فهرست مطالب p. fasahat

The sugar beet crop has always been attacked by various pests and diseases. Rhizomania viral disease, which has spread in different regions of sugar beet cultivation, has become a disease of prime importance for the crop in the last three decades. Resistant cultivar usage is the only reliable way to manage rhizomania disease. In order to identify promising genotypes, eleven sugar beet genotypes with natural infection to rhizomania, in a company with three controls, were assessed in a Randomized Complete Block Design (RCBD) with four replications. The experiment was conducted in six research stations of Karaj, Khoy, Kermanshah, Mashhad, Miandoab, and Shiraz for two cropping seasons (2020 and 2021). Based on the rhizomania score, all genotypes had acceptable resistance to the disease. The Additive Main Effects and Multiplicative Interaction (AMMI) stability analysis illustrated that the first five principal components were significant and specified 88.8% of the total genotype by environment interaction variance. Gen-7, Gen-10, Gen-11, and Gen-2 were selected as stable genotypes based on the AMMI model. Genotype plus Genotype by Environment Interaction (GGE) biplot results also confirmed the superiority of Gen-10 and Gen-11 regarding sugar yield and stability in disease-infected environments. According to the results of the Multi-Trait Stability Index (MTSI), genotypes Gen-4, Gen-1, Gen-2, and Gen-11 were identified as stable genotypes under rhizomania-infected conditions. By applying different stability measurement methods, in addition to identifying the genotypes’ adaptation to different environments, accurate decisions for future breeding or cultivar registration can be achieved.

To assess root and white sugar yield stability of 11 spring sugar beet genotypes together with three check cultivars, a field experiment was carried out using randomized complete block design with four replications in six agricultural research stations; Toroq (Mashhad), Zarghan, Khoy, Kermanshah Miandoab, and Karaj, Iran, in 2020 and 2021. Combined analysis of variance showed that genotype × environment interaction was significant (P < 0.01), and genotypes had different performance in different environmental conditions. Based on regression coefficient, deviation from regression, Shukla’s stability variance, Wrick's ecovalence, and coefficient of determination, GB-6 and GB-10 genotypes were identified with high root and white sugar yield and yield stability. Although the number of genotypes with yield stability increased by using superiority measure and coefficient of variation, three genotypes including; GB-11, GB-10, and GB-2 showed the highest yield stability for root and white sugar yield, respectively. Using GGE biplot method, GB-11, GB-10, GB-2 and GB-6 were identified with higher root and white sugar yield, than average of all genotypes, and higher yield stability, respectively. Considering the results of this research, GB-6, GB-11, GB-2, and GB-10 were identified as high-yielding genotypes with high yield stability.

Recently, concerns over food and energy security, threats from global warming, and the challenges that the commodity market has faced since the new millennium have placed the agricultural market at the center of academia and policy. In this revived consciousness, sugar plays a special and essential role. The sugar market is far from the stable and conventional condition and brings more challenges and unrest alone. An unusual combination of free and protected markets, special trade agreements, and extremely volatile prices distinguishes this trade from other agricultural commodities. Historically, sugar has been one of the most volatile agricultural commodities and countering that volatility is a real challenge for market makers and policymakers. In addition, depending on domestic markets, sugar prices can vary from country to country. The purpose of this paper is to analyze the characteristics of the sugar market and the medium-term forecasts for global markets for the period 2019-28. The price, production, consumption, and commercial transactions of sugar beet, sugar cane, sugar, molasses, and high fructose corn syrup are discussed. Lastly, the risks and uncertainties affecting the global sugar markets over the next ten years are discussed.

Rhizomania is the most destructive disease in spring sugar beet along with root-knot nematode and are spreading in some parts of Iran. The best control method against these two diseases is using resistant cultivars. Therefore, the aim of this study was to develop and select a high yield hybrid resistant to rhizomania and root knot nematode. Twenty-seven full-sib families (S1) from SB-34 origin which screened with molecular markers for rhizomania and root knot nematode resistance gene, were used to develop double resistant hybrids. In the spring of 2015, vernalized families were crossed to one single cross (7112*SB-36) in separate isolates. In summer, S1/S2 seeds from the paternal plants and three-way cross hybrid seeds from maternal plants were harvested and cleaned. Out of 27 isolates, only 19 isolates had adequate seeds from both parental lines. In autumn of the same year, selected hybrids were planted in greenhouse in Karaj. Seedlings were analyzed by SCAR and SNP markers linked to rhizomania and root knot nematode resistance genes to determine gene frequencies in hybrids. Based on the results of molecular evaluation, 14 hybrids were selected. In the spring of 2016, selected hybrids along with some controls, overall 20 varieties, were planted in two rhizomania-infected areas in Khorasan Razavi and Fars based on randomized complete block design with six replications. Roots were harvested in autumn and qualitative and quantitative characteristics such as root yield, sugar content, and white sugar yield were measured. Data were analyzed using SAS 9.1.3 software. According to the results of field trials and the frequency of rhizomania resistance gene and root node nematode in the laboratory, hybrid SB36*(7112*930620) with 10.92 t/ha white sugar yield to be used.