Effect Of Different Fertilization Modes On Canopy Characters And Source-Sink Metabolism Of Superhigh-yielding Summer Maize

Summer maize is one of main food crops in China, and its yield affects directly incomes of farmers and construction of harmonious society.It has been an involved issue to ensure natural foodstuff generativeness and safeguard unfaltering elevation of grain yield,and therefore Ministry of National Science and Technique started science and technology project for food production. In order to found one or two sets fertilization modes which is simple, matching, high-yielding and efficient, and provide theoretical basis and technical support for saving cost and increase peasants'income, this paper studied the effect of different fertilization modes on canopy characters and source-sink metabolism of superhigh-yielding summer maize in Irrigated Region of Northern Henan Province.A field experiment using hybrid Zhengdan 958 was conducted to study the effect of different fertilization modes on canopy characters,source-sink metabolism,matter metabolism at grain filling stage and competence of stresses-resistance.The fertilization modes used in the study were fertilizing in seed furrow (T1), fertilizing in seed furrow + topdressing nitrogen at small bugle stage (T2), fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) and using controlled-release fertilizer (T4).The rusults are as follows.Plant dry matter accumulation decided economic yield of summer maize.The results showed that all of fertilization modes used in the experiment could improve leaf area index, shoot dry weight, plant height,ear height and stem diameter to a certain extent,but the best way was fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) and next came using controlled-release fertilizer (T4).,which illustrated that higher yield required logical leaf area index and shoot dry weight.The rusults indicated that chlorophyll content in leaves was in sequence of T3>T4>T2>T1>CK,as well as Fv/Fm,ΦPSII,qP, photosynthesis rate and stomatal conductance,which showed that T3 was better to improve chlorophyll content,PSII potential activity and most photochemical efficiency, reduce heat dissipation of light energy, increase catch and efficiency of PSII antenna pigment to light energy, accumulate more assimilate, and further lead to higher yield.The results showed that SPS activity was in sequence of T3>T4>T2>T1>CK,and topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) was more beneficial to accumulate sucrose in leaves of summer maize,improve assimilate supply capability of source and obtain high yield.45-65 days after insemination, soluble sugar content in leaves under all fertilization modes were less than CK, however,75-95 days after insemination were reverse.At the same stage, topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) was better than other fertilization treatments,which showed that T3 was classic for accumulating soluble sugar in leaves at prophase and transfer to grains at anaphase.The results showed that the highest SS and AI activity were fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) in the whole growth period and next came using controlled-release fertilizer (T4).,which illustrated that both of them were better to decompose sucrose,accelerate starch accumulation and growth and development of grains.Grain dry matter accumulation in maize was the key to formate grain yield. This study showed that the maximum speed of dry matter accumulation appeared at 15～25d after pollination when was the key period of dry matter accumulation and yield formation. In the grain development of maize, there was a rapid increase in volume and dry weight of grains. The results indicated that T3 was more beneficial to accumulate grain dry matter than others. Maize kernel development was closely associated with starch accumulation.The test showed that the content of total soluble sugar and starch had an increasing trend 5-35d after pollination,and the content of starch had an rapid increasing 5-15d after pollination. Meanwhile, the content of sucrose and protein were down trend,and the former descended rapidly.The results showed that T3 and T4 had higher SOD activitives and lower MDA content and relative conductivity,which indicated that fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) and using controlled-release fertilizer (T4) were beneficial to improve the ability of mesophyll cell on scavenging activity of active oxygen, could effectively control the level of membrane lipid peroxidation, further kept the cell membrane stability, improved competence of stresses-resistance of maize, and finally got to high yields.The result obtained in the present study confirmed that the differences of ear rows, row grains, 1000-grain weight and yield of all the fertilization modes reached significant level compared with CK. The ear rows, row grains and yield of T3 was significant higher than the treatment of T1, T2, T4, but the 1000-grain weight of T4 was significant higher than the treatment of T1, T2 and T3. The yield of each treatment were in sequence of T3>T4>T2>T1>CK, T3 was significant higher than others,which separately increased by 44.61%, 25.65%, 23.16%, 20.16% compared with CK, T1, T2, T4. It was believed that fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) had maximum contribution on increasing yield ,which was based on fertilizer requirement of plants,so fertilizer efficiency and nutrient utilization were increased, quantitative trait of population,source-sink metabolism and competence of stresses-resistance of maize were improved, and finally we achieved the goal of high yields.In a word,the summer maize characters in four different fertilization modes used in the study[fertilizing in seed furrow (T1), fertilizing in seed furrow + topdressing nitrogen at small bugle stage (T2), fertilizing in seed furrow + topdressing nitrogen at jointing stage + topdressing nitrogen at big bugle stage (T3) and using controlled-release fertilizer (T4)]had been improved to varying degree.The treatment T3 was better to improve leaf area index, shoot dry weight, plant height,ear height and stem diameter,and ameliorate significantly canopy characters of summer maize. The treatment T3 could improve chlorophyll content,Fv/Fm,ΦPSII,qP, photosynthesis rate and stomatal conductance,and low NPQ and transpiration rate in leaves. The treatment T3 enhanced not only NR and SPS activities in leaves,but also SS and AI activities in grains. T3 was more beneficial to improve.grains filling rate,soluble sugar content,sucrose content,starch content and protein content,and accumulate grain dry matter than other fertilation modes.The treatment T3 and T4 had had higher SOD activity and lower MDA content and relative conductivity. The treatment T4 was best to increase 1000-grain weight,but T3 had maximum contribution on increasing yield.