Tomatoes are an important agricultural product because they contain high concentrations of bioactive substances, such as folate, ascorbate, polyphenols, and carotenoids, as well as many other essential elements. As a result, tomatoes are thought to be extremely beneficial to human health. Chemical fertilizers and insecticides are routinely utilized to maximize tomato production. In this context, microbial inoculations, particularly those containing PGPR, may be utilized in place of chemical fertilizers and pesticides. In this study, we investigated the effects of PGPR (Bacillus subtilis, and Bacillus amyloliquefaciens) and cyanobacteria when utilized alone, and in conjunction with each other, on the growth, quality, and yield of fresh fruits of tomato plants. The results showed that the inoculation significantly increased all measured parameters of tomato plants compared with the control. Combined use of B. subtilis and B. amyloliquefaciens had a positive impact on tomato yield, increasing fruit yield. Moreover, leaflet anatomical characteristics were altered, with increased thickness of the upper epidermis, lower epidermis, palisade tissue, spongy tissue, and vascular bundles. Tomato fruit quality was improved, as measured by an increased number of fruit per plant (76% increase), fruit weight (g; 33% increase), fruit height (cm; 50% increase), fruit diameter (cm; 50%), total soluble solids (TSS; 26% increase), and ascorbic acid (mg/100 g F.W.; 75% increase), relative to the control, in the first season. In addition, fruit chemical contents (N, P, and K) were increased with inoculation. The results suggest that inoculation with B. subtilis and B. amyloliquefaciens could be successfully used to enhance tomato plant growth and yield.

Fennel fruits (Foeniculum vulgare Mill.) represent one of the plant-based natural spices. This study aims to improve the fruit yield and essential oil (EO) quality by reducing the undesirable component, estragole, under different fertilizer treatments. The fertilizers included chemical nitrogen, phosphorus, and potassium (NPK), and also the organic additive, rabbit manure (RM). For bio-fertilization, plants were inoculated with a mixture of N-fixing bacteria, and P- and K-solubilizing bacteria with/without vesicular-arbuscular mycorrhizal fungi. The results showed that fruit and EO yield parameters, total phenolic content (TPC), total flavonoid content (TFC), and DPPH scavenging activity of fruit extracts were enhanced by fertilizer treatments in both growing seasons. NPK at 150% of the recommended dose (NPK150) and RM at 60 m³/fed (RM60) recorded the highest values of plant height, umbel number/plant, 100-fruit weight, fruit yield, chlorophyll, carbohydrates, N and P content, EO content, and yield. TPC and TFC were enhanced by using biological fertilizers. DPPH scavenging activity was higher in organically and biologically fertilized fennel. The GC-MS analyses of EO revealed higher contents of the desirable trans-anethole in the organically and chemically fertilized fennel. However, the highest proportion of estragole, the undesirable compound, was recorded for NPK150 and unfertilized plants. On the contrary, increases in the EO content and yield of fennel fruits were achieved by RM along with a reduction in estragole, enhancement in trans-anethole, and increments in other favorable compounds such as fenchone and limonene. In addition, the inhibition of estragole formation was recorded with bio-fertilizers, which also increased the trans-anethole content. Furthermore, the trans-anethole/estragole ratio was significantly higher with the application of organic and bio-fertilization. Hence, organic and bio-fertilizer resources can produce high-quality fennel fruit and EO. The reduction in the use of chemical fertilizers can help to reduce environmental pollution.

Integrated biofertilizers such as Plant Growth-Promoting Rhizobacteria (PGPRs), cyanobacteria, and yeast can considerably improve the growth, integrity, and overall health of crops, including cowpea. In this study, we assess the benefits of applying microbial fertilizers as an eco-friendly approach to partially substitute chemical fertilizers while maintaining growth and yield characteristics in cowpea plants. We investigated the role of the three microorganisms, Bacillus amyloliquefacien (B), Nostoc mucorum (C), and Saccharomyces cerevisiae (Y), individually and in four possible combinations (B + C, B + Y, C + Y, and B + C + Y) as integrated bio-fertilizers on the microbial enzyme activities, plant growth parameters, and yield characteristics of cowpea. Plants inoculated with B + C + Y mixture resulted in significant improvement in dehydrogenase enzyme activity by 390%, chlorophyll by 180%, plant dry weight by 130%, and in the pod length and dry weight by 68% and 190%, respectively, compared to non-inoculated plants. The grain total carbohydrates increased by 170% over the control due to treatment with B + C + Y. The B + C + Y treatment also positively influenced the anatomy of the terminal leaflet with a 16.6% higher thickness of the midrib zone, 22.6% increase in vascular bundle length, and 42.4% and 33.5% increases in upper and lower epidermal leaf layers, respectively. Additionally, palisade and spongy tissues increased by 36.9% and 26.5%, respectively, compared to the control. An integrated nutrient management program using biofertilizers is recommended for achieving higher yields and environmentally safe cowpea production.