Study On Physiological Mechanism Of Panicle And Grain Abortion Of Oat With Different Genotypes

In order to explore the physiological causes of sterility and flower grain abortion of oat spikelet and the important physiological indexes affecting the formation of grain number per spike,this experiment conducted a field experiment for three consecutive years using 10varieties with different genotypes,sources,maturity,spike type,plant type,and spikelet number as experimental materials.By measuring the developmental characteristics of young spikes in oat,combining physiological indicators such as carbon metabolism,endogenous hormones,and source sink relationships,methods such as variance analysis,principal component analysis,cluster analysis,and correspondence analysis were used,To explore the differences in the number of grains per ear,grain weight,and the formation process of strong and weak potential grains in different genotypes of oat,in order to reveal the physiological mechanism of ear and grain abortion in oat.The main research results are as follows:1.There are genotypic differences in the formation process of grain number per spike of oat.Bayou 1,Bayou 9,Caoyou 1,and Bayou 18 are varieties with high grain number per spike,Baiyan 5,Mengyan 1 have moderate grain number per spike,and Baiyan 2,Huabei 2,Dingyou 8,and Pin 5 are varieties with low grain number per spike;The grain number per spike of the high grain number per spike variety was significantly higher by 15.23%～153.79%than that of the low grain number per spike variety（P<0.05）.The varieties with high spike grain number have better young spike differentiation,laying a foundation for reproductive growth of high spike grain number;The content of gibberellin（GA₃）in high spike grain number varieties was significantly higher than that in low spike grain number varieties by14.69%～53.08%,the sucrose conversion efficiency in the spike was 4.46%～18.72%,the net photosynthetic rate（P_n）was significantly higher by 5.45%～97.00%,and the sucrose phosphate synthase activity（SPS）was significantly higher by 2.60%～34.11%.The leaf physiological activity during the formation of spike grain number was higher,providing nutritional protection for the flowering and ear formation processes.2.There are genotype differences in the formation process of oat grain weight.Bayou1,Bayou 9,Caoyou 1,Baiyan 5,and Bayou 18 are higher grain weight varieties,while Baiyan 2,Huabei 2,Mengyan 1,Dingyou 8,and Pin 5 are lower grain weight varieties.The grain weight per spike of the varieties with higher grain weight was significantly higher than that of the varieties with lower grain weight by 12.50%～226.51%,SPS was significantly higher by 8.08%to 69.49%,and P_n was significantly higher by 16.48%～69.06%;The efficiency of sucrose conversion in the ear is 11.89%～49.66%higher,the content of GA₃ is5.16%～104.47%higher,and the content of IAA is 6.74%～118.20%higher.During the grain filling process of varieties with higher grain weight,leaf sources provide sufficient nutrients and promote the coordinated regulation of growth hormones,which is a physiological advantage for late assimilation transport and high yield.3.The upper and middle grains of oat ear are strong grains,while the lower grains are weak grains.The sucrose decomposition rate and starch synthesis rate in the strong and weak potential particles of Bayou 1,Bayou 9,Bayou 18,and Caoyou 1 were higher,and the sucrose starch transport ability was stronger than that of Baiyan 2,Baiyan 5,Huabei 2,Dingyou 8,and Pin5.The ABA content in the upper,middle,and lower grains of high yielding varieties was significantly higher by 10.42%to 69.43%,7.30%to 139.69%,and56.15%to 198.04%than that of low yielding varieties;The content of GA₃ was significantly lower by 7.07%to 39.02%,10.07%to 43.40%,5.47%to 47.51%in strong and weak potential grains of high yielding varieties.The ABA,IAA,and adenosine diphosphate glucose pyrophosphorylase（AGP）that promote grain filling and starch synthesis in strong and weak potential grains were synergistically regulated.GA₃ in the strong and weak potential grains of low yield varieties inhibits grain filling to some extent,and the sucrose synthesis process is more active than the sucrose decomposition process,resulting in a slow starch accumulation rate,which leads to relatively weak grain filling and grain weight formation in the upper strong grains.4.High yield varieties include Bayou 1,Bayou 9,Bayou 18,Caoyou 1,and Baiyan 5.Low yield varieties include Mengyan 1,Huabei 2,Baiyan 2,Dingyou 8,and Pin 5.The grain yield of high yielding varieties was significantly higher than that of low yielding varieties by 5.43%～79.36%,the number of spikelets bearing seeds was significantly higher by8.16%～128.48%,and the number of spikelets on flower tips was significantly lower by10.66%～93.31%;High yielding varieties have a lower degree of abortion,more fertile spikelets,and fewer spikelets on flower tips;Low yield varieties have a higher degree of abortion,fewer fertile spikelets,and more spikelets on flower tips.Grain abortion significantly affects yield.5.The content of GA₃ in flag leaves during heading and flowering is a decisive indicator that affects the physiological process of grain number formation per spike.Endogenous hormones,assimilate transport,photosynthesis,and enzyme activity jointly regulate grain number formation per spike.SPS activity and Pn in flag leaves during grain filling stage are decisive indicators that affect the physiological process of grain weight formation.Endogenous hormones,photosynthesis,and sucrase activity jointly regulate grain weight formation.High yield varieties have more grains per spike,which in turn increases the grain weight per spike.Strong or weak potential grain weight per thousand grains,i.e.,the weight of a single grain,is not a key factor determining high yield.Increasing the number of grains per spike can be used as a breakthrough to improve yield;Attention should be paid to the leaf GA₃ content,SPS activity,P_n,and ABA,IAA content and AGP activity in the strong and weak potential grains during the heading,flowering,and heading processes,as well as during the filling and grain filling processes;Through cultivation measures to regulate enzyme activity,coordinated supply of source and sink,and hormone dynamics,ensure the number of grains per spike,reduce the degree of abortion,and tap the high yield potential of oat.