Abstract: A field experiment was designed to explore zinc (Zn) accumulation characteristics in mature paddy rice plants (Japonica rice Yang Yu No.2) after agronomic Zn biofortification. Zn fertilizers were distributed to the paddy field during the tillering and filling stages. Rice plants were harvested and analyzed in the mature stage. The results show that Zn contents in all organs and Zn accumulation per plant increase with the increasing level of fertilization, while Zn distribution vary with different treatments. The highest Zn content in stems is up to (1349±209)mg·kg-1, which is 43 times that of the control group (tillering stage), while Zn contents in brown rice increase by not more than 209% and 297% for the tillering and filling stage treatments, respectively. Zn accumulation in the tillering stage treatment is significantly higher than that in the filling stage (the maximum accumulation is 4540 μg for the tillering stage and 2662 μg for the filling stage). In contrast, Zn harvest index is up to 0336 for the filling stage, much higher than that of the tillering stage with a maximum of 0194. Zn biofortification through soil-applied Zn fertilizers can not only significantly increase Zn accumulation of the rice plants but also increase Zn content and Zn mass in grains. Compared to the tillering stage, it is more conducive to improve Zn level in rice grains during the filling stage.

Key words: field trials, soil-applied fertilizers, agronomic Zn biofortification, paddy rice, Zn accumulation