| This study was conducted on the Experimental Farm of Jiangsu Provincial Key Lab of Crop Genetics and Physiology during the two wheat growing seasons from2011to2013. Yangfumai4, a medium-gluten wheat variety, was used as the tested variety. The objective of this study was to investigate the characteristics of grain yield, population quality, canopy microclimate, plant morphology, the accumulation of nutrient element, the physiological activity of flag leaf, and the grain quality under different row-spacing and density treatments. Lodging-resistance was also analyzed to evaluate the applicability of different row-spacing and density configurations in the region of south Huaihe River. The study was helpful to provide theoretical basis and technical support for achieving high grain yield under different row-spacing and density configurations. The main results were as follows:1. In the region of south Huaihe River, the best row-spacing and density configuration of Yangfumai4was150～180×104/hm2basis seedlings with an equal row-spacing of30cm and with a wide-and-narrow row-spacing20+40of cm. Other row-spacing and density configurations like150～180×104/hm2basis seedlings with strip-drilling25cm(20+5) and225～270×104/hm2basis seedlings with an equal row-spacing of25cm and30cm, and with a wide-and-narrow row-spacing20+40cm also got grain yields higher than7500kg/hm2in the two growing years. At the same density level, the ear number in the broadcast treatment was the least as compared with other treatments. With increased row-spacing, the number of ear was decreased and the number of grain per spike and1000-gain-weight was increased.2. The population quality indexes of Yangfumai4with grain yield above7500kg/hm2, sown in an equal row-spacing of30cm and in a wide-and-narrow row-spacing20+40cm were:LAI6.2-6.8at booting stage,4.7～5.5at anthesis, and3.3at milk-ripe stage; dry matter accumulation10500-11000kg/hm2at anthesis,14800～15200kg/hm2at milk-ripe stage,16500-18000kg/hm2at maturity, and5200～6400kg/hm2after anthesis.3. Different row-spacing and density configurations had significant effects on the canopy microclimate of Yangfumai4. The broadcast treatment had lower light-transmittance at anthesis and milk-ripe than the line-sown treatments. The treatments sown in an equal row-spacing of30cm and in a wide-and-narrow row-spacing of20+40cm had higher light-transmittance and lower leaf extinction coefficient at different layers of canopy. The populations of Yangfumai4with grain yield above7500kg/hm" had the following extinction characteristics. At anthesis, the extinction coefficient was0.35～0.60at the layer of top～60cm,0.46～0.50at the layer of60-40cm,0.30-0.50at the layer of40～20cm, and0.45～0.65for the entire canopy. The vertical distribution characteristics of proper range of discrepancy between canopy and air temperature at the layer of spike,60cm and40cm of canopy was2.5～3.5℃,1.5～4℃and3.0～4.5℃, respectively.4. The individual plant type indexes of Yangfumai4with grain yield above7500kg/hm2were as follows:plant height79～83cm, spike length8-9cm, the proportion of basal internode length to the upper4internodes was1:2:(2.5～3.0):(4-5):(7-8) and the ratio of the uppermost internode length to the total length of all internodes was38%～44%. The area of flag leaf, the second upper leaf and the third upper leaf were25.5-28.5cm2,25～30cm2, and20～26cm2. The specific leaf weight of those leaves was4.5-5.5mg/cm2,4.3～5.3mg/cm2, and4.0～4.5mg/cm2. The grain/leaf ratio was11.5～13.0mg/cm2or0.31～0.38grains/cm2. The specific leaf weight of flag leaf of the broadcast treatment was lower than that of the line-sown treatments. The specific leaf weight was increased with the expanding of row-spacing in the line-sown treatments.5. The broadcast treatment had lower lodging-resistance-torque than the line-sown treatments. The lodging-resistance-torque of the treatments with an equal row-spacing of30cm and with a wide-and-narrow row-spacing of20+40cm were higher than other treatments. The wall thickness of the second basal internode had the highest correlation coefficient with the lodging-resistance-torque so it could be used to predict the lodging-resistance ability of wheat plants at maturity.6. The nitrogen and phosphorous accumulation characteristics of the population with grain yield more than7500kg/hm2were as follows. The nitrogen accumulation of population was33-42kg/hm2at the beginning of winter,60～85kg/hm2at elongation stage,140-148kg/hm2at booting stage,177～185kg/hm2at anthesis,200～210kg/hm2at milk-ripe stage, and250～265kg/hm2at maturity. The phosphorous accumulation was4.5～6kg/hm2at the beginning of winter,9～14kg/hm2at elongation stage,21～25kg/hm2at booting stage,31～34kg/hm2at anthesis,38～40kg/hm2at milk-ripe stage,43～48kg/hm2at maturity. The ratio of soluble sugar to nitrogen was2-3at elongation stage,6.0～6.5at booting stage,8～9at anthesis,6～7at milk-ripe stage, and0.3-0.5at maturity.7. Comparison with the line-sown treatments, the broadcast treatment had lower photosynthetic rate, stomata conductance, transpiration rate, and higher intercellular CO2concentration. Of the line-sown treatments, the photosynthesis of flag leaf after anthesis was increased with the expanding of row-spacing. Sowing in an equal row-spacing of30cm and in a wide-and-narrow row-spacing of20+40cm slowed not only the decline of photosynthetic rate, stomata conductance and transpiration rate but also the increase in intercellular CO2concentration. Photosynthetic rate, stomata conductance, and transpiration rate had significantly positive correlation with grain yield, while intercellular CO2concentration had significantly negative correlation with grain yield. The broadcast treatment had faster senescence process than the line-sown treatment. With the expanding of row-spacing, the senescence process was retarded, the equal row-spacing30cm and the wide-and-narrow row-spacing of20+40cm had higher activities of SOD, CAT and POD and less MDA content of flag leave and than other treatments after anthesis. The SPAD reading, the activities of SOD, CAT, POD, and the soluble protein content of flag leaf had significantly positive correlation with yield. The MDA content of flag leaf had negative correlation with yield.8. As a whole, row-spacing and density didn’t affect the grain quality of Yangfumai4. The quality indexes of the grains of all treatments in the two growing seasons were in conformity with the quality standard of medium-gluten wheat. The populations with high yield had basically the same grain quality with other populations. And the flour of the populations with yield had higher final viscosity, peak time, and softening degree. The formation time and stability time of the flour of high yield populations were increased with the expanding of row-spacing. And the treatment with an equal row-spacing of20cm and the treatment with a wide-and-narrow row-spacing of20+40cm had the highest softening degree as compared with other treatments. |
