Aims This study aimed to evaluate the potential of hydrotime analysis as a selection tool for identifying rice lines tolerant to osmotic stress during germination. Specifically, the study sought to compare the effectiveness of hydrotime analysis with the multi-trait genotype-ideotype distance index (MGIDI) in distinguishing between stress-sensitive and stress-tolerant rice genotypes. The objective was to determine whether hydrotime parameters could be a practical and efficient selection tool for identifying rice lines that demonstrate tolerance to osmotic stress, with potential applications in rice breeding efforts. Methods In this study, a diverse population of 150 rice lines, derived from a cross between Shahpasand (an Iranian landrace) and IR28, was evaluated for osmotic stress tolerance during germination. Osmotic stress was induced using different concentrations of polyethylene glycol (PEG). Germination components and seedling morphological characteristics were measured meticulously. The MGIDI was performed using all traits. Additionally, five hydrotime models based on different mathematical distributions were evaluated based on cumulative germination percentage to determine the most appropriate distributionfor predicting rice germination under osmotic stress over time. Results The imposition of osmotic stress resulted in decreased germination rates and various changes in germination components and seedling morphological characteristics among the rice lines and their parents. The hydrotime analysis based on Gumbel and Logistic distributions outperformed other models, achieving high adjusted R2 values (up to 0.95), low RMSE values, and the lowest AICc values. There was no significant difference between the selection differential obtained with the MGIDI index and the hydrotime estimated parameter <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11104_2025_7235_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">${\Psi }_{\text{b}(50)}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">Ψ</mi> <mrow> <mtext>b</mtext> <mo stretchy="false">(</mo> <mn>50</mn> <mo stretchy="false">)</mo> </mrow> </msub> </math></EquationSource> </InlineEquation>, which was calculated using the best mathematical model. The hydrotime analysis and MGIDI index showed a 78.57% similarity in selecting osmotic-tolerant lines under a selection intensity of 10%.  Conclusion Germination in osmotic-tolerant rice lines can be accurately predicted by hydrotime analysis, particularly when Gumbel and Logistic distributions are used. Hydrotime analysis yielded the <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11104_2025_7235_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">${\Psi }_{\text{b}(50)}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">Ψ</mi> <mrow> <mtext>b</mtext> <mo stretchy="false">(</mo> <mn>50</mn> <mo stretchy="false">)</mo> </mrow> </msub> </math></EquationSource> </InlineEquation> parameter, which showed selection efficiency similar to the multi-trait-based MGIDI index. Additionally, <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11104_2025_7235_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">${\Psi }_{\text{b}(50)}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="normal">Ψ</mi> <mrow> <mtext>b</mtext> <mo stretchy="false">(</mo> <mn>50</mn> <mo stretchy="false">)</mo> </mrow> </msub> </math></EquationSource> </InlineEquation> showed a strong association with the morphological characteristics of seedlings, confirming its use as a simple and trustworthy marker for identifying osmotic-tolerant lines during germination.

How does hydrotime analysis facilitate the selection of osmotic-tolerant rice lines at the germination stage?

期刊论文
发表日期：

2025年1月31日

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Sheida Veisi,
Atefeh Sabouri,
Amin Abedi

摘要

Aims

This study aimed to evaluate the potential of hydrotime analysis as a selection tool for identifying rice lines tolerant to osmotic stress during germination. Specifically, the study sought to compare the effectiveness of hydrotime analysis with the multi-trait genotype-ideotype distance index (MGIDI) in distinguishing between stress-sensitive and stress-tolerant rice genotypes. The objective was to determine whether hydrotime parameters could be a practical and efficient selection tool for identifying rice lines that demonstrate tolerance to osmotic stress, with potential applications in rice breeding efforts.

Methods

In this study, a diverse population of 150 rice lines, derived from a cross between Shahpasand (an Iranian landrace) and IR28, was evaluated for osmotic stress tolerance during germination. Osmotic stress was induced using different concentrations of polyethylene glycol (PEG). Germination components and seedling morphological characteristics were measured meticulously. The MGIDI was performed using all traits. Additionally, five hydrotime models based on different mathematical distributions were evaluated based on cumulative germination percentage to determine the most appropriate distributionfor predicting rice germination under osmotic stress over time.

Results

The imposition of osmotic stress resulted in decreased germination rates and various changes in germination components and seedling morphological characteristics among the rice lines and their parents. The hydrotime analysis based on Gumbel and Logistic distributions outperformed other models, achieving high adjusted R² values (up to 0.95), low RMSE values, and the lowest AICc values. There was no significant difference between the selection differential obtained with the MGIDI index and the hydrotime estimated parameter ${\Psi }_{\text{b}(50)}$ $Ψ_{b (50)}$ , which was calculated using the best mathematical model. The hydrotime analysis and MGIDI index showed a 78.57% similarity in selecting osmotic-tolerant lines under a selection intensity of 10%.

Conclusion

Germination in osmotic-tolerant rice lines can be accurately predicted by hydrotime analysis, particularly when Gumbel and Logistic distributions are used. Hydrotime analysis yielded the ${\Psi }_{\text{b}(50)}$ $Ψ_{b (50)}$ parameter, which showed selection efficiency similar to the multi-trait-based MGIDI index. Additionally, ${\Psi }_{\text{b}(50)}$ $Ψ_{b (50)}$ showed a strong association with the morphological characteristics of seedlings, confirming its use as a simple and trustworthy marker for identifying osmotic-tolerant lines during germination.