Reta Drăghici

The study on the valorization of natural resources through cowpea cultivation represents a challenge to mitigate the negative effects of climate change on the environment and on the food security of the population in drought-affected areas globally, and specifically in the sandy soil area of Romania. Thus, the existence in Romania of an area of approximately 439,000 ha with sands and sandy soils, soils with low natural fertility (below 1.2% humus) and with deficient hydrophysical properties, implies finding solutions for their efficient valorization through ecological modeling of the species/varieties structure, depending on the adaptability of the plant in a given area. In this sense, given the economic importance of cowpea, given by the plant’s properties (drought resistance, source of increasing the organic matter content in sands, source of atmospheric nitrogen fixation, good precursor plant, source of protein for humans and animals), the cultivation of this species in a sustainable agricultural system is outlined, as an alternative solution to the cultivation of other leguminous plants. Considered a crop suitable for a climate change scenario, the conservation of genetic biodiversity and the establishment of technological inputs are essential objectives for promoting cowpea in a sustainable agricultural system, given the increasing drought in the world and the increasing need for protein.

The purpose of this study was to monitor the biological potential of sunflower cultivation to capitalize on the pedoclimatic conditions in the sandy soil area of southern Oltenia. The results obtained during 2024-2025 showed that sunflowers capitalized on the microclimate in this area, carrying out all the physiological processes of plant growth and development over a period of about 108,9 days, under conditions in which the air recorded a total thermal resource of 2491°C. Positive correlations were highlighted between the soil humus content and the morphological characteristics of the plant, namely, plant height and leaf area index. The seed production obtained from sunflowers varied within the limits of 3281-4326.5 kg, with a thousand-seed weight of 55.8-66.7 g and a hectoliter weight of about 28.7-34.05 kg/hl. The 0.23% increase in soil humus content led to statistically significant differences in seed production and seed quality indices (thousand-seed weight and oil).

This study was conducted in the experimental field cultivated with peanuts at Research and Development Station for Plant Culture on Sands Dabuleni during the period 2023-2024. The objective of this study was to determine some agronomic characteristics of some peanut genotypes used in the breeding process. In this study, five indigenous peanut genotypes and six foreign genotypes were used as plant material, arranged in randomized blocks with three replications. According to the average results over two years, the number of pods per plant of the peanut genotypes varied between 26.4-35.5 pods per plant, the weight of the pods per plant between 57.8-88.2 g per plant, the weight of 1000 grains between 657.5-951.5 g, the peeling percentage between 63-67.3 %, and the average pod production between 2539-5828 kg/ha.

The research was carried out in the period 2024-2025 and aimed at the comparative competition culture behavior of seven new cowpea lines obtained at the Research and Development Station for Plant Culture on Dăbuleni Sands, in order to introduce the most valuable ones into culture. The results obtained showed that the vegetation period of the new cowpea lines lasted 69.5-82.5 days, by accumulating total thermal resources in the air of 1637.9-1970.7 0C, standing out by earliness of 12.5-15.5 days compared to the Doljana variety (control), the LD 5/2020 and LD 6/2020 lines. Compared to the control variety, the new cowpea lines recorded lower values of plant height and leaf index and better fruiting of the plant. The lines with the best production results (1718.51-2007.11 kg/ha) were highlighted: LD 3/2020, LD 5/2020 and LD 6/2020, which stood out significantly and distinctly significantly from the Doljana variety. The grain production obtained from the assortment of cowpea genotypes studied was distinctly significantly positively correlated with the number of pods/plant (r=0.838**) and significantly negatively correlated with the leaf area index (r= - 0.754*). From the point of view of production quality, the lines LD 1/2020, LD 3/2020, LD 5/2020 and LD 6/2020 stood out for their high crude protein content in the grain (26.19-26.72%), with differences of 1.59-2.2%, statistically assured compared to the control variety.

Field experiment was conducted to evaluate the vegetative growth, main productivity elements and the production of eight peanuts genotypes grown on sandy soils and to assess relationships among their yield components. The experiments were carried out in the period 2021-2022 at the Research Development Station for Plant Culture on Dăbuleni Sands. The results showed that the percentage of flowers transformed into gynophores and the percentage of gynophores transformed into pods were characteristics that contribute to the increase of production in peanuts grown on sandy soils. The total number of flowers per plant was negatively correlated with the percentage of flowers transformed into gynophores and pods, while the percentage of flowers transformed into gynophores and pods were positively correlated with pod production. The highest pod production was obtained in the Viviana genotype which had the lowest number of flowers per plant and the highest percentage of flowers that developed into pods.

The purpose of this study was to study the behavior of wheat under non-irrigated conditions in the context of recent climate changes, with the objective of choosing the soil for the maximum manifestation of the plant's biological potential under conditions of thermohydric stress. In this sense, five work points were placed in plots sown with the Glosa wheat variety on two types of soil (loamy-sandy and chernozem), in order to evaluate the plant's behavior according to fertility. The obtained results highlighted a degree of twinning of the plant of about 89.74%, in the wheat crop placed on chernozem, exceeding by 16.8% the degree of twinning recorded in wheat plants grown on sandy-loamy soil, where the average of the analyzed points was 72.94%. The analysis of the phytosanitary state of the wheat crop revealed a degree of attack of 46-64% caused by the infection with Puccinia striiformis + Septoria tritici and 0-1.9% caused by Erysiphe graminis, the intensity of the attack being slightly higher with the sown wheat on the chernozem type soil as a result of a higher density of plants and the induction of a wetter microclimate the architecture of the leaf apparatus. The results obtained during the harvesting of the plant, highlighted the recording of the highest productions in the plots of wheat sown on chernozem soil (3664-4735kg/ha), exceeding on average by 82.5% the production recorded on sandy-loamy soil.

The aim of this study was to monitor the development of the maize plant depending on the preceding plant (rye; alfalfa for forage), with the objective of promoting crop rotation with alfalfa jumping plots within the agricultural system practiced on sandy soils. The results obtained showed that alfalfa incorporated into the soil after five years had a positive effect on soil fertility and implicitly on the behavior and productivity of maize. Thus, the content of organic matter, left in the soil after incorporating alfalfa, was 4.3 times higher than that recorded in the soil with the preceding plant rye. The beneficial role of the alfalfa precursor plant was highlighted on the stress behavior of the maize plant, which best regulated its resistance mechanism to stress conditions by binding at the cellular level a percentage of water bound to 3.03%, higher by 0.43% compared to maize sown after rye. Also, the maize sown after alfalfa showed better character stability, the coefficients of variability having lower values compared to the maize grown after rye, and at harvest the grain production was 27.9% higher, compared to the sown after rye, the difference in production being statistically significant.

This study investigates the effects of the Bacillus licheniformis (BL) ATCC 21424 strain, as a potential bacterial probiotic in broiler diets based on soybean meal (SBM) or cowpea seeds (CWP), on growth performance (GP), bone mineralization, and intestinal/fecal microbiota status (0 to 42 d age). A 2 × 2 factorial arrangement was employed in a completely randomized design, with four dietary treatments: SBM and CWP diets with or without BL supplementation (1.0 × 10¹¹ CFU spores g⁻¹ feed). A total of 480 one-day-old mixed-sex Ross 308 broiler chickens were randomly assigned to the treatments, with 6 pens of 20 chicks each. The results showed that broilers fed with CWP diets showed comparable body weight gain (BWG), feed intake (FI), and feed conversion rate to those fed the SBM diet (p > 0.05). The inclusion of BL improved BWG during the grower and finisher periods (p = 0.01) and overall study (p < 0.001), resulting in a numerical increase in FI (p = 0.054). In addition, BL in birds’ diets reduced abdominal fat (p = 0.032) and influenced cecum weight (p = 0.040). Additionally, BL improved tibia iron (Fe) and phosphorus (P) bone mineralization and reduced the calcium–phosphorus (Ca:P) ratio (p = 0.0001). Microbial analysis revealed that BL inclusion decreased Coliforms counts in the CWP diet (p = 0.073), reduced E. coli in the ileum (p ≤ 0.05), and lowered Clostridium spp. and Enterococcus spp. in the cecum broilers on SBM diets (p ≤ 0.05). The presence of Staphylococcus spp. in broiler feces was also reduced in both SBM and CWP groups (p < 0.05). In conclusion, the addition of BL to broiler diets enhanced growth performance and bone mineralization and positively influenced gut and excreta bacterial populations in both SBM and CWP diets.

This study was carried out on the rotation of cowpea-rye + cowpea in successive crops for green manure-sorghum grains, with the objective of increasing the fertility of sandy soils by incorporating green cowpea manure into the soil in combination with chemical fertilization with NPK. In this sense, after harvesting the rye plant, the cowpea was sown, which was then incorporated into the soil during the formation of the beans in the pod. Before incorporating the cowpea biomass into the soil, the initial fertility status of the soil was assessed, and in the spring, the soil was sown with sorghum grain in two fertilization variants (N80P80K80 and N150P80K80). The soil chemical analyses carried out at the end of the vegetation cycle of the sorghum plant showed that by incorporating 52.4 t/ha green cowpea biomass (9.24 t/ha dry biomass), the quality properties of the soil were significantly improved, with annual increases of 0.17–0.29 g/kg in total nitrogen, 9.5–13.33 mg/kg in extractable phosphorus, 11.33–24 mg/kg in exchangeable potassium, and 0.08–0.12 g/kg in organic carbon, also depending on the sorghum fertilization system. It has also been shown to reduce the acidity of the soil pH and improve the water holding capacity of the soil.

As a result of the low organic matter content of the sandy soils in Romania, for the success of most crops, large amounts of chemical fertilizers are needed, which can often lead to the pollution of groundwater with nitrates, given the poor hydrophysical properties in terms of retaining chemical elements by these soils. In this sense, the study carried out in the period 2020-2023 within the rotation cowpea-rye+cowpea successive crop-sorghum for grains, aimed to promote the system of sustainable agriculture, by incorporating into the soil, in the form of green manure, the cowpea sown in succession after the rye. The soil quality analyses, carried out the following year after harvesting sorghum for grains, showed that by incorporating 52.4 t/ha of cowpea biomass into the soil between October 15-20, the quality characteristics of the sandy soil improved significantly. Thus, compared to the initial state of soil fertility, there were annual increases of 0.017-0.029%, in total nitrogen, by 9.5-13.3 ppm, in extractable phosphorus, by 11.333-24 ppm, in exchangeable potassium and by 0.008-0.012%, to organic carbon, also depending on the sorghum fertilization system. Also, the incorporation of green cowpea manure into the soil contributed to reducing the acidity of the soil pH and improving the water holding capacity of the soil profile.