Ameliorative effects of some priming treatments on germination and emergence of lettuce seeds under high temperature conditions

Abstract

The maximum temperature range for lettuce (Lactuca sativa L.) germination is 25 to 30°C. Temperatures above this optimum range inhibit germination of imbibed lettuce seed and causes non-uniform stand establishment. One of the effective methods to overcome this thermoinhibition is seed priming. The effects of incorporating prohexadione-calcium (Pro-Ca) into priming solutions on germination and emergence performances of lettuce seeds ('Carioca') at 20, 30, and 35°C were investigated. Priming was accomplished by imbibing lettuce seeds for 20 h at 15°C in darkness in solutions of KNO3 or KH2PO4, each at -1.50 MPa, containing 0, 50, 100, or 150 mg L-1 Pro-Ca. Priming treatments reduced thermodormancy and increased seed germination by up to 90% and emergence by more than 300% compared to control. The results indicated that inclusion of Pro-Ca into the priming solutions can be used as an effective method to overcome thermoinhibition and improve germination and emergence performances of lettuce seeds at high temperatures. © 2020 International Society for Horticultural Science. All rights reserved.