| The vital condition for achieving high yield through dense planting are the interaction of suitable planting density and ideal plant types.The maize density tolerance is closely related to plant type,and excessive density will inhibit maize growth per plant,decrease photosynthetic production capacity,and ultimately induced the yield loss of planting population.Exploring the interaction effect of planting density and different plant type varieties on maize leaf photosynthetic characteristics and yield formation can provide a theoretical basis and technical support for maize high-yield and high-efficient cultivation and plant type improvement.In the present experiment,the agronomic characteristics,photosynthetic properties and yield under the interaction of two plant types[Jingke 968(968,normal plant type)and Jingke Y968(Y968,modified plant type)]and three densities(D1,D2,D3,with density of 60000,75000,and 90000 plants/m2)were studied.The generated results reveal the mechanism involved in the canopy photosynthetic performance and the coordination of root-crown in spring maize production.The main results are as follows:1.The results of two years’ experiments showed that the plant and ear heights were similar between the modified and the conventional plant types at three densities.The stem diameter was negatively correlated to the plant density,and the value was higher in Y968 than that in 968.The number of taproots,root dry weight and root-shoot ratio of the two plant types decreased with the increase of density.And those three parameters of Y968 were higher than that of 968,with increased by 6.9%,7.4%and 15.6%under D1,D2,and D3,respectively.2.The pant type was negatively correlated to leaf area per plant and positively correlated to the leaf area index(LAI)of population.With the increase of planting density,the leaf area per plant was gradually decreased in both plant types,and the decrease of 968 was serious than that of Y968.The population LAI was gradually increased,and the increase was higher in Y968.The PAR of the two plant types gradually decreased with the increase of planting density,and the decrease of Y968 was less than that of 968.The higher the density,the greater difference of PAR between the two plant types were observed.There was no significant difference in SPAD between the two plant types at D1.With the increase of density,the decrease of ear leaf SPAD in Y968 was less than that of 968.Under the D1 condition,the net photosynthetic rates decreased gradually with the proceeding of plant growth,and the decrease rate of 968 was greater than that of Y968.Under the high density,the difference of net photosynthetic rate was aggravated between the two plant types.3.With the increase of planting density,the dry matter accumulation per plant decreased gradually,while the dry matter accumulation per population gradually increased.In comparison with 968,the dry matter accumulation of Y968 was similar under D1 conditions,whereas the value was increased by 4.3%and 10.9%under D2 and D3 conditions.The ear length and ear diameter of Y968 were gradually decreased with the increase of density,and the decreases of those two parameters were less than that of 968.The yield of the two plant types gradually increased with the increase of planting density,and the yield of Y968 was higher than that of 968 under different densities.Under the condition of high density,the yield of Y968 was increased by 10.1%than that of 968.4.Comprehensive analysis of the plant morphology,photosynthetic characteristics,dry matter accumulation and transportation,and the yield and its components between the two plant types under three densities,the results indicated that the improved maize plant type under the high density condition is easily to form smaller angle between leaf and stem,which can increase the light interception amount,promote population LAI,leaf SPAD values and photosynthetic capacity.In addition,reasonable root morphology is beneficial to coordinate the root-shoot ratio,improve the population photosynthetic productivity and maintain stable material productivity,ultimately improve grain yield. |
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