Yield and Yield Components of Faba Bean (Vicia faba L.) as Influenced by Supplemental Irrigation under Semi-arid Region of Tunisia

Abstract A field experiment was conducted at the research station of Higher Agriculture School of Kef located in a semi-arid region of Tunisia to study the effect of supplemental irrigation on yield and yield components of four Tunisian faba bean genotypes (Bachaar, Badii, Chahbi and locale). Two supplemental irrigations were applied at the flowering and pod formation stages. Results showed a significant effect of supplemental irrigation on biological yield (BY/P), seed number per plant (SN/P), 100-seed weight (100 SW), grain yield (GY/m 2 ), harvest index (HI) and number of days to maturity (NDM). Grain yields under supplemental irrigation varied from 83.9 to 208.7 g/m2, and they varied from 18.6 to 65.8 g/m 2 under drought conditions. Average 100-seeds weight increment due to supplemental irrigation condition was 52.8%. Results showed also that under rain fed condition, Bachar genotypes required minimum number of days to maturity (134.3 days). Drought susceptibility index (DSI) values for grain yield ranged from 0.8 to 1.13. Chahbi was relatively drought resistant (DSI values <1). This genotype proved high yielding and drought tolerant and can be incorporated in stress breeding programme for the development of drought tolerant faba bean varieties

Tunisian population of Mycosphaerella graminicola is still sensitive to strobilurin fungicides.

International audienceSeptoria tritici blotch caused by the fungal pathogen Mycosphaerella graminicola (anamorph: Zymoseptoria tritici) is one of the most frequently occurring diseases on both bread and durum wheat crops worldwide. One hundred and sixty four durum wheat-adapted isolates of this fungus were sampled during the 2012 growing season from five distinct geographical locations of Tunisia (Bizerte, Béja, Kef, Jendouba and Siliana) in order to examine the status of strobilurin resistance of M. graminicola in this country. Resistance was assessed by screening the G143A substitution (Cytochrome b) which confers resistance to this class of fungicides. We used a PCR-based mismatch mutation assay allowing the amplification of either G143 (sensitive) or A143 (resistant) allele. All isolates were found to contain the sensitive wild-type G143 allele and therefore to be sensitive. Our study confirms recent reports on M. graminicola in Tunisia and shows that the Tunisian population of the fungus remains fully sensitive to strobilurins. A durability-oriented management of strobilurin applications in Tunisia is thereby recommended to prevent the development and widespread of the corresponding resistance such as in Europe, where pathogen populations are nowadays fully resistant to strobilurins

Circularly polarized emission from ensembles of InGaAs/GaAs quantum rings

Magneto-photoluminescence spectroscopy measurements were performed on self-assembled InGaAs/GaAs quantum rings. We report exciton exchange energy as a function of interband emission energy; we measure a decrease from 163 μ e V to 43 μ e V in the range of 1.30 eV to 1.40 eV. This result is remarkable and compatible with the exciton exchange energy in self-assembled InAs/GaAs quantum dots. Our results reveal the high value of exciton exchange albeit the quantum rings shape. We show that the exciton energy is sensitive to a magnetic field.Peer reviewe

Effect of host resistance on genetic structure of core and accessory chromosomes in Irish Zymoseptoria tritici populations

In agricultural pathosystems resistant cultivars are typically only temporarily effective, as widespread growth of said cultivars drives selection for pathogen genotypes capable of infecting them. A gene-for-gene interaction between Z. tritici and wheat has been demonstrated for one cultivar; however results of studies into the relevance of these interactions in the field remain inconsistent. Because genetic drift does not appear to occur between Z. tritici populations that are not widely geographically separated, according to neutral genetic theory if adaptation to different host cultivars is occurring, reduced genetic variation, and some differentiation between populations sourced from different cultivars should be observed. Selectively neutral microsatellite markers were used to genotype 260 isolates of Z. tritici taken from two naturally infected randomized block trials of four different cultivars, representing a spectrum of resistance to Z. tritici from susceptible to resistant. By calculating genetic parameters such as overall heterozygosity and FST from this genotypic data, the presented study aimed to determine if genetic drift or host selection is impacting on the genetic structure of the Irish Z. tritici population. Results indicated that diversity was distributed almost entirely within, rather than among populations, with little or no differentiation, and almost no clone isolates were present in the dataset. However this result was not reflected in the accessory chromosomes, where evidence of minor but significant genetic structure was found. This lack of structure in the core chromosomes and weak structure in the accessory chromosomes confirms that forces of genetic drift and selection are minor compared to sexual reproduction, in concurrence with multiple previous studies on other populations worldwide.</p