Effect of solution concentration from a center pivot fertigation system on the growth and yield of summer maize in sub-humidclimate

摘要

To avoid the leaf burns caused by fertilizes intercepted in crop canopy during sprinkler fertigation, fertilizer concentration for a center pivot fertigation system should be carefully selected. Field experiment was conducted to study the effect of fertilizer solution concentration fertigated from a center pivot on plant height, leaf area index (LAI), SPAD, chlorophyll fluorescence characteristics, and yield of summer maize in the North China Plain. Five solution concentrations in mass fraction of 0.048%, 0.105%, 0.146%, 0.178%, and 0.312% (referred to as Nl, N2, N3, N4, and N5) were tested. Urea and ammonium sulfate mixed in a mass ratio of 3:1 was applied during jointing stage of summer maize. The total amount of nitrogen applied in the whole growth season, including the basal fertilizer of 132 kg ha~(-1), was 170, 215, 248, 273, and 380 kg ha~(-1)for Nl, N2, N3, N4, and N5, respectively. The results indicated that there was no significant difference in plant height, LAI, and SPAD for the five nitrogen rates tested. When a concentration of solution lower than or equal to 0.105% was used, a fertigatlon event would significantly increase the PSII activity Fv/FO and the photochemical efficiency Fv/Fm of plant compared to the values prior to fertigatlon. However, a significant reduction of Fv/FO and Fv/Fm was observed when the fertigatlon concentration used was greater than 0.105%. The yield of N2 treatment (12.51 ha~(-1)) was significantly higher than that In N3, N4, and N5 treatments, while therewas no significant difference in yield between Nl and the other treatments. The results suggested that fertigatlon through center pivot could Improve the photosynthetic activity of plant and enhance the efficiency of fertilizer production when a favorable fertilizer solution concentration was selected. A nitrogen rate of 215 kg ha~(-1) that was fertlgated at a concentration of 0.105% was recommended for sprinkler fertigatlon by this study.