Allelopathic Effects of Locally Cultivated Rice Varieties on Growth and Germination of Lettuce (Lactuca sativa L.) Using Sandwich and Seed Relay Assays

Abstract

This study aimed to evaluate the allelopathic potential of locally cultivated rice varieties in Isabela province, focusing on their effects on the germination and growth of lettuce (Lactuca sativa L.). The research employed two bioassay methods: the sandwich method, where crushed rice seeds were layered between agar with lettuce seeds, and the relay seeding method, which involved germinating rice seeds in petri dishes before co-culturing them with lettuce seeds. Using a Completely Randomized Design with five replications across eleven treatments, data on germination percentage, root length, shoot length, and dry weight were collected and analyzed. The results indicated significant allelopathic potential. The sandwich method revealed a notable decrease in lettuce germination, while the relay seeding method exhibited higher germination rates. The findings demonstrated that different rice varieties possess varying degrees of allelopathic potential, with NSIC Rc210H showing the most significant inhibitory effects on lettuce germination and growth.