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The information about the use of plant growth-promoting endophytic bacteria (PGPEB) with ornamental plants is still scarce. This study was designed to isolate and characterize PGPEB from different ...

The plant growth-promoting rhizobacteria (PGPR) application could reduce the use of synthetic fertilizers and increase the sustainability of crop production. Halophilic bacteria that have PGPR characteristics can be used in different environmental stresses. Two different strains isolated, purified, characterized as a PGPRs and phylogenetic identification using 16sRNA which was revealed to be closest matched at 99% with Bacillus halotolerans and Lelliottia amnigena. The isolates possessed plant growth promoting properties as exopolysaccharides (EPS) and indole acetic acid (IAA) production, Bacillus halotolerans had the ability to fix elemental nitrogen and the two strains have the ability to P-solubilization. Furthermore, the strains were evaluated in alleviation of different levels of salt stress on wheat plant at two experiments (Pots and a Field). Strains under study conditions significantly increased the plant height, straw dry weight (DW g plant-1), spike number, 1000 grain DW recorded 31.550 g with Lelliottia amnigena MSR-M49 compared to un-inoculated and other strain in field, grain yield recorded 2.77 (ton fed-1) with Lelliottia amnigena as well as N% and protein content in grains recorded 1.213% and 6.916 respectively with inoculation with Lelliottia amnigena, also, spikes length, inoculated wheat show reduction in both proline accumulation in shoots and roots especially with Lelliottia amnigena recorded 2.79 (mg g-1DW), inoculation significantly increased K+ in root-shoot, K+/Na+ in root-shoot and reduced Na+ in root-shoot compared with control. This confirmed that this consortium could provide growers with a sustainable approach to reduce salt effect on wheat production.

The world’s burgeoning population faces a great challenge concerning food security, which could be achieved through different sustainable agricultural practices. Trichoderma, as a ubiquitous fungus, is one of the most promising microorganisms that might offer several avenues for sustainable agriculture. Trichoderma spp. may guarantee a better solution for conventional problems in agriculture through several approaches including the protection of cultivated plants from undesirable abiotic and biotic conditions under changing environments and promoting their growth in poor or limited soil nutrients. The promising role of Trichoderma for vegetable production as a biocontrol and biofertilizers has been confirmed but this role of Trichoderma as a plant pathogen still needs more studies. Trichoderma could inhibit or suppress the growth of soil phytopathogens, promoting plant growth and soil health, through activation of many mechanisms including synthesis of antibiotics, mycoparasitism and competition for nutrients against plant deleterious microorganisms. The sustainable approaches of Trichoderma including biofortification, bio-remediation and phyto-remediation as well as exploring future research opportunities will be also handled in this work.

Broomrape parasitism on faba bean (Vicia faba L.) is the most destructive factor for this crop in Egypt. Pot experiments were conducted during the two successive seasons 2017/2018 and 2018/2019 to study the mitigation of broomrape stress on faba bean using a ten-fold dilution of 10% (w/v) spent mushroom substrate extract (SMSE) of Pleurotus ostreatus and the same dilution of culture filtrate of mushroom (MCF) grown in potato dextrose broth (PDB) at a rate of 48 l hectare&minus, 1 compared with the commercial herbicide Roundup (Glyphosate 48% emulsifiable concentrate) at a rate of 144 cm3 ha&minus, 1 on the two varieties (Misr3 and Sakha3) cultivated in broomrape-infested soil. The treatments include the use of mushroom products as foliar spray and/or soil amendment in addition to Roundup spraying as a recommended treatment. Using Gas Chromatography-Mass Spectrometry (GC-MS) spectroscopy, our results indicate that the major components of the two mushroom products were bioactive compounds such as polyphenol and high molecular weight aliphatic and aromatic hydrocarbons that may interfere with parasite and host metabolism. These results indicated that SMSE of P. ostreatus and MCF of the same mushroom grown in potato dextrose broth (PDB) gave the best control of broomrape, and increased plant height, root length, leaf area, chlorophyll concentration, relative water content and seed yield (g plant&minus, 1), as well as anatomical characters of leaves in the two faba bean varieties (Misr3 and Sakha3), such as upper and lower epidermis, palisade tissue, spongy tissue and vascular bundles. Additionally, electrolyte leakage was decreased in the treated plants compared to control plants and the plants treated with Roundup (glyphosate) because of the important role of SMSE and MCF in the improvement of faba bean water status.

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.

It is well established that the nutrients of plant play a vital role in all plant processes starting from the emergence, development, productivity, and metabolism reaching to the promotion and protection of plants. These plant nutrients could be in general characterized as macronutrients (e.g., Ca, Mg S, N, K, and P) and micronutrients (i.e., Fe, B, Cu, Mn, Cl, Ni, Mo, Co, and Zn) as well as beneficial elements (e.g., Si, Se, Na, and V). These previous mineral nutrients also could protect crop plants against both abiotic and biotic stresses by enhancing the plant resistance power and regulating the mineral nutritional status. Therefore, any plant nutritional problems (like poor soil fertility, imbalance, and deprived delivery of nutrients) definitely will lead to reduce the global production of foods. Thus, it should protect crop production from different stresses through the appropriate agricultural management. Soil salinity was and still one of these plant stresses. A distinguished role of plant nutrients (e.g., N, K, Se, and Si) in ameliorating soil salinity stress has been reported as well as nano-selenium and nano-silica. Several reports have confirmed the great role of these previous plant nutrients under saline soil conditions. Therefore, this review will focus on the role of selenium and silicon in conventional and nano-forms under saline soil conditions. The phytoremediation of these saline soils and the role of plant nutrients will be also highlighted.

The application of both selenium (Se) and silicon (Si) could ameliorate different negative effects of abiotic and/or biotic stresses on plant growth. Under salt-stress conditions, selenium and silicon also could improve plant growth as well as increase the activity of enzymatic antioxidants, improving the balance of ions and osmotic adjustment. They could also use as a resistance provider against plant diseases and the attacks of insects as well as a nutrient supplement. They could also maintain the fertility of soils through improving the bioavailability of nutrients in soils for plants. Apart from selenium and silicon, nano-selenium and nano-silicon have gained a great attention nowadays as eco-friendly technologies. These technologies are considered very important for expanding the biological applications of the nanomaterials. These Se- and Si-nanomaterials have been developed in the field of nanotechnology in order to biosynthesize different nanomaterials for more applications. Many organisms recently have been used in biosynthesizing different varieties of inorganic nanomaterials in well-defined chemical composition. Nano-selenium and nano-silicon are considered promising nanoparticles in agriculture due to their significant roles in the biological systems. Many benefits could be gained from using these nanomaterials such as protection of plants against diseases and different stresses. These nanoparticles should be investigated in more details concerning the nano-safety research. Therefore, this chapter focuses on the beneficial roles of selenium and silicon elements for higher plants in the terrestrial environments, especially plant growth, uptake, and metabolism as well as biogenic synthesis of their elements by some organisms.

The field of nanotechnology has gained a great progress regarding the agriculture and food industry. Thereby, an excessive use of engineered nanomaterials has led to spread huge amounts of nanoscale materials in the agroecosystems. Soil–plant system was and still one of the most environmental compartments regarding the fate and behavior of nanoparticles. This system, which has more than a treasure, also represents the rhizosphere area including dynamic and fate of different nutrients as well as the microbial activity in soils. These treasures include the significance of soil–plant system in plant nutrition, the biogeochemistry of nutrients, pedosphere and its interactions with nutrients, phyto- or bioremediation and biofortification, soil fertilization, and the sustainability of agroecosystem. No doubt that nanoparticles may exhibit both negative and beneficial effects on higher plants including the physiological, molecular, and biochemical parameters of various plant parts. So, there is a crucial need for understanding different biochemical and physical processes of plants associated with the exposure for nanoparticles and evaluating the role of these nanoparticles in either enhancing or retarding these plant features. Therefore, the tasks of nanoparticles in mitigating or ameliorating the plant stress and phytotoxicity should be investigated in more detail. Furthermore, more comprehensive studies are needed in order to perform the expanded knowledge on the alterations induced by different nanoparticles on different plant mechanisms including the biochemical, physiological, and molecular levels. Moreover, long-term investigations are also needed to be conducted to evaluate different roles of nanoparticles in regulating various plant physiological processes under stress. One great mission is also requested regarding the construction of a global database, which would be helpful for setting a global nano-agro-database accessible and useful worldwide.

The plant root–soil interfaces could be considered the rhizosphere area, which is the most important active zone in the soils for different microbial activities, biodegradation of pollutants and plant nutrition. Polluted soils are characterized by low organic matter content, limiting their microbial activity, nutrient availability and degradation of pollutants. Soil phyto- and/or bioremediation is mainly based on the use of plant roots and their associated soil microorganisms, whereas conventional approaches are based on physico-chemical methods in soil remediation. Plant root exudates are the most important compounds in the rhizosphere, which play a crucial role in the interactions between plant roots and soil microbes. It is worthy to mention that several plant species and soil microbes have been used in soil remediation for different pollutants. The role of rhizosphere and its significance in plant nutrition are mainly controlled by the change in climatic attributes including temperature, moisture content, precipitation, etc. Therefore, global warming and climate changes do have a great and serious effect on the agricultural production through their effects on the rhizosphere and in turn plant nutrition. Hence, the aim of this review is to evaluate the significance of rhizosphere in plant nutrition under the changing climate. Soil biological activity and its security will be also highlighted.