Estimation of Variability and Correlation of Various Seed Vigour Traits in Rice (Oryza sativa L.) under In Vitro PEG-Induced Moisture Stress Condition

Author: Jyotirmayee Mishra, P. Sanghamitra, Devraj Lenka, Sharat Kumar Pradhan, Simanta Mohanty, Kailash Chandra Samal, Rajkumari Bhol, Iswar Chandra Mohanty and Subrat Kumar Mahapatra

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Abstract

Rice, which is regarded as a primary diet by half of the global population, is particularly susceptible to a variety of abiotic stresses. Drought is one of the most formidable challenges, owing to its detrimental effects on yield. Rice, a drought-sensitive cereal, demonstrates notable varietal variability in its drought tolerance, particularly during the germination and seedling stages. The assessment of drought tolerance in field conditions is a time-consuming and labour-intensive procedure. Consequently, an alternative approach involves the use of polyethylene glycol (PEG-6000) as an artificial inducer of drought stress, which enables the analysis of a diverse range of rice genotypes. The present study mainly examined the variability and correlation of various seed vigour-related physiological traits in 30 rice genotypes, specifically in response to moisture stress induced by 20% (w/v) solutions of polyethylene glycol (PEG)-6000 (osmotic potential of -0.49 Mpa). The results indicated that most rice genotypes exhibited a noticeable decrease in germination and seed vigour-related physiological parameters under moisture stress (MS) condition compared to the control (distilled water; 0 MPa). Among all the genotypes tested under MS condition, Karinellu was identified as the genotype with the highest germination potential (71.33%), while Magura exhibited the maximum seed vigour index I and II (774.17, 2.524). This study revealed significant genotypic variability among the seed vigour-related traits studied under MS condition, with the highest heritability exhibited by shoot length (99.8%), seedling length (99.6%), root length (99.3%), seed vigour index I (99.2%), seed vigour index II (98.5%), speed of germination (98.3%), germination (95.3%), and seedling dry weight (91.0%). Out of the 30 genotypes tested under MS condition, 9 genotypes exhibited the highest SVI-I, and 12 genotypes exhibited the highest SVI-II. The genotypes exhibited a significant amount of variation in every aspect of seed quality examined under MS condition. Principal component analysis (PCA) was performed to identify the most significant contributing variables for diversity, revealing the highest degree of variation by the first two principal components, that is, 82.67% and 12.44%, respectively. Subsequent correlation analysis revealed strong positive relationships among these traits under the imposed MS condition. Remarkably, seed vigour index I showcased strong and positive correlations with germination (0.946), shoot length (0.948), root length (0.963), seedling length (0.982), seedling dry weight (0.940) and seed vigour index II (0.975). The identification of tolerant genotypes that exhibit a higher degree of variability in the seed vigour-related traits, particularly those that are strongly correlated with drought resistance, can be a valuable source of donor parent candidates in future drought tolerance breeding programs. Variability and correlation analyses demonstrated a more effective selection of target traits for improving seed vigour under moisture-stress situations

Keywords

Drought, Seed vigour index, Moisture stress, Polyethylene glycol, Variability, Correlation, Rice

Conclusion

Drought is the foremost abiotic constraint on rice (Oryza sativa L.) production in India. Rice, a drought-sensitive crop, exhibits notable varietal variability concerning its drought tolerance, especially during the germination and seedling stages. The assessment of drought tolerance in field conditions is a time-consuming and labour-intensive procedure. In-vitro screening using polyethylene glycol is easy, as it facilitates more germplasm to be screened at once under a natural drought stress environment for further reliable and accurate results. Polyethylene glycol (PEG-6000) can be used as an alternative approach to artificially induce drought stress and enable the analysis of a diverse range of rice genotypes for the identification of drought tolerance in rice. The present study mainly examined the variability and correlation of various seed vigour-related physiological traits in thirty rice genotypes, specifically in response to moisture stress induced by 20% (w/v) solutions of polyethylene glycol (PEG)-6000 (osmotic potential of -0.49 Mpa). The results indicated that most rice genotypes exhibited a noticeable decrease in germination and seed vigour-related physiological parameters under moisture stress (MS) condition compared to the control (distilled water; 0 MPa). Among all the genotypes tested under MS condition, Karinellu was identified as the genotype with the highest germination potential (71.33%), while Magura exhibited the maximum seed vigour index I and II (774.17, 2.524). This study revealed significant genotypic variability among the seed vigour-related traits studied under MS condition, with the highest heritability exhibited by shoot length (99.8%), followed by seedling length (99.6%), root length (99.3%), seed vigour index I (99.2%), seed vigour index II (98.5%), speed of germination (98.3%), germination (95.3%), and seedling dry weight (91.0%). Out of the 30 genotypes tested under MS condition, 9 genotypes displayed the highest SVI-I, and 12 genotypes exhibited the highest SVI-II. The genotypes exhibited a significant amount of variation in every aspect of seed quality examined under MS condition. Principal component analysis (PCA) was performed to identify the most significant contributing variables for diversity, revealing the highest degree of variation by the first two principal components, that is, 82.67% and 12.44%, respectively. Subsequent correlation analysis illuminated strong positive relationships among these traits under the imposed MS condition. Remarkably, seed vigour index I showcased strong and positive correlations with germination (0.946), shoot length (0.948), root length (0.963), seedling length (0.982), seedling dry weight (0.940), and seed vigour index II (0.975). The identification of tolerant genotypes that exhibit a higher degree of variability in the seed vigour-related traits, particularly those that are strongly correlated with drought resistance, can be a valuable source of donor parent candidates in future drought tolerance breeding programs. Variability and correlation analyses demonstrated a more effective selection of target traits for improving seed vigour under moisture-stress situations

References

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How to cite this article

Jyotirmayee Mishra, P. Sanghamitra, Devraj Lenka, Sharat Kumar Pradhan, Simanta Mohanty, Kailash Chandra Samal, Rajkumari Bhol, Iswar Chandra Mohanty and Subrat Kumar Mahapatra (2022). Estimation of Variability and Correlation of Various Seed Vigour Traits in Rice (Oryza sativa L.) under In Vitro PEG-Induced Moisture Stress Condition. Biological Forum – An International Journal, 14(5): 63-79.