Effect of Osmotic Potential on Seed Germination and Biochemical Indices of different Christ's thorn (Ziziphus spina–christi) Populations

Seed is the most important sexual reproductive factor in plants that plays an important role in transmitting hereditary characteristics, plant distribution, and establishment in different regions. Seed germination as one of the most important and complex stages in the life cycle of plants is affected by genetic and environmental factors. Drought stress is one of the main barriers of crop plants and trees, production in many parts of the world, especially in arid and semi-arid regions such as Iran. The purpose of this study was to investigate the effect of drought stress on biochemical and seed germination indices of different seed lot of Ziziphus spina–christi as suitable medicinal species for controlling soil erosion in arid regions.

This experiment was conducted as a factorial based on a completely randomized design with four replications at the Seed Science and Technology Laboratory of Yasouj University in 2018. Experimental factors included Ziziphus spina–Christi seeds collected from the regions of Minab, Kazeroon, Masjed Soleiman, and Dehdasht and five water potentials including zero, -2, -4, -6, and -8 bar.

In the present study, the effect of osmotic potential, seed lot, and their interaction were significant in each seed lot on germination (germination percentage, germination rate, seedling length, allometric index, longitudinal vigor) and biochemical (hydrogen peroxide, soluble protein content, Proline, catalase, and ascorbate peroxidase) indices of Ziziphus spina–christi. The results showed that except for allometric index response of all studied germination traits to osmotic potential was decreasing, Also with increasing osmotic potential, seed soluble protein was decreased and the amount of proline and activity of catalase and ascorbate peroxidase increased. With increasing osmotic stress, the root length was significantly increased, which increased the allometric coefficient of the seedling.

Germination and biochemical indices of seeds of all seedlots had significant changes with the reduction of osmotic potential and the reduction of osmotic potential was associated with reduced germination and plant establishment capability. These results can help us to recognize the prerequisites of germination and the development of the forests.

1- Germination indices of seeds related to several Ziziphus spina–christi seed lots were investigated under different water potentials.2- Biochemical aspects related to seed dormancy in several Ziziphus spina–christi seed lots were evaluated.