Salinity impedes soil and crop productivity in over 900 million ha of arable lands worldwide due to the excessive accumulation of salt (NaCl). To utilize saline soils in agriculture, halophytes (salt-tolerant plants) are commonly cultivated. However, most food crops are glycophytes (salt-sensitive). Thus, to enhance the productivity of saline soils, gypsum (CaSO4·2H2O) as well as bio-organic (combined use of organic materials, such as compost and straw with the inoculation of beneficial microbes) amendments have been continuously recognized to improve the biological, physical and chemical properties of saline soils. CaSO4·2H2O regulates the exchange of sodium (Na+) for calcium (Ca2+) on the clay surfaces, thereby increasing the Ca2+/Na+ ratio in the soil solution. Intracellularly, Ca2+ also promotes a higher K+/Na+ ratio. Simultaneously, gypsum furnishes crops with sulfur (S) for enhanced growth and yield through the increased production of phytohormones, amino acids, glutathione and osmoprotectants, which are vital elicitors in plants’ responses to salinity stress. Likewise, bio-organic amendments improve the organic matter and carbon content, nutrient cycling, porosity, water holding capacity, soil enzyme activities and biodiversity in saline soils. Overall, the integrated application of gypsum and bio-organic amendments in cultivating glycophytes and halophytes is a highly promising strategy in enhancing the productivity of saline soils.

The antimicrobial activity of six plant extracts from ocimum basilicum (Sweat Basil), Azadirachta indica (Neem), Eucalyptus chamadulonsis (Eucalyptus), Datura stramonium (Jimsonweed), Nerium oleander (Oleander), and Allium sativum (Garlic) was tested for controlling Alternaria solani in vitro and in vivo. In in vitro study the leaf extracts of D. stramonium, A. indica, and A. sativum at 5% concentration caused the highest reduction of mycelial growth of A. solani (44.4, 43.3 and 42.2%, respectively), while o. basilicum at 1% and 5% concentration and N. oleander at 5% concentration caused the lowest inhibition of mycelial growth of the pathogen. In greenhouse experiments the highest reduction of disease severity was achieved by the extracts of A. sativum at 5% concentration and D. stramonium at 1% and 5% concentration. The greatest reduction of disease severity was achieved by A. sativum at 5% concentration and the smallest reduction was obtained when tomato plants were treated with o. basilicum at 1% and 5% concentration (46.1 and 45.2 %, respectively). D. stramonium and A. sativum at 5% concentration increased the fruit yield by 76.2% and 66.7% compared to the infected control. All treatments with plant extracts significantly reduced the early blight disease as well as increased the yield of tomato compared to the infected control under field conditions.

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Nine isolates of Trichoderma were collected from Assiut Governorate, Egypt, as leaf surface and endophytic fungi associated with onion flora stalks. Four isolates were identified as Trichoderma harzianum, while five isolates were belonging to Trichoderma longibrachiatum. The antagonistic activity of these isolates against onion purple blotch pathogen Alternaria porri was studied in vitro using dual culture assay. All tested Trichoderma isolates showed mycoparasitic activity and competitive capability against the mycelial growth of A. porri. Mycoparastic activity of Trichoderma was manifested morphologically by the overgrowth upon the mycelial growth of the pathogen and microscopically by production of coiling hyphae around pathogen hyphae. Isolates of T. harzianum exhibited high ability to compete on potato dextrose agar (PDA) medium causing the maximum rate of pathogen inhibition (73.12%), while isolates of T. longibrachiatum showed inhibition rate equalling 70.3%. Chitinase activity of Trichoderma was assayed, and T. harzianum Th‐3013 showed the maximum value contributing 2.69 U/min. Application of T. harzianum Th‐3013 to control purple blotch disease in vivo under greenhouse conditions caused disease reduction up to 52.3 and 79.9% before and after 48 h of pathogen inoculation, respectively, while the fungicide Ridomil Gold Plus caused disease reduction comprising 56.5 and 71.7%, respectively. This study proved that T. harzianum Th‐3013 as a biocontrol agent showed significant reduction in onion purple blotch disease compared with the tested fungicide.

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Rhizobacteria have been reported as bioagents of bacterial diseases and plant growth promoters. The present in vitro study and greenhouse experiment aimed to evaluate the efficiency of Bacillus subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, and P. aeruginosa for the control of bacterial wilt caused by Clavibacter michiganensis subsp. michiganensis and promoting the growth of tomato plants. Effect of formulated and cell suspensions on disease reduction and the pathogen colonization frequency in plants were assessed. The tested bacterial species were able to inhibit the growth of the causal pathogen in vitro. Under greenhouse conditions, the highest reduction in disease severity was detected in tomato plants treated with formulated B. amyloliquefaciens (74.4%), followed by P. aeruginosa (66.7%), while the lowest reduction occurred in tomato seedlings treated with cell suspensions of P. fluorescens (40%) and B. subtilis (53.3%). The four bacterial species produced siderophores, hydrogen cyanide and indole acetic acid in different concentrations. The study confirmed that the use of the four bacterial species as suspensions or formulations could be applied as future eco-friendly alternatives to the synthetic fungicides for controlling the bacterial wilt of tomato caused by C. michiganensis subsp. michiganensis.

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