The Effects Of The Introduction Of Dwarfgenes On Water Use Efficiency Of Winter Wheat

The discovery and use of dwarfing and semi-dwarfing genes had greatly improved the yield of wheat in the world, which was also the foundation of the first "green revolution". Application of dwarfing genes on decreasing plant height, improving the lodging resistance, yield potential and harvest index had become one of the most important ways to developing high yielding wheat varieties. Most of dwarfing and semi-dwarfing wheat varieties showed higher yield in well water and fertilizer conditions at present,but the effects of increasing yield was not obvious.Therefore, studying the effects of different dwarfing genes on water use efficiency and yield related traits, and to select more dwarfing genes with better drought resistence and higher water use efficiency has very important significance to wheat breeding in the semi arid region.Recombinant inbred lines(RILs; Rhtl3, Rht8, Rhtl3+Rht8 and rht) developed from R/ht8-contained bread wheat variety’Jinmai47’and the Rht 13-donor Magnif Ml, and four kinds of wheat varieties with different dwarfing genes and contain none dwarfing gene were used in this study. The objective of this study was to determine the effects of dwarfing genes on growth development, yield and water use efficiency of winter wheat under different water status using a combination of field and pot experiments and assess the possibility of application of dwarfing genes in wheat breeding in semi arid area. The main results were as follows:1.The effects of different genes on photosynthetic rate (Pn), transpiration rate and (Tr) and water use efficiency (WUEl) of winter were different. At jointing and anthesis stages, dwarfing gene Rht8, Rhtl3 and Rht8+Rhtl3 had no significantly effects on Pn,overall could greatly reduced Tr, thereby increased the WUEl of wheat. The ability to increase WUEL of Rht8 and Rhtl3 were higher than Rht8+Rhtl3,and there was no significant difference between the ability to increase WUEl of Rht8 and Rhtl3. Under drought conditions, Rht8, gene Rhtl3 and Rht8+Rhtl3 was favor to maintain higher relative water content. At the anthesis stage, compared with high stem varieties (Bima), Pn of Wenmai (Rht8+Rht-Dlb) and Aike(Rht 10) significantly reduced under same water condition in the field experiment. Under drought condition in the field experiment, Tr of Wenmai and Changhan 58 (Rht-Blb) significantly increased. Tr of Aike, Changhan58, weimai and Xiaoyan 6 had no significantly difference under irrigation condition in the field experiment. WUEl of Weimai were significantly reduced in two kinds of water conditions of field experiment compared with the tall cultivar. in addition, WUEl of Wenmai and Aike significantly reduced under the drought condition.2.Dwarfing gene could reduce plant height of wheat at different degrees and the effect to plant height was by shortening the internode length. Under the field experiment, the ability of reducing plant height of the dwarfing gene Rht8+Rhtl3 was greater than single dwarf gene Rht8 or Rhtl3, the ability of reducing plant height of Rht8 and Rhtl3 was similar. Rht8+Rhtl3 significantly shortened the length of the first and second internode length, while Rht8 and Rhtl3 significantly shortened the length of the first internode length. These four kinds dwarfing wheats (Weimai, Aike, Changhan58, Xiaoyan6)could significantly reduce plant height. The plant height of Weimai was the lowest, and the next was Aike, Changhan 58 and xiaoyan 6 was similar. The length of each internode of these four dwarf wheats decreased significantly compared with tall cultivar.3.Dwarfing genes could improve wheat yield potential at different degrees. Compared with the high wheat line (ZX16), Rht8 and Rhtl3 could significantly increase the spikelet number per spike, kernel number per spike and 1000 grain weight, so significantly increase yield and harvest index, the ability of increasing of Rht8 and Rhtl3 was similar. Under the drought conditions, Rht8+Rhtl3 decreased 1000 grain weight and yield, but it could increase them under the irrigation condition. Rht8+Rhtl3 had no adverse effect on harvest index. Compared with the tall variety (Bima 1),1000 grain weight, panicles and spikelets of Weimai, Aike, Xiaoyan 6 and Changhan 58 increased at a certain extent. The number of grains per spike of Changhan58, number of spikelets and 1000 grain weight of Aike increased significantly. The yield and harvest index of these four kinds of dwarfing wheats were higher.4. The water consumption of wheat was less affected by dwarfing gene, but water use efficiency at yield and biomass levels were differently affected. Compared with the high wheat line, under the same water conditions in the field experiment, dwarfing gene Rhtl3, Rhl8, Rht8+Rhtl3 had no significant effect on wheat consumption, yield WUE and biomass WUE. Rhtl3 and Rht8 increased yield WUE more and both increased the harvest index, while Rht8+Rhtl3 had no adverse effect on the yield WUE. Biomass WUE of four wheat lines were no significant difference under the same water treatment in the field experiments. Compared with the high variety, water consumption of these four dwarfing wheat cultivars had no significantly effect with tall cultivar in the same water condition, but yield WUE increased significantly. The biomass WUE of Weimai, Aike, Xiaoyan 6 and Changhan 58 were higer than the tall cultivar significantly.