| Objective:Early spring’s low temperature significantly reduce soil phosphate availab ility,which is not conducive to phosphorus nutrition in maize seedling stage.After the extensive application of drip irrigation technology in Xinjiang,the fertilization system has changed significantly.the amount of base fertilizer has decreased year by year,almost all fertilizers are applied to the soil through the drip irrigation system,resulting in insufficient phosphorus nutrition in maize seedling stage.Maize seedling stage is very sensitive to phosphorus nutrition,and its critical nutrition period is at three leaf stage.Phosphorus deficiency in seedling stage has an irreparable impact on the later growth of maize.Therefore,the application of starter phosphorus fertilizer is an important way to solve the above problems.This paper provides a scientific reference for different application methods and different application rates of phosphate fertilizer on the growth and phosphorus nutrition improvement of Maize in Xinjiang.Methods:（1）Effect of different application methods of starter phosphate fertilizer were carried out in Tianye Agriculture Experiment Station,Shihezi City,Xinjiang,in 2020.Three fertilizer application methods:hole application of starter phosphate fertilizer（PH）,drip application of starter phosphate fertilizer（PD）,and no starter phosphate fertilizer（CK）was set up.Maize growth and development at seedling stage,nutrient accumulation,net photosynthetic rate,yield and yield components in the middle and later stage of maize was tested.The amount of starter phosphate fertilizer was P2O5 30 kg·hm-2,and the tested maize variety was Xinyu 65（zea mays L.）.（2）The experiment of different application rates of starter phosphate fertilizer was carried out in Tianye Agriculture Experiment Station in Shihezi City,Xinjiang in 2021.The does for hole application of starter fertilizer were P2O5 30 kg·hm-2（PH30）,P2O5 30 kg·hm-2 for band application（PB30）,P2O5 30kg·hm-2 for drip application（PD30）,P2O5 60 kg·hm-2 for band application（PB60）,P2O5 60 kg·hm-2 for drip application（PD60）and no starter phosphate fertilizer（CK）.The tested maize variety was Xinyu 65.（3）An experiment on the response of maize root system to the location of starter phosphate fertilizer application at seedling stage was carried out in the greenhouse of Shihezi University in 2021.The tested maize variety was"Xinyu 65".In this experiment,the root box was used to analyze the effect of starter phosphate fertilizer on the root system of maize at seedling stage.The specific treatm ents were drip application of starter phosphate fertilizer（T1）,5 cm below by 5 cm side of seed of maize for hole application（T2）,and 12 cm below and 5 cm side of seed for hole application（T3）and no starter phosphate fertilizer（CK）.The amount of starter phosphate fertilizer was P2O5 0.2 g·kg-1 soil.Results（1）PD and PH treatments significantly increased the total root length,the root surface area,the shoot and root biomass of maize at four-leaf stage and six-leaf stage.At the six-leaf stage,compared to CK,the root length in PD and PH increased by 21.10%and 30.35%,the root surface area increased by 23.48%and29.20%,and the shoot and root biomass increased by 31.24%and 52.38%,33.61%and 57.81%,respectively.Compared to the contrast,starter phosphate fertilizer promoted nitrogen,phosphorus and potassium uptake,and improved the nutrients harvest coefficient.Compared to the contrast,PD treatment and PH treatment,harvest coefficient of nitrogen,phosphorus,and potassium by 4.79%and 6.40%,4.65%and 9.79%,11.47%and 20.56%,respectively.The ear length,the grain ear row number,and the yield and partial productivity of phosphorus fertilizer of maize had a PH>PD>CK arrangement.（2）Higher rate of starter phosphate fertilizer can no further improvement the growth and development and yield increased of maize.The root morphology,biomass accumulation,nutrient accumulation of maize at seedling stage showed PH30 treatment was the best,PB30 and PB60 treatment was the second,PD30and PD60 treatment was the worst.PH30,PB30,PB60,PD30 and PD60 treatment increased yield by20.88%,18.03%,18.38%,8.15%and 7.08%compared to CK treatment,respectively.（3）The results showed that at 14 d and 21 d after emergence,the starter phosphate fertilizer significantly increased the total root length,the total root surface area,number of first lateral roots and number of second lateral roots.The overall performance was that T2 was the highest,followed by T1 and T3,and CK was the lowest.But the number of maize primary roots and main radicle root length showed no significant difference among the various fertilization treatments.At 21 d after maize emergence,the soil available phosphorus of T1 was mainly distributed in the vertical range of 0～9 cm and the horizontal range of 0～18 cm,which was mainly distributed in the vertical range of 3～12 cm and the horizontal range of0～11 cm in T2,and in T3,the soil available phosphorus was distributed in the vertical range of 11～20 cm and horizontal range of 0～11 cm.The root distribution of T1 was mainly concentrated in the 0～9 cm soil layer,which was mainly concentrated in the vertical 5～15 cm and horizontal 0～12 cm soil layer of T2treatment,and the root distribution of T3 treatment was mainly concentrated in the soil layer of 12～18 cm vertical and 0～9 cm horizontal.In each fertilization treatment,the spatial matching degree of root and soil phosphorus nutrient distribution was that T2 was the highest,followed by T3,and T1 was the lowest.At 7d after maize emergence,there was no significant difference in the dry weight and phosphorus nutrient accumulation of maize among all these treatments.At 14 d and 21 d after maize emergence,the dry weight and phosphate uptake of maize in the treatment with phosphorous fertilizer were significantly higher than that of CK,and the dry weight and phosphorus uptake of T2 were the highest and significantly higher than those of T1 and T3.ConclusionThe application of starter phosphate fertilizer significantly increase maize yield,the main mechanism was that starter phosphate fertilizer stimulated the root growth of maize at seedling stage,which established first mover advantage for nutrient absorption in the later stage of maize growth.In addition,the hole application of the starter phosphate fertilizer showed better effects than drip application,mainly due to the deeper and more intensive distribution of available phosphate nutrients in the soil,which is more conducive to the absorption of phosphorus nutrients by maize root system.The application rate of P2O5 30 kg·hm-2phosphate fertilizer could fully meet the phosphorus demand of maize at seedling stage,increasing the rate of starter phosphate fertilizer showed no further promote maize performance.The effect of starter phosphate fertilizer on maize growth and yield was the best when applied at 5 cm below the side of the seed.The main mechanism is to induce a large number of proliferation of maize lateral roots in the fertilizer area,expand the contact area between roots and phosphorus fertilizer,and improve the spa tial matching degree of phosphorus nutrients between roots and soil,so as to increase the absorption of phosphorus nutrients by maize. |
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