭系数qP、单位面积吸收的光能ABS/CSm及单位面积电子传递的产额ETo/CSm分别提高1.37%、33.31%、17.52%、3.35%及5.33%,而单位面积热耗散DIo/CSm和单位反应中心耗散掉的能量DIo/RC分别降低5.41%和16.40%。【结论】外源脯氨酸促进盐胁迫下芹菜的生长、根系形态建成、生物量的积累及叶绿素的含量,通过热耗散途径减少芹菜叶片PSII过剩激发能,降低反应中心的激发压力,促进PSⅡ的性能,增强单位截面PSⅡ反应中心的活性和光合作用,从而缓解盐胁迫下芹菜的生长,其中以0.3 mmol/L脯氨酸效果最佳。

[Objective]Salt stress is an important abiotic stress influencing crop growth and yield.This study investigated the effect of proline(Pro)on the growth and photosynthetic characteristics of celery under salt stress,in order to select the best concentration to alleviate the stress.[Method]This study used“American Celery”as the test material,a total of nine treatments,including celery without salt stress and spraying proline as control 1(CK1),under salt stress(100 mmol/L NaCl),foliar spray of 0 mmol/L Pro as control 2(CK2),and the spray of 0.1,0.3,0.9,1.5,3,4.5,6 mmol/L were set to measure the growth and photosynthetic characteristics of celery.[Result]The results showed that compared with CK1,salt stress significantly inhibited plant height,stem diameter,root morphogenesis and biomass accumulation in celery,the chlorophyll content of celery leaves and the transfer efficiency of photosynthetic electrons from primary quinone receptor QA to secondary quinone receptor QB were significantly reduced,it also deformed the rapid chlorophyll fluorescence induction kinetic curve(OJIP),and inhibited photosynthesis.Foliar sprays of proline at appropriate concentrations can effectively alleviate the decline in height,stem thickness and leaf chlorophyll content of celery under salt stress,promote root morphology and biomass accumulation,restore OJIP curve,and enhance photosynthesis.Compared with CK2,the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr)and photosynthetic performance index(PI_(ABS))of celery leaves treated with 0.3 mmol/L Pro were increased by 60.24%,31.90%,22.00%and 3.07%,respectively.The maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency Y(II)of photosystem II(PSII),photochemical quenching coefficient(qP),(ABS/CSm)per unit area and electron transfer yield per unit area ETo/CSm were increased by 1.37%,33.31%,17.52%,3.35%and 5.33%,respectively,while the thermal dissipation DIo/CSm per unit area and the energy dissipated DIo/RC per unit reaction center decreased by 5.41%and 16.40%,respectively.[Conclusion]Exogenous proline promotes the growth,root morphology,biomass accumulation and chlorophyll content of celery under salt stress,reduces the excess excitation energy of PSII in celery leaves through heat dissipation,reduces the excitation pressure of reaction centers,promotes the performance of PSII,and enhances the activity of PSII reaction centers and photosynthesis per unit cross-section,thus alleviating the growth of celery under salt stress.Among the treatments,0.3 mmol/L proline has the best optimal effect.