Understanding the gibberellin sensitivity of the Rht genes Rht14,Rht16 and Rht18 in tetraploid wheat and the effects on agronomic traits are crucial for the proper utilization of these Rht genes in yield improve-ment of wheat. Five cultivars,namely,the tetraploid wheat near isogenic lines of ANW16D,ANW16F and ANW16G which contains Rht14,Rht16 and Rht18 gene,respectively,the recurrent parent LD222 and hexaploid wheat Chi-nese spring were served as materials in present studies. The heights of five cultivars before and after GA 3 treatment were measured respectively to study the gibberellin response type. At the mature period,some main agronomic traits,such as plant height,main spike length,the first internode length under main spike,internode of epidermal cells,grain epidermal cells and grain volume were measured to acquaint the effects of Rht14,Rht16 and Rht18 on them. Results indicated that ANW16D,ANW16F and ANW16G were GA-sensitive,and their sensitivity order was Chinese spring<ANW16G <ANW16F <ANW16D <LD222. 10 -4 mol/L GA3 was the best concentration level to spray with dwarf cultivars,which can restore the plant height to the normal control LD222′s height. Analysis of these agronomic traits showed that the most essential reason that Rht14,Rht16 and Rht18 reduced plant height was short-ening the first internode epidermal cell length,and the reducing effect order was Rht18 <Rht16 <Rht14. But the three Rht genes did not affect the seed size while minimizing the height.

Aiganfanmai is one of the important dwarfing germplasm in tetraploid wheat(Treaticum turgidum L.var.turgidum) landrace.Understanding the GA sensitivity of new wheat dwarfing sources Aiganfanmai and the effects of coleoptile length of dwarfing gene Rht22 is crucial for the proper utilization of Rht22 gene.Six cultivars,namely,tetraploid wheat landrace Aiganfanmai,Langdon(LDN,T.turgidum L.var.durum),hexaploid common wheat(T.Aestivum L.) variety Chinese Spring,Chuanmai 42,Chuanmai 43 and Chuanmai 55,were served as materials.The seedlings heights of six cultivars before and after GA3 treatment were measured respectively to study the gibberellin response type of Aiganfanmai.Molecular markers related to dwarfing genes and coleoptiles length of the six cultivars were measured.Result indicated that Aiganfanmai and the other five varieties were GA-sensitive.Molecular marker test results showed that Chuanmai 42 carried with Rht8 gene,Chuanmai 43 with RhtB1b and Rht8 genes,and Chuanmai 55 with RhtB1b gene.The effect of reducing coleoptile length of Rht22 gene was less than the other dwarf genes,such as Rht8 gene(Chuanmai 42),and RhtB1b + Rht8 genes(Chuanmai 43).The effects of reducing coleoptile length with dwarfing genes are Rht22 Rht8 RhtB1b + Rht8.