The effect of mesoporous titanium dioxide nanoparticles on germination traits of black saxaul seeds (Haloxylon aphyllum (Minkw.) Iljin) under drought stress

Nowadays, due to land use change and destruction of natural resources induced by human activities, attention to desertification has immensely become widespread. One of the most important species for biological rehabilitation of desert areas on a large scale is the hawthorn plant. Hawthorn is a plant belonging to the family Amaranthaceae, the two species of which are called white saxaul (Haloxylon persicum Bunge ex Boissier & Buhse) and black saxaul (Haloxylon aphyllum (Minkw.) Iljin) are more notorious and widespread in Iran. These plants own extensive root systems and stabilize running sands. The aim of this study was to investigate the effect of mesoporous titanium dioxide nanoparticles on germination traits of black saxaul seeds under drought stress, as an important species in desert areas.

The experiment was performed as a factorial experiment in a completely randomized design with 3 replications. Experimental treatments included five titanium nano dioxides with concentrations of 0, 25, 50, 100 and 200 mg / l and six drought stress levels including 0, -4, -8, -12, -16 and -20 bar. After nanopriming, black saxaul seeds were subjected to drought stress for 15 days in a germinator at a temperature of 20 °C with four replications. After germination, in each of the treatments, germination percentage (GP), germination rate (GS), mean germination time (MGT) and seed vigor index (VI) were calculated.

The results of two-way ANOVA and mean comparison of germination indices showed that the highest germination percentage (74%) belonged to the zero level of stress treatment with a concentration of 200 mg/l and the lowest one (3%) belonged to -20 bar treatment with 25 and 200 mg/l nano-titanium dioxide. With increasing drought stress intensity from zero to -20 bar level, germination rate decreased from 7.01 to 0.43 seeds per day. The highest amount of seed vigor index at zero drought level belonged to the treatment of 200 mg/l concentration of nano-titanium, with a rate of 325.77.

The results showed that germination indices and initial growth of black saxaul seeds decreased in all primed and unprimed treatments with increasing drought stress, and nanopriming with titanium dioxide had a positive effect on seed germination traits.