نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده علوم زراعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران
2 استاد، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده علوم زراعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران
3 دانشیار پژوهش، مؤسسه تحقیقات برنج کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، رشت، ایران
4 دانشیار، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده علوم زراعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
In recent years, the decline in precipitation and water resources has emerged as a major constraint to rice production. Drought is one of the most widespread abiotic stresses, posing a significant threat to vast areas of rice cultivation. Rice yield can be adversely affected by drought at any growth stage; however, the reproductive stage is particularly sensitive. Therefore, identifying drought-tolerant genotypes is a key strategy to mitigate the impact of water deficit. Several indices have been proposed to evaluate plant responses to stress and to assess yield stability under adverse conditions. Accordingly, this study utilized drought tolerance and susceptibility indices to evaluate different rice genotypes under drought stress and to identify drought-tolerant varieties based on grain yield and root biomass.
Materials and methods
This study was conducted in 2023 at the Rice Research Institute of Iran to evaluate 36 rice genotypes under two conditions: non-stress and drought stress. The experiment was arranged in a randomized complete block design (RCBD) with three replications. It was performed under a rainout shelter using controlled PVC pipes, each with a diameter of 20 cm and a length of 100 cm. The shelter was open-sided, ensuring that temperature and relative humidity did not differ significantly from ambient outdoor conditions. The pipes were filled with equal volumes and densities of soil, composed of one-third sand and two-thirds field soil. The required amount of chemical fertilizer was calculated based on soil test results and thoroughly mixed into the soil. After determining the field capacity (set at 91%) for the drought treatment pipes, seedlings with 3–4 leaves were transplanted individually. Drought stress was imposed at the maximum tillering and panicle initiation stage, while in the non-stress treatment, irrigation was continued regularly until maturity. When the soil moisture in the drought treatment reached 20%, grain yield and root biomass traits were measured and stress tolerance and sensitivity indices were calculated. Pearson correlation coefficients were computed using SPSS software. Cluster analysis and two-dimensional biplot diagrams based on grain yield were drawn by NTSYS 2.02 and XLSTAT 2019.2.2 software.
Research findings
The results indicated that the highest and lowest average grain yield in non-stress conditions belonged to Gohar and IR58 cultivars, respectively, and under drought stress conditions belonged to Mohamadi Chaparsar and Hassani cultivars. The lowest reduction in grain yield in stress conditions (49.57%) was attributed to the Mohamadi Chaparsar cultivar and the highest percentage increase in root biomass (63.45%) was related to the Hassani cultivar. The results of correlation coefficients showed that grain yield in non-stress conditions had a positive and significant correlation with the mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), tolerance index (TOL), and stress tolerance index (STI), respectively, and the highest correlation was observed with MP index (r=0.906). Also, under drought stress conditions, grain yield showed a high correlation with MP, GMP, HM, STI, yield index (YI), yield stability index (YSI), and relative drought index (RDI), the highest of which was related to yield index (r=1.00). Also, root biomass in non-stress conditions was highly significantly and positively correlated with the indices MP, GMP, HM, YI, STI, TOL, Stress susceptibility index (SSI) and average root biomass under stress (Ys), respectively, and the highest correlation was observed with MP index (r=0.903). Under drought stress conditions, the indices MP, GMP, HM, YI, YSI, RDI and STI showed a high correlation with root biomass, and the highest correlation was related to yield index (r=1.00). Cluster analysis based on drought tolerance indices for grain yield separated rice genotypes into four groups. Cultivars in the second group (Group A) including Mohamadi Chaparsar, Gharib Siah Reihani, Hashemi, Dular, Kian, Anam, along with ten genotypes from the first group including Alikazemi, Nemat, Sahel, Danial, Gilaneh, Domzard, Dorfak, Gohar, Neda and Toka, were identified as drought-tolerant genotypes. Twelve drought-tolerant genotypes were identified for grain yield using the biplot method based on the Yn, STI, HM, GMP, and MP indices.
Conclusion
Based on the evaluation of drought tolerance and susceptibility indices and their correlation with grain yield and root biomass under both stress and nonstress conditions, the indices MP, GMP, HM, STI, and RDI were identified as the most effective indicators. The results obtained from comparing cluster analysis, biplot and correlation coefficients indicated that the genotypes Daniyal, Gohar, Nemat, Gilaneh, Dorfak, Dular, Domzard, Salari, Toka and Mohamadi Chaparsar were high-yielding cultivars with high root biomass and drought-tolerant, while the genotypes Ahlami Tarom, Binam, Sang Jo, Hasan Sarayi Atashgah, Kados, Rash, IR28, IR50 and IR64 were low-yielding cultivars with low root biomass and drought-sensitive cultivars.
کلیدواژه‌ها [English]
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