Journal of Crop Production and Processing

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Jamalzadeh R, Sabouri A, Ebadi A. Evaluation of Physicochemical Grain Traits in Promising Rice Lines in Comparison with Local Check Varieties. Journal of Crop Production and Processing 2025; 15 (2) :41-59
URL: http://jcpp.iut.ac.ir/article-1-3360-en.html

Extended Abstract
Introduction
Rice is Iran's second most strategic crop after wheat, serving as a staple food with significant economic and cultural importance. Its high consumption highlights its key role in food security, household diets, and the nation's agricultural economy. Among the various attributes valued by Iranian consumers, cooking and eating quality traits such as grain appearance, elongation after cooking, texture, and aroma are paramount. These traits directly affect consumer preferences and market demand, thereby playing a critical role in determining the commercial success of a variety. Therefore, a major goal of rice breeding programs in Iran is to combine the cooking and eating quality of local varieties with the high yield of improved lines. In this context, the present study was conducted to evaluate the grain quality characteristics of a set of rice lines developed through backcrossing and crossing strategies involving both local and improved varieties, aiming to identify lines with improved eating quality suitable for further development and release.

Material and Methods
The experiment was carried out during the 2022 cropping season at the research farm of the Rice Research Institute of Iran in Rasht. A total of 40 genotypes, including 36 advanced lines and four check varieties (Anam, Hashemi, Domsiah, and Hasansarai), were evaluated in a randomized complete block design with three replications. Genotypes were cultivated in plots of 3 × 3 meters. Transplanting was performed at a spacing of 20 × 20 cm with single seedlings at four weeks of age, corresponding to the three- to four-leaf stage. After harvesting, grain quality traits were measured, including paddy length and width, milled grain length and width, cooked grain length, elongation ratio, amylose content, and gelatinization temperature. Paddy length and width, as well as milled grain length and width, were measured using a photo enlarger device. For each trait, the mean of measurements taken on five random samples was recorded. Statistical analyses, including analysis of variance (ANOVA), mean comparisons, cluster analysis, and measuring person correlation coefficients, were performed using SAS and SPSS software and packages "metan" and "ggpubr" in R to assess variability and identify superior genotypes.

Results and Discussion
The analysis of variance revealed significant differences (P<.05) among the genotypes for all evaluated traits, indicating the presence of substantial genetic variation that can be exploited in breeding programs. Mean comparison showed that lines BC2F4-18-2-1 and BC2F4-37-2-3 outperformed others in terms of paddy length, milled grain length, and cooked grain length, traits that are highly valued by consumers for their contribution to the visual and textural appeal of cooked rice. These lines exhibited high elongation ratios and medium amylose content, both associated with desirable cooking quality. Cluster analysis grouped the genotypes into three main clusters, with the first cluster including lines that combined favorable physicochemical traits with cooking quality comparable to that of local varieties. Mean comparison of the clusters showed that Cluster I had higher averages for paddy length and width, and grain length, and was classified as having medium amylose content (20-25%), similar to local check varieties (Hashemi, Hasansarai, and Domsiah). From the perspective of Iranian consumers, this group possessed the best lines in this study regarding marketability and desirability, as high-quality rice is characterized by good grain shape, strong aroma, proper cooking, soft texture, lightness, and lack of cracking. Cluster II consisted of 10 lines, which had higher average amylose content compared to the other two groups. The improved variety Anam, with 25% amylose, was in this group. Cluster III included 6 lines that showed higher averages for cooked grain length and elongation. They also had lower averages for gelatinization temperature and amylose content (18.55%) compared to other groups. Because low amylose content leads to sticky and gummy rice that does not expand in volume, this group has low desirability among Iranian consumers from this perspective. 
Conclusion
The study highlighted the effectiveness of using backcross and cross-breeding approaches to enhance cooking and eating quality traits in rice. The identification of superior lines with characteristics similar to high-quality local varieties but with potentially improved performance supports the ongoing efforts in rice breeding programs in Iran. These results indicate success in improving rice cooking and eating quality through genetic improvement and selection of superior lines, which can enhance the marketability and economic value of rice in Iran.