Effects And Mechanism Of Seed Soaking And Foliar Spraying Of Manganese,Iron And Molybdenum On Growth And Absorb Of Wheat

Trace elements play an important role in the growth and development of plants.Recently,the biomass output per unit area of cultivated land increases,and the trace elements in soil are consumed constantly due to increasing chemical fertilizer input of nitrogen,phosphorus and potassium and also due to reduction of organic fertilizer input,which lead to the fact that trace elements gradually become an important factor restricting crop yield and nutrition quality,especially in the lime soil in Northwest China.The types and quantities of diseases caused by the lack of trace elements in China have been increased.Hence,it is of great importance to improve the trace elements in the crop grains to supplement the lack of trace elements in human body.However,the application of micro-nutrients in food crop production is not extensive,and the studies of different application methods of trace elements and its effect on physiological mechanisms affecting crop growth and absorption are not fully understood.Therefore,we systematically investigated the effects of different application methods,application times and concentration of manganese,iron,and molybdenum on the growth,physiology,yield and bioavailability of trace elements in wheat through pot experiment and field experiment.The main results are as follows:1.Seed soaking of manganese,iron and molybdenum effectively influenced growth and physiology of wheat.The application of seed soaking increased the root growth at seedling stage,root activity,photosynthetic characteristics,dry matter accumulation after flowering,the 1000-grain weight and yield per plant.?1?Seed soaking of manganese promoted root growth before wintering and photosynthetic characteristics throughout the whole growing period.The maximum occurred under the concentration of 30mg·kg^-1.The root surface area and root length at the tillering stage increased by 115.7%and 67.6%,respectively.The root activity at the tillering and wintering stage increased by 62.8%and 250.8%,respectively.It also increased the dry matter accumulation and the source organs at the grain-filling stage by increasing the activity of SOD enzymes and delaying the reduction of green leaf area at the later growth stage.Compared to the control,the yield per plant and the 1000-grain weight under seed soaking of manganese respectively increased by 15.9%and 6.4%.?2?Seed soaking of iron enhanced the root activity at the tillering stage,and it significantly increased the root length,root diameter and root surface area of wheat at the wintering stage.Moreover,seed soaking of iron simultaneously increased the leaf area,above-and below-ground dry matter accumulation of wheat before flowering,as well as the chlorophyll pigments and the photosynthetic rate at the grain-filling stage.The 1000-grain weight under the treatment of 1 g·L^-11 FeSO₄ was increased by 12.9%,and the yield per plant of 5 g·L^-1 FeSO₄ was increased by 4.8%.?3?Seed soaking of molybdenum significantly enhanced root growth before wintering and leaf area before wintering.The application of seed soaking of molybdenum increased dry matter accumulation at the wintering and reviving stage,as well as chlorophyll content at the re-greening and grain-filling stage,but it decreased antioxidant activity.The root activity increased with the molybdenum concentration increased,and the root activity under 2 g·L^-1Na₂MoO₄ was the highest.The root activity at the tillering and wintering stage was 61.2%and 48.0%higher than that of the control,respectively.The number of kernels per panicle,1000-grain weight and grain weight per plant increased by 8.3%,5.7%and 13.0%,respectively.?4?Seed soaking of iron and molybdenum increased the emergence rate of wheat,enhanced the tillering before wintering,improved the growth,the number of panicles per unit area,and grain yield.The emergence rate of wheat presented an increasing trend as increasing the concentration of iron.Compared with the control,the emergence rate of wheat under 5 g·L^-1 FeSO₄ treatment was increased by 16.8%,and the number of panicles per unit area were increased by 6.9%.Seed soaking under the treatments with 1³ g·L^-1 FeSO₄concentrations increased the number of grain per panicle and 1000-grain weight of wheat.Treatment with 3 g·L^-1 FeSO₄ showed the best effectiveness.The effective tiller per plant was 2.4%higher and the yield increased by 8.5%than the control.Treatment with 1 g·L^-1Na₂MoO₄ showed the best.The emergence rate increased by 5.4%,and the number of panicles per unit area,the number of grains per ear and the yield increased by 8.4%,11.4%and 21.1%,respectively.2.Spraying manganese,iron and molybdenum fertilizer solutions on the leaves promoted the growth of wheat,effectively improved the photosynthetic performance of wheat after flowering,coordinated the components of wheat yield,and improved the transfer efficiency of the source reservoir after flowering.?1?Spraying of manganese,iron and molybdenum at the jointing stage significantly increased the photosynthetic rate at the grain-filling stage.The treatment with 0.5%MnCl₂·4H₂O,0.1%FeSO₄,and 0.025%-0.1%Na₂MoO₄ presented the best,which was respectively increased by 15.2%,29.6%,and 31.2%compared with the control.Spraying of iron and manganese at the flowering stage significantly increased the chlorophyll content of wheat at the grain-filling stage,with 0.4%FeSO₄ and 1.0%-1.5%MnCl₂·4H₂O being the highest.Nevertheless,spraying of molybdenum had no significant effect on the chlorophyll content.?2?Spraying of manganese,iron and molybdenum promoted wheat growth.Spraying of iron at the jointing stage increased the leaf area coefficient of wheat during the early grain-filling stage and increased dry weight and panicle weight of leaf and stem during the later grain-filling stage.Spraying of manganese enhanced the leaf area coefficient of wheat at the flowering and grain-filling stages.The LAI treated by 1.0%MnCl₂·4H₂O was increased by over 29.0%,and the panicle weight was increased by more than 16.2%compared with the control.With respect to the control,the LAI of 0.1%Na₂MoO₄was increased by more than 30.8%,and the ear weight was increased by 7.5-14.4%at the flowering stage.In addition,the application of 0.025-0.05%Na₂MoO₄ at the flowering stage postponed the senescence of leaves.The LAI during the early grain-filling stage was increased by 4.5-47.9%than that of the control.Compared with the control,the leaf weight and ear weight was increased by 11.1-13.0%and 12.6-18.0%,respectively.?3?Spraying of manganese,iron and molybdenum at the jointing stage significantly increased grain number per spike,1000-grain weight,and grain yield,except for grain number per spike with spraying of molybdenum.The treatment of 0.5%MnCl₂·4H₂O,0.4%FeSO₄ and 0.025 Na₂MoO₄ showed the best.The grain yield increased by 12.0%,8.6%and4.3%compared with the control.The harvest index with spraying of iron and manganese respectively increased by 2.0%and 7.6%compared with the control.The effect of spraying at the flowering stage on yield and its influencing components was not significant.3.The concentrations of trace elements in wheat grains increased by different treatments of manganese,iron and molybdenum.Seed treatment with trace elements had a stimulating effect on wheat absorption,and seed treatment and spraying had a synergistic effect on wheat absorption.?1?Treatment with manganese increased the content of manganese and molybdenum elements in wheat grains.The content of manganese element in wheat grains under treatment of seed dressing and 180 mg·kg^-1 MnCl₂·4H₂O was increased by 10%and 27.5%,respectively.The concentration of molybdenum element in wheat grains under treatment of seed dressing and 30-60 mg·kg^-1 MnCl₂·4H₂O was increased by 89.0%and 78.5%-86.0%,respectively.The concentration of manganese and iron element in wheat grains under the treatment of spraying with 1.5%and 1.0%MnCl₂·4H₂O at the flowering stage was increased by 77.8%and 36.2%,respectively.?2?Treatment with iron increased the concentrations of manganese and iron elements in wheat grains.The concentration of iron in wheat grains under 0.8%FeSO₄ increased by190.3%and manganese by 26.3%compared with control.The content of iron in wheat grains under spraying with 0.1%and 0.4%FeSO₄ at the flowering stage was respectively increased by 13.9%and 22.3%;and manganese by 17.2%and 7.9%compared with control.?3?Treatment with molybdenum increased the concentration of manganese,iron,molybdenum,and zine four elements in wheat grains.The manganese concentration in wheat grains under treatment with seed soaking of 1 g·L^-1 Na₂MoO₄ was increased by 15.8%compared with the control.The iron concentration in wheat grains was increased by 140.2%and 39.2%,and the manganese concentration increased by 1.7%and 12.7%,and the molybdenum concentration was increased by 278%and 22.4%,and the zine concentration was increased by 21.4%and 12.7%,respectively,by spraying with 0.05%and 0.1%Na₂MoO₄ at the flowering stage.From above mentioned,the increase of wheat field under seed soaking of manganese,iron and molybdenum can reach 8.5%-21.1%,which was higher than the increasing rate of4.3%-12%under spraying at jointing stage,it may be related to the root activity and the absorption ability by enhancing the stress tolerance at the early growth stage.Seed soaking of manganese,iron and molybdenum as well as spraying at the flowering stage can significantly increase the concentration of trace elements in wheat grains.Based on the results of the present study,it is depicted that the application of micro-fertilizer seed soaking technology is an important research direction to improve trace elements in grains and yield of crops as well as nutritional quality in semiarid regions of China.