【作者】 赵紫平；

【导师】 邓西平；

【作者基本信息】 西北农林科技大学 ， 生态学， 2009， 硕士

【摘要】 灌浆时期是小麦粒重和产量形成的关键时期,在我国北方,小麦灌浆期常常遭受不同程度的土壤和大气干旱,严重影响小麦的灌浆过程,进而限制产量提高。深入研究灌浆期干旱对不同倍性小麦光合及其同化物转运关键酶活性和产量的影响,对于探讨干旱条件下小麦源库关系及其对产量形成的调节具有重要的科学意义和应用前景。本文选取了6个基因型小麦(二倍体:野生一粒,栽培一粒;四倍体:野生二粒,栽培二粒;六倍体:长武134,陕253)为材料,采用盆栽称重控水方式,在小麦灌浆期进行水分胁迫处理,测定了灌浆期小麦的光合参数、糖代谢和产量等指标,研究灌浆期水分胁迫对不同倍性小麦光合作用、糖代谢和产量的影响,主要研究结果如下:1.不同倍性小麦旗叶光合速率开花期达到最大值,而后开始下降,呈单峰曲线变化。光合作用是对干旱比较敏感的生理过程,不同倍性小麦最大净光合速率随着水分胁迫的加重而下降,干旱在一定程度上抑制了光合作用,在重度水分胁迫下,促使光合速率提前达到最大。六倍体小麦平均最大净光合速率为22.03 CO2μmol/(m2 s),高于二倍体和四倍体小麦。2.灌浆期,不同倍性小麦旗叶叶绿素含量和气孔导度(Gs)的变化趋势同光合速率的变化趋势基本一致。灌浆后期,随着叶绿素含量的减少光合速率也随之下降。六倍体小麦的叶绿素含量缓降期(RSP值),略大于四倍体和二倍体。并且六倍体小麦的胞间CO2浓度(Ci)始终维持较低的水平,直到花后15 d才开始上升,表明六倍体小麦旗叶花后衰老慢,光合功能期比其他供试材料长。3.小麦旗叶水分利用效率随染色体倍性的增加而增加,不同倍性小麦最大水分利用效率随着水分胁迫的加重而减小。六倍体小麦平均最大水分利用效率约为7.12μmol CO2/mmol H2O ,分别是四倍体和二倍体的1.63倍和2.05倍,并且在灌浆开始时达到最大。因此,小麦长期进化过程中,六倍体小麦花后较强的光合能力和较高的水分利用效率以及较长的持续期是提高小麦产量的重要生理基础。4.小麦从2n进化6n的过程中,倒二茎中贮存的碳水化合物各组分的相对含量是比较稳定的。茎秆关键储藏碳水化合物—果聚糖含量最高;其次是蔗糖含量较大;再次是果糖,葡萄糖含量最少。果聚糖的相对含量随着小麦倍性的增加而增加,长武134的果聚糖相对含量占到水溶性碳水化合物总量的72%,野生一粒的最小。随着小麦的进化,茎秆中的关键储藏碳水化合物—果聚糖含量有增大的趋势.小麦茎秆中果聚糖的含量与产量呈显著的正相关关系(r=0.781,P<0.05),所以茎秆中果聚糖含量是影响产量的一个重要因素。5.随着小麦染色体倍性从2n到6n的进化,小麦不同部位的糖含量及其关键酶活性也相应的变化。开花14天时,旗叶中的蔗糖含量,茎秆中的果糖和葡萄糖的含量的变化趋势表现为:四倍体>六倍体>二倍体;籽粒中的蔗糖含量、茎秆中的果聚糖含量的变化趋势表现为:六倍体>四倍体>二倍体。旗叶磷酸蔗糖合成酶(SPS)活性和茎秆中的果聚糖外水解酶(FEH)活性的变化趋势表现为:二倍体>四倍体>六倍体;籽粒SPS活性:六倍体>四倍体>二倍体;茎秆SPS活性的变化趋势表现为:六倍体>二倍体>四倍体。以上结果表明,除旗叶SPS活性和茎秆中的FEH活性二倍体最大外,无论是主要的糖含量,还是关键酶活性,都是六倍体的较大。在灌浆中期,六倍体小麦的糖代谢比其他倍性的小麦活跃,在不同器官中累积了大量的碳水化合物。6.在小麦染色体倍体由2n→4n→6n进化的过程中,小麦的根干重呈现先增加后减少的趋势,根冠比逐渐减小,地上生物量、千粒重、粒数、产量、收获指数和水分利用效率都显著增加。灌浆期的水分条件是影响收获指数和水分利用效率的关键因素。随着土壤水分胁迫的加剧,收获指数先增大后减小,分别为0.41,0.42和0.38;生物量水分利用效率逐渐增大,分别为2.39,2.43和2.53g kg-1;产量水分利用效率分别为1.06、1.10g kg-1和1.05g kg-1。灌浆期适度得水分胁迫,有利于收获指数增加和水分利用效率的提高。更多还原

【Abstract】 The grain filling stage is the critical period for seed weight and yield formation of wheat. In northern China, wheat grain-filling stage is often subjected to different levels of soil and atmospheric. Drought has seriously affected the course of wheat grain filling, thereby decrease the yield. There is important scientific significance and application prospects to understand for the source-sink relationship under drought conditions during wheat yield formation and its impact on the regulation by further studying that effect of water deficit on photosynthetic, the activity of transporting key enzyme and yield of different ploidy wheat during grain filling stage. of. Taking six wheat species (two diploid Species: Triticum. boeoticum,T. monococcum; two tetraploid species: T. dicoccoides, T. dicoccon; two hexaploid species: Changwu No 134 and Shaan No 253) as test materials, the photosynthetic parameters, sugar metabolism and yield were measured under different water conditions during grain filling stage with pot experiment, to investigate the effect of water deficit on grain photosynthetic capacity, sugar metabolism and yield. The major results are as follows:1. The photosynthetic rate of flag leaves in different ploidy wheat reached maximum at flowering stage, and then begin to decline, showing a single peak curve. Comparative photosynthesis of drought-sensitive physiological processes, with the soil water from control level to severe stress, the average maximal net photosynthetic rate decreased gradually. To some extent, drought inhibited the photosynthesis. The severe water stress made the maximum photosynthetic rate come earlier than controll. For Hexaploid wheat, the average maximum net photosynthetic rate of 22.03 CO2μmol / (m2 s), was higher than the diploid and tetraploid wheat.2. During filling stage, leaf chlorophyll content and stomatal conductance (Gs) of flag leaves in different ploidy wheat had the same trend with the changes of photosynthetic rate by and large. The late of wheat grain filling stage, photosynthetic rate decreased with the reduction of chlorophyll content. Chlorophyll content Descent Phase (RSP value)of Hexaploid wheat was slightly higher than tetraploid and diploid. The intercellular CO2 concentration (Ci) of Hexaploid wheat had remained at a relatively low level, and began to increase till 15 d after flowering, which indicatedthat hexaploid wheat flag leaf senesce more slowly than other materials after flowering and the period of photosynthetic function was longer than other test material.3. Water use efficiency of flag leaf increased with the chromosome ploidy, the average maximal water use efficiency gradually decreased with the soil water from control level to severe stress. The average maximal water use efficiency of hexaploid species was 7.12μmol CO2/mmol H2O, which were 1.63 and 2.05 times of diploid and tetraploid species, respectively, and it reached the maximum at the beginning of grain filling stage. This study indicated that improved photosynthetic capacity, water use efficiency and duration after anthesis are bases for enhancing grain yield with evolution from diploid to hexaploid wheat. 4. The relative contents of carbohydrate components in stem II were stable during the wheat evolution from diploid to tetraploid and hexaploid. there were main carbohydrates accumulated in stem - fructan content was the most; followed by the larger sucrose; fructose and glucose content was at least. Relative content of fructanin gradually increased with the wheat evolution from diploid to tetraploid and hexaploid. The relative fructan content of Changwu 134 accounted for 72% water-soluble carbohydrates, it was the smallest in Triticum. boeoticum . The key stored carbohydrates in stem - fructan content increased with the evolution of wheat. The content of fructan in stem and yield had positive correlation(r=0.781,P<0.05), so Stem’s fructan content plays an important role for yield.5. The sugar content and its key enzyme activity on different parts of wheat corresponding changes with the wheat evolution from diploid to tetraploid and hexaploid. 14 days after flowing, the trend on sucrose content in the flag leaf and fructose and glucose content of stem as follows: tetraploid> Hexaploid> diploid; the trend on surcrose content in seeds and fructan content in stem as follows: Hexaploid> tetraploid> diploid. The activity Sucrose phosphate synthase (SPS) in flag leaf and Fructan exter-hydrolase (FEH) in the stem changes as follows: diploid> tetraploid> Hexaploid; SPS activity in seeds: Hexaploid > tetraploid> diploid; the trend of SPS activity in stem as follows: Hexaploid> diploid> tetraploid. These results showed that SPS activity in flag leaf and Fructan exter-hydrolase (FEH) in stem of diploid larger than the other, regardless the or Hexaploid had higher main sugar content and key enzyme activity than other in the mid- grain filling stage. Sugar metabolism of Hexaploid wheat was more active than other material and a large number of carbohydrates accumulated in different organs.6. In the evolution of wheat from diploid to tetraploid and hexaploid, dry weight of root system increased firstly and then decreased, Root/shoot ratio decreased gradually, and aboveground biomass, 1000-seed weight, seed yield, grain yield, harvest index and water-use efficiency increased gradually. Water condition was key factor influencing harvest index and water use efficiency during grain filling stage. With the aggravation of drought, harvest index of wheat increased firstly and then decreased, the values of harvest index were 41.38 %, 42.26 % and 38.20 %, respectively, water use efficiency for biomass gradually increased, the values of them were 2.39, 2.43g kg-1 and 2.53g kg-1, respectively, and water use efficiency for grain yield were 1.06, 1.10g kg-1 and 1.05g kg-1, respectively. Therefore, moderate water stress was helpful to improve harvest index and water use efficiency for crop.更多还原