不同遮阴强度对猕猴桃“桂海4号”光合特性及果实品质的影响

Responses of Photosynthetic Characterization of Kiwifruit(Actinidia chinensis Planch cv.Guihaia 4) Submitted to Shading

关键词:  遮阴  光合作用  荧光  品质  猕猴桃

Key words:  shading  photosynthesis  Chl a fluorescence  quality  Kiwifruit

摘要:

以中华猕猴桃"桂海4号"(Actinidia chinensis Planch cv.Guihaia 4)为研究对象,采用LI-6400便携式光合测定系统测定不同程度(0,40%和60%)遮阴对其光合、荧光特性和果实品质的影响。结果表明,与全光照相比,40%和60%的遮阴强度显著降低了猕猴桃的光饱和速率(A_max)、表观量子效率(AQY)、光饱和点(LSP)、光补偿点(LCP)和暗呼吸速率(R_d)(P<0.05),对其水分利用效率(WUE)和叶绿素含量(Chl content)均无显著影响(P>0.05),但是潜在水分利用效率(WUE_i)随着遮阴强度的增加而增加。猕猴桃的初始荧光(F_o)、可变荧光(F_v)、最大荧光(F_m)和PS最大光能转换效率(F_v/F_m)在全光照和不同遮阴处理间无显著差异(P>0.05),表明一定程度的遮阴对其F_o、F_v、F_m、F_v/F_m无明显影响,但是与全光照相比,40%的遮阴强度显著降低了PS光能捕获效率(F'_v/F'_m)、PS电子传递量子效率(PhiPS2)和光化学猝灭系数(qP),而60%遮阴强度其F'_v/F'_m、PhiPS2和qP与全光照下的无显著差异(P>0.05)。全光照和遮阴条件下猕猴桃光合和荧光参数相关关系存在明显差异,表明猕猴桃"桂海4号"随着环境条件中光照的改变其光合器官进行了一定的调整,使其适应变化了的环境条件。遮阴对猕猴桃"桂海4号"的果实外观无显著影响,但是却显著影响了其果实品质,40%遮阴强度显著降低其维C含量、总糖、可溶性固体物和酸含量。

Abstract:

Shading is good or not for the plant performance under field environmental conditions, especially for some economic crops and fruit that distribute a large area in the world.To characterize the role of shading on the modulate of the physiology of plant, three levels of shading (full sunlight (0, 40%, 60% of solar radiation interception) on the photosynthesis and Chl a fluorescence were studied in Kiwifruit (Actinidia chinensis Planch cv.Guihaia 4).The results showed full sunlight treatment resulted in higher A_max, AQY, LSP, LCP and R_d than that of the 40% and 60% shading, while there was no difference between the latter two shading treatments.WUE and Chl content were not affected by the light regime.Pronounced changes for Chl a fluorescence parameters were only found in F'_v/F'_m, PhiPS2 and qP, under full sunlight and 40% shading, and F_o, F_v, F_m, F_v/F_m did not differ significantly among all the light regimes.Full sunlight resulted in higher qP than 40% shading, while there was no significant difference compared with 60% shading.In conclusion, Kiwifruit under shading did not affect the maximum intrinsic efficiency of photo-system 2 (PS2) (F_v/F_m) in these species, suggesting shading had no effect on photosynthesis by inactivation of PS2 reaction centers.A_max, φ, LSP, LCP, and R_d were reduced when submitted to shading, while there was no difference between the two shading levels, indicating that the Kiwifruit photosynthetic apparatus was prepared to cope with increasing shading levels.Shading did not have large influence on the fruit external appearance, while dramatically affect the fruit quality, as the fruit weight and size were nearly the same (P>0.05), but the content of Vitamin C, total sugar content (Reducing sugar and sucrose), soluble solids and the content of acid differed significantly between full sunlight and different shading levels.