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Fruit drop from pear trees causes serious losses in income. However, the application of plant bio-regulators improves the internal physiology of developing fruit by ensuring that they receive an adequate supply of water, nutrients, and other compounds necessary for their proper growth and development, which leads to improved size, quality, and ultimately better yield in a variety of fruit crops. This study investigated the foliar application of three plant growth regulators: CPPU at 10, 15, and 20 ppm, GA3 at 25, 50, and 75 ppm and NAA at 25, 50, and 75 ppm. The pear trees were sprayed four times: before flowering, full bloom, after three weeks, and after six weeks. The results showed that the spray of GA3 at 50 and 75 ppm gave the highest effect in increasing the shoot length, shoot thickness, leaf area, and leaf total chlorophyll. The spraying of NAA at 50 and 75 ppm was the best treatment in increasing the fruit set percentages, fruit yield, fruit weight, and fruit dimensions as well as the fruit content from soluble solids, and fruit sugars, while they reduced the fruit drop percentages comparing with the other applied treatments.

The influence of exogenous application of the amino acids Glutamic acid (Glu), Methionine (Met), L-Tryptophan (L-Try), and Lysine (Lys) at concentrations of 250 and 500 ppm was studied relative to the growth of peach trees. The trees were sprayed three times; before flowering, during full bloom, and one month later by 250 ppm Glu + 250 ppm Met + 250 ppm L-Try + 250 ppm Lys (combination 1) and 500 ppm Glu + 500 ppm Met + 500 ppm L-Try + 500 ppm Lys (combination 2), in comparison to trees that were not sprayed (control). A randomized complete block design was used. The individual application of four amino acids positively improved the shoot diameter, leaf chlorophyll, leaf area, and productivity as opposed to not spraying the trees. Additionally, the applied amino acids increased the fruit weight, size, firmness, length, and diameter, and the fruit content from the percentages of total soluble solids (TSS), TSS-acid, and anthocyanin contents, in contrast to the control. They also improved the fruit content from total, reduced, and non-reduced sugars as well as vitamin C and the leaf nutritional content from NPK. The application of combination 2, over the two seasons, was more beneficial.

The study aimed to comprehensively investigate the structural dynamics of a soil microbial community within a 100-year agricultural field experiment. The experimental design encompasses three distinct soil management practices, namely monoculture, five–year rotation, and random rotation, each with or without the incorporation of legumes and manure. Soil microbial communities were determined by the Next-Generation Sequencing (Illumina MiSeq analysis) of both the V3 and V4 hypervariable regions of the 16S rRNA gene for bacteria and Archaea, as well as ITS1 for fungi. In all soils, dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, and dominant orders were Actinomycetales, Rhizobiales, Acidimicrobiales, and Sphingomonadales. However, dominant fungal phyla were Ascomycota, Basidiomycota, and Zygomycota, and dominant fungal orders were Pleosporales, Eurotiales, Hypocreales, or Mortierellales. Compared to fallow land, agricultural soil management affected the microbial community of the soil, reducing the ratio of oligotrophs (e.g. Acidobacteria and Armatimonadetes) to copiotrophs (Actinobacteria or Gemmatimonadetes). Moreover, agricultural soil management contributed to an increased number of plant growth-promoting bacterial groups (PGPB), antagonistic to many fungal (e.g., Fusarium spp.) and bacterial pathogens (e.g., Bukholderiales, Xanthomonadales). However, generally in the study, there were no significant differences in microbial communities between monoculture and crop rotations. Moreover, two taxa can be considered as potential indicators of “healthy soil”: the nitrifying bacteria Nitrospira spp. whose abundance was strongly dependent on nitrogen, potassium, phosphorus, organic carbon, and soil pH, and the PGP fungi of the genus Mortierellla which depended mainly on nitrogen and pH. Finally, the genus Mortierellla was generally the most abundant in agricultural soils, especially in the five–year rotation with legumes, while fallow soils did not favour these microorganisms. In conclusion, various soil management practices strongly affect the soil microbiota and thus their ability to support land productivity.

This study aimed to evaluate how the combined presence of the synthetic fungicide azoxystrobin (AZ) and the biosurfactant-producing Bacillus sp. Kol B3 influences the growth of the phytopathogenic fungus Fusarium sambucinum IM 6525. The results showed a noticeable increase in antifungal effectiveness when biotic and abiotic agents were combined. This effect manifested across diverse parameters, including fungal growth inhibition, changes in hyphae morphology, fungal membrane permeability and levels of intracellular reactive oxygen species (ROS). In response to the presence of Fusarium and AZ in the culture, the bacteria changed the proportions of biosurfactants (surfactin and iturin) produced. The presence of both AZ and/or Fusarium resulted in an increase in iturin biosynthesis. Only in 72 h old bacterial–fungal co-culture a 20% removal of AZ was noted. In the fungal cultures (with and without the addition of the bacteria), the presence of an AZ metabolite named azoxystrobin free acid was detected in the 48th and 72nd hours of the process. The possible involvement of increased iturin and ROS content in antifungal activity of Bacillus sp. and AZ when used together are also discussed. Biosurfactants were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Microscopy techniques and biochemical assays were also used.

Salinity is a major social, economic, and environmental menace in climates with low rainfall and high evapotranspiration, and it influences plant growth and causes restriction to crop production in the world. Additionally, under salinity stress, numerous physiological processes such as photosynthesis, biomass accumulation, and photosynthate transfer are also harshly lessened, and it also limits the absorption of adequate water by plants and leads to a dimension in plant water status. Therefore, the current study was conducted to investigate the soil application of humic acid (HA) at 0, 0.5, 1 and 2 kg/tree alone or in combination with the foliar spraying of 0 mg ZnO2 + 0 mg TiO2, 200 mg ZnO2 + 60 mg TiO2 and/or 300 mg ZnO2 + 80 mg TiO2 through the two successive seasons 2022 and 2023. The results demonstrated that the use of HA alone or in combination with the spraying of TiO2 and ZnO2 greatly improved the leaf chlorophyll, flower number, fruit set percentages, fruit yields in kg or in ton per hectare, fruit weight, fruit size, and fruit firmness. Additionally, the same used treatments greatly improved the fruit content from TSS and oil percentages and also the leaf mineral content from N, P and K, while they minimized the fruit drop percentage and fruit moisture content as compared to control. The most positive influence was observed with the soil implementation of 2 kg HA combined with 300 mg ZnO2 + 80 mg TiO2 in the two experimental seasons.