| Spring maize area of northeast of China is the main production and output region for spring maize in China,so increasing the production in this region have important meaning for corn security strategy of China.Increasing plant density is supposed to be the main way for obtaining high yield of maize,whereas it would bring about enhanced competition among individuals of canopy and topsoil,which may restrict the yield in return.Numerous studies showed that cultivation measures such as subsoiling,widenarrow rows planting and chemical regulation could obviously optimize maize population structure and individual function under intensive planting condition,and it was proved to have a significant positive regulator effect on maize grain yield in crowding stress.At present,the yield which depends on the single cultivation measure has been stuck in bottleneck,so integrated cultivation measures constructed the highyield population and using the overall function advantages to obtain the noticeable yield would play an extremely fundamental role in the future yield development.But the regulation mechanism of cultivation measures interaction on spring maize population structure were not clear by far.At meanwhile,the high-yield mechanism of single or multiple cultivation measures interaction on Northeast spring maize were still lack of detailed reports.Thus,the present research is aim to(1)display the effects and yield contribution rate of cultivated measures,and measures interaction by studying the regulating effect of subsioling,wide-narrow rows and chemical regulation on maize yield;(2)explore the regulation effects of different optimizing cultivation patterns on the structure and function of canopy and topsoil among intensive maize populations;(3)clarify the regulation mechanism of the subsoiling and wide-narrow rows interactions for the post-silking dry matter transport under high planting density(105,000 plants ha-1),through which might obtain useful information for providing appropriate maize cultivation mode and enhancing grain yield in intensive spring maize.The main results were as follow:(1)Chemical regulator(C)had significant positive effects on yield in the integrated measures mode(contribution rate,27%-41%),which could realize an increasement of 11700 plants ha-1 at plant density under single chemical regulator treatment;wide-narrow planting(W)showed obvious different effects among the treatments;However,the effect of subsoiling(S)on yield was giving priority to indirect effect(contribution rate,24%-37%),nevertheless,subsoiling plus wide-narrow planting compared with traditional mode(RU;CK)could increase yield by 11.28%.Compared with traditional mode,the yield improvement of multiple measures interaction was much higher than double measures interaction or single measure,and the increasement were 31.27%,15.57% and 7.96% respectively in a normal year(2013);and were 15.02%,11.32% and 5.65% respectively in the drought year(2014).And theyield increasing was mainly due to the population density enhancing,by coordination regulation among Radiation use efficiency(RUE),Growth degree days use efficiency(GUE)and Nitrogen partial factor productivity,and then achieved the high yield and high efficiency under integrated measures.(2)Cultivation measures and measures interaction could build high-yield maize populations by obviously improving the coordination of shoot-root structure.Widenarrow rows and chemical regulation could significantly optimize the spatial distribution of dry matter to build efficient canopy configuration which looks like "spindle-shaped",whose transmittance,and radiation interception of low leaf layer have been increased significantly.And its photosynthetic capacity has been significantly improved.However,the increasement of canopy also depended on the ability of topsoil supply.Subsoiling significantly improved the topsoil structure,elevated the depth more than 10 cm,increased soil porosity,raised effective water from 2% to 5%-7% and so did the precipitation utilization efficiency of topsoil.In addition,they enlarged the distribution of root,the root quantity increased by 80%-88% in 10-30 cm soil layer,which due to the fibrous roots increasing.Subsoiling,wide-narrow rows and chemical regulation changed the ratio of shoot and root,the root to shoot ratio and shoot to root area ratio increased significantly,the shoot to root area ratio trended to 1.(3)Cultivation measures and measures interaction could optimize dry matter accumulation and distribution of canopy in maize intensive population.Subsoiling and wide-narrow rows significantly improves the accumulation amount after silking(5.2%?13%);improved the balance of C and N metabolism after silking,harvest stem C/N significantly decreased(-4%?39%);Which enhanced differentiation of the vascular bundle system at the early growth stage,and maintained its function after silking.Increased matter transportation efficiency(11%?42%),enhanced grain filling rate,grain number,and grain weight significantly,and resulted in high grain yield of spring maize.In summary,integrated cultivation measures have significant positive regulation effect on maize grain yield under high density population.And among those treatments,subsoiling plus wide-narrow rows plus chemical regulation shows the highest yield.This mode could construct optimized shoot and root structure,which would improve the canopy light interception and increase material production during the filling stage.In addition,this integrated modeled to expansion of root distribution,which improved the nutritional environment of high density population.It could also increase the differentiation of vascular system,increase transportation and accumulation of biomass at filling stage,increase the grain number and grain weight synchronously,and finally achieved the high-yielding in intensive spring maize of Northeast region in China. |
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