Physiological Mechanism Of Deep Phosphorus Fertilizer Improving Phosphorus Efficiency Of Spring Maize Under Subsoiling Measure

Modern maize cultivar root present characteristics of horizontal tighten and vertical strengthen, under the densification and subsoiling cultivation measures,the trend of root dry weight at the deep soil layer more apparent.Xiliaohe plain is the main maize production area in Inner Mongolia.Many years of small machinery operation and high levels of phosphorus,bringing soil phosphorus accumulation in surface layer and underlayer content not enough.The spatial distribution of Soil phosphorus nutrient and high yield spring maize root matching poor, is the main cause of affect phosphorus absorb utilization efficiency. To reveal deep phosphorus fertilizer to the control of spring maize phosphorus efficiency physiological mechanisms in the subsoiling measure, during 2013-2015,in Xiliaohe plain irrigated area.Zhengdan 958 and Xianyu 335 were used as the test material,using a combination of field and soil pillar cultivation method. Studied the effect on root crown characteristic, physiological property,accumulation of material,yield and phosphorus absorption efficiency spring maize by phosphorus down under subsoiling and subsoiling measures.The main conclusions are as follows:1.Subsoiling improved spring maize root crown structure and anti-aging, improving the ability of spring maize biomass production and phosphorus absorption efficiency. Subsoiling improved spring LAI,upper leaves particularly obvious,SOD and POD activity in leaves increased,MDA content declined,leaves senescence slowed down. LAI high values maintain stage growth, Pn and NAR to improve; Promoted root depth distribution, root number and specific root length increased, amplitude decreased.root extension decreased;Root activity under 60cm soil showed apparently.Active absorption area 0-20cm soil showed significantly;enhanced the root of SOD and POD activity,MDA content declined. Improvement of root crown structure and delay of aging increase the dry matter and phosphorus accumulation of spring maize. Transit more smoothly,the contribution rate higher for grain,to increased grain yield and phosphorus absorption efficiency for spring maize. Zhengdan 958 more sensitive to subsoiling.2.Under subsoiling,different manuring phosphorus depth,the root crown characteristic,physiological characteristics, material production capacity existed difference,impact on phosphorus absorption and utilization efficiency.LAI,the SOD,POD activity of the leaves, Pn and NAR manuring phosphorus depth treatment showed P12>P18>P6>P24, MDA content show P6>P24>P18>P12,total root weight showed P12>P6>P18>P24.Root number in 10cm soil layers showed P6> P12>P18>P24,in 20cm soil layers showed P12>P6>P18>P24,in 30cm soil layers showed P24>P12>P18>P6.Specific root length showed P12>P6>P18> P24.Under rotary tillage measure,in 0-20cm soil layers root activity,SOD,POD activity showed P12>P6>P18>P24,under subsoiling+rotary measure showed P12 >P18>P6>P24;under rotary measure MDA content showed P24>P18>P6> P12,under subsoiling+rotary measure showed P24>P18>P12>P6.Spring maize dry matter and phosphorus accumulation amount, transshipment amount and the contribution rate showed P12>P6>P18>P24,phosphorus absorption efficiency, harvest index,partial productivity and grain yield showed P12 treatment highest. Differences among treatments in subsoiling measures especially apparent, among variety Zhengdan 958 was more apparently than Xianyu 335.3.Under earth pillar cultivar,further confirmed on deep phosphorus fertilizer for spring maize physiological characteristics and phosphorus efficiency has a certain impact, but suitable phosphorus depth different from field trials.Manuring phosphorus depth treatments,spring maize LAI,the SOD,POD activity of leaves,Pn、LAD and NAR showed P18>P12>P6>P24,MDA content showed P24>P6>P12>P18.Root dry weight in 0～10cm、10-20cm soil layers showed P18>P12>P6>P24,in 20～ 30cm、30-40cm soil layers showed P18>P24>P12>P6.Root number in 10cm soil layers showed P6>P12>P18>P24,in 20cm soil layers showed P12>P18>P6> P24,in 30cm,40cm soil layers showed P18>P24>P12>P6. Specific root length showed P18>P12>P6>P24,P18 has reached the significant differences with the other treatments (p<0.05).In 10-20cm soil layers root activity showed P18>P12 >P6>P24,active absorption area showed P12>P18>P6>P24.P18 with higher dry matter and phosphorus accumulation amount,transshipment amount and the contribution rate,phosphorus absorption efficiency,harvest index, partial productivity and grain yield showed higher than other treatments.Due to limited earth pillar in the horizontal space and the decrease of soil bulk density,lead to root further downward, so resulting in earth pillar under the conditions of cultivation depth (18cm) deeper than field suitable for phosphate fertilizer depth (12cm)4.Under earth pillar cultivar,layer manuring phosphorus treatments spring maize root crown characteristics,physiological characteristics and material production capacity overall better than CK.Under layer manuring phosphorus treatments,the activity of LAI,SOD,POD, Pn,LAD and NAR all showed PⅣ(6cm、12cm、18cm respectively 1/3)> PⅢ(12cm part 2/3、18cm part 1/3)> PⅡ (12cm manuring all the amount)>PⅠ (12cm part 2/3、6cm part 1/3), MDA content showed PⅠ>P Ⅱ>PⅢ>PⅣ.Root dry weight 0～10cm soil layers showed PⅠ>PⅣ>PⅡ>PⅢ,in 10-20cm soil layers showed PⅡ>PⅢ>PⅠ>PⅣ. In 20-30cm and 30-40cm soil layers showed PⅣ>PⅢ>PⅡ>PⅠ.Root number 10cm showed PⅣ>PⅠ>PⅡ> PⅢ,below 20cm soil layers showed PⅣ>PⅢ>PⅡ>PⅠ.Specific root length showed PⅣ>PⅠ>PⅡ>PⅢ,except PⅣ with PⅠ the difference was not significant, with other treatments reached significant levels (p<0.05).In 10-20cm soil layers root activity showed PⅡ>PⅢ>PⅣ>PⅠ, active absorption area showed PⅡ>PⅢ>PⅠ>PⅣ.PⅣ treatment spring maize with higher dry matter and phosphorus accumulation amount, transshipment amount,the contribution rate to grain is high, phosphorus absorption efficiency, harvest index, partial productivity and grain yields were higher than other treatments.5. For years of small power machinery operation of maize major production areas, The subsoiling and moderate deep phosphorus fertilizer can improve the spring maize phosphorus absorption and utility efficiency,was high-yielding condition effective ways to reducing phosphorus and increase efficiency.