火龙果不同月龄枝条的叶绿体超微结构及叶绿素荧光特性

为揭示发育过程中火龙果枝条光合特性变化的生理机制,给火龙果的高效栽培提供参考依据,研究了不同月龄火龙果枝条的叶绿体超微结构、叶绿素荧光参数及光合色素含量。分别采集1月龄(S1)、2.5月龄(S2)、3.5月龄(S3)、11月龄(S4)的火龙果枝条,测定枝条外观形态及其正背面的叶绿体超微结构、叶绿素荧光参数及光合色素含量等指标。结果表明,S1—S4月龄火龙果枝条的正面、背面均具有完整的叶绿体结构,随月龄增加,叶绿体中的淀粉逐渐增多。S3月龄火龙果枝条的实际光化学效率、光化学猝灭系数均达到峰值。S4月龄枝条的最大光化学效率、非光化学猝灭系数均明显降低。综上所述,S1—S3月龄火龙果枝条的光合机构发育成熟,光合能力增强,为枝条后期营养物质的快速积累提供了条件,之后枝条肉质厚度增加,使枝条由营养生长向生殖生长转化,进入结果期;S4月龄枝条光合能力减弱,易发生光抑制。

Chloroplast ultrastructure and chlorophyll fluorescence characteristics of different months old branches in Hylocereus undulatus

In order to learn physiological mechanism of changes of photosynthetic characteristics in Hylocereus undulatus branches during development, and to provide some references for highly effective cultivation of H. undulatus, we researched chloroplast ultrastructure, chlorophyll fluorescence parameters and photosynthetic pigment contents in different month-old branches in H. undulatus. In this study, we collected H. undulatus branches at different months old as materials, including 1-month-old (S1), 2.5-month-old (S2), 3.5-month-old (S3) and 11-month-old (S4), and measured appearance shape indexes and some other indexes reflecting differences between upper epidermis and lower epidermis of branches, including chloroplast ultrastructure, chlorophyll fluorescence parameters, photosynthetic pigment content, and so on. The results showed that complete chloroplasts existed in both upper epidermis and lower epidermis of H. undulatus branches at S1-S4 months old. Starch content was significantly increased in chloroplast as age increasing. Actual photochemical efficiency and photochemical quenching coefficient in S3 branch reached obvious peak values. The maximum photochemical efficiency and no-photochemical quenching efficiency in S4 branch were obviously decreased. In summary, photosynthetic apparatus in H. undulatus branches were established from S1 to S3, and photosynthetic capacity was enhanced, which provided materials for rapid accumulation of nutrients in branches at late stage. After that, branches were thicken, and transferred from vegetative growth to reproductive growth. Photosynthetic abilities of S4 branches were significantly decreased, and photoinhibition was easy to occur.