The Comparisons Of Competitive Abilities And Yield Characters Of Different Ploidy Spring Wheat Cultivars

Pot experimental method and field experimental method were used to measure competitive ability, grain yield, drought resistance and water use efficiency of three spring wheat (Triticum aestivum L.) cultivars under different water stress. The three wheat (Triticum aestivum L.) cultivars were chosen for study because of their genetic differences. 'MO1' is diploid wheat cultivar (2n). 'DM22' is tetraploid wheat cultivar (4n). Longchun8275 is hexaploid wheat cultivar (6n). Main results in this study are listed as follows:1. Both pot experimental method and field experimental method results showed that: wheat chromosome ploidy changed from 2n to 4n or even 6n during its evolvement, make taxis of competitive ability, LC8275(6n) > DM22(4n) > M01(2n) under water sufficiency;DM22(4n) > LC8275(6n) >M01(2n) under drought stress(Table 4-2, Table 4-11).2. Pot experimental results showed that(Fig 4-1): wheat chromosome ploidy changed from 2n to 4n or even 6n during its evolvement, wheat grain yields exhibit increasing trend with the increasing of chromosome ploidy under all treatments (Complete water supply(CK), Moderate drought stress(MS), Severe drought stress(SS)), statistical differences was considered significant;while grain yield of three cultivars (MO1(2n), DM22(4n) and LC8275(6n)) increased greatly with the improvement of water condition. Field experimental method results showed that(Fig 4-7): in control group(CT), yield taxis as follows: DM22(4n) >LC8275(6n) >M01(2n), statistical differences was considered significant;in stress treatment group(ST), yield of both LC8275(6n) and DM22(4n) are more than that of M01(2n), statistical differences of LC8275(6n) and DM22(4n) was not considered significant, while yield of MO1(2n) and DM22(4n) increased greatly with the improvement of water condition.3. Pot experimental results showed that(Fig 4-5, Fig 4-6): wheat chromosome ploidy changed from 2n to 4n or even 6n during its evolvement, water use efficiency based on shoot biomass(WUEB) and water use efficiecy based on grain yield(WUE_G) of wheat increased with the increasing of chromosome ploidy under all treatments (CK, MS, SS) , statistical differences was considered significant;WUE_B and WUE_G of three cultivars (MO1(2n), DM22(4n) and LC8275(6n)) decreased obviously with the aggravation of water stress. Field experimental method results showed that(Fig 4-9, Fig 4-10): in the group of Control group(CT) and Stress treatment group(ST), wheat chromosome ploidy changed from 2n to 4n or even 6n during its evolvement, thereinto, statistical differences of diploid wheat cultivar MO1(2n) and tetraploid wheat cultivar DM22(4n) were considered significant, but statistical differences of tetraploid wheat cultivar DM22(4n) and hexaploid wheat cultivar LC8275(6n) were not considered significant;WUE_B of three cultivars (MO1(2n), DM22(4n) and LC8275(6n)) decreased obviously with the aggravation of water stress. In CT group, WUE_G of tetraploid wheat cultivar DM22(4n) and hexaploid wheat cultivar LC8275(6n) are more than that of diploid wheat cultivar MO1(2n), WUE_Gof DM22(4n) are more than that of LC8275(6n), statistical differences was not considered significant;in ST group, WUEg of tetraploid wheat cultivar DM22(4n) and hexaploid wheat cu!tivarLC8275(6n) are more than that of diploid wheat cultivar MO 1 (2n), WUEG of DM22(4n) are less than that of LC8275(6n), statistical differences was not considered significant. While WUEg of M01(2n) in ST group are less than it in CT group;there is no considered significant of statistical differences for WUEg of DM22(4n) and LC8275(6n) in CT group and in ST group.4. Pot experimental results showed that (Table 4-7, Table 4-8, Table 4-9): all factors of three kind of spring wheat have positive relativity, thereinto, the quotiety of a spike weight, number of grains per spike, water use, above ground biomass and grain yield all reach the most significantly positive relative level;three kind of spring wheat of water use efficiency and drought resistance all reach significant positive relative level.5. Field experimental method results showed that (Table 4-14): drought stress completely inhibited the plant height and structure of yield of all kinds of cultivar, but their decreasing degree are different because of the differences of cultivar. Hexaploid wheat cultivar LC8275(6n)'s parameter is little, tetraploid wheat cultivar DM22(4n) middle, diploid wheat cultivar M01(2n) most.