Study On The Factors Affecting The Differentiation Of Young Spike And Seed Yield Of Bromus Inermis L.

Bromus inermis L.is a perennial cool-season high-quality forage,but there is a big difference between the actual seed yield and the theoretical seed yield.Therefore,the following four related studies on seed yield were carried out in this paper with Bromus inermiss Leyss.cv.Wusu No.1 as experimental materials:(1).Division of the differentiation stages of young spike in B.inermis;(2).The effect of sowing method on the differentiation of young spike and seed yield of B.inermis.Set up broadcast sowing,drill sowing and acupoint sowing three ways.(3).Effects of habitat on young spike differentiation and seed yield of B.inermis,where are desert oasis area(Sanping Farm,Urumqi)and high altitude area(Xiejiagou,Nanshan,Urumqi).(4).Effects of growth years on young spike differentiation and seed yield of B.inermis,three treatments were set in the second,third and fourth year of growth.Based on the above experiments,the growth and development law and distribution of reproductive pattern of B.inermis were explored,and the regulatory effect and response mechanism of young spike differentiation were revealed.In order to provide theoretical evidence for increasing effective spike number,improving seed yield and quality,reducing floret abortion rate and properly producing seed propagation through field management measures.The results of the study are as follows:1.The results showed that the young spike differentiation of B.inermis began from tillering stage to heading stage,which could be divided into 8 stages: vegetative stage,elongation stage,single ridge stage,spikelet primordial stage,floret primordial stage,stamen primordial formation stage,stamen formation stage,spike completion stage.Young spike differentiation started from the first branch primordium and floret primordium at the top of the growth cone.The primordia on the same branchlets and floret primordia developed from bottom to top.The flowering sequence of the whole spike was from top to bottom,and the flowering time of the lower branch was less than the upper branch,and the flowering period of a single inflorescence is about 12 days;the florets on the spikelets bloom from bottom to top,and the flowering period of a single spikelet is about 7 days.2.The start time of young spike differentiation is the same under the hole seeding,drill seeding and broadcast seeding.There was no difference in the time of spike differentiation between the hole seeding and drill seeding treatments.However,the differentiation period of young spike under broadcast seeding treatment was 3 days longer than that of other treatments.The total content of endogenous hormone cytokinin(CTK)and gibberellin(GA)in young spike was the highest under the treatment of drop sowing,the highest content of abscisic acid(ABA)was under the treatment of broadcast sowing from the stamen primordial formation stage to the spike completion stage,and the highest total content of soluble protein in leaves was under the treatment of drill sowing.3.Compared with the desert oasis area(Sanping Farm,Urumqi),in the high-altitude area(Xiejiagou,Nanshan,Urumqi),the start time of young spike differentiation of B.inermis was 28 days later,and the period was shortened by 6 days.The contents of gibberellin and abscisic acid in the spike(between the elongation stage and the stamen primordial formation stage)and leaves were relatively higher,while the cytokinin content and 1000-grain weight of seeds were lower,but the number of mature seeds per spike,seed yield and seed setting rate were higher,respectively 19.39,13.39%,25.37%.The order of correlation degree of different physiological indexes in the process of young spike differentiation of B.inermis is gibberellin,abscisic acid,leaf soluble protein and cytokinin.4.In the second year and the third year of growth,the differentiation time of young spike was the same,and the differentiation period was about 41 days.In the fourth year of growth,the differentiation time of young spike was 2 days later and 1 day earlier,and the differentiation period was about 38 days.The contents of endogenous hormone bscisic acid and soluble protein in spike and cytokinin and gibberellin in leaf of young spike were the highest in the fourth year of growth,and the seed yield and yield components in the third year of growth were also the highest,which were 35.53% and 74.40% higher than those in the second and fourth year,respectively.The order of correlation degree of different physiological indexes in the process of young spike differentiation of B.inermis is cytokinin,gibberellin,bscisic acid and leaf soluble protein.