褪黑素对两种穗型冬小麦小花发育成粒及营养供应的影响OA北大核心CSTPCD

[Objective]To clarify the regulatory effects of exogenous melatonin(MT)on floret development into grain and nutrient supply in winter wheat of two spike types,and provide technical references for the application of exogenous regulators to increase grain number and improve yield in wheat field production.[Method]Using the multi-spike variety'Yumai 49-198'(V1)and the large-spike variety'Zhoumai 22'(V2)as experimental materials,foliar spraying of 100 μmol·L-1 MT and fresh water control(CK)treatments were applied prior to the peak period of florets degradation(approximately 20 days after wheat jointing)under field conditions.This setup was used to investigate the effects of melatonin on floret development into grain,nutrient supply and yield formation in winter wheat with two spike types.[Result]Spraying MT could effectively increase the number of fertile florets across different spike positions for two spike types varieties under field conditions,and the effect of floret promotion in the weaker position was better.Additionally,MT treatment could increase the floret survival rate and floret setting rates by 4.13%and 5.35%in V1,and by 6.01%and 6.19%in V2,and the regulating effect on V2 variety was higher than V1 variety.Pathway analysis showed that net photosynthetic rate of top spread leaves and spike organ soluble sugar had the greatest direct effect on the number of fertile florets,followed by SPS enzyme activity of top spread leaves and spike dry matter accumulation.Spraying MT could effectively increase the chlorophyll a and chlorophyll b content,net photosynthetic rate,SPS enzyme activity of top spread leaves,and also the soluble sugar and dry matter accumulation in the stem,leaf and spike organ in the two spike types varieties from 0-15 days(d)after spraying treatment,and which provided sufficient nutrient supply for floret differentiation and development in winter wheat of two spike types.Spraying MT significantly increased the yield and grain number per spike of the two spike types varieties.Compared with the respective CK treatment,the two spike types varieties increased the yield by an average of 531.59 kg·hm-2(V1)and 744.57 kg·hm-2(V2),with an increase range of 6.35%(V1)and 8.63%(V2),respectively.The average increase in the grain number per spike by 2.07 grains(V1)and 2.64 grains(V2),with respective increase ranges of 5.65%(V1)and 6.71%(V2),respectively.However,the regulatory effects on the number of spikes and 1000-grain weight did not reach significant levels.[Conclusion]Under field conditions,spraying MT before the peak of wheat floret degradation can effectively increase the chlorophyll content,net photosynthetic rate and SPS enzyme activity in top spread leaves of the two spike types varieties.This led to enhanced the photosynthetic production capacity of top spread leaves in wheat,and promote the accumulation of soluble sugars and dry matter in the stem,leaf and spike organ,providing sufficient nutrients for the development of the floret into grains.Consequently,MT application achieved the goal of promoting flowering,increasing grains and improving yield,and which had a better regulation effect for the large spike variety'Zhoumai 22'than the multi-spike variety'Yumai 49-198'.