Allelopathic Potential of Rice Residues of Selected Rice Varieties (Oryza sativa L.) Against Echinochloa crus-galli

Abstract

Allelopathic compounds will play a vital role in sustainable weed control in paddy cultivationin future. Exploitation and implementation of this technology in weed management has beenconsidered as ecologically sound, resource conserving and economically viable method. Theobjective of this study was to asses the allelopathic traits of rice residues of selected (BG359,LD365, BG407, AT401, BG358, AT362, AT402, BG450, BG300, Herathbanda andHandiran) rice cultivars to control of barnyard grass (Echinochloa crus-galli) one of the mostdestructive weed in Sri Lankan paddy ecosystem. Completely Randomize Design was usedwith three replicates for each cultivar. According to the research findings, significantdifferences (p≤0.05) were observed among cultivars and amount of residue mixed with sand(2.0, 4.0, 6.0 g of ground residue per 500.0 g of sand) in terms of barnyard grass plant height,number of leaves, germination and total dry weight. Among those measured variablesgermination and dry matter of barnyard grass showed significant reduction when increasingamount of rice residue. Among different cultivars used LD365 showed the highest inhibition% for all above measured variables and the lowest was the Herathbanda. As an example theinhibition percentages of plant height, seed germination and shoot dry weight of LD365 were60%, 56% and 65% respectively. In contrast, rice cultivar Herathbanda caused 27%, 26% and26% inhibition respectively for above mentioned parameters. When comparing three levelsof rice residue mixture 63% dry weight reduction was observed in 6.0 g rice residue and(51%) 4.0 g and 27% with 2.0 g mixture. Furthermore percentage germination also reducedwith increased amount of rice residue mixture. It indicated that highest in 6.0g, which is 49%closely followed by 4.0 g (41%) and the lowest is 2.0 g by 12%. Therefore, it could besuggested that the allelopathic potential of rice residue significantly changes with cultivar andamount of residue mix with soil. Knowledge of rice allelophathic properties of rice residuewill offer several possibilities for ecological management of weeds in paddy fields of SriLanka.