Afshar Estakhr

Extended Abstract Background: Maize is an important crop that is cultivated in many parts of the world. The evaluation of genotypes in breeding programs often faces two important challenges, the genotype × environment interaction effect for the target trait and unfavorable relationships between the target traits. Even though many methods ...

Sorghum (Sorghum bicolor (L.) Moench) is the fifth important cereal considered a drought-tolerant crop. However, its reduction of grain yield considerably occurs in a shortage of water. In the current study, 10 sorghum genotypes were assessed for their grain yield under normal irrigation and water deficit irrigation. As well, the efficacy of several drought indices was evaluated for the selection of high-yield and drought-tolerant genotypes. The experiment was conducted as a split-plot considering three irrigation levels as main-plot and 10 genotypes as sub-plot. Correlation among the indices, clustering of the genotypes along with principal component analysis was employed. Yield production was significantly and positively correlated with indices MP (mean productivity), STI (stress tolerance index), GMP (geometric productivity), HM (harmonic mean), and YI (yield index) in all the irrigation levels. Therefore, these indices are more effective in the selection of high-yielding genotypes under different water conditions. Rank means of stress indices for each genotype revealed that genotype TN-04-79 in mild deficit irrigation and genotypes KGS23 and TN-04-79 in severe deficit irrigation were the most tolerant.

In present study, the putative resistance capacity of thirty five maize inbred lines against Iranian maize mosaic virus (IMMV) was studied. Reaction to IMMV was analyzed under natural field infection and controlled conditions in a greenhouse in 2010 and 2011. In the greenhouse experiments, the maize plants were inoculated at two-leaf stage using the planthopper Laodelphax striatellus. In the field trials, an early sowing cultivation was used to facilitate a higher infection rate. The responses of inbreds to IMMV were assessed by symptom development and ELISA. The rate of natural infection of IMMV in susceptible control (SC704) was about 20%. MO17 showed about 40% infection in the first year. Both field and greenhouse results confirmed that MO17 was more susceptible to IMMV than SC704 and more reliable to be used as susceptible control in future studies of IMMV. Sowing one row of SC704 as vector spreader between every 5 rows of inbred lines caused sufficient vector propagation and virus transmission. Results of both field and greenhouse experiments showed little and no IMMV infection on K1263/1 and K3547/5, respectively. Hence, they were considered as IMMV-resistant. These lines with CIMMYT origin can also be used for production of resistant hybrids. Results showed that resistance to IMMV was not associated with maize maturity because resistance and susceptibility were found in both early and late matured inbred lines. Disease incidence and ELISA values were strongly correlated. Reduced plant height, ear weight and ear diameter and length and delayed silking were observed in plants infected with IMMV.

The production of locally adapted maize hybrids requires parental material with adequate genetic variation in the relevant traits. The objective of the present study was to evaluate 20 European maize hybrids under temperate region for their potential use in direct cultivation or as parent material in local breeding programs. Results showed that European hybrids except BC 566 had higher kernel yield (11.4–14.3 t ha⁻¹) than local cultivars (KSC705 and KSC704). Korimbos, Krebs, BC 566, and BC 532 had lower kernel moisture (14–15%) compared to KSC705 (21.7%) and KSC704 (22.7%). Cluster analysis categorized these hybrids in three groups. Cluster 2 comprised of Korimbos, BC 612, DKC 6589, and 89May70. These hybrids had high plant height, thousand kernel weight, and kernel yield. Due to high kernel moisture, the hybrid 89May70 could not be proposed for direct cultivation but it can be involved in transferring high grain yield to local hybrids. Genotype × environment analysis showed that Korimbos and Krebs had low S²_i and low genotypic coefficient of variation, high and stable performance and low kernel moisture. Therefore, Korimbos and Krebs can possibly be used for direct cultivation in temperate regions of the Fars Province.

The availability of more resistance genes to Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko) may provide additional protection from new virulent strains or biotypes of the insect. This genetic study was conducted to determine the allelic relationships of resistance genes in two Iranian wheat (Triticum aestivum L.) lines, SHZ.W.102 and SHZ.W.104 and lines PI 137739, PI 262660, PI 372129, PI 294994 and PI 243781, carrying resistance genes Dn1, Dn2, Dn4, Dn5 and Dn6 respectively. The two Iranian lines were crossed to each of the other resistant lines, and F₁ and F₂ seedlings were screened for RWA reaction. The resistance gene in 102 was allelic to Dn1, however, the resistance gene in 104 was different from other known genes. The resistant line 104 is an effective source of genetic resistance to RWA and the gene symbol Dn7 is proposed for its resistance gene.