The Effect of Sowing Date and Density on the Characters and Yield of Maize in Chongqing

Honglin TlAN，Hua YANG，Zhicheng JlANG，Pihui ZHANG，Ye Ll，Ruping ZHOU，Junjuan CUl，Minglu XU*

1.Maize Research Institute，Chongqing Academy of Agricultural Sciences，Chongqing 401329，China；

2.Chongqing Keguang Seed Co.，Ltd.，Chongqing 400060，China；

3.Agriculture Commission of Shizhu County Chongqing，Chongqing 409100，China

The Effect of Sowing Date and Density on the Characters and Yield of Maize in Chongqing

Honglin TlAN1，Hua YANG1，Zhicheng JlANG1，Pihui ZHANG1，Ye Ll1，Ruping ZHOU2，Junjuan CUl3，Minglu XU1*

1.Maize Research Institute，Chongqing Academy of Agricultural Sciences，Chongqing 401329，China；

2.Chongqing Keguang Seed Co.，Ltd.，Chongqing 400060，China；

3.Agriculture Commission of Shizhu County Chongqing，Chongqing 409100，China

In order to investigate the most suitable sowing period and the optimum planting density of new corn variety ‘Yudan 30’in Chongqing region，using split plot experiment design，the effect of sowing date and planting density on main agronomiccharacters and yield ofmaize in the field wasstudied.The results showed that in Chongqing，the delay of sowing date could shorten the fertility period，and reduce 100-grain weight and yield，but could increase plant height and ear height，panicle traits did not change significantly.With the density increasing，plant height and ear height also increased，while ear length，ear diameter，stem diameter，row number and kernel number also decreased.100-grain weight and yield also increased with the increase of density，but to a certain threshold，yield and 100-grain weight decreased with the increase of density.The yield of 3 sowing periods presented as A1＞A2＞A3，the yield of 4 kinds of density presented as B3＞B4＞B2＞B1，and the yield under sowing time and density interaction presented as A1B3＞A1B4＞A2B3＞A2B4＞A3B3＞A3B4＞A2B2＞A1B1＞A2B1＞A3B1.So proper early sowing and increase of planting density could raise the yield of maize per unit area，and A1B3 was the optimum planting configuration in Chongqing area.

Corn；Sowing time；Density；Agronomic traits；Yield

C rop production is the process of population［1-2］，density and sowing date are two factors of cultivation affecting crop production and final yield in a certain ecological environment［3］，but in common experiment，only a particular aspect is focused on.In mountainous regions of Chongqing，the hilly and mountainous areas with barren soil［5］，which can not be planted with rice，are planted with maize.In this region，maize production will not only be hit by late spring coldness during the seedling stage，but also experience extreme weather like heat-forced maturity during grain-filling stage，thus the yield per unit in this area is far lower than national average level；with global warming，the ecological environment of the earth changes，traditional sowing time not only is bad for production，but also causes huge waste of sunshine and heat resources，thus toputthe maximum photosynthetic efficiency period of crops into the mostfavorable climatic conditions［6］，the selection of sowing time is the key.Appropriate sowing time is the guarantee for taking full advantage of sunshine and heat resources in the ecological environment［7］，rational planting density is the basis for making use of sunshine and heat resources in the ecological environment，building good group structure and optimizing population physiological indexes［8-10］；the authors showed that increasing planting density appropriately can improvethe yield per unit area［4］，the optimized combination of the two can make the physiological mechanism of maize population adjusted and optimized comprehensively，thereby giving full play to the yield-increasing potential of the variety.For the effect of sowing time or density on maize yield and quality，Lv Xin et al.showed that if the density was increased，the photosynthetic area ofthe population willbe enlarged，and the yield will be improved［11］，Liu Ming et al.proved that the growth and development as well as the yield of spring maize at different sowing dates had significant differences［12］，Li Yuehua et al.showed that with the delay of harvest time，1 000-seed weight of summer maize increased［13］，but for the differences of varietal characteristic and production area，its research results were also different. Therefore，combined with the practical production of Chongqing region，4 kinds of planting density and 3 sowing dates were designed targetedly in this study，so as to study the main agronomic traits and yield of different maize varieties under different sowing dates and densities，thereby providing a theoretical basis and technological support for high-yield production of maize in this region.

Materials and Methods

Experimental sites and materials

The experiment was carried out at Daguan Base of Nanchuan in Maize Research Institute of Chongqing Academy of Agricultural Sciences respectively in 2013 and 2014，the data in this paper were the mean of two years，the experimental variety was ‘Yudan 30’bred by Chongqing Academy of Agricultural Sciences，and it was the hybrid maize with proprietary intellectual property rights.

Experimental design

In the experiment，split block design with three replications was adopted，the primary area was sowing time，the secondary area was density，there were 3 sowing dates（A1:5 d before Tomb-sweeping Day，A2:sowing in the Tomb-sweeping Day，A3:5 d after TombsweepingDay）and4densitylevels（B1:37 500 plants/hm2，B2:45 000 plants/hm2，B3:52 500 plants/hm2，B4:60 000 plants/hm2），field management was comparable to local production level.

Survey items and methods

The lodging situation of maize during growth period was recorded，the weight gain of ear and the grouting progress of grains each 10 d after the pollination were surveyed；then before the harvest，the stem diameter，plant height and ear height of the 3rdsection of 10 maize plants from the 4thplant were measured continuously；after the harvest，the indoor survey on ear length，ear diameter，ear rows，kernels per row，bare top length and 100-grain weight was carried out，and the yield was measured.

Data analysis

Excel and DPS softwares were used for disposing experimental data.

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Results and Analyses

The grain filling progress of‘Yudan 30’

From Fig.1 and Fig.2，the characteristics of grain filling of‘Yudan 30’can be seen.The grain filling of‘Yudan 30’during the whole filling stage showed a rising trend，the grain filling rate was the fastest in the first 30 d，and then reduced.The grain filling rate of‘Yudan 30’showed a rising trend in the first 30 d of different stages，then showed a slowly declining trend after the 30thd.For agricultural production，based on the regional characteristics of Chongqing，early sowing can ensure that grain filling can avoid the extreme weather of heatforced maturity in the first 30 d.

The yield and field characters of‘Yudan 30’in different sowing dates

From Table 1，it can be drawn that field agronomic characters and yield of‘Yudan 30’showed differentvariation trends with the change of sowing dates，plant height and ear height increased with the postponing of sowing dates，the changes of ear length，ear thickness，ear barren tip and grains per row were not significant，100-grain weight and yield reduced with the postponing of sowing dates.Based on the multiple comparisons in Table 2，it can be seen that if sowing 5 d early，the yield was increased significantly compared with regular sowing，thus showing that the growth period of early sowing was 9 and 14 d longer than that of suitable sowing and late sowing，respectively；the vegetative period was long，the grain filling was sufficient，100-grain weight was high，and the yield was high；if late sowing，the intuitive sense of grains was wizened for the insufficient grain filling，thus the yield reduced.

The yield and field characters of‘Yudan 30’in different densities

From Table 3，it can be seen that field agronomic characters and yield of‘Yudan 30’showed different variation trends with the increase of density，plant height and ear height increased with the increase of density，ear length，ear thickness，stem diameter and grains per row all decreased with the increase of density，100-grain weight and yield increased with the increase of density within a certain range，but to a certain density，it would gradually decrease.Based on the multiple comparisons inTable 4，it can be seen that the yield of‘Yudan 30’in Chongqing area first increased with the increase of planting density，butwhen the density increased to 52 500 plants/hm2，the yield decreased with the increase of planting density，which was consistent with the research results of the first two years by the authors.The increase of the density caused the plunder of resources，thus causing certain effect on the individual，so plant height and ear height increased with the increase of density，however，earlength，ear thickness，stem diameter，grains per row，yield and 100-grain weight decreased with the increase of density.

Table 2 Multiple comparisons on different sowing dates

The yield and field characters of‘Yudan 30’under density interaction during sowing period

As seen in Fig.3，the yield of early sowing under different densities was higher than that of other sowing dates. From the multiple comparisons in Table 2，it was shown that the sowing date of‘Yudan 30’in Chongqing area can be advanced 5 d；in different sowing dates，the yield of‘Yudan 30’increased with the increase of planting density，butwhen the density increased to 52 500 plants/hm2，the yield would not increase with the increase of planting density；from the multiple comparisons in Table 4，it was seen that when the planting density was 52 500 plants/hm2，the yield was the highestand reached the highest value.Therefore，the threshold value of planting density of‘Yudan 30’in Chongqing area was 52 500 plants/hm2.The variance analysis in Table 5 showed that under the interaction between sowing date and density，the difference was significant.

Table 3 The yield and field characters of‘Yudan 30’in different sowing dates and densities

Conclusions and Discussions

The production of maize in Chongqing area will not only be hit by late spring coldness during the seedling stage，but also experience extreme weather like heat-forced maturity during grain-filling stage.Improving maize yield per unit area has always been the ultimate goal of maize breeding and cultivation researchers［8］. In this experiment，the representative latest variety was selected to study the effect of sowing time and density on maize character and quality，and analyze the field and yield characters of maize in different densities and different sowing dates in Chongqing area，thereby making the existing varieties draw on advantages and avoid disadvantages under the premise of the change of global climate environment，the results can provide some guidancefor future production and some bases for breeding and cultivation researchers.

Table 4 Multiple comparisons on different densities

Table 5 The variance analysis of yield under different densities in different sowing dates

The research showed that the suitable planting density of‘Yudan 30’ in differentsowing dates in Chongqing area was 50 000-55 000 plants/hm2，the yield was the highest under the planting density of 52 500 plants/hm2in the 5th d before appropriate sowing，namely 13 702.5 kg/hm2. In differentdensities，the yield-increasing effect of 5 d before appropriate sowing was better than that of commonsowingand late sowing，which was consistent with the research results by Xue Jiqian et al.［14］，Xing Yaowu et al.［15］and Tong Pingya et al［16］.

In this experiment，a single variety was chosen and planted in two kinds of ecological areas，different varieties have their own characteristics and ecological adaptability，thus different varieties planted in the same region have certain guiding significance to production，but early sowing may cause the change of microenvironment among individuals after increasing the density，thereby causing a series of problems，such as increasing plant diseases and insect pests，etc.，the physiological indexes among individuals will be studied next.

［1］WEINER J.Plant population ecology in agriculture［A］.In Agro Ecology.（Eds.C. Ronald Carol et al.）McCray-Hill Publishing Company，New York，1990:235-262.

［2］ZHAO SL（赵松岭），LI FM（李凤民），ZHANG DY（张大勇），et al.Crop production is a population process（作物生产是一个种群过程）［J］.Acta Ecologica Sinica（生态学报），1997，17（1）:101-104.

［3］MA GS（马国胜），XUE JQ（薛吉全），LU HD （路海东），et al.Effects of planting date and density on population physiological indices of summer corn（Zea mays L.）in central Shaanxi irrigation area（播种时期与密度对关中灌区夏玉米群体生理指标的影响）［J］.Chinese Journal of Applied Ecology（应用生态学报），2007，18（6）:1247-1253.

［4］TIAN HL（田红琳），YANG H（杨华），XU ML（许明陆），et al.Effects on agronomic characteristics and yield of maize planting density（种植密度对不同玉米性状和产量的影响）［J］.Chinese Agricultural Science Bulletin （中国农学通报），2013，29（30）:100-104.

［5］LIU YH（刘永红），LI BG（李本国），WU GQ（吴光清），et al.The suitable planting range of several maize varieties in Sichuan（几个玉米品种在四川的适宜种植范围）［J］.Southwest China Journal of Agricultural Sciences（西南农业学报），1998（11）:217-222.

［6］LI MQ （李明启）.The relationship between photosynthetic efficiency and yield and the intrinsic factors affecting photosynthetic efficiency（作物光合效率与产量的关系及影响光合效率的内在因子）［J］.Plant Physiology Communications（植物生理学通讯），1980（2）:1-8.

［7］LI CH（李潮海），SU XH（苏新宏），XIE RZ（谢瑞芝），et al.Study on relationship between grain-yield of summer corn and climatic ecological condition under super-high-yield cultivation（超高产栽培条件下夏玉米产量与气候生态条件关系研究）［J］.Scientia Agricultura Sinica（中国农业科学），2001，34（3）:311-316.

［8］SU YM（苏玉梅），WANG XL（王晓立）. Problems in planting density of spring maize varieties and the improvement measures（春播大穗型玉米品种种植密度存在的问题及改进措施）［J］.Modern Agricultural Sciences and Technology（现代农业科技），2012（6）:114-117.

［9］FENG G（丰光），LI YY（李妍妍），JING XQ（景希强）.Effects on agronomic characteristics and yield of maize planting density（玉米不同种植密度对主要农艺性状和产量的影响）［J］.Journal of Maize Sciences（玉米科学），2011，19（1）:109-111.

［10］YANG JS（杨吉顺），GAO HY（高辉远），LIU P（刘鹏），et al.Effects of planting density and row spacing on canopy apparent photosynthesis of high-yield summer corn（种植密度和行距配置对超高产夏玉米群体光合特性的影响）［J］. Acta Agronomica Sinica （作物学报），2010，36（7）:1226-1233.

［11］LV X（吕新），BAI P（白萍），ZHANG W（张伟），et al.Analysis on effect of ecological factors on maize dry weight accumulation in different sowing periods（不同播期对玉米干物质积累的影响及分析）［J］.Journal of Shihezi University（Natural Science）（石河子大学学报:自然科学版），2004，22（4）:285-288.

［12］LIU M（刘明），TAO HB（陶洪斌），WANG P（王璞），et al.Effect of sowing date on growth and yield of spring-maize（播期对春玉米生长发育与产量形成的影响）［J］.Chinese Journal of Eco-Agriculture（中国生态农业学报），2009，17（1）: 18-23.

［13］LI YH（李月华），HOU DS（侯大山），LIU Q（刘强），et al.Effect of harvest period on 1 000-grain weight and yield of summer maize（收获期对夏玉米千粒重及产量的影响）［J］.Journal of Hebei Agricultural Sciences（河北农业科学），2008，12（7）:1-6.

［14］XUE JQ（薛吉全），ZHANG RH（张仁和），MA GS（马国胜），et al.Effects of plant density，nitrogen application，and water stress on yield formation of maize（种植密度氮肥和水分胁迫对玉米产量形成的影响）［J］.Acta Agronomica Sinica（作物学报），2010，36（6）:1022-1029.

［15］XING YW（星耀武），SHI XH（史新海），WANG KL（王慷林），et al.Studies on the production and agronomic traits of different plant type maize hybrids （不同株型玉米杂交种的产量及农艺性状的研究）［J］.Journal of Maize Sciences（玉米科学），2005，13（4）:92-94.

［16］TONG PY（佟屏亚），CHENG YN（程延年）.Study on the relationship between the density and yield of maize（玉米密度与产量因素关系的研究）［J］.Beijing Agricultural Sciences（北京农业科学），1995，13（1）:23-25.

Responsible editor：Nanling WANG

Responsible proofreader：Xiaoyan WU

播期与密度对重庆山区玉米性状及产量的影响研究

田红琳1，杨 华1，蒋志成1，张丕辉1，李 晔1，周汝平2，崔俊娟3，许明陆1*（1.重庆市农业科学院玉米研究所，重庆 401329；2.重庆科光种苗有限公司，重庆 400060；3.重庆市石柱县农业委员会，重庆409100）

为探明玉米新品种'渝单30'在重庆地区的最适播期及最佳种植密度，通过大田裂区试验设计，研究播期与种植密度对玉米田间主要农艺性状和产量的影响。结果表明：在重庆地区，播期延后，生育期天数缩短、百粒重及产量降低，株高、穗位高随播期的延后而增加，穗部性状变化不显著。密度增加，株高、穗位高也随之增加，穗长、穗粗、茎粗、行数、行粒数等随密度的增加而减少，百粒重、产量随密度的增加而增大，但到一定阀值后，密度增加，产量和百粒重则减少。3种播期下产量表现为A1＞A2＞A3，4种密度下产量表现为B3＞B4＞B2＞B1，播期密度互作下产量表现为A1B3＞A1B4＞A2B3＞A2B4＞A3B3＞A3B4＞A2B2＞A1B1＞A2B1＞A3B1。因此适当提前播种和增加种植密度可增加玉米单位面积产量，确定了A1B3是重庆地区的最佳种植配置。

玉米；播期；密度；农艺性状；产量

重庆市公益性科研院所基本科研业务费“不同株行距配置下产量及光合性能研究”（cstc-2014jbky-00510）；国家玉米产业技术体系（CARS-02-74）；“十二五”主要农作物良种创新工程重大攻关项目“玉米高产高效配套新技术研究与集成示范”（cstc2012ggC80007）。作者简介 田红琳（1985），男，重庆彭水人，助理研究员，硕士，主要从事作物栽培与耕作研究，E-mail：thl198588@sina.com。*通讯作者，研究员，硕士，主要从事玉米栽培与农业科技管理工作，E-mail：mingluemail@163.com。

2015-05-28

Supported by the Fundamental Research Fund of Chongqing Public Welfare Research Institutes"On the Yield and Photosynthetic Performance under Different Plant-Row Spacing"（cstc-2014jbky-00510）；National Maize Industry Technology System（CARS-02-74）；Key Innovation Project of Main Crop Varieties during"the 12thFive-Year Plan" "On High Yield and High Efficiency Cultivation Techniques for Maize and the Integration and Demonstration"（cstc2012ggC80007）.

*Corresponding author.E-mail:mingluemail@163.com

Received:May 28，2015 Accepted:November 12，2015

修回日期 2015-11-12