نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشآموخته کارشناسی ارشد، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده تولید گیاهی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
2 دانشیار، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده تولید گیاهی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
3 دانشآموخته دکتری، گروه اصلاح نباتات و بیوتکنولوژی، دانشکده تولید گیاهی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
The water deficit is one of the most important problems in rice cultivation, particularly when the decrease in rainfall and dry season affects its vegetative growth and grain yield. Drought stress is known as one of the most effective factors of yield reduction in crops. Identifying and introducing tolerant genotypes is a good way to cope incompatible environmental conditions. For easier evaluation of genotypes under drought conditions and identification of drought tolerant genotypes, various indices have been suggested as criteria for selection of genotypes based on their yield under stress and non-stress conditions. The present study was conducted to evaluate some rice genotypes under drought stress conditions as well as to introduce drought tolerant genotypes using important tolerance and sensitivity stress indices.
Materials and methods
This experiment was conducted in split plots based on randomized complete block design with three replications in Azadshahr, Golestan province, Iran. The main factor included two irrigation levels (drought stress and flooding as control) and the sub-factor included eight rice varieties. The experimental plots were three m2 with a distance of one m from each other. After randomly assigning the treatments to the experimental units, transplanting was done as four plants per pile. Each genotype was cultivated in six two-meter rows with a distance of 25 × 25 cm. Irrigation of the experimental field under both stress and non-stress conditions until the tillering stage of the genotypes was conducted as flooding. Then, under stressful conditions, irrigation was carried out from 40 days after transplanting (maximum tillering stage) until the end of the cropping season at an interval of 25 days, which according to the climatic conditions of the studied region, irrigation was done only once in stressful conditions. From the six rows planted in each plot, one row from around each plot was removed as border and the second to fourth rows were selected for sampling. After measuring traits and calculating different indices, the data were analyzed by SAS software. Two-dimensional biplot diagram was also drawn by STATGRAPHIC software.
Research findings
The results of analysis of variance showed a significant difference between the genotypes for all studied traits under both drought stress and flooded (control) conditions. Comparison of means showed that the highest average grain yield under both control and stress conditions belonged to Fajr, IRAT216, Sang-Jo, and Sang-Tarom Gerdeh genotypes, and the lowest grain yield belonged to the Sepidrood variety. The results of the correlation coefficients showed that grain yield in control conditions had a positive and significant correlation with mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HARM), and drought tolerance (TOL) indices, respectively, and the highest correlation was observed between grain yield and MP index (r = 0.918). Also, under drought stress conditions, grain yield showed a high correlation with the harmonic mean (HARM), geometric mean productivity (GMP) and mean productivity (MP) indices, the highest of which was related to harmonic mean index (r = 0.933). The results of principal component analysis showed that 94.31% of the total variation between data was justified by the first and second principal components. Cluster analysis based on drought stress indices separated rice genotypes into three groups, and the genotypes in the first cluster had the highest drought tolerance.
Conclusion
The results of biplot analysis and correlation between stress indices indicated that GMP, MP, and HM indices were the best indices for selecting high-yielding genotypes under both stress and non-stress conditions in this experiment. Based on these indices and biplot diagram, Fajr, Sang-Tarom Gerdeh, Sang-Jo, and IRAT216 genotypes were identified as high-yielding and drought-tolerant genotypes, and Sepidrood and Gharib Siah Reyhani varieties as low yielding and drought sensitive genotypes.
کلیدواژهها [English]