Effects Of Spacing Pattern And Chemical Control With PP₃₃₃ On Population Dynamic And Grain Yield Of Winter Wheat

In order to clarify the effects of spacing pattern and chemical control with PP333onpopulation quality, growth and development characters, and grain yield of winter wheat,and to provide reasonable technology for high-yielding and super high-yielding winterwheat in Hebei Province, a field experiment by split plot design was carried out inGaocheng City, Hebei Province during2011-2012growing season with spacing patterns(including15cm,12cm,12.5cm+12.5cm+20cm) as main plots, and chemical controlwith PP333(including foliar spraying at erecting stage, jointing stage, and control withoutany spraying) as split plots. A winter wheat cultivar, Shimai18, was used as experimentalmaterials. The results showed that, the interaction between spacing pattern and chemicalcontrol with PP333on the parameters determined were usually insignificant. The maineffects of spacing pattern and chemical control with PP333on the main parametersdetermined were summarized as follows.1. The population culms per hectare at various growth stages of wheat, the spikes perhectare, total spiking percentage and tiller spiking percentage at maturity, the leaf areaindex, dry matter accumulation and secondary roots per hectare were almost the highestunder the row spacing of15cm in the three spacing patterns, and those of12.5cm+12.5cm+20cm and12cm spacing patterns were lower and insignificant between them. Thespiking percentage, leaf area index, and dry matter accumulation of wheat of the treatmentswith foliar-sprayed PP333at erecting stage or jointing stage were improved, especially forthat of the treatment sprayed PP333at jointing stage were more significantly improved. Butthe effect of PP333spraying on the number of secondary roots at maturity was notsignificant.2. The analysis on the net photosynthetic rate and photosynthesis related parametersof flag leaves showed that, net photosynthetic rate of flag leaves was significantly positivecorrelated to SPAD value, stomatal conductance and transpiration rate, and wassignificantly negative correlated to intercellular CO2concentration.The base angle andopened angle of flag leaf were the biggest in those of the top three leaves, then those of thesecond leaf from top, with those of the third leaf from top the smallest. The opened anglesand drooping degrees of the top three leaves of wheat were smaller, and the plant type wascloser for wheat planted in15cm row spacing, comparing to those planted in the other twospacing patterns. The net photosynthetic rate and other photosynthesis related parametersof flag leaves of wheat planted in the row spaces15cm and12.5cm+12.5cm+20cm were superior to those in12cm row spacing. The net photosynthetic rate and SPAD valuein flag leaves of wheat sprayed PP333at jointing stage were significantly improved thanthose of wheat sprayed PP333at erecting stage and control without any spraying. But theeffect of PP333spraying on the other photosynthesis related parameters of top leaves ofwheat was insignificant.3. The stem quality and lodging resistance of wheat planted in different spacingpatterns showed that, the plant height, stem gravity height and basal internode length ofwheat planted in15cm row spacing were all the shortest, and those in12cm row spacingwere the tallest in the three spacing patterns. The diameter, wall thickness and dry weightper cm of basal internodes, stem mechanical strength and lodging resistance index showedthe opposite trend among the three spacing patterns. The plant height, stem gravity heightand basal internode length of wheat sprayed PP333at erecting or jointing stage weresignificantly shorter than those of control without any spraying. The diameter and wallthickness of basal internodes, and stem mechanical strength increased, and the lodgingresistance index were significantly larger in wheat sprayed PP333at erecting or jointingstage, comparing with those of control. The lodging resistance index was significantlynegatively correlated to plant height, stem gravity height and basal internode length, butsignificantly positively correlated to stem mechanical strength, dry weight per cm length ofthe1st and2nd internodes and wall thickness of the2nd internode and insignificantlypositively correlated to the diameter of the2nd and3rd internodes and wall thickness ofthe3rd internode.4. The grain yield and the three yield components of wheat planted in15cm rowspacing were all the highest, and then those in the row spacing12.5cm+12.5cm+20cm,with those in12cm row spacing the tallest in the three spacing patterns. In thoseparameters, the spike numbers per hectare of wheat in the three spacing patterns werestatistically insignificant (P＞0.05). The grains per spike,1000grain weight and grainyield of wheat planted in15cm row spacing were significantly (P＜0.05) higher than thosein12cm row spacing; and the grains per spike and grain yield in15cm row spacing werealso significantly (P＜0.05) higher than those in the row spacing12.5cm+12.5cm+20cm. The spike number per hectare and1000grain weight of wheat sprayed PP333aterecting or jointing stage were all higher than those of control, but only the differencesbetween those of the treatment sprayed PP333at jointing and control were statisticallysignificant (P＜0.05). In contrast, the grains per spike of wheat sprayed PP333at erecting orjointing stage were all less than those of control, but only the difference between that of thetreatment sprayed PP333at jointing and control was significant. The grain yields of thethree treatments of PP333spraying, as a result of interaction among the three yieldcomponents, showed the order of control (without any spraying)＜spraying at erecting＜spraying at jointing stage. The grain yield of wheat sprayed at jointing were significantly higher than those sprayed at erecting and control, but the grain yielddifference between erecting stage spraying and control was not significant. These resultsshowed that, PP333spraying at jointing stage is more beneficial to improving grain yield ofwheat. But the side-effect of PP333spraying at jointing stage on grain number per spike isalso noteworthy, so as to achieve the optimum combination of the three yield componentsof wheat for high yield.According to the results, for high-yielding and super high-yielding production ofwheat in Hebei Province, the technical combination of15cm spacing pattern withchemical control at erecting or jointing stage with PP333, can not only improve individualplant traits and form ideal plant type of wheat, but also benefit the development ofpopulation culms and leaf area, improve population photosynthetic characteristics and drymatter production. The technical combination can also coordinate the interaction of thethree yield components, so as to achieve the optimum combination of yield components,and provide a good production technique for high-yielding and super high-yielding wheat.