Effects Of Phosphate Fertilizer And Lime Application On Yield,Phosphorus Absorption And Utilization And Arbuscular Mycorrhizal Fungi Infection Of Sweet Corn

Sweet corn is an important economic crop in China because of its abundant nutrients and unique flavor.It is widely demonstrated that phosphorus application rates can significantly affect the yield of sweet corn.As a kind of symbiotic microorganism,arbuscular mycorrhizal（AM）fungi can form associations with roots of crops,and enhance growth and nutrient uptake of host plants.However,phosphorus application may induce negative effect on the mycorrhizal symbiosis as high phosphorus inputs likely decrease mycorrhizal colonization.Liming is an effective approach amending soil acidity for agricultural soils in Hainan province.Yet,the effects of phosphorus application rates and liming on sweet corn yield and mycorrhizal colonization are still unclear.In this study,Guang Liang Tian 27 sweet corn was used as the material to study the effects of phosphate fertilizer and lime application on the yield,AM fungal infection and phosphorus absorption and utilization of sweet corn.It provides theoretical and technical support for the sustainable development of phosphate fertilizer management measures for sweet corn in this region.Split plot design was manipulated in the field experiment,the main plot was four phosphate fertilizer rates:P0(0kg hm^-2),P60(60 kg hm^-2),P120(120 kg hm^-2),P180(180 kg hm^-2);the split plot was two lime levels:L0(0 kg hm^-2)and L1(750 kg hm^-2).The microcosm experiment was adopted with completely random design,with four phosphate fertilizer levels:P0(0 kg hm^-2),P60(60 kg hm^-2),P120(120 kg hm^-2)and P180(180 kg hm^-2).The main results were as follows:（1）In the field experiments,lime application significantly increased soil p H by 0.74units on average.But phosphorus application had no significant effect on soil p H;in the second season,the p H of P60 under L1 treatment was the highest,which was 7.06.Application of phosphate fertilizer and lime had no significant effect on soil organic matter,available potassium and total nitrogen.Application of Phosphate fertilizer significantly increased soil microbial biomass phosphate,total phosphate and available phosphate.After planting sweet corn for two consecutive seasons,there was no significant difference in soil available phosphorus between P60 treatment and the initial value.Compared with the initial value,soil available phosphorus in P120 and P180 treatments were increased by 103.8%and228.4%respectively,indicating that the accumulation of soil available phosphorus in soil surface（0-20 cm）increased significantly.（2）In the field experiment,phosphate fertilizer significantly reduced the infection intensity,arbuscular abundance and vesicle abundance of AM fungi both at the silking and fresh feeding stage of sweet corn in the second season.Under L1 treatment,at the silking stage of sweet corn in the second season,the infection intensity of AM fungi in P60 treatment was significantly higher than that of the P120 and P180 treatments which were increased by80.2%and 116.3%respectively.Under no phosphorus treatment,L1 significantly increased the infection of AM fungi on sweet corn roots compared with L0 treatment.（3）In the microcosm experiment,phosphate fertilizer significantly increased the biomass of sweet corn plants,but significantly decreased the root-shoot ratio of sweet corn plants.Phosphorus application significantly reduced the infection intensity,arbuscular abundance and vesicle abundance of AM fungi.There were significant positive correlation among plant biomass,phosphorus accumulation and soil available phosphorus,and the ratio of root to shoot,which were negatively correlated with AM fungal infection intensity,and arbuscular and vesicles abundance.（4）In the field experiment,L1 significantly increase the yield of sweet corn under P60treatment,compared with L0 treatment,which was increased by 12.7%.But there was no significant difference of the yield of sweet corn among P60,P120 and P180 treatments.These results indicated that the high yield of sweet corn can be achieved by the combination of P60 and L1 treatment.The plant biomass and phosphorus accumulation of sweet corn were significantly increased by phosphorus fertilizer application.The application of phosphorus fertilizer significantly reduced the fresh ear yield,phosphorus harvest index and phosphorus physiological efficiency of 1 kg phosphorus production of.The agronomic efficiency,utilization rate and partial productivity of phosphorus fertilizer of sweet corn under P60 treatment with lime addtion were significantly higher than that of P120 and P180treatments.In conclusion,the combination of 60 kg hm^-2 phosphorus application and 750 kg hm^-2lime application could be an effective way achieve high-yield,phosphorus absorption and utilization efficiency,and mycorrhizal infection intensity of sweet corn while reducing phosphorus fertilizer application rate and maintaining the content of soil available phosphorus.