RĂSPUNSUL GRÂULUI COMUN LA ACȚIUNEA ASOCIATĂ A FACTORILOR DE STRES BIOTIC ȘI ABIOTIC

Abstract

The Integral Plant Vigor Index recorded high specificity of Alternaria alternata, Drechslera sorokiniana and Fusarium solani isolates in phenotype formation, with both tolerance and susceptibility of the trait being attested. The highest Percentage Index reduction was recorded for the interactions of fungal isolates with M614. The M614 genotype showed a greater trait reduction in wheat response to the separately acting PEG 6000 treatment. The concomitant action of biotic and abiotic stress factors caused negative effects, namely additivity (increased susceptibility), but also positive effects (tolerance) for Plant Vigor Index. The combined action of the three A. alternata isolates with PEG 6000 produced the greatest reduction in the index, a phenomenon associated with the high aggressiveness of Alternaria spp. toxins under drought conditions. The action of D. sorokiniana and F. solani in coexistence with drought modulated the reduction or increase of the effect of the associated action of stress factors. F. solani isolates in coexistence with drought induced the positive tolerance effect of the index. The similar distribution (Ward`s method) of wheat genotypes in the PEG treatment separately, but also in the combined FC + PEG treatment confirms the importance of drought in modulating wheat x necrotrophic fungi interactions.