جستجوی مقالات مرتبط با کلیدواژه "testcross" در نشریات گروه "کشاورزی"

Sugar beet cultivation faces significant challenges from diseases such as rhizomania and cyst nematode, both in Iran and globally. The most effective and straightforward approach to mitigate the damage caused by these diseases is the use of resistant varieties. The Hosna cultivar was developed after extensive preliminary and advanced research. This variety was produced by crossing a pollinator inbred line from the SB27 population, which carried resistance genes for both rhizomania and cyst nematode, with a monogerm single cross maternal line. A value-for-cultivation and use (VCU) test was conducted in Hamadan, Mashhad, Shiraz, and Miandoab under rhizomania-infected conditions and in Karaj under non-infected conditions to evaluate this variety's performance. Simultaneously, the resistance of the hybrids to cyst nematode was evaluated in another experiment under controlled conditions (greenhouse). The results showed the superior performance of Hosna cultivar, which produced an average white sugar yield of 11.52 tha-1, outperforming the foreign control variety Azare (11.36 tha-1) and the domestic control varieties Shokoufa and Arta (10.19 and 10.12 tha-1, respectively). However, no significant difference was found between Hosna and the foreign control Rosier (12.02 tha-1). Hosna is a diploid monogerm cultivar, resistant to both rhizomania and cyst nematode, and suitable for spring cultivation across various regions of the country. In addition to its disease resistance, this cultivar has a high potential for sugar yield.

Choice of efficient breeding program depends on the knowledge of the genetic system controlling the character to be improved. To estimate the genetic parameters for yield, yield components and some other morphological traits in corn (Zea mays L.), B73×MO17 and B73×K74/1 crosses were studied by triple testcross method. The experiments were conducted at research field of Seed and Plant Improvement Institute (SPII) in 1999-2001. Significant differences were observed among means of F1 , P1 and P2 testcrosses for all of the traits in both crosses. The B73 testcrosses generally had greater means than MO17 and K74/1 testcrosses except for number of leaves in two crosses, cob weight in cross B73×MO17 and anthesis silking interval in cross B73×K74/1. B73 testcross seems to contribute significantly in the expression of positive epistatic effects. Epistasis effects were significant for all of the traits in both crosses. Partitioning of the epistasis effects into fixable and non-fixable components revealed that additive×additive effects (fixable) were not significant for the traits except for days to silking in both cross, anthesis silking interval and plant height in cross B73×MO17, but additive×dominance and dominance×dominance effects (non-fixable) were significant for all of the traits in both crosses.