Peg- Induced Drought Stress Effects on Spinach Germination Parameters

Abstract

Exposure to the drought stress reduces germination rate and seedling's growth with significant variations from crop to crop. An unavoidable consequence of drought exposure is the generation of reactive oxygen species. They can be extremely reactive with several cellular constituents such as proteins, lipids, and nucleic acids. Spinach (Spinacia oleracea L.) is one of the most consumed vegetable species, rich in vitamins, such as vitamin C, and minerals, which are essential for human health. Besides, spinach contains large amounts of bioactive molecules such as glucuronic acid derivatives of flavonoids and p-coumaric acid derivatives that exhibit strong antioxidant activity Osmotic solutions of polyethylene glycol (PEG) are commonly used to control water potential in seed germination studies. PEG reduces the water potential of osmotic solutions but may limit oxygen availability to germinating seeds. The purpose of this study was to determine whether seed immersion in PEG solution had a detrimental effect on total Germination percentage, Relativized percentage, Mean germination time, Mean germination rate, Coefficient of variation of germination time, Coefficient of the velocity of germination, Germination index, Uncertainty of germination process, Synchronization index, Time to 10% germination, Time to 25% germination, Time to 50% germination, Time to 75% germination, Time to 90% germination, Time from 10 to 90% germination, Time from 25 to 75% germination, Mean daily germination Percent, Peak value for germination, Germination value. A controlled experiment was conducted to investigate the effects of drought stress, induced by PEG, on these germination parameters in Spinach. For control, seeds were treated with nutrient solution, and 2.5% PEG was used to induce drought stress. The seeds were germinated geotropically between moisten filter papers. Each roll contained 30 seeds. Overall germination parameters showed a decrease as compared to control. The germination percentage of control seeds of Spinach oleracea L. was 79% while those treated with PEG were only 63%. Similarly, the relativized percentage decrease was observed in the case of PEG-treated seeds. Relativized percentage of control seeds was 91% as treated seeds were only 73%. Both showed a significant decrease as compared to the control.