Search

Wheat is a staple crop in Tunisia, but little is known about the response of Tunisian durum wheat (Triticum turgidum ssp. durum) and bread wheat (Triticum aestivum L.) to water stress. In semi-arid regions, where cereals are concentrated, grain yield is subject to water deficit especially due to variability in rainfall. Therefore, the objective of this study was to evaluate the response to water stress of three durum wheat (Mâali, Nasr and Salim) and two bread wheat (Tahent and Utique) varieties. The experimental design was a complete randomized block, water treatments were rainfed conditions (T0) and irrigation applied at the tillering and flowering stages (T1, control) with three replications per treatment, and data was analyzed by ANOVA and Tukey test to compare treatments means (p≤0.05). Variables analyzed were grain yield and yield-related components: plants per square meter (NP), tillers per square meter (NT), ears per square meter (NE), seed per ear (NSE) and 1000-kernel weight (TKW). NP, NE, NSE and TKW were significantly affected by water stress, but there was no change on NT. Seed yield was weakly correlated with NE (r=0.376) but significantly correlated with NSE (r=0.604) and NP (r=0.639). Supplemental irrigation increased grain yield by 74.4 %, 42.3 %, 36.1 %, 33.7 % and 24.5 % for Utique, Tahent, Nasr, Maâli and Salim, respectively, compared to control. Four drought tolerance indices, stress tolerance index (STI), stress tolerance (TOL), stress susceptibility index (SSI), and mean productivity (MP), were assessed and were adjusted based on grain yield under drought (Ys) and normal (Yp) conditions. A positive and significant correlation between Ys and Yp with SSI and PM, respectively, indicate that they are the most suitable variables to select wheat genotypes in drought stress. These indices were able to screen a drought-tolerant genotype (Nasr), which showed the highest STI (1.10). In contrast, Salim showed the lowest STI (0.47) and was considered to be a drought-susceptible genotype. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is the principal Fusarium head blight (FHB) causal agent in Argentine wheat, diminishes yields, reduces grain quality and end-use, and liberates mycotoxins. The aim of this study was to identify new sources of resistance to FHB in Argentine wheat cultivars and lines for comparion with known resistant international cultivars. We evaluated the Triticum aestivum behavior against F. graminearum indicative of resistance to wheat-spike penetration by FHB (type-I resistance). The assays were performed under field conditions in Marcos Juárez (62° 6' 7" W, 32° 41' 39" S; 116 masl), Córdoba province, Argentina, during spring 2010, with moisture controlled by a microsprinkler system. For this study we distributed 210 wheat varieties with spikes inoculated by hand-spraying on a hill plot, as the experimental unit, and they were planted and inoculated in duplicate. The experimental design was randomized complete blocks and results were analyzed by ANOVA and the Fisher-LSD test (p≤0.05) for comparing the mean values of incidence and severity among treatments. Resistance was evaluated through pathometric criteria and yields. The F. graminearum isolate's high infectivity enabled disease evaluation for all wheat varieties. All variables, except incidence, were statistically different among the Argentine wheat cultivars, whereas only the thousand-grain weight differed significantly in the international cultivars. Of the 92 advanced wheat-line genotypes of three different growth cycles, 57 % were moderately resistant and 40 % moderately susceptible to infection. FHB resistance evaluated in all cultivars and domestic- and international-genotype lines identified varieties of five different disease-resistance levels. Knowledge of the genetic behavior can contribute to new crosses to generate varieties with improved resistance against FHB. [ABSTRACT FROM AUTHOR]