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 (SiO_2) and titanium dioxide (TiO_2) 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 30ᵒ 49 41.4 N and 32ᵒ 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 (T_1), 2.Copper oxychloride Cu_2(OH)_3Cl at concentration of 5000 ppm (T_2), 3.SiO_2 25ppm (T_3), 4.SiO_2 50ppm (T_4), 5.TiO_2 25ppm (T_5), 6.TiO_2 50ppm (T6), 7.SiO_2 25ppm + TiO_2 25ppm (T7), 8.SiO-2 25ppm + TiO_2 50ppm (T-8), 9.SiO_2 50ppm + TiO_2 25ppm (T_9) and 10.SiO_2 50ppm + TiO_2 50ppm (T10). The results indicated that incidence and severity of powdery and downy moilew significantly decreased with SiO_2 NPs whether sprayed at low or high concentration or if it was separate or in mixed with TiO_2 NPs when compared with control (T_1). Powdery mildew not response to individual sprayed TiO_2 NPs but in opposite, incidence and severity of downy moilew significantly decreased with increasing TiO_2 NPs concentration. up to 50 ppm compared with control. The obtained results revealed that foliar application with the tested materials include Cu_2(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 TiO_2NPs whether in low or high concentration achieved superior promotion than SiO_2 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 T_1 and T_2. Furthermore, no significant effects were recorded between T_10, T_8, T_6, T_5, T_9 and T_7 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, TiO_2 NPs. Subsequently, control treatment and TiO_2 NPs in low or high concentration whether individual or in combination with low concentration of SiO_2 NPs significantly produced the highest heavy fruit weight per plant and plot while the lowest unmarketable fruit weights and number were achieved from foliar sprayed SiO_2 NPs with their concentrations in addition to T_10. For what it was no significant differences were found between T_10, T_2, T_9, T_8, T_7, T_4 and T_3 treatments, there achieved the maximum production whether per plant, plot or feddan as well as marketable yield compared with control treatment. Spraying SiO_2 NPs at concentration of 50 ppm achieved minimum un-marketable yield. Chemically, photosynthetic pigments, NO ⁻, P_2O_5-- and K⁺ contents significantly increased with all treatments compared with control while the highest accumulate in plant tissues were gotten from T_10. 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 SiO_2 and TiO_2 NPs compared with control or cupper oxychloride. Also, of observation that TiO_2 NPs increased photosynthetic cortical and exchangeable gas spaces more than SiO_2 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 T_10, T_6, T_8, T_6, T_6 and T_6.