| The field experiment was conducted that was used with maize hybrid variety Denghai 605 as experimental material from 2018 to 2019 in Tai’an,Shandong,China.In the experiment we set up cultivation modes by comprehensively optimizing the planting density,fertilizer management and planting mode,they were super-high-yield cultivation mode(SH),high-yield and high-efficiency cultivation mode(HH).And we set up the farmer management mode(FP)in accordance with the habitual cultivation mode of local farmers.We analyzed the variations of changes include canopy structure,plant growth and photosynthetic performance of ears leaf,carbon and nitrogen metabolism enzyme activities,dry matter accumulation and transportation to grain in different cultivation modes.We explored the effects of different cultivation modes on the canopy structure of summer maize.To explore the regulation of different treatments on photosynthetic performance and plant physiological metabolism of ear leaf in summer maize after silking.In order to get clear about the reasons for the yield gap formation among different cultivation modes.It is expected to provide a theoretical basis for formulating cultivation measures that can improve the photosynthetic performance of summer corn after silking,extend the duration of high photosynthesis,and improve the utilization rate of light energy.The main results were as follows:1.Effects of cultivation modes on canopy structure and light energy interception rate of summer maize.Compared with the FP,the LAI and its high value duration,and LAD were both improved in SH and HH.The stem-leaf angle of upper leaves were smaller and its leaf orientation value were greater in SH and HH treatments.The upper leaves of SH and HH treatments were compact and convergent,and they were conducive to receiving light energy.Compared with FP,the interception rate of light energy of SH and HH were increased by 9.0% and 6.9%,respectively.And the duration of high value of light energy interception was prolonged by 12.9%and 7.6%,respectively.Comprehensive optimization of cultivation measures has constructed a reasonable group canopy structure,increased the interception rate of light energy,and improved the light environment within the population.2.Effects of cultivation modes on photosynthetic performance in ear leaf of summer maize after silking stage.Compared with FP,the LAI of SH and HH treatments were increased by 35.4% and 17.5%respectively,and the population LAD of SH and HH increased by 34.5% and 13.1%respectively,which prolonged the photosynthesis time of plants.The SH and HH treatments increased the leaf chlorophyll content and specific leaf weight,especially,the chlorophyll content increased by 16.8% and 10.1% at the mature stage,respectively,and then delayed leaf senescence.SH and HH ear leaf ensured the integrity of the chloroplast structure.And the number of chloroplasts in the mesophyll cell were increased by 31.5% and 24.1% respectively.The chloroplast morphology was regular and the membrane structure was clear.The number of basal particles in the chloroplast were increased by 16.7% and 10.6% respectively,and the number of basal lamellae were increased by 12.9% and 8.7% respectively.SH and HH treatments increased the maximum photochemical efficiency of PSⅡ and the light absorption performance of the reaction center,improved the performance of the electron donor and acceptor side of t PSⅡ electron transport chain,increased the PSⅡ electron transfer efficiency and the ability to transfer electrons downstream.SH and HH improved the activity of PSⅡreaction center and the coordination between PSⅡ and PSⅠ.The photosynthesis of the ear leaf in SH and HH treatments was significantly enhanced.The high-value duration of photosynthesis were prolonged by 19.9% and 13.5% respectively,compared with FP.SH and HH treatments had improved the photosynthetic performance of ear leaf and increased the accumulation of photosynthetic products,which was conducive to achieving high yields3.Effects of cultivation modes on leaf carbon and nitrogen metabolism and their coordination of summer maize.Optimized cultivation mode could improve the carbon and nitrogen metabolism capacity of summer maize after silking.And it could promote the absorption,transport and fixation capacity of nutrients,and could increase the accumulation of carbon and nitrogen metabolites,and promote the transportation to the grain,so as to increase the yield.Compared with FP,the activities of Ribulose-1,5-bisphosphate carboxylase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC)in the ear leaf of SH and HH plants were enhanced significantly after silking.SH and HH enhanced the photosynthetic carbon assimilation ability.The activities of the enzymes were enhanced,which were the nitrate reductase(NR),glutamine synthetase(GS),glutamate synthase(GOGAT)and glutamate dehydrogenase(GDH)in ear leaf of SH and HH plants after silking stage.The result is to promote nitrogen metabolism and utilization capacity.SH and HH increased the accumulation of total soluble sugar and total nitrogen after silking stage.And the C/N in stem of SH and HH were less than FP,while the C/N of leaf was lover than FP.The results show that the carbon and nitrogen metabolism processes of SH and HH are more coordinated.The carbon assimilation transfer ability of the stems and the carbon assimilation ability of the leaves were improved in SH and HH,which promoted the accumulation of assimilation and the transportation capability to the grain,and increased the grain yield.4.Effects of cultivation modes on dry matter accumulation and grain yield of summer maize.Optimized cultivation measures could increase the dry matter accumulation and grain yield of summer maize population.Compared with FP,the SH and HH increased the dry matter accumulation rate of summer maize,and the dry matter accumulation increased by 27.8%,7.5%on average,respectively.SH and HH promoted the transportation of dry matter to the grain.The grain yield of SH and HH increased by 14.2% and 4.9% respectively,and achieved high yield. |
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