Comparative Studies Using Nanotechnology on Fungal Diseases Defense to Productivity Improvement of Squash Crop

The objective of this paper was to study the effect of silicon dioxide (SiO₂) and titanium dioxide (TiO₂) nanoparticles NPs sprayed separate or in combination compare with traditional practices on plant ability to resist fungal diseases and improving growth and productivity of zucchini squash (Cucurbita pepo L.) crop in Al-Kantara Sharq experimental station located 30^o 49' 41.4" N and 32^o 24' 11.4" S, Eastern part of Al-Ismailia governorate within Sinai, Egypt during summer seasons of 2015 and 2016.
The treatments were: 1.Control spraying with distilled water (T₁), 2.Copper oxychloride Cu₂(OH)₃Cl at concentration of 5000 ppm (T₂), 3.SiO₂ 25ppm (T₃), 4.SiO₂ 50ppm (T₄), 5.TiO₂ 25ppm (T₅), 6.TiO₂ 50ppm (T₆), 7.SiO₂ 25ppm + TiO₂ 25ppm (T₇), 8.SiO₂ 25ppm + TiO₂ 50ppm (T₈), 9.SiO₂ 50ppm + TiO₂ 25ppm (T₉) and 10.SiO₂ 50ppm + TiO₂ 50ppm (T₁₀).
The results indicated that incidence and severity of powdery and downy moilew significantly decreased with SiO₂ NPs whether sprayed at low or high concentration or if it was separate or in mixed with TiO₂ NPs when compared with control (T₁). Powdery mildew not response to individual sprayed TiO₂ NPs but in opposite, incidence and severity of downy moilew significantly decreased with increasing TiO₂ NPs concentration. up to 50 ppm compared with control.
The obtained results revealed that foliar application with the tested materials include Cu₂(OH)₃Cl compared with control showed significant effect on all studied morphological growth characters, yield components and marketable yield as well as photosynthetic pigments and nitrogen, phosphorus and potassium (NPK) contents. Results refer that individual TiO₂NPs whether in low or high concentration achieved superior promotion than SiO₂ NPs on vegetative growth characters which expressed as shoot height, number of branches and leaves plant^-1, largest leaf area, fresh and dry weight plant^-1 and dry matter percentage, while the maximum values were attained from T₁₀ compared with T₁ and T₂. Furthermore, no significant effects were recorded between T₁₀, T₈, T₆, T₅, T₉ and T₇ but there were achieved the highest values of fresh and dry fruit weight and fruit dry matter percentage when compared with control while the highest number of fruits were attained from all tested materials except, TiO₂ NPs. Subsequently, control treatment and TiO₂ NPs in low or high concentration whether individual or in combination with low concentration of SiO₂ NPs significantly produced the highest heavy fruit weight per plant and plot while the lowest un-marketable fruit weights and number were achieved from foliar sprayed SiO₂ NPs with their concentrations in addition to T₁₀. For what it was no significant differences were found between T₁₀, T₂, T₉, T₈, T₇, T₄ and T₃ treatments, there achieved the maximum production whether per plant, plot or feddan as well as marketable yield compared with control treatment. Spraying SiO₂ NPs at concentration of 50 ppm achieved minimum un-marketable yield. Chemically, photosynthetic pigments, NO₃^-, P₂O₅^-- and K⁺ contents significantly increased with all treatments compared with control while the highest accumulate in plant tissues were gotten from T₁₀. Anatomically, results and photomicrograph indicated that thin epidermis layers surrounded malformed and destroyed palisade and spongy tissues as a result to fungal diseases infection were observed in untreated plants (control). On opposite, leaf thickness and upper and lower epidermis layers as well as space area (%) were increased when plants treated with separate or mixing at low or high concentration SiO₂ and TiO₂ NPs compared with control or cupper oxychloride. Also, of observation that TiO₂ NPs increased photosynthetic cortical and exchangeable gas spaces more than SiO₂ NPs which increased cell wall thickness. The maximum leaf thickness, palisade length, sponge length, upper epidermis thickness, lower epidermis thickness and area space (%) were attained from T₁₀, T₆, T₈, T₆, T₆ and T₆.