Effect Of Epibrassinolide On The Yield Formation Of Highly Yielding Winter Wheat

In order to clarify the effects of epibrassinolide on growth and development and grain yieldformation of highly-yielding winter wheat and its application techniques, with a winter wheat cultivarShimai18as materials, a field experiment designed as spilt plots, with three foliar spraying stagecombinations, i.e. erecting stage, erecting+booting stage, booting stage, as main plots, and fourspraying concentrations of epibrassinolide,0,0.05,0.1and0.15mg·L-1as split plots, was conductedat Gaocheng, Hebei Province, during2012-2013. The main results were showed as followsPn, Gs, Ci, Tr and SPAD of flag leaf increased gradually since anthesis, and peaked at10daysafter anthesis (10DAA) for SPAD, while for Pn, Gs, Ciand Tr, they all peaked at15DAA.Comparison among all the treatments were showed that, the changes of all the photosyntheticparameters and SPAD during the measuring period were in the order of0.1mg·L-1＞0.05mg·L-1＞0.15mg·L-1＞0mg·L-1(CK) in the main plots with once spraying at erecting stage and twice sprayingat erecting+booting stage, and the differences between the parameters of0.1mg·L-1and those ofother concentrations were statistically significant (P＜0.05). In the main plot with once spraying atbooting stage, however, the values of the parameters were in the order of0.05mg·L-1＞0.1mg·L-1＞0.15mg·L-1＞0mg·L-1(CK), and the parameters of0.05mg·L-1were significantly higher than thoseof other concentrations. All the photosynthetic parameters and SPAD of the treatment twice spraying0.1mg·L-1at erecting+booting stage were the highest in all treatments during the measuring period.The differences of photosynthetic parameters among treatments were more significant than those ofleaf SPAD among treatments.The nitrogen concentrations and accumulation amounts in various organs of wheat, thedistribution percentage of nitrogen in stems and spikes during late growing period, the total netabsorption and net partitioning of nitrogen to grains of wheat were all increased. The effectsmentioned above was most significant for the treatment0.1mg·L-1epibrassinolide in the fourconcentrations sprayed at erecting stage or double sprayed at erecting and booting stages, but wasmost significant for the treatment0.05mg·L-1in the four concentrations sprayed at booting stage. Inall treatments, the effects of epibrassinolide was most significant for the treatment doubled sprayed0.1mg·L-1at both stages, then those for the treatment sprayed0.1mg·L-1at erecting stage. The effectof epibrassinolide sprayed at erecting stage was more prominent than those sprayed at booting stage.The endogeneous Z+ZR content in spikes of wheat reached maximum on6DAA when the Z+ZR content of the treatment sprayed0.1mg·L-1epibrassinolide was the highest in the fourtreatments once spraying at erecting stage and spraying twice at erecting+booting stages,respectively. The Z+ZR content in spikes of wheat sprayed0.05mg·L-1epibrassinolide, however, wasthe highest in the four treatments once spraying at booting stage. The endogeneous ABA contentincreased on3DAA in spikes of wheat of the treatments spraying0.15mg·L-1epibrassinolide once aterecting or twice spraying at erecting+booting stages, but the ABA content in spikes of wheatspraying0.05mg·L-1epibrassinolide once or twice. The endogeneous ABA content in spikes of wheatsparyed epibrassinolide once at booting stage were all lower than that in CK, especially that of thetreatment sparyed0.15mg·L-1epibrassinolide was the lowest. The higher Z+ZR content in spikes ofwheat sprayed suitable concentration of epibrassinolide on6DAA is beneficial to grain formation ofwheat, as6DAA is a key stage for grain genesis.The effect of sprayeing four concentrations of epibrassinolide at three growth stage combinationson the amount of spike was insignificant, but the effect on the grain numbers per spike,1000grainweight and grain yield was statistically significant. The grains per spike and1000grain weightincreased in the treatments with0.05or0.1mg·L-1epibrassinolide sprayed at erecting stage orbooting stage or both stages, but those in the treatments with0.15mg·L-1epibrassinolide sprayed atthe three stage combinations were insignificant, compared to those of CK. The most grain numbersper spike, highest grain weight and highest grain yield were achieved in the treatments sprayed0.1mg·L-1epibrassinolide once at erecting stage, and twice at erecting+booting stage, but in thetreatment sprayed0.05mg·L-1epibrassinolide once at booting stage, respectively. In all the treatments,the most grain numbers per spike was achieved in the treatment sprayed0.1mg·L-1at erecting stage,and the highest grain weight and highest grain yield were achieved in the treatment of twice spraying0.1mg·L-1epibrassinolide at erecting+booting stage.As mentioned above, the leaf area index (LAI) and SPAD of flag leaf during middle and lateperiod increased, thus the ability of Pn and dry matter producrion were improved by sprayingEpibrassinolide. The nitrogen contents and the amount of nitrogen accumulation and translocation inwheat plants was also increased, the endogeneous hormone balance level in spikes of wheat improvedin the treatments of spraying Epibrassinolide. The grains numbers per spike and1000grain weightwas significantly increased, so that more reasonable combination of yield components and highergrain yield achieved by spraying Epibrassinolide. According to the results, for the purpose ofregulating growth and development in wheat production, it is recommended to spray epibrassinolidewith a concentration of0.1mg·L-1two times at erecting and booting stage (about670kg/ha eachtime). If spraying once, however, the concentration0.1mg·L-1at erecting stage, or0.05mg·L-1atbooting stage, is recommended.