Evaluation of the Response of Four Species of Weeds and Some Rice Cultivars to Pathogenicity of Curvularia lunata and Alternaria pellucida

Abstract

Background and Objectives: Herbicides are essential inputs in agriculture that despite their many benefits in controlling weeds, can cause damages such as creation resistance to weeds, environmental effects and threats to human health. Therefore, to reduce consumption or reduce their concentration, alternative methods such as weed control using biological microorganisms have been proposed, which to achieve this goal, it is necessary to have a complete understanding of pathogen-host relationships. Achieving such understanding can be difficult and challenging, particularly for large data sets with complex host genotype-by-pathogen strain interactions. To evaluate the pathogenicity of fungi in plant species, in addition to conventional quantitative and descriptive evaluations, the host genotype-pathogen isolates biplot can be used in a single scatter plot. This study was conducted to evaluate the virulence of two funguses on five rice cultivars and four weeds. Materials and Methods: In this research, pathogenicity of Curvularia lunata and Alternaria pellucida were studied in two separate experiments on five rice cultivars (Hashemi, Alikazemi, Sepidroud, Khazar, Binam), Eichinochloa oryzicola, E. crus-galli, Sagitaria trifolia and Alisma plantago – aquatica in a completely randomized design with three replications in pot condition, in the greenhouse of Islamic Azad University, Rasht Branch, at 2018. Principal component analysis was performed on two-way data of host genotype -pathogen. The biplot was plotted with the first two principal axes (PC1 and PC2) using GGEBiplotGUI packages (Bernal & Villardon, 2016) in R software. Results: Analysis of variance was performed separately for weed species and rice cultivars. There were significant differences between rice cultivars in terms of reduction of plant height and fresh and dry weight of the plant in inoculation with C. lunata and in terms of reduction in plant height and dry weight of the plant in inoculation with A. pellucida. In addition, there was a significant difference between weed species in terms of disease rating, decrease in plant height and fresh weight of the plant in inoculation with C. lunata and in all four traits in terms of inoculation with A. pellucida. Comparison of means showed that Hashemi and Ali Kazemi cultivars had the highest disease rating, reduction of plant height and fresh and dry weight of the plant in treatment with C. lunata. Biplot analysis showed the relationships between fungi (as pathogens) and weed species and rice cultivars (as host genotypes) in a pathogen-host view in terms of traits. Average-Tester-Coordination (ATC) view (average of PC1 and PC2 scores for all genotypes) of biplot were indicated that A. plantago – aquatica and E. crus-galli were as the most sensitive and Sepidroud as tolerant genotypes to two fungi according to their disease rating. Based on disease rating, C. lunata can be used for biocontrol of A. plantago–aquatica and E. crus-galli in Ali Kazemi and Binam genotypes. Based on this trait, A. pellucida can be used for biocontrol of S. trifolia in Hashemi. According to dry weight, C. lunata can be used for biocontrol of Sagitaria trifolia in all of the genotypes. Conclusion: In conclusion, based on disease rating and reduction of plant height and dry and fresh weight of plants, C. lunata was a better antagonistic fungus in dealing with weeds compared to the other fungus especially for A. plantago–aquatica and this fungus could be a potential mycoherbicide for weeds control in paddy fields in the future.