| In this experiment,large panicle wheat Tainong 18(TN18)and multiple spike wheat Shannong 20(SN20)were used as materials.Sowing dates were set up on October 9(S1),October 16(S2)and October 23(S3),respectively,and 1.5 million/hm2(D1),2.25 million/hm2(D2),3 million/hm2(D3),and 3.75 million/hm2(D4)density treatments,were used to study the relationship between soluble sugar,soluble protein and endogenous hormone content and ratio during panicle differentiation.The purpose of this study was to investigate the effects of sowing date and density on the differentiation of young spikelets of different panicle types of wheat,and to provide theoretical basis for stable yield and high quality of wheat resistance to stress.The main findings are as follows:1 Effects of sowing date and density on the differentiation process of young spikelets in wheatSowing date and density significantly affected the differentiation process of wheat spikelets.In the sowing stage of S1 and S2,the planting density had little effect on the time of the large panicle cultivar TN18 entering the stage of panicle differentiation and S3 sowing date was earlier with increasing density.The multiple panicle type SN20 The planting density increased,and the sowing differentiation process was advanced in advance.The spike differentiation process of the two varieties S1 and S2 in the sowing period did not significantly respond to the density,and the late sowing high density delayed the differentiation of the young spikes.The sowing date and density significantly affected the duration of spike differentiation in wheat.The differentiation process of panicle showed the trend of"slow-fast-slow".The differentiation process from the primordium differentiation stage to the stamen primordium differentiation stage was faster,after the drug formation period panicle differentiation slowed down,and the process of panicle differentiation in each treatment was basically the same.The sowing date of S1 and S2 had no significant effect on the duration of each stage of panicle differentiation.The S3 sowing date had a greater impact on the duration of panicle differentiation than the first two sowing dates.In the same sowing date,the effect of density on the duration of differentiation of spike differentiation was not significant.2 Studies on the effects of sowing date and density on the differentiation and mechanism of young spikes in different panicle types of wheat2.1 Study on the effects of sowing date on the differentiation and mechanism of young panicles in different spike types of wheatWith the accelerating process of panicle differentiation,the content of ABA in young panicle of two varieties increased gradually,and the content of ZR and GA7 in panicle increased first and then decreased.The hormone and its ratio in panicle of large spike type wheat TN18 were higher than that of multiple spike type wheat SN20.With the delay of sowing date,before the differentiation of floret primordium,there was no significant difference in ABA in panicle of different wheat,but the ZR/ABA,GA7/ABA in panicle increased.From the beginning of pistil primordium differentiation,the change trend of ABA in panicle was basically the same,the ZR/ABA,GA7/ABA increased first and then decreased,and the ABA increased in tetrad period.Before the differentiation of stamen and pistil primordium,the sowing date was postponed,the contents of ZR and GA7 in panicle were increased,which indicated that the synthesis of ZR and GA7 in panicle was more than that in stamen and pistil initiation of panicle differentiation,and it played a positive regulatory role in the process of panicle differentiation.Late panicle differentiation was dominated by ABA,but it led to floret abortion,which played a negative role in panicle differentiation.At different stages of spike differentiation,the contents of sucrose,fructose and glucose in leaves were as follows:large spike type wheat(TN18)>multiple spike type wheat(SN20).The results showed that the large spike type wheat could provide more material basis and reduce the abortion of floret than the multiple spike type wheat.During panicle differentiation,sucrose content in TN18 leaves of large spike type wheat first increased and then decreased with the delay of sowing date,sucrose gradually increased before SN20 floret primordium differentiation stage,and increased and then decreased after pistil primordium differentiation stage in multiple spike type wheat.The results indicated that the delayed sowing date was beneficial to the increase of sucrose content in the leaves,which provided the material basis for the differentiation of young spikelets in wheat.The fructose content in the leaves of both varieties decreased with the delay of sowing date.The delay of sowing date was not conducive to the formation and accumulation of fructose in leaves.With the delay of sowing date,the glucose content in the leaves of large spike type varieties decreased gradually,and that of multiple spike varieties increased first and then decreased with the delay of sowing date after the formation of septum.The results indicated that delayed sowing date and large spike type wheat were not conducive to the synthesis and accumulation of glucose in the late stage of spike differentiation,and proper delay of sowing date in multiple spike type wheat was beneficial to the accumulation and formation of glucose.When sowing date was delayed,soluble protein in leaves increased gradually,which indicated that delaying sowing date was beneficial to the formation and accumulation of soluble protein content in leaves.2.2 Study on the effects of density on the differentiation and mechanism of different panicle types of wheatWith the process of spike differentiation,the contents of ABA,ZR and GA7 in young spikes showed different trends,but the difference between the two varieties was not obvious.Before the differentiation of the androgen primordium,the effect of density on ABA and ZR content was not obvious,but the formation of drug partition began,and the content of GA7 and ZR in the ear decreased gradually with the increase of density,and the content of ABA increased gradually.In the tetrad stage,the ABA content in the spike of TN18 increased first and then decreased with the increase of density,and the multiple spike type SN20 decreased first and then increased.It indicated that the low density condition was conducive to the accumulation and formation of GA7 and ZR in the late stage of spike differentiation,which was not conducive to the synthesis and accumulation of ABA,It indicated that the high content of ZR and GA7 under low density condition is beneficial to guide the differentiation of panicle and high content of high-density ABA,which is not conducive to the formation of fertile floret.With the development of panicle differentiation,sucrose content increased first,then decreased and then increased,reached the highest value at the differentiation stage of floret;fructose content decreased gradually with differentiation process;glucose content increased first and then decreased.The contents of fructose and glucose in large spike wheat TN18 reached the highest level at the differentiation stage of floret primordium.The contents of fructose and glucose increased first and then decreased with the increase of density,indicating that too low or too high planting density was not conducive to the synthesis and accumulation of fructose and glucose.The sucrose content of large spike type TN18 was the highest in middle density and middle high density,and the effect of density on sucrose content was not significant in the late panicle differentiation stage of multiple spike type SN20.In the course of panicle differentiation,the change trend of soluble protein content of the two varieties was basically the same.The content of pistil and stamen primordium was the lowest in the differentiation period,and the content of the two varieties decreased first and then increased with the increase of planting density,and the content of D3 density was the lowest in the whole.It indicates that the reduction of high-density soluble protein is not conducive to providing a material basis for wheat spike differentiation.3 Effects of sowing date and density on yield traits of wheatWith the delay of sowing date,there was significant difference in panicle number between the two varieties.There was no significant difference in grain number per ear and 1000-grain weight in the first two sowing dates of large spike type wheat TN18,but there was significant difference in grain number per panicle in different sowing dates of multi-panicle type SN20.Early sowing or too late sowing was not conducive to the improvement of wheat yield,and the yield of both cultivars was the highest at S2 sowing date.With the increase of density,the number of panicles increased gradually.There was no significant difference in the number of grains per spike,1000-grain weight and yield between the densities of D1 and D2.The yield of large spike type wheat was the highest under D3 density and that of multiple spike type wheat was the highest under D2 density.The results showed that large spike type varieties were more suitable for dense planting than multi-panicle varieties.When sowing date and density interacted,the yield of large spike type wheat was the highest under S2D3 density,and that of multiple spike type wheat was the highest under S2D3 density. |
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