| چکیده انگلیسی مقاله |
Introduction and Objectives: Sugar beet stands as a cornerstone crop in global agriculture, holding a pivotal position in sugar production and significantly shaping the sweetener industry. Given its fundamental role, enhancing traits crucial for sugar beet growth and yield is imperative to meet the escalating sugar demand forecasted for the future. Consequently, sugar beet breeding has long been a critical domain of research and development, focusing on enhancing yield, quality, and resistance to disease of this essential commodity. Breeders have effectively cultivated sugar beet varieties boasting elevated quantitative and qualitative yields, alongside enhanced disease resistance, achieved through meticulous selection and crossbreeding of diverse sugar beet lines. The current study undertakes the comprehensive evaluation of sugar beet genotypes across various traits encompassing quantitative and qualitative performance, aiming to pinpoint and select superior genotypes for future breeding initiatives.
Materials and Methods: In this research, a selection of 49 sugar beet genotypes was meticulously chosen, comprising 44 novel hybrids and five control varieties, encompassing three domestic and two foreign cultivars. These innovative hybrids emerged from a cross between 22 pure pollinator lines of sugar beet as the paternal parent and two commercial monogerm male-sterile single crosses as the maternal parent in 2020 at the Sugar Beet Seed Institute (SBSI), Karaj, Alborz, Iran. The phenotypic assessment of these experimental genotypes was conducted throughout the 2021 crop year at the Hamedan Agricultural Research Station utilizing a augmented randomized complete block design. The genotypes were cultivated in eight-meter rows spaced 50 cm apart within five incomplete blocks. Following data collection, variance analysis was carried out using R software. Subsequently, based on the augmented design implementation and the variance analysis outcomes for the various traits under study, trait values for each hybrid were adjusted. The corrected trait averages were then employed for subsequent statistical analyses.
Results: The results obtained from the variance analysis of various evaluated traits such as white sugar yield, root yield, sugar content, sodium, potassium, and alpha amino nitrogen, revealed that the adjusted block effect non-significantly influenced all the studied traits. This non-significance indicates the homogeneity of the incomplete blocks concerning controllable or uncontrollable environmental conditions. Notably, the adjusted treatment effect proved significant for all traits except root yield and potassium content at a 1% probability level. When dissecting the treatment effect into hybrid and control impacts, it emerged that only the sugar content trait exhibited a significant hybrid effect, while all investigated traits showed a significant control effect. Analysis of the hybrid versus control effect unveiled a significant disparity solely in terms of sodium and alpha amino nitrogen content at a 1% probability level, with no notable difference observed for other traits. Among the experimental hybrids and controls, two controls, 8K801 and BTS 1885, along with genotypes 33, 12, and 24, demonstrated commendable average white sugar yields ranging from 9.15 to 10.52 tons per hectare. These hybrids notably outperformed domestic controls like Hosna, Kimia, and Shokoufa, indicating the superiority of the new improved hybrids over internal control varieties. Genotype 42 exhibited the least favorable condition in white sugar yield and ranked lowest. The phenotypic diversity coefficient ranged from 4.99% for sugar content to 22.53% for sodium content, while the genetic diversity coefficient varied between 1.96% for potassium content to 14.23% for sodium content. Traits like alpha amino nitrogen, sodium, and root yield displayed moderate genetic advance, whereas potassium, sugar content, and white sugar yield showed lower genetic advance. Notably, high heritability was observed alongside favorable genetic advance for the alpha amino nitrogen, suggesting additive genetic effects. The SIIG index results highlighted genotype 12 as the closest to the ideal genotype and farthest from the non-ideal genotype, earning it the highest SIIG value of 0.82, designating it as the best genotype. Following this, control variety 8K801 and genotypes 35 and 33 secured subsequent ranks with SIIG values of 0.72, 0.71, and 0.71, respectively, denoting them as suitable genotypes.
Conclusion: The findings underscore significant genetic diversity evident in the majority of traits among the experimental hybrids, highlighting substantial genetic alterations within hybrid breeding endeavors. This rich diversity within the studied germplasm is attributed to the diverse paternal line, resulting in the assignment of experimental hybrids into distinct groups based on all traits evaluated. Overall, the results firmly establish the superior performance of three key genotypes, namely 12, 35, and 33, surpassing other tested genotypes in the study. |