PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Presently, finding an effective alternative to mineral N-fertilizers is the biggest challenge in sustainable development especially after some research has proven that synthetic nitrogen fertilization is related to the increase of impurities in sugar beet. A field trial was executed in a split plot design to study the possibility of using titanium dioxide as a substitute for mineral N-fertilizers with sugar beet plants grown on salt-affected soil (EC=6.25 dSm^-1) and irrigated simultaneously with water having an EC value of 4.86 dSm^-1. Treatments were N-fertilization (applied or not) as main plots and ten Ti treatments represented subplots, where the Ti was added as titanium dioxide (TiO₂) at rates of 5.0,10.0 and 15.0 mgL^-1 using different application methods i.e., foliar application, soil addition and combination of both methods (foliar+ soil) in addition to control treatment (without titanium dioxide). Plant performance at period of 90 days from sowing i.e., plant height and chlorophyll content as well as top and roots yield, juice quality and soil available N, P and K at harvest stage were evaluated. The findings indicated that plants that received N possessed performance better than that grown without N-fertilization. Concerning Ti treatments, Ti combined application method (foliar+ soil) was the most effective followed by foliar application method alone then soil addition method alone, where the best performance with all studied application methods was recorded when plants were treated with Ti at rate of 5 mg L^-1 then the performance decreased as the Ti rate increased. In other words, the addition of Ti at rate of 5.0 mg L^-1 as foliar and soil addition together (as combined application method) was the superior treatment. For example, the plants untreated with both N and Ti had the lowest chlorophyll value (35.97, SPAD) which increased with N addition only without Ti addition to 40.15 (reading SPAD), while the value increased to 41.98, 40.83 and 42.90 (reading SPAD) when plants were treated with Ti at rate of 5 mg L^-1 under foliar application, soil addition and combined application method, respectively.