JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2020, Vol. 44 ›› Issue (3): 81-88.doi: 10.3969/j.issn.1000-2006.201903004

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Photosynthetic characteristics of grafted plants of different Carya illinoinensis varieties

TANG Wenhua1(), DOU Quanqin2(), PAN Pingping1, JI Yanhong1, XIE Yinfeng1()   

  1. 1.Co -Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
    2.Jiangsu Academy of Forestry, Nanjing 210014, China
  • Received:2019-03-01 Revised:2019-08-26 Online:2020-05-30 Published:2020-06-11
  • Contact: DOU Quanqin,XIE Yinfeng E-mail:1481971986@qq.com;douqq2008@163.com;xxyyff@njfu.edu.cn

Abstract: Objective

To provide scientific basis for the selection and popularization of Carya illinoinensis varieties, an experiment was conducted to investigate the photosynthetic characteristics of six C. illinoinensis varieties, including ‘Forket’, ‘Western’, ‘Cape Fear’, ‘Moore’, ‘Sioux’ and ‘Apache’.

Method

The Li-6400 portable photosynthetic system and other equipment were used in the study. The photosynthetic physiological characteristics of the six varieties including diurnal variation of photosynthesis, light response curves, and chlorophyll fluorescence parameters were analyzed. The gas exchange and fluorescence parameters were analyzed together so that the photosynthetic physiological characteristics of the six varieties could be more comprehensively understood and identified. While analyzing the diurnal variation of photosynthesis, the reasons for midday depression in photosynthesis were investigated. The extent of the influence of physiological and ecological factors on the net photosynthetic rate (Pn) was explored by grey relational analysis. Through grey relational analysis, the main factors that affected the Pn could be clearly found and understood, based on which accurate and appropriate measures could be taken to change certain factors to improve the photosynthetic capacity of the varieties. Correlation analysis was also used to analyze the light response and chlorophyll fluorescence parameters. The light response parameters were able to reflect the photosynthetic capacity of plants under ideal conditions in some ways and chlorophyll fluorescence parameters could reflect the photosynthetic potential of plants, and hence, they were recognized as molecular probes for photosynthetic analysis. The results of the correlation analysis could be used to understand the correlation between the fluorescence and light response parameters and to explore the internal cause of high light efficiency of the varieties from the perspective of photosynthetic mechanism.

Result

The diurnal variation of photosynthesis of ‘Moore’ was unimodal and the diurnal variation of the other five varieties was imodal. Limitation of non-stomatal factors was considered as the main reason for midday depression in photosynthesis in ‘Moore’. The peak values and average values of the Pn of ‘Western’ were significantly higher than those of the other five varieties. Through grey relational analysis, it was found that the diurnal variation of the Pn and grey relational analysis was different for different varieties. The varieties with poor diurnal variation in the Pn were more susceptible to physiological and ecological factors. The main physiological factors that affected the Pn of the six varieties were stomatal conductance (Gs) and transpiration rate (Tr), and the environmental factor that affected the Pn of the six varieties was atmospheric temperature (Ta). The results of the analysis of light response parameters revealed that the maximum net photosynthetic rate (Pn, max) and light saturation point (Lsp) of ‘Western’ were significantly higher than those of the other varieties, which meant that its adaptability to strong light was the best, followed by ‘Forket’. The light compensation point (Lcp) of ‘Forket’ was significantly lower than that of the other varieties, followed by ‘Western’. The results of the analysis of chlorophyll fluorescence parameters revealed that the apparent quantum efficiency (AQY) and dark respiration rate (Rd) of ‘Western’ and ‘Forket’ were better than those of others, which meant that they were more adaptable to weak light. The PSⅡ maximum photochemical quantum yield (Fv/Fm) and potential photochemical activity (Fv/F0) of ‘Western’ were the highest, followed by those of ‘Forket’. The Fv/Fm and Fv/F0 of ‘Moore’ were significantly lower than those of the other varieties. The correlation analysis showed that there was a significant correlation between the fluorescence parameters and characteristic parameters of the light response curve. The Fv/Fm and Fv/F0 were positively correlated with Pn,max, which reflected the photosynthetic efficiency of the varieties.

Conclusion

The photosynthetic characteristics of six different varieties of C. illinoinensis were quite different. According to the results of this study, the photosynthetic characteristics of ‘Western’ were recognized as the best of all with the characteristics of ‘Forket’ being slightly inferior to those of ‘Western’. The characteristics of the other four varieties were average compared to those of ‘Western’ and ‘Forket’. It was clear that ‘Western’ and ‘Forket’ have a wide range of light adaptations and high photosynthetic efficiency and thus have a great potential for popularization and utilization.

Key words: Carya illinoinensis, diurnal variations of photosynthesis, light response curves, chlorophyll fluorescence

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