Study On Preharvest Sprouting Tolerance In Triticum Durum-Aegilops Tauschii Synthetic Hexaploid Wheat

Pre-harvest sprouting is a serious disaster of wheat production.It makes seed cache break up,and leads the low yield,the low planting quality and the low process quality of flour.Improving pre-harvest sprouting resistance is an important target of wheat breeding programs as a quality and resistance character.However,because pre-harvest sprouting is quantitatively inherited and strongly affected by environmental factors,this goal is difficult to be achieved.Limited sources of sprouting resistance in hexaploid wheat has led to attempts to introduce such characteristics from the wild relatives of wheat,most of which exhibit some measure of grain dormancy.In order to find out the novel resistance to preharvest sprouting from A.tauschii,four accessions of synthetic hexaploid wheats SHW-Z1,SHW-Z2,SHW-Z3 and SHW-Z4 were obtained by artificial hybridization and spontaneous chromosme doubling from Triticum durum L cv.Langdon(2n=6x=42,AABB) and Aegilops tauschii(2n=2x=14,DD).In this paper,tolerance to preharvest sprouting of SHW-Z1,SHW-Z2,SHW-Z3 and SHW-Z4 were examined by four ways in 6 different growing periods after anthesis.The objective is to identify the resistance to preharvest sprouting and a preparatory discussion of resistant mechanism.These synthetic hexaploid wheats expressed high tolerance to preharvest sprouting which is derived from Ae.tauschii.The average germination percentages of pre-harvest intact spike of SHW-Z1,SHW-Z2,SHW-Z3 and SHW-Z4 were only 1.75%, 0.31%,1.09%and 0.17%,respectively.The SHW-Z2 and SHW-Z4,which the male parent is Ae.tauschii(As65),had a higher tolerance to preharvest sprouting than the synthetic hexaploid wheats RSP.The tolerant factors of the four synthetic hexaploid wheats mainly depended on the inhibitors in spikes and seed dormancy,while the inhibitors in glume contents has a comparative low effect on tolerance to preharvest sprouting.