Effect of titanium as a stimulant of atmospheric nitrogen fixation on faba bean plants [electronic resource]

Includes bibliographic reference

Stimulants that enhance atmospheric nitrogen fixation, whether biological or non-biological,
can potentially decrease the reliance on industrial nitrogen fertilizers. Biological stimulants
involve living organisms, while non-biological stimulants involve naturally occurring substances.
Therefore, a field experiment was conducted to assess the impact of using TiO2 (extracted from the
mineral ilmenite, which has the chemical formula FeTiO3) as a catalyst to facilitate the conversion of
atmospheric nitrogen into nitrate without the involvement of microorganisms. The tested plant in this
investigation was faba bean plants. The primary treatments in the experiment consisted of T1: Without
titanium or rhizobium inoculant (as control1); T2: Soaking seeds before sowing in a solution having a
titanium concentration of 6 mg L-1; T3: With rhizobium inoculant (as control2) and T4: Soil injection of
titanium at rate of 6 mg L-1. The sub-main factor involved the foliar application of various rates of
titanium: F1: Without titanium (control); F2: With titanium (3 Ti mg L-1); F3: With titanium (6 Ti mg L-
1); F4: With titanium (9 Ti mg L-1). The obtained results show that the soaking seeds before sowing in
a solution having a titanium concentration of 6 mg L-1 (T2 treatment) was the superior for obtaining
the maximum values of nitrogen content in leaves as well as growth performance (e.g., plant height,
fresh and dry weights…etc.) and productivity (e.g., seed yield, seeds content of protein and
carbohydrate…etc.) followed by T3 treatment then T4 treatment and lately T1 treatment. Regarding
foliar applications, there was a notable and gradual impact of titanium on nitrogen content in leaves,
thus all the growth and productivity characteristics that were studied. As the concentration of titanium
was increased from 0 mg L-1 to 3 and 6 mg L-1, there was a gradual increase observed in these traits,
followed by a significant decrease when the concentration of titanium reached 9 mg L-1. Furthermore,
it was observed that the values obtained from the control treatment, which did not involve any
titanium foliar application, were higher than those found with the plants sprayed with 9 Ti mg L-1,
indicating that excessive titanium application have a negative effect on the traits. In general, the
obtained results revealed that soaking faba bean seeds before sowing in a solution containing 6 mg Ti
L-1 with foliar application of solution having a concentration of 6 mg Ti L-1 resulted in the highest
nitrogen content in leaves, growth performance, and productivity. Finally, the study indicates that
TiO2 has the potential to serve as a cost-effective partial substitute for synthetic nitrogen fertilizers.
Nevertheless, it is crucial to bear in mind that the process of non-biological nitrogen fixation on TiO2
surfaces is still a new and under-explored field of research. More studies are necessary to comprehend
the complete potential of TiO2 as a nitrogen fixation stimulant and to assess its efficacy in diverse
crop types and environmental conditions.
Keywords: TiO2, rhizobium, N fixation, Nitrogen uptake.

Summary in Arabic