Nurseries alter the absorption of imidacloprid in rice

Tray and dry nursery systems increase the absorption of imidacloprid applied in rice seed treatment. The effect occurs due to greater retention of the insecticide on the seed surface and the concentration of the product in the rhizosphere. This is the conclusion of a study by Chinese researchers (DOI 10.1002/ps.71098).

Scientists evaluated the absorption and translocation dynamics of imidacloprid in rice seedlings under different nursery systems. The objective involved identifying the mechanisms responsible for the efficiency of the product applied via seed coating.

In the tray-based nursery, the biological concentration factor of imidacloprid in the aerial part reached 0,0278 after seven days. In the dry nursery, the index reached 0,0167 in the same period. These values ​​represented increases of 7,13 times and 4,28 times, respectively, compared to the conventional nursery in a flooded area.

The absorption pathway assays showed that root absorption contributed most to shoot accumulation. This pathway surpassed seed-mediated absorption by 1,68 to 5,61 times.

Quantitative analysis indicated a longer persistence of the insecticide on the seed surface in non-flooded systems. The concentration-time index of imidacloprid on the seed surface was 5,73 times higher in the tray nursery and 5,14 times higher in the dry nursery, compared to the flooded nursery, at seven days.

Experiments in soil columns also indicated retention of imidacloprid in the root zone under non-flooded conditions. In the conventional flooded nursery, rapid vertical leaching occurred.

According to the researchers, tray and dry systems enhance the systemic delivery of the insecticide through two routes. They prolong the retention of the product in the seed and concentrate the active ingredient in the rhizosphere. The result may guide nursery management to improve seed treatment efficiency and initial protection of rice seedlings.