Natural and Induced Glufosinate-resistance in selected Rice (Oryza sativa L.) Varieties in Sri Lanka

Purpose: Herbicide-resistant rice varieties in combination with post-emergent broad-spectrum herbicides improve the effectiveness of weed management in rice fields. Herbicide-resistance can be acquired naturally or induced by classical or modern breeding techniques. In the present study, screening of Sri Lankan rice varieties to glufosinate was examined and attempts were made to develop glufosinate-resistant rice varieties with the help of the breeding technique, mutagenesis. Research Method: Natural glufosinate-resistance was studied in seven (7) traditional and eighteen (18) inbred rice varieties under 0.27, 0.30 and 0.33 kg ha -1 glufosinate concentrations. Induced glufosinate-resistance in seed-derived calli of four glufosinate-susceptible rice varieties using Ethyl Methane Sulfonate was also observed and these were then treated with 0.2% (v/v) glufosinateto to determine induced glufosinate-resistance in seed-derived calli. Findings: Two traditional varieties (Pachchaperumal, Ma Wee) and fifteen inbred varieties (At362, Bg250, Bg300, Bg352, Bg357, Bg358, Bg359, Bg360, Bg366, Bg369, Bg379/2, Bg403, Bg450, Bg454, and Bg94-1) were resistant to glufosinate. Hardly any distinct yield penalty in Bg94-1, Bg403, Bg454, Bg379-2 and Ma Wee was observed under all glufosinate concentrations. Visual symptoms and chlorophyll damages caused by glufosinate for all varieties recovered within 14 days of treatment. Higher glufosinate-resistance was observed in EMS-mutated calli derived from seeds of naturally glufosinate-susceptible varieties. Molecular (AFLP) analysis confirmed in vitromutation and theM31E10 primer combination was a potential AFLP marker to identify glufosinate-resistance in rice varieties. Research Limitation: The study reports the results of screening natural and induced glufosinate-resistance in Sri Lankan rice. Inheritance of glufosinate-resistance is to be tested through several generations in Sri Lankan rice varieties. Original Value: Study provides a screening method applicable to Sri Lankan Rice varieties in identification of herbicide-resistance to permitted concentrations of glufosinate.