The Effects of Seed Priming on Germination and Physiological Response of Hot Pepper (Capsicum annuum) under Drought Stress Conditions

抄録

Drought stress is a major production constraint for fruits and vegetable crops not only in arid and semi-arid regions but also all over the arable lands. This study was conducted to investigate the effects of seed priming on the total germination percentage and physiological responses of hot pepper under drought stress. Polyethylene glycol (PEG 6000) was used as a priming agent with 5 concentrations (-0, -0.4, -0.8, -1.2 and -1.6 MPa). The seeds were half soaked in each concentration solution for 48 hours at 25°C, while -0 MPa treatment seeds were soaked in distilled water for the same duration. The seeds were dried to the recommended moisture percentage. The germinated seeds were raised in a seed tray and transplanted in small plastic pots at the 3 to 4 leaf stage. The drought stress treatment was started ten days after transplanting with mild (daily watering), moderate (7 day-interval irrigation), and severe (9 day-interval irrigation) treatment. The results showed that the seed priming with higher concentrations of PEG (-1.2 MPa and -1.6 MPa) significantly increased germination percentage and enhanced drought tolerance of the seedlings than lower concentrations. Whereas, the seed priming with lower concentrations of PEG (-0, -0.4 and -0.8 MPa) under moderate and severe stress on the 3^rd week of experiment significantly reduced the photosynthetic rate, stomatal conductance and ethylene production. The present findings revealed that the seed priming of hot pepper seeds with higher concentrations of PEG might well alleviate drought stress disorders.