Responses in nutrient uptake in rice roots to infestation of brown planthopper,Nilaparvata lugens(Stål) (Homoptera: Delphacidae)

This study investigates the uptake of nitrogen (N), phosphorus (P), and potassium (K) by rice roots as a response to infestation by the rice brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae) at two developmental stages (i.e. beginning-heading and grain-filling) of two rice varieties, Zhendao 2 (japonics rice) and Xieyou 63 (hybrid indica rice), respectively. The results show that the impact of N. lugens infestation at the beginning-heading stage on N, P, and K uptake was not only more serious, but also that the recovery rate of root uptake after the removal of N. lugens was slower, as compared to the grain-filling stage. The percent reduction of N uptake following N. lugens infestations at the beginning-heading stage of Xieyou 63 was significantly greater in comparison to Zhendao 2 at the same stage. There was no significant difference in N uptake between two developmental stages, but P and K uptake by roots following N. lugens infestation were significantly different between the two developmental stages. The maximum reduction of K uptake was shown at the beginning-heading stage in both rice varieties. The recovery rate of N, P, and K uptake by roots after the removal of N. lugens from rice plants varied with the rice variety, developmental stage of rice and infestation duration. In Xieyou 63, the recovery rate of K uptake by roots of the plants infested at the beginning-heading stage was slower than that at the grain-filling stage. Plants of Zhendao 2 infested at the two developmental stages had showed slower recovery rate of K uptake compared with N and P uptakes. These findings partially explain the virulence of N. lugens feeding on rice plants, and thus may have important implications for integrated management of N. lugens.