Welcome to visit Scientia Silvae Sinicae，Today is

Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (7): 84-90.doi: 10.11707/j.1001-7488.20150709

Previous Articles     Next Articles

Effect of Plant Growth-Promoting Rhizobacteria on Photosynthetic Characteristics in Walnut Seedlings under Drought Stress

Liu Fangchun1, Ma Hailin1, Ma Bingyao1, Du Zhenyu1, Jing Dawei2, Xing Shangjun1   

  1. 1. Shandong Academy of Forestry Shandong Engineering Research Center for Ecological Restoration of Forest Vegetation Shandong Walnut Engineering Technology Research Center Jinan 250014;
    2. Dezhou University Dezhou 253023
  • Received:2014-01-05 Revised:2014-09-09 Online:2015-07-25 Published:2015-08-14

PDF (PC)

645

Abstract:

[Objective] Plant growth-promoting rhizobacteria (PGPR) are rhizosphere inhabitants that can promote plant growth and suppress diseases. The study of PGPR effect on photosynthetic characteristics will provide scientific basis for application potential under drought stress and technical support for afforestation and vegetation ecological restoration in arid environments. [Method] A pot experiment was conducted in order to evaluate the effects of PGPR on the photosynthetic characteristics under drought conditions. A dominant species of PGPR with the ability to produce cytokinins, namely Bacillus cereus L90, was selected to use in this study. Walnut (Juglans regia) seedlings were inoculated with B. cereus L90 and then subjected to moderate soil drought stress. The net photosynthesis rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci) and chlorophyll (Chl) content of the walnut seedlings were measured with a LI- 6400 portable photosynthesis system and a portable chlorophyll meter. [Result] The results indicated that drought stress and B. cereus L90 inoculation had significant effects on the Pn, Gs, Ci and Chl content of walnut leaves. Compared with the control, the Pn and Gs under drought stress (DS) were significantly decreased by 21.78% and 29.47%. However, the decreases with inoculation of B. cereus L90 were only 11.62% and 23.84%, respectively. Therefore, B. cereus L90 inoculation was able to relieve negative effects of DS on Gs and Pn. The relieving effect of B. cereus L90 inoculation on DS increased along with the prolonged period of stress after the initial stage of drought. The Ci of walnut leaves in DR treatments decreased significantly at the initial stage, and then continuously elevated, whereas the Gs continuously declined. The result suggested that the reductions in net photosynthetic rate resulted from both stomatal and non-stomatal limitations. In B. cereus L90 treatment, Ci and Gs decreased continuously, indicating that the Pn reductions mainly resulted from stomatal limitations. The Chl contents of leaves decreased with drought stress. In the late period of drought stress, the chlorophyll content of walnut seedlings in DR treatment significantly decreased 9.22%, compared with the control. However, the chlorophyll content with inoculation of B. cereus L90 was 9.49% higher than that of the DS. B. cereus L90 inoculation could significantly decrease the decomposition of chlorophyll content under drought stress. In re-watering after DS, the Pn, Gs and Chl content were still lower than the control, by 9.46%, 10.29% and 5.86%, and the Ci was higher than the control by 8.72%. However, re-watering the drought-stressed seedlings inoculated with B. subtilis increased Pn, Gs and Chl contents to the control’s level, and the contents were higher than the DR seedlings by 7.01%, 12.15%, 5.81%, respectively. The photosynthetic ability of B. cereus L90 inoculated seedlings was more easily recovered to the level of control after re-watering.[Conclusion] The present study demonstrated that Pn, Gs and Chl content of walnut leaves significantly decreased due to water stress. Cytokinin-producing, B. cereus L90 inoculation under drought conditions could alleviate non-stomatal limitations and interfere with the suppression of net photosynthetic rate. Additionally, L90 is conductive to the photosynthetic ability recovery of walnut leaves after re-watering.

Key words: drought stress, plant growth-promoting rhizobacteria(PGPR), Bacillus cereus, walnut seedlings, photosynthesis

CLC Number: