f. hamdi

High yield and yield stability across a range of environmental conditions is one of the main objectives of crop breeding programs. In this study, white sugar yield stability of nine sugar beet cultivars commercially released in Iran from 2011 to 2020 with an introduced foreign cultivar as check was evaluated using randomized complete block design with four replications in six research field stations; Karaj, Ardabil, Kermanshah, Mashhad, Moghan, Miandoab, in four cropping seasons 2017-2021. The combined analysis of variance revealed that effects of genotype, year, location, and year × location, genotype × year, genotype × location and genotype × year × location were significant (p ≤ 0.01) on white sugar yield. Analysis of genotype × environment interaction showed that the first seven components were significant (p ≤ 0.01). Based on AMMI1 analysis, cv. Asia, cv. Shokoufa and cv. Arta had white sugar yield stability. Linear mixed model analysis showed that the effects of genotype and genotype × environment interaction were significant (p ≤ 0.01) on white sugare yield. Based on the BLUP method, cv. Perfecta, cv. Asia and cv. Shokoufa had the highest predicted mean value of white sugar yield. Biplot of white sugar yield with the WAASB index showed that cv. Asia, cv. Arta and cv. Shokoufa had higher sugar yield as well as higher white sugar yield stability. Ranking of sugar beet cultivars based on WAASB/white sugar yield ratio identified cv. Arta, cv. Asia and cv. Shokoufa as high yielding with white sugar yield stability. Simultaneous ranking and selection of cultivars based on 50:50 WAASB/white sugar yield ratio resulted the same. Therefore, cv. Asia followed by cv. Shokoufa and cv. Arta had relatively higher WAASBY indices. Considering the results of this study, cv. Asia, cv. Shokoufa and cv. Arta were identified as high yielding with higher white sugar yield stability.

Monogerm and multigerm seed varieties are used in sugar beet cultivation. Singling is inevitable and mechanization almost impossible when multigerm seed varieties are used. For this and for some other reasons, economically sound and fully mechanized cultivation of sugar beet calls for the use of monogerm seed varieties. Throughout Europe, only monogerm varieties are used in sugar beet production. In sowing monogerm seeds, special types of machineries are implemented and land preparation techniques play a very important rule. In the past, lack of suitable machineries and well prepared lands discouraged farmers from sowing monogerm varieties and therefore, monogerm seed production showed no improvement in quality, quantity and diversity for many years. In recent years, with the growing interest of sugar beet producers, Sugar Beet Research Institute of Iran has focused on monogerm seed production. With the development of varieties suitable for different climatic areas, this institute has reached a high level of commercial success in monogerm seed production. In a multigerm seed production field, some fraction of the crop is monogerm. One way of monogerm seed production, called technical monogerm, is the separation of this fraction of monogerm seed from the multigerm seeds using a combination of round and slotted screens. Another type of monogerm seed is hybrid monogerm and its production is rather complex and requires special tools and material with a growing demand for monogerm seed, Sugar Beet Seed Research Institute has been focusing on the production and development of high quality basic seeds of monogerm type in recent years and the increasing level of commercial production of hybrid monogerm is a clear indication of its success. Table 1 shows the trend of commercial hybrid monogerm seed production in an interval of 5 years. Each year, field performances of domestic varieties are compared with top quality foreign varieties by researchers and technical staffs of SBSI, agricultural organizations and agricultural sectors of sugar refineries. Data gathered from 70 sugar beet production farms with a total of 203 hectares in Western Azerbaijan province for the production year of 2002 is shown in Table 2. At a large scale, average root yield is 5 tons per hectare with 9.01 tons of gross sugar. Domestic varieties show unique superiorities over foreign varieties and in some cases 40% yield increase is observed. Sugar Beet Seed Research Institute has developed Rhizomania and Nematode resistant lines and farmers will have access to the new varieties in the coming years.