Identification Of The Elite Germplasm On Root And Spike Traits In Tetraploid Wheat(Triticum Turgidum.L)

Wheat is one of the most important crops all over the world.Modern breeding program results in the genetic bottleneck to make the narrow genetic background and homogenization of wheat,which limits the further improvement of wheat and exerts great potential threat to wheat production.It has had a great impact on the high yield and high quality breeding and improvement of wheat.As a ancestor of hexaploid wheat,tetraploid wheat(Triticum turgidum.L)is an important germplasm resource and gene pool for genetic improvement of common wheat because of its larger spike,big grain,high protein content and strong stress resistance.In this study,different types of tetraploid wheat(including wild,cultivated and durum wheat)were used as materials to investigate and compare their agronomic traits,grain-related traits and root-related traits,with the purpose to identify and explore the excellent germplasm materials for providing the indispensable germplasm and material basis for wheat improvement for high yield and excellent quality.The main results are as follows:1.We firstly investigated the agronomic traits of wild and cultivated tetraploid wheat,such as,plant height,spike length,peduncle length and the 1000-kernel weight.Results showed that huge variations were found among them.The genetic diversity of wild emmer wheat was ranked from high to low as follows: 1000-grain weight >chlorophyll > length under the ear > plant height > ear length while that of cultivated wheat was: chlorophyll > 1000-grain weight > length under the ear > plant height >ear length.During the domestication of tetraploid wheat,plant height and peduncle length increased significantly,while spike length decreased significantly.On the whole,the variation coefficients of plant height and spike length are small in both of wild and cultivated emmer wheat,indicating that the selection of the two traits is limited when breeding.In the selection process,it is necessary to expand the selection population to improve the selection effect.2.Comparison of the grain-related traits of wild,cultivated and durum wheat found that grain length and grain area of wild emmer wheat were significantly higher than those of cultivated emmer wheat and durum wheat.But there was no significant difference in grain length and width,grain circumference and grain area between cultivated emmer wheat and durum wheat.This result indicated that the grain evolved from slender cognac to short and full during the domestication of tetraploid wheat,and the overall yield increased.3.The quality traits of wild,cultivated and durum wheat were analyzed by statistical analysis and independent t test.Result found that wild emmer wheat had excellent processing quality and bake quality but its grain was slender and not full.The seeds of cultivated emmer and durum wheat are full and the milling quality is good.The different type of tetraploid wheat possessed the specific quality,which can be selected for their purpose and use to improve the processing,baking and milling quality of common wheat.4.The hydroponic culture of the tetraploid wheat seedlings was carried out to investigate the root-related traits.The whole roots of plants grown for four weeks under hydroponic conditions was measured using the root scanner system.It found that the root length of wild emmer wheat was the shortest among them with the low growth,the large number of lateral roots and the dense branches,which is able to absorb water and nutrients with wide range way.The cultivated emmer wheat has a slender root with a small number,but the amount of branching is dense.They mainly rooted deeply in soil to get water and nutrients.The roots of durum wheat are sparse,with strong main root and slow growth,which is weak compared to wild and cultivated emmer wheat.In this study,the root and spike traits of wild emmer,cultivated emmer and durum wheat were preliminarily investigated and compared,and the differences and evolution trends of root and spike traits among them were clarified,which provided the useful information for further study on the evolution and mechanism of tetraploid wheat evolution,and also laid a material foundation for wheat genetic improvement of the related traits.