Dorina Bonea

Cytogenetic effects induced by the fungicide Royal Flo to maize (Zea mays L.)

Abstract The present study investigates the cytogenetic effects of the fungicide Royal Flo on mitotic cell division in maize (Zea mays L.) root cells. The maize grains were treated with various fungicide concentrations (50, 70, and 80%) for 20, 24 and 48 h exposure times. The results obtained indicate that the fungicide Royal Flo had some cytogenetic effects, by reducing the mitotic index and inducing various cytologic and chromosomal anomalies. These effects manifested differently, their intensity being proportional to the concentration and exposure time. The most frequent chromosomal anomalies were bridges, fragments and binucleated cells, but sticky chromosomes, rings chromosomes and cells with a micronucleus have also been seen. This study proves that the fungicide Royal Flo, even when administered in smaller quantities than generally recommended, reduces the germination and the mitotic index of maize cells and induces a large number of chromosomal anomalies, which suggests its toxic, mutagenic potential. Consequently, we should identify the optimal concentrations for each agricultural species, so that the efficacy of the fungicide does not diminish and, at the same time, its cyto-genotoxic potential is kept low.

The allelopathic, cytotoxic and genotoxic effect of Ambrosia artemisiifolia on the germination and root meristems of Zea mays

Abstract The problem of the invasion of the invasive species Ambrosia artemisiifolia L. is particularly important for Romania and other countries. Besides the fact that this species is a strong allergen, its presence in agricultural crops can aggravate the growth and development of plants, just like other weeds. The purpose of this study was to investigate the allelopathic effect of different concentrations of aqueous extracts obtained from the above-ground part (leaves and stems) and from the underground part (roots) of Ambrosia artemisiifolia on the germination and growth of Zea mays. Furthermore, for the first time, we have conducted a study of the cytotoxic and genotoxic effects of these extracts in meristematic cells of Zea mays. All extracts, and in particular 10% above-ground extract, significantly reduced the germination of the seeds and had a different effect on the growth of maize seedlings. Also, these extracts reduced the mitotic index (MI) and induced chromosomal alterations such as multinucleated cells, C-metaphases and sticky, ring, fragment, and bridge-type chromosomes, thus revealing a strong cytotoxic and genotoxic effect on maize.

Effect of Sweet Marjoram (Origanum majorana L.) Cogermination and Aqueous Extracts on Maize (Zea mays L.)

Abstract The purpose of this study was to examine the allelopathic effect of sweet marjoram (O. majorana) on the germination and early stages of maize seedlings. Two experiments were performed under laboratory conditions (in Petri dishes). In the first experience, Origanum majorana seeds were cogerminated with maize (Zea mays) seeds in the same Petri dish. For the second experience were used aqueous extracts from fresh and dry aboveground biomass of the sweet marjoram (stem, leaves) in concentrations of 1%, 2% and 3%. Cogermination of O. majorana with maize seeds has significantly stimulated the germination index (Gi) and growth of maize seedlings. Aqueous extracts of sweet marjoram in a concentration of 1% and 2% have significantly stimulated shoot length of maize. On the other hand, aqueous extracts at a concentration of 3% significantly inhibited root length of maize. These results suggest that the cogermination with sweet marjoram seeds may be an alternative to biostimulation of maize initial growth, and aqueous extracts in low concentrations could be used as growth bioregulators.

THE INFLUENCE OF THE HYDRIC STRESS ON THE CAPACITY OF GROWTH AND DEVELOPMENT ON THE SUNFLOWER

The purpose of the present work was to highlight the effect of the climatic conditions of the year 2007, which is characterized through an extreme drought, on a set of 10 hybrids of sunflower found in the tests at SCDA ?imnic. The knowledge of this aspect has great importance in the zoning of the sunflower hybrids. It was detected that in such conditions the seeds of sunflower can remain in the latent state (an enough long period) until they find the optimal conditions of germination. Also, the complex metabolic and physiological whole of the plant modified, the phonological phase of development became shorter and the physiological maturity was rushed.