پژوهشهای حبوبات ایران (Dec 2024)
Evaluation of the Tolerance of Promising Genotype of Bean (Phaseolus vulgaris Linnaeus) to Two-Spotted Mite (Tetranychus urticae Koch (Acari: Tetranychidae)) in Field Conditions
Abstract
IntroductionLegumes are one of the rich sources of plant protein after cereals and the second most important food source for humans. The most important biotic stresses that lead to reduced growth, performance, and sometimes the death of plants are pests, diseases, and weeds. The two-spotted spider mite, due to its extensive host range, rapid population growth, and ability to develop resistance to pesticides, is one of the key pests. Therefore, the use of tolerant varieties for damage control is considered as most reliable, healthy, and cost-effective method in an integrated management system. The feeding of this mite on bean (Phaseolus vulgaris Linnaeus) leaves leads to the formation of yellow spots on the leaf surface (Dorri et al., 2015). The activity of two-spotted spider mite Tetranychus urticae Koch, is mainly associated with webbing, which leads to the accumulation of dust, decreasing of the photosynthesis and increasing the pest damage (Hosseini, 2018). Therefore, due to the importance of this pest, this research was conducted to identify resistant genotypes of beans among promising bean genotypes. Materials and MethodsFor the experiments, Type 1 promising bean genotypes (KS-21216, KS-21181, KS-21538, KS-21565, KS-21563, KS-21602, KS-21500, KS-21601, KS-21600, and KS-21607), Type 2 genotypes (KS-21573, KS-21597 and KS-21606), and Type 3 genotypes (KS-21255 and KS-21574) along with a susceptible genotype Sadri were cultivated in a field at Khomein National Bean Research Station in a randomized complete block design with three replications during 2022-03. Sampling for damage assessment was carried out weekly from the third leaf stage until the end of the season. From each plot, 10 plants were selected randomly. Two leaves, one from the bottom and the other from the top of each plant, were selected and scored (on a scale of 1-6). To assess performance and its components, field cultivation was conducted under the specified conditions in two separate plots. One plot was treated with pesticide spraying, while the other remained untreated. Characteristics such as pod number per plant, seed number per pod, plant height, and weight of one hundred seeds were measured under both mite-infested and non-infested conditions. Based on the performance of the genotypes under T. urticae mite-infested and non-infested conditions, productivity indices, geometric mean productivity, stress tolerance, and stress sensitivity were calculated. Results and DiscussionThe yield and yield components of the genotypes under the presence and absence of T. urticae were evaluated. Genotype KS-21538 had the highest (2166.67 kg.ha-1) and the sensitive check had the lowest performance (995.17 kg.ha-1). The highest (16.24) and lowest (4.88) percentage of yield reduction were related to the sensitive check and genotype KS-21538, respectively. The highest and lowest number of pods per plant were observed in genotype KS-21538 and Sadri cultivar with 17.95 and 8.87 pods, respectively. The highest and lowest damage scores under unsprayed conditions were 3.06 and 4.56 in genotype KS-21538 and Sadri respectively. The results of calculating the indices showed that the highest efficiency index, average geometric efficiency index, and stress tolerance index were observed in genotypes KS-21538 and KS-21216, respectively, and the lowest observed in the Sadri and genotype KS-21607. The lowest stress sensitivity index was observed in genotypes KS-21538 and KS-21216, respectively, and the highest observed in Sadri and genotype KS-21607. Researchers examined how planting density and different bean varieties (Akhtar, Derakhshan, and 285) affect the population of two-spotted spider mites. They discovered that the pest density on the Akhtar variety is higher than on Derakhshan and 285. Due to the differences in the bean varieties studied in this research and the current study, the results do not show similarities. The results of this study also showed that pest density is significantly influenced by the bean variety (Karimi et al., 2019). In a study, it was revealed that the Derakhshan, Akhtar, and local Khomein (Sadri) varieties were sensitive to T. urticae, while Dorsa and Kousha varieties and lines 21191 and 31169 showed greater resistance to the two-spotted spider mite and also had acceptable yield compared to other varieties (Kazemi et al., 2019). In the present study, the Sadri variety was also identified as sensitive to damage by the two-spotted spider mite, which is consistent with these results. ConclusionsAccording to the results genotypes KS-21538 and KS-21216 are recommended as the first and second priority for cultivation in the region due to the higher yield, lower percentage of yield reduction, and the lower damage scale.
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