Investigating the current situation of chemical pesticides trade in Tripoli region and its suburbs in Libya

This study was conducted within the framework of a research program at the Agricultural Research Center for Sustainable Development during the 2021-2022 agricultural season through field visits to pesticide marketing and storage sites in Tripoli and its suburbs to investigate the condition of commercial stores and their suitability to health conditions, the nature of their activity and their legal status, along with the status of the people working in them, their educational level and the extent to which their awareness of the dangers of pesticides and their impact on their health. Some questions were also about the types of pesticides traded in the Libyan market, their physical condition, their specialties, their commercial sources, and how to dispose of their empty containers. It became clear from this study that approximately half of the pesticide shops were in the main streets of Tripoli, and only 27% of them were in rural areas. Moreover, no less than 50% of the stores do not have warehouses, and those that do have warehouses are considered inappropriate for storing these dangerous materials. It was also shown that there is a lack of attention and implementation of the sanitary conditions in pesticide stores, including ventilation, air conditioners, and the height of the stores. We also noticed that the percentage of licensed shops designated for selling pesticides did not exceed 35%, and that many of them hold licenses not designated for selling pesticides, and some of them don’t have license. As for the materials that are marketed alongside pesticides, most of them are agricultural equipment, with the presence of fertilizers and seeds. Regarding the persons that are selling pesticides, their ages range from the twenties to the fifties, and their educational levels vary, as the percentage of illiterate people was 15%, the percentage of those who obtained compulsory primary, middle, and secondary education was 49%, the percentage of those who obtained an intermediate and higher diploma was 23%, and the percentage of university salespeople was 13%. It is striking that 79% of the sellers are not specialized in the agricultural field. As for the level of knowledge of the sellers about the dangers of chemical pesticides, it was found that 72% of them have little to moderate knowledge. In addition, 77% of them do not wear protective clothing, and only sometimes at best, which shows that 43% of the workers’ health was negatively affected by their handling of pesticides. Finally, this study showed that the pesticides circulating in the Tripoli area are liquid, solid and gaseous in approximately equal proportions. As for the specialties of pesticides on offer, it turned out that 22% of them are insecticides, 21% are herbicides, 21% are fungicides, 19% are rodenticides, and 17% are acaricides. As for the sources of pesticides offered on the market, 36% of them were issued by commercial agents of international companies or from well-known wholesalers with clear addresses. However, 27% of the pesticides offered were imported by unknown importers or obtained through unlicensed and often unknown street traders. As for the methods used to dispose of containers, the study showed that 50% of the containers are disposed of by filling them up, burning them, or using the containers to place other materials such as food and medicines, which is generally considered a violation of internationally recognized health methods. This study is considered a model for the other Libyan cities and will contribute to providing decision-makers with important and vital information for regulating the pesticide trading sector in Libya

Effect of NaCl and Polyethylene glycol on the in vitro growth of two potato fungal pathogens Rhizoctonia solani and Fusarium solani

Soil salinization and drought can adversely affect microorganisms inhabiting this compartment and modulate their interaction with plants. In this study we evaluated the tolerance of two soil born fungal strains belonging to the species Rhizoctonia solani and Fusarium solani to grow at different concentrations of salt (0 to 1000 mM of NaCl ) and polyethylene glycol 6000 (0 – 37 % of PEG6000) in PDA and LB media. The results showed that R. solani showed better tolerance to NaCl concentration in LB in comparison to PDA medium, whereas the opposite behavior was noticed for F. solani. In addition, F. solani showed better tolerance to both NaCl and PEG6000 concentrations in comparison to R. solani. These results may help to understand and predict the impact of soil and water salinization on the development soil born fungal pathogens on cultivated plants

Reduced nitrogen and phosphorus fertilization combined with mycorrhizal inoculation enhance potato yield and soil mineral fertility

To improve sustainable agriculture it becomes crucial to minimize the use of chemical inputs and involve new practices that are more productive and healthier for humans and environment. Biofertilization with arbuscular mycorrhizal fungi (AMF), known for increasing the productivity of many crops including potatoes, could be considered as one of these sustainable practices. The purpose of this study was to determine whether mycorrhizal inoculation can minimize chemical fertilization for potato (Solanum tuberosum L.), one of the most demanding species in mineral elements. Thus, by studying the effect of chemical fertilization and mycorrhizal inoculant on potato yield and soil quality. Two doses of chemical fertilizer (NP) corresponding to 50 % and 100 % of the recommended dose has been applied in the presence or not of the mycorrhizal inoculant. The results have shown that adding arbuscular mycorrhizal fungi in combination with 50 % of the chemical fertilizer dose gives the best effects. A significant increase in yield, root colonization, and P soil content has been observed (P < 0.001). Thus mycorrhizal inoculation could reduce the application of synthetic fertilizers and thus improve yield while preserving the environment

A novel aspect of essential oils: Coating seeds with thyme essential oil induces drought resistance in wheat

Coating seeds with biostimulants is among the promising approaches in crop production to increase crop tolerance to drought stress. In this study, we evaluated the potential of coating durum wheat seeds of the cultivar 'Karim' with thyme essential oil on enhancing seed germination and seedling growth, and on plant growth promotion and induction of drought resistance. Coated seeds were pre-germinated, grown in hydroponics, and grown in pots under controlled well-watered and progressive water/nutrient stress conditions. Seed coating with thyme oil increased germination rate and enhanced seedling growth development in hydroponics. In the pot experiment, thyme oil increased, when well watered, root and shoot development, chlorophyll, nitrogen balance index (NBI), abscisic acid (ABA), anthocyanins and flavonoids in leaves, decreased nitrogen isotope composition (δ15N) and increased carbon isotope composition (δ13C) of shoots. Increasing water/nutrient stress in control plants induced higher accumulation of ABA and anthocyanins coupled with a transient decrease in chlorophyll and NBI, a decrease in shoot and root development, the Normalized Difference Vegetation Index (NDVI), shoot C content, δ15N, and an increase in δ13C, revealing the avoidance strategy adopted by the cultivar. Thyme oil had the potential to enhance the avoidance strategy by inducing roots elongation, reducing the loss of shoot and roots dry matter and chlorophyll, maintaining balanced NBI, an decreasing anthocyanins, flavonoids, and δ13C via maintaining lower ABA-mediated-stomatal closure. Thyme oil increased shoot N content and δ15N indicating preferential uptake of the 15N enriched NH4+. Coating seeds with thyme oil is suggested as a promising alternative approach to improve plant's water and nutrient status and to enhance drought resistance

Endophytic microbes modulate plant responses to abiotic stresses: a review

Many groups of microorganisms have been studied for their benefits towards humankind due to their capacity to produce natural compounds that can be valorized in many economic sectors such as agriculture. Due to the extensive use of chemicals pesticides and fertilizers, current agriculture systems facing several major problems such as emergence of resistant in pathogens and pests, soil infertility and bioaccumulation of toxic residues in the environment and particularly in foods which negatively affects human health. The use of natural products harmless to plants, humans and biodegradable constitute a promising way to overcome these problems. Modern agriculture systems are moving toward the use of beneficial microorganisms isolated from the soil, plant surfaces and inside tissues for developing eco-friendly products such as biofertilizers and biopesticides. Recent literatures show that colonization of plants by endophytes is the rule in nature and endophyte-free plant is a rare exception. Endophytes are microbes living inside plant tissues and supporting them in growth and development, as well as stresses tolerance without causing any apparent disease symptom. Abiotic stresses have a great impact on growth, production and health of plants. Many literatures show the role of endophytes in abiotic stress tolerance as well as mechanisms involved to cope with these constraints via the induction of stress-related genes and molecules. This review provides a summary of literature on how endophytes modulate plant growth and responses to abiotic stresses which may help to better understand their role in plant adaptation to environmental constraints and valorize their use in agriculture

Prospecting bacterial volatile organic compounds antifungal activities against postharvest diseases

Chemical pesticides have a plenty of negative impacts on human health and on the environment. Thus, modern agriculture cropping systems are moving towards more eco-friendly alternatives. This study aims to investigate the bioprotective effect of three volatile organic compounds (VOCs: N-Ethylaniline, 2-Heptanone and 3-Methylbutan-1-ol) produced by endophytic bacteria against 21 phytopathogenic fungal strains and their bioprotective effect on horticulture products i.e. tomato and lemon fruits and Potato tubers. The results showed that N-Ethylaniline and 3-methylbutan-1-ol had better antagonistic activity against the fungal strains by inhibiting the mycelia growth of the studied fungal strains at different concentrations. The N-Ethylaniline showed the lowest effective concentration (EC50) against B. cinerea strain S5 (0,258 mL/L headspace), Fusarium solani strain SB4.15.1 (0,496 mL/L headspace) and Colletotrichum gloeosporioides strain ManS3Fr02 (0,206 mL/L headspace). At EC50 this compound significantly reduced B. cinerea and C. gloeosporioides infections on tomato and lemon fruits, respectively. However, N-Ethylaniline didn’t showed significant effect on F. solani infection on Potato tubers. This study showed the broad spectrum of in vitro antifungal activity of N-Ethylaniline and its effect to reduce postharvest infections of some fungal diseases suggesting its potential use as a biofumigant

Variation of Medicago sativa varieties tolerance to Phoma medicaginis infection.

Due to its very important agronomic value and nutritional quality, Medicago sativa L. is considered as the queen of fodder and the first cultivated forage crop in the world. In field conditions, M. sativa is exposed to several biotic and/or abiotic constraints that affect its quality. In this regard, research is still underway to improve M. sativa resistance to many biotic stresses and, in this context, we analyzed the responses of a core collection of 10 varieties of M. sativa to Phoma medicaginis infection. Results from ANOVA showed that most growth parameters exhibited significant differences between the studied varieties. Nevertheless, only the number of healthy leaves among infection parameters varied significantly between the varieties. The local variety Gabès2355 exhibited the highest biomass. Positive correlations were found between the measured parameters. PCA based on the traits showing significant differences among the studied lines showed that the Gabès variety formed a separate group. Cluster analysis revealed that the studied varieties are classified into three major groups. The first group is formed by Gabès2353, the second group is composed of the Californian and El Hamma varieties, and the third group is constituted of the seven remaining varieties. Gabès2355 was the most tolerant to the Pm8 strain of P. medicaginis while Magna601 variety was the most susceptible. These two varieties will be useful to analyze the physiological and genetic determinants for M. sativa tolerance to P. medicaginis infection

Comparative study of the effect of salt stress, Alternaria alternata attack or combined stress on the Cakile maritima growth and physiological performance

Cakile maritima is a halophytic plant model that is well known by its ability to tolerate high salt concentrations. Salinity was reported to improve the tolerance of halophytes to several abiotic stresses; however, the involvement of salt in the tolerance to biotic stress is still scant. In the present work, the effect of salt on C. maritima responses towards the pathogenic Alternaria alternata was investigated. For that, C. maritima seeds were germinated for four weeks. Plants were then divided into four groups: i) Plants irrigated with salt (200mM NaCl); ii) Plants infested by fungus; iii) Plants irrigated with salt and infested by fungus and finally control plants (0mM NaCl, without inoculation). Our results showed that upon salt stress or fungal attack, plants reduced biomass production, hydration status and photosynthetic performance which were associated with a decrease in the gas exchange and chlorophyll fluorescence parameters, with a more pronounced effect upon fungal attack. However, under combined stress, a significant increase of these parameters was noticed, with a level close to that of control. Concerning nutrient contents, K, Zn, Fe, Cu and Mg decreased in the C. maritima leaves exposed to both stresses applied individually. In contrast, all these nutrients were increased in plants grown under combined stress. Taken together, we can conclude that plants grown under combined stresses had better growth rate and physiological performance compared to all other treated plants, and that salt may be the key in improving the C. maritima ability to tolerate fungal attack

High diversity of responses among Medicago truncatula lines to Phoma medicaginis infection.

Medicago truncatula is an omni-Mediterranean species grown as an annual forage legume. In addition to its small genome size and simple genetics, M. truncatula harbors several attributes, which make it an attractive model forage plant. In this study, we investigated the variation of responses in ten parental lines of M. truncatula to Phoma medicaginis infection. Plants were cultivated in the growth chamber under controlled conditions and were inoculated after two months with P. medicaginis. At harvest, 13 quantitative traits of growth and pathogenicity were measured. Results from ANOVA showed that the variation of analyzed parameters was explained by the effect of line. All measured parameters, except the root fresh weight, showed significant difference among the 10 studied lines. Most tolerant lines are those with the lowest ratios of the number of infected and dead leaves. Studied lines were clustered into three groups according to their responses to P. medicaginis infection. The most resistant TN6.18 line and most sensitive F83005.5 to P. medicaginis are useful for the exploration of physiological mechanisms and genetic determinants for M. truncatula tolerance to this constraint