Abstract: This paper studied the effects of different nitrogen and phosphorous application rates (112.5～337.5 kg N·hm^-2 and 90～270 kg P₂O₅·hm^-2) on the population growth and grain yield of hybrid wheat C6-38/Py85-1 under field condition. The results showed that the total number of population stems (PS), population dry weight (PDW), leaf area index (LAI), photosynthetic potential (PP) and crop growth rate (CGR) were the lowest under low fertilization rate(112.5 kg N·hm^-2 and 90 kg P₂O₅·hm^-2), PS and PDW were higher under high fertilization rate (337.5 kg N·hm^-2and 270 kg P₂O₅·hm^-2) than under medium fertilization rate (225 kg N·hm^-2and 180 kg P₂O₅·hm^-2), and LAI, PP and CGR were higher under high than under medium fertilization rate before flagging, jointing, and anthesis stage, respectively, but in adverse after these stages. Under low and medium fertilization rates, PS had no mid-parent heterosis (H_m), while under high fertilization rate, it had the positive values of 6.3%, 49.7%, 4.2% and 10.8% at before winter, jointing, anthesis, and maturing stages, respectively. The H_m of LAI and PDW increased significantly with increasing fertilization rate, except that the H_m of LAI was 3.8% higher under medium than under high fertilization rate at filling stage while that of PDW had no significant difference between these two fertilization rates at maturing stage. The H_m values of PP and CGR were the lowest in the whole growth period under low fertilization rate, and lower before jointing-flagging and flagging-anthesis stage but higher after these stages respectively under medium than under high fertilization rate. The grain yield and itsH_m of the hybrid wheat were the highest under medium fertilization rate, lower under high fertilization rate, and the lowest under low fertilization rate. The grain yield under medium fertilization rate was 216.2 kg·hm^-2 higher than that under high fertilization rate, but its H_m had no significant difference between these two fertilization rates.

Key words: Liriomyza sativae, Parasitoids, Life table, Controlling effect