摘要
为探讨低温下白菜型冬油菜叶绿素荧光特性及其抗寒性关系,在大田条件下,以白菜型冬油菜陇油7号、陇油8号和天油4号为试材,测定在冬前自然降温过程中冬油菜幼苗叶片叶绿素荧光特性指标.结果表明:随着气温由10月7日(6.7℃)降低到11月25日(-8.3℃)时,3个白菜型冬油菜品种叶片的初始荧光量(Fo)呈上升趋势,且Fo表现为陇油8号>陇油7号>天油4号,叶片最大荧光(Fm)、PSⅡ的电子传递(Fm/Fo)、可变荧光产量(Fv)、最大光化学效率(Fv/Fm)、PSII受体库的大小(Area)均呈下降趋势,且Fm、Fm/Fo和Fv表现为天油4号>陇油8号>陇油7号;Fv/Fm和Area表现为天油4号>陇油7号>陇油8号.放氧复合体活性状态(Fo-k)、QA被还原能力(Fk-j)、QB(含快还原PQ库)被还原能力(Fj-i)和QB(慢还原PQ库)被还原的能力(Fi-p)呈下降趋势,且Fo-k,Fk-j和Fi-p表现为陇油8号>天油4号>陇油7号,Fj-i表现为天油4号>陇油8号>陇油7号.单位反应中心吸收光能(ABS/RC)、反应中心关闭程度(Vj)呈升高趋势,且ABS/RC表现为陇油7号>天油4号>陇油8号,Vj表现为陇油8号>陇油7号>天油4号;PSⅡ潜在光化学活性(Fv/Fo)和光合性能指数(PI)呈下降趋势,且Fv/Fo表现为陇油8号>天油4号>陇油7号;PI表现为天油4号>陇油8号>陇油7号.采用典型相关分析表明:Fo与ABS/RC和Vj呈极显著正相关,Fo与Fm、Fm/Fo、Fv、Fv/Fm、Area、Fo-k、Fk-j、Fj-i、Fi-p、Fv/Fo、PI呈极显著负相关.经隶属函数法综合评价3个白菜型冬油菜品种耐寒性强弱为陇油8号>陇油7号>天油4号,此研究结果为寒旱区冬油菜抗寒种质创新提供试验依据.
Abstract
This study investigates the relationship between chlorophyll fluorescence characteristics and cold resistance in winter turnip rape(Brassica rapa L.)at low temperatures.Under field conditions,winter rapeseed varieties Longyou 7,Longyou 8,and Tianyou 4 were selected to determine the chlorophyll fluorescence characteristics of winter rapeseed seedlings during the natural cooling process before winter.The results showed that as the temperature decreased from October 7(6.7℃)to November 25(-8.3℃),the initial fluorescence content(Fo)of the leaves of the three winter turnip rape varieties exhibited an increasing trend,with the order being Fo for Longyou 8>Longyou 7>Tianyou 4.The maximum fluorescence(Fm),PSII electron transfer(Fm/Fo),variable fluorescence yield(Fv),maximum photochemical efficiency(Fv/Fm),and PSII receptor library size(Area)in the leaves of Tianyou 4 demonstrated a decreasing trend.The order for Fm,Fm/Fo,and Fv was Tianyou 4>Longyou 8>Longyou 7,while for Fv/Fm and Area,the order was Tianyou 4>Longyou 7>Longyou 8.Additionally,the activity state of the oxygen-re-leasing complex(Fo-k),the ability of QA to be reduced(Fk-j),the ability of QB(including fast reduction PQ library)to be re-duced(Fj-i),and the ability of QB(slow reduction PQ library)to be reduced(Fi-p)all showed a decreasing trend.The perfor-mance for Fo-k,Fk-j,and Fi-p was Longyou 8>Tianyou 4>Longyou 7,while Fj-i showed the order Tianyou 4>Longyou 8>Longyou 7.The light energy absorbed per unit reaction center(ABS/RC)and the closing degree of the reaction center(Vj)ex-hibited an increasing trend,with ABS/RC being Longyou 7>Tianyou 4>Longyou 8 and Vj being Longyou 8>Longyou 7>Tianyou 4.The potential photochemical activity(Fv/Fo)and photosynthetic performance index(PI)of PSII showed a decreasing trend,with Fv/Fo as Longyou 8>Tianyou 4>Longyou 7 and PI as Tianyou 4>Longyou 8>Longyou 7.Canonical correlation analysis indicated that Fo was positively correlated with ABS/RC and Vj,while it was significantly negatively correlated with Fm,Fm/Fo,Fv,Fv/Fm,Area,Fo-k,Fk-j,Fj-i,Fi-p,Fv/Fo,and PI.Based on a multivariate evaluation using membership function analysis,the order of cold tolerance was determined to be Longyou 8>Longyou 7>Tianyou 4.These results provide an experi-mental basis for the innovation of cold-resistant germplasm in winter turnip rape(B.rapa L.)in cold arid regions.
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