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.

Drought is one of the major abiotic stress factors limiting crops production in Oltenia area, Romania. In order to study the response of six maize hybrids to drought stress, the trials were conducted in research field of ARDS Simnic – Craiova, during 2017-2018 (non-stressed conditions) and 2018-2019 (drought stress). Six tolerance indices including: abiotic tolerance index (ATI), stress susceptibility percentage index (SSPI), Stress tolerance index (STI), mean productivity (MP), relative drought index (RDI) and golden mean (GM), were utilized on the basis of grain yield. Results from analysis of variance showed that there is a significant difference in 1% of probability level among hybrids in terms of grain yield and tolerance indices. The yield in non-stress conditions (Yp) showed significant positive correlations with ATI, SSPI, STI and MP, and negative correlation with RDI and GM. The yield in drought conditions (Ys) showed significant positive correlation with RDI and GM, and negative correlation with ATI and SSPI. None of the tolerance indices used could identify the high yielding hybrids under drought and non-stress conditions. Based on the ranking method, the hybrids ‘Felix’ and ‘P 9903’ were the most droughts tolerant. Therefore, they hybrids are recommended to be grown under drought prone areas and to be used as parents for breeding of drought tolerance in other cultivars.

Rosa canina (wild rose, bush, bramble) is a shrub commonly encountered in the wild flora of Romania, spread from the coast up to altitudes of 1200 m (1700), with low requirements to pedoclimatic factors. From this species are used the false-fruits (Cynosbati fructus) mature, dried, harvested from wild flora or cultures, with food and therapeutic importance, due to their multiple properties, but mostly because of its high content of vitamin C. In this way, it was studied the germoplasm existent in some areas of Oltenia (Romania) to identify biochemically and technology valuable biotypes from biochemically and technologically point of view. The results indicate a high and very high variability in the biochemical and technological parameters analyzed. Thus, the content of TSS was recorded between 10% (B2) and 18% (M1), the vitamin C was over 560 mg / 100g to populations S1​​, S3 and the acidity in was 1.4 to 3.6%. Recorded values ​​for the mass of 100 fruit-technological and economically significant, were between 117g (A1) and 286g (B3 and T4) and the percentage of pulp/100g fruit ranged from 49.2 (M1) and 66.5 (T1).

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.

Maize yield is highly influenced by environmental factors, especially by increasing average temperature and the uneven distribution of rainfall, in the Oltenia area. Our study evaluated the relationship between maize yield and two climatic factors, namely rainfall and average temperature, using correlation analysis and linear regression method. The experiments with 20 Romanian maize hybrids were placed at Agricultural Research and Development Station Şimnic, during four years (2015-2018). The results show significant impact of average temperature and rainfall on maize yield in this region. The average temperatures during grain-filling period, that correlated strongly negative with the yield (r = -0.973*) and the rainfall during sowing to anthesis period, that correlated strongly positive with the yield (r = 0.966*), were dominant climatic factors which explained of 94.6% and 93.3% respectively, of inter-annual variability of maize yield. Understanding the challenges associated with variation in rainfall and average temperature at specific phenological stages in maize is essential for efficient management of crop production in each area.

For organic agriculture, wheat cultivars with good and stable grain yield across years are needed. Grain yield and hectolitre weight of 10 cultivars were estimated in field trials for three years at conventionally and organically production systems under the central part of Oltenia, Romania conditions. Our research evidentiated that cultivar influenced significant only hectolitre weight; production system influenced significant the both grain yield and hectolitre weight, and interaction between cultivars x production system was non-significant for the both traits. On average for the study period, the grain yield from the organic production system was by 35% lower than that achieved from the conventional production system. Hectolitre weight was also, affected by production system showing in the organic system values by 2% lower than in the conventional system. The cultivar Miranda was more stable than the other studied cultivars in both conventional and organic production system. On average most cultivars fulfilled the requirements for Grades 2 and 3, but the percentage of cases below the 72 kg/hl limit (non bakery value) varied from 0 to 66.7% in both production systems.