جستجوی مقالات مرتبط با کلیدواژه « half » در نشریات گروه « زراعت »

Alfalfa with a genetic constitution of 2n=4x=32 and autotetraploid with allogamous fertilization has more genetic diversity. In fact, genetic diversity is critical for breeding selection programs to improve trait, generate new adapted cultivars. The enzymatic markers showing tetrasomic inheritance patterns can be used to perform genetic diversity analysis. The aim of this study was to determine genetic variations levels and clustering based on enzymatic band (0 and 1) in alfalfa populations.
Genetic diversity of 12 alfalfa half-sib families was studied by use enzymatic electrophoresis (rubisco, superoxide dismutase, esterase and peroxidase). 35 individuals of each variety, were investigated in the Agricultural Research Station of University of Tabriz.
For enzyme markers rubisco and superoxide dismutase isozymes showed only one monomorphic band in all populations, but esterase and peroxidase enzymes had polymorphic bands. The resulting data based on presence and absence of enzymatic band (0 and 1) for 11 polymorphic isozymic bands were analyzed. Isozymic analysis showed that there were high levels of intra-family and low level of inter-family diversity. Average heterozygosity, as an index of within-population genetic diversity, was 0.289. Nei’s genetic distances among families were low (0.002 to 0.059). Dendrogram was constructed via the Jaccard similarity coefficient and UPGMA method, that lead to the classification of the alfalfa populations in two groups, with 11 families in one group and only Chaleshte half-sib in the other group were located that were conform the pervious conclusion.
It might be possible to use these enzymes as markers to select alfalfa genotypes in the early breeding stages after the stability of markers were verified in other experiments.

Sugar beet (Beta vulgaris) is one of the hosts for root-knot nematodes. In this study, two open-pollinated populations and their half-sib families (37 families), two hybrids of sugar beet and the commercial resistant cultivars to cyst nematode (Heterodera schachtii), including Tucan, Cactus, Saneta, Pauletta, Paulina, Fernando, Sucarra and Shokufa, were evaluated against Meloidogyne javanica and M. arenaria in the separate experiments under greenhouse condition. Seedlings were inoculated with 500 and 750 second-stage juveniles. About 70 days after inoculation, the plants were taken off and the number of root-galls in roots was counted. Individual plants with 10 and less than 10 galls in root were considered as a resistant. Results indicated that SB33 and SB34 open-pollinated populations and total their half-sib families were resistant to root-knot nematode and the resistance in SB33 population is inherited in a dominant manner. Also the all resistant cultivars to cyst nematode, were susceptible to root-knot nematode.

One of the most effective ways to deal with drought stress and increase water use efficiency is the development of drought-tolerant varieties which display less reduction in yield per unit water reduction. Therefore, the breeding of diploid pollinators was considered as an essential measure for producing drought-tolerant hybrids. In this study, from 4 diploid pollinator populations, 45 half-sib families were developed and evaluated under drought stress condition and subsequently superior families with high root yield were selected. New families were produced and after final evaluation, 23 families with high performance were selected and crossed with a male sterile monogerm single cross as female parent and eventually 23 test-cross hybrids were produced. These hybrids together with Gadook cultivar and a drought-tolerant hybrid (IR7), as controls, were evaluated in a randomized complete block design with four replications in two experiments including normal irrigation and drought-stress condition at Torogh Research Station in Mashhad, Iran for two years, 2007-08. Normal irrigation was performed after 90 mm evaporation from class A evaporation pan but under stress condition, irrigation was performed based on soil moisture measurement at different soil depths (after soil moisture depletion reached to wilting point). Results showed significant difference among the families in terms of sugar yield in both experiments. Sugar yield was decreased from 15.20 t ha-1 in normal irrigation to 7.10 t ha-1 under drought stress condition. Under drought stress, the highest root yield (55.78 t ha-1) was obtained in test-cross hybrid 12 [(436*231)*SBSI-DR I-HSF-14-P.35)] which was placed in superior group with hybrids 7, 6, 14, 2, 5, 10 and 3. Furthermore, the highest sugar yield (7.93 t ha-1) was obtained in hybrid 7 [(436*231)*SBSI-DR I-HSF-14-P.7]. In order to select drought-tolerant hybrids, Stress Tolerance Index (STI), Stress Susceptibility Index (SSI) and Tolerance (TOL) indices were calculated based on sugar yield. According to the results, test-cross hybrids 7, 9, 12, 18 and 22 were identified as drought-tolerant hybrids but based on sugar yield results, hybrids 7 and 12 were selected as promising hybrids with 7.93 and 7.51 t ha-1 sugar yield, respectively.