Physiological Assessment of Radiation and PVP/ Zn-Nanoparticles on Sour Orange Seedling

Aims: The objective of this study is evaluate the effects of both pre-sowing gamma irradiation at low dose of 0 or 20 Gy and the soaking part of radiated seeds in zinc nanoparticles (Zn NPs) solutions at rate 0, 500, 1000 and 2000 ppm on behavior and physiological changes of sour orange seedling.

Study Design: The design of the study is Two-Way Randomized Blocks.

Place and Duration of Study: The present study was carried out during two successive seasons of 2016-2017 and 2017-2018 on sour orange rootstock (Citrus aurantium) grown at the experimental farm of the Horticulture Institute, Giza , Egypt.

Methodology: Eight different treatments were used as follow: 1) Control, 2) Gamma radiation at 0 Gy + soaking in Zn NPs at 500 ppm. 3) Gamma radiation at 0 Gy + soaking in Zn NPs at 1000 ppm. 4) Gamma radiation at 0 Gy + soaking in Zn NPs at 2000 ppm. 5) Gamma radiation at 20 Gy + soaking in tap water Zn NPs at 0 ppm. 6) Gamma radiation at 20 Gy + soaking in Zn NPs at 500 ppm. 7) Gamma radiation at 20 Gy + soaking in Zn NPs at 1000 ppm. 8) Gamma radiation at 20 Gy + soaking in Zn NPs at 2000 ppm.

Results: Transmission electron microscope (TEM) images showed multiple shapes and uniform distribution of Zn NPs through the polymer network and the mean size of Zn NPs ranging is 40.9 nm. Generally, the results reveal that, 20 Gy combined with 1000ppm Zn NPs treatment increased seed germination percentage and stem length. While, 20 Gy plus 500 ppm Zn NPs treatment increased stem diameter and plant pigments concentration. Protein analysis of sour orange seedling treated with gamma radiation and then Zn NPs showed that, protein groups pattern (10-20 KD) enhanced with gamma rays 20 gray alone or with Zn NPs at 500 or 1000 ppm, while the protein groups pattern above 60 KD disappeared.

Conclusion: Using gamma irradiation and then soaking part of irradiated seeds in Zn NPs solutions had significant effects on vegetative growth and root characters as well as some chemical properties of sour orange leaves. In addition, there are variable differences in the protein pattern between treated and untreated sour orange seedlings with gamma radiation and / or Zn NPs. Although, 20 Gy + 500 ppm Zn NPs treatment increased stem diameter, which is the main characteristic for the success of grafting process, the obtained results showed changes in proteins and it possible the gene structure had been changed due to this treatment.