Titanium: An Element of Non-Biological Atmospheric Nitrogen Fixation and A Regulator of Sugar Beet Plant Tolerance to Salinity

There is unprecedented interest in the biological and non-biological atmospheric nitrogen fixation via some elements e.g., titanium, nickel, vanadium .....etc to reduce the mineral N-fertilizers in the future, especially under salinity conditions. Also, it is known that synthetic nitrogen fertilization may increase the impurities in the sugar beet. So, A field trial ( as an exploratory experiment) was executed in a randomized complete block design (RCBD) to highlight the role of the Ti element in non-biological atmospheric nitrogen fixation and regulating sugar beet plant tolerance to salinity conditions ( soil EC value =6.25 dSm-1 & irrigation water EC value =4.86 dSm-1). Treatments were as follows; T1: Without Ti (0.0 mg L-1); T2: Adding Ti as foliar application (5.0 mg L-1); T3: Adding Ti as foliar application (10.0 mg L-1); T4: Adding Ti as foliar application (15.0 mg L-1); T5: Adding Ti as soil injection (5.0 mg L-1); T6: Adding Ti as soil injection (10.0 mg L-1); T7: Adding Ti as soil injection (15.0 mg L-1); T8: Combination of both methods (Soil + foliar) (5.0 mg L-1); T9: Combination of both methods (Soil + foliar) (10.0 mg L-1) and T10: Combination of both methods (Soil + foliar) (15.0 mg L-1). At the harvest stage, top &roots yield and juice quality were evaluated.

The findings illustrate that the difference due to the studied treatments was significant, where the sequence order of the evaluated Ti treatments from the most effective to the less was as follows;T8>T2>T3>T9>T5> T6 >T1> T7>T4>T10. Through the statistical comparison among the studied treatments, it can be noticed that the combined addition method of Ti (foliar plus soil) was the most effective then foliar application method as alone followed by the soil injection method alone. Also, the best Ti rate was 5.0 mg L-1 under all studied application methods, but the performance decreased as the Ti rate increased and this may be due to Ti toxicity at high concentrations. Also, it can be noticed that the plant performance under the control treatment was better than that treated with 15.0 Ti mg L-1 under all studied application methods. Generally, a better understanding of titanium toxicity in plant tissues may promote risk assessment and safe use of it.