Objectives In order to increase the efficiency utilization of phosphate fertilizer in coastal salinized flavo-aquic soil, the syngism of spraying plant elicitor, Paecilomyces variotii metabolite,and coating diammonia phosphate with polyureathane were studied in htis paper.
Methods A pot experiment was carried out using summer maize cultivar 'Zhengdan 958' as test crop and coastal salinized flavo-aquic soil as the test soil. No phosphorus application was used as control, and two P application levles were set up (normal, 1.80 g/pot and 20% reduction,1.44 g/pot). Four phosphorous fertilizer treatments included as: diammonium phosphate (DM), DM pluyspraying elicitor (PE + DM), coated DM (C-DM), coated DM pluyspraying elicitor (PE + C-DM), making a total of 9 treatments. At the 58 days after sowing, rhizosphere soil samples were collected for determiantion of soil acide phosphatase activity and available P contents, and the biggest founctional leaf samples were collected for the measurement of activities of photothysetic related enzymes. At harvest, the biomass, yield and P contents of maize plants were investigated, and the soil available nutrient contents in maize rhizosphere were measured.
Results Under the same P input level and compared with DM, C-DM could significantly increase yield by 5.89%–10.10%, P use efficiency by 6.8–8.1 percentage points; PE + DM could significantly increase yield by 7.46%–9.31%, P use efficiency by 4.8–6.2 percentage points, acid phosphatase activity in maize rhizosphere by 17.65%–27.90%; PE + C-DM significantly increased yield by 7.78%–16.30%, P use efficiency by 8.8–14.0 percentage points.When P input was reduced by 20%, coating and spraying elicitor showed synergism. Compared with C-DM and PE + DM, PE + C-DM significantly increased acid pohosphatase activity in rhizosphere by 21.8% and 11.7%, pyruvate dikinase activity by 33.3% and 14.3%, AGPase activity by 75.5% and 47.6%; increased soil available P contents by 33.7%, 19.4% and 15.0%, 26.1% at the 58 and 103 days after sowing, and the yield in PE + C-DM was not significantly different from that in DM under normal P (1.80 g/pot) put treatment.
Conclusions Under the tested conditions, coating diammonium phosphate with polyureathane and combined with spraying elicitor on soil surface could increase the activity of phosphatase in rhizosphere soil during the key growth period of maize, enhance the supply intensity of soil phosphorus, and increase the activities of photosynthase and amylase in leaves, so improve the utilization rate of phosphate fertilizer. When the phosphorus input was reduced by 20%, the maize yield could maintain stable with the two measurement.
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