【作者】 董淑琦；

【导师】 马永清；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2013， 博士

【摘要】 本文依据冬小麦可以刺激列当种子发芽，作为“诱捕作物”来防除列当科杂草。研究了向日葵列当和瓜列当种子的打破休眠的方式、最佳预培养时间和观察时间。通过水培方法收集冬小麦根系分泌物，并进行了分离纯化和物质鉴定。采集不同生育期冬小麦根际土、根系和地上部，利用蒸馏水和甲醇两种浸提剂提取列当科种子发芽刺激物质刺激向日葵列当和瓜列当种子发芽，依据两种列当种子的发芽率来比较冬小麦不同器官之间刺激列当种子发芽率的高低；比较两种提取剂的效果；筛选出在不同生育时期选用能刺激列当种子发芽率高的冬小麦品种来防除列当科杂草；反映不同基因型冬小麦对其化感作用的强弱。以轮作方式种植不同基因型冬小麦，后茬种植寄主向日葵，调查向日葵列当寄生数量及测定寄主株高、胸径和生物量，反映不同基因型冬小麦能否诱捕向日葵列当，并提高寄主产量。本研究得到的主要结论如下：1.蒸馏水预培养向日葵列当和瓜列当种子可以打破其休眠。两种列当最少需要预培养3天，预培养1-2周的种子发芽率趋于稳定。2.乙酸乙酯萃取三次即可将根系分泌物中发芽刺激物质萃取到乙酸乙酯相中。不同浓度根系分泌物刺激向日葵列当和瓜列当种子的发芽率高低顺序为：100mg/L>10mg/L>1mg/L。在三个浓度下，冬小麦根系分泌物刺激向日葵列当和瓜列当种子的发芽率伴随着小麦基因型倍体的加倍而呈现逐步上升趋势，不同品种间达到差异显著（P<0.05）水平。利用LC-MS/MS质谱多反应监测技术分析了小麦样品中发芽刺激物质的结构，与14种已知独脚金类似物结构对比，没有发现已知的物质，小麦中能刺激列当种子发芽的物质有可能是不同于上述14种物质，其结构有待选用新方法来进一步地分离鉴定。3.苗期不同基因型冬小麦根际土均可直接刺激向日葵列当和瓜列当种子发芽，说明小麦在自然状态下分泌的发芽刺激物质可以有足够的浓度使受体列当种子发芽。拔节期不同基因型冬小麦根际土及其浸提液刺激两种列当种子的发芽率伴随着冬小麦基因型倍体的增加而增加，六倍体基因型冬小麦刺激其发芽率最高。冬小麦刺激列当种子发芽物质是在根部合成，且根系和地上部浸提液刺激向日葵列当和瓜列当种子的发芽率呈现正相关关系。抽穗期陕253根系刺激向日葵列当种子发芽率最高为32.4%，而瓜列当种子的发芽率在20%-30%之间；六倍体基因型陕139和陕253茎甲醇浸提液刺激瓜列当种子发芽率最高为49%和51.1%；比较冬小麦不同器官蒸馏水浸提液刺激向日葵列当种子的发芽率，叶片最高，根系与茎、麦穗相近，且根系与茎杆、叶片和麦穗之间都呈现正相关关系。表明小麦根部合成的发芽刺激物质已经向地上部运输。成熟期不同基因型冬小麦根际土直接刺激向日葵列当和瓜列当种子发芽率降低，而地上部发芽率出现增高的趋势，其中陕139茎杆蒸馏水浸提液刺激向日葵列当发芽率最高为28.1%，甲醇浸提液刺激其发芽率均在30%以上，陕253茎杆浸提液刺激其发芽率最高为27.7%（蒸馏水）和23.7%（甲醇）；栽培一粒叶片甲醇浸提液刺激向日葵列当种子发芽率最高为45.9%，六倍体基因型冬小麦陕253叶片浸提液刺激瓜列当种子发芽率最高为24%（蒸馏水）和29%（甲醇）；陕253颖壳浸提液刺激向日葵列当种子发芽率最高为26.8%（蒸馏水）和37.6%（甲醇），陕253颖壳甲醇浸提液刺激瓜列当种子的发芽率最高为33.2%。根据冬小麦植株不同部位器官浸提液刺激向日葵列当种子发芽率，根系与茎和籽粒之间呈现正相关关系。对于瓜列当种子的发芽率而言，根系与茎、叶片、籽粒和颖壳均呈现正相关关系。地上部积累着能够刺激列当种子发芽的物质，秸秆还田后这些物质的释放有可能进一步刺激列当种子发芽，但需要进一步实验验证。4.随着冬小麦基因型的加倍，在苗期、拔节期、抽穗期和成熟期不同部位器官浸提液（蒸馏水和甲醇）刺激向日葵列当和瓜列当种子的发芽率呈现逐步上升的趋势，冬小麦对两种列当的化感作用逐步增强。5.前茬种植陕253和陕139，收获后再种植向日葵，每株向日葵上向日葵列当寄生株数分别为3.2和4.6，是对照的1/6和1/4，可以显著降低向日葵列当的寄生率。后茬种植的向日葵胸径比对照要粗0.2mm，平均株高要高10cm多，向日葵被寄生后的鲜重和干重是没有被寄生的46%和37%。前茬种植冬小麦有助于后茬向日葵胸径、株高和生物量的增加，显著地减少了向日葵列当的寄生数量，间接地提高向日葵的产量。更多还原

【Abstract】 The winter wheat can stimulate Orobanche seed germination to be as one ‘trap crop’ forcontrolling the weeds of Orobanchaceae. Based on this, we studied the method of breakingdormancy, the best pre-conditioning time and observation time of Orobanche seeds. Throughthe hydroponic method, winter wheat root exudates were collected, and then purified andidentified by LC-MS/MS. Rhizosphere soils, roots and shoots at different growth stages ofwinter wheat were collected, and these samples were extracted by distilled water or methanoland then diluted to four concentration. The extracts (distilled water and methanol) were testedto stimulate O. cumana and O. aegyptiaca seeds germination. According to the twoOrobanche seeds germination rates, the stimulation effect among different organs of winterwheat were compared and the better solvent would be identified; the winter wheat whichperformed better at different growth stages could also be screened out to control Orobancheweeds; it could also reflect the allelopathy potential of different winter wheat genotypes.Through winter wheat/sunflower rotation, the O. cumana parasitic quantity were investigatedand the diameter at breast height (DBH), plant height and biomass of sunflower were alsotested. Through these indexes, we could found if different winter wheat genotypes can be as‘trap crops’ for O. cumana and increase sunflower production.The main conclusions of this study are as follows:1. Pre-conditioning O. cumana and O. aegyptiaca seeds by distilled water could breaktheir dormancy. They should be pre-conditioned at least for3days, and the germination ratetended to be stable after pre-conditioning for1-2weeks.2. After extracting for three times, ethyl acetate could extract the germination stimulantfrom the root exudates into ethyl acetate phase. The root exudates at the differentconcentration stimulated O. cumana and O. aegyptiaca seed germination followed the role of100mg/L>10mg/L>1mg/L. At the three concentration, the germination rate of O. cumanaand O. aegyptiaca increased as the ploidy of wheat genotypes doubled, and there weresignificant differences (P <0.05) among the different varieties. LC-MS/MS mass spectrometrymultiple reactions monitoring technology was used to analyze the germination stimulant inwheat samples and its structure were different with the14known strigolactones. Maybe the germination stimulant in wheat was not any one of the14substances. The structure needs tobe further isolated and identified by new methods.3. At seedling stage, the rhizosphere soil of different winter wheat genotypes coulddirectly stimulate O. cumana and O. aegyptiaca seed germination. It was shown that thegermination stimulant secreted from winter wheat at natural state could stimulate Orobancheseed germination at certain concentration.At jointing stage, the rhizosphere soil and its extracts of different winter wheat genotypescould stimulate the two Orobanche seed germination. The germination rate increased as theploidy of winter wheat genotypes doubled, and the hexaploid winter wheat stimulated thehighest germination rate. The germination stimulant was synthesized in the roots of winterwheat. There were positive correlations between Orobanche seed germination induced by rootand shoot extracts of winter wheat.At heading stage, the roots of Shaan253stimulated the highest germination rate of O.cumana seed (32.4%), while the O. aegyptiaca seed germination rate was between20%to30%. O. aegyptiaca seed germination rate induced by the stem methanol extracts of hexaploidgenotypes of Shaan139and Shaan253were up to49%and51.1%. Among O. cumana seedgermination induced by distilled water extracts of different organs of winter wheat, the leaveswas the highest, roots, stems and ears were similar. There were positive correlations betweenthe roots and stems, leaves and ears according to the germination rate. It showed that thegermination stimulant was synthesized in the wheat root and transported to the shoot.At maturity stage, O. cumana and O. aegyptiaca seed germination directly induced bythe rhizosphere soil of different winter wheat genotypes decreased gradually, while thegermination rate induced by aboveground extracts increased. The stem distilled water extractsof Shaan139stimulated the highest germination of O. cumana (28.1%), and methanolextracts stimulated the germination rate more than30%. The germination rate stimulated bythe stem extracts of Shaan253were up to27.7%(distilled water) and23.7%(methanol). O.cumana seed germination rate induced by the leaf methanol extracts of T. monococcum L. wasup to45.9%. O. aegyptiaca seed germination rate induced by the leaf extracts of hexaploidwinter wheat of Shaan253were up to24%(distilled water) and29%(methanol). O. cumanaseed germination rate induced by the glume extracts of Shan253were up to26.8%(distilledwater) and37.6%(methanol), and O. aegyptiaca seed germination rate was up to33.2%induced by its methanol extracts. Among O. cumana seed germination stimulated by theextracts of different organs of the winter wheat, there were positive correlations between theroots and stems, roots and grains. According to O. aegyptiaca seed germination rate, itshowed positive correlations among the roots, stems, leaves, grains and glumes. The germination stimulant was accumulated aboveground. Maybe the stalk could further releasethese substances to stimulate Orobanche seed germination, and this requires experimentalverification in future.4. The extracts (distilled water and methanol) of different organs of winter wheatstimulated O. cumana and O. aegyptiaca seed germination at seedling, jointing, heading andmaturity stages, and the germination rate increased gradually as the ploidy of winter wheatgenotype doubled.5. Planting the winter wheat of Shaan253and Shaan139in front stubble of sunflower,the parasitic number of O. cumana were3.2and4.6on per sunflower, which was1/6and1/4compared to the control. It could significantly reduce the parasitic rate of O. cumana. TheDBH of sunflower was0.2mm more than the control. The average plant height of sunflowerwas10cm more than the control. The fresh and dry weights of parasitized sunflower wereonly46%and37%of unparasitized sunflower. So planting winter wheat in front stubble ofsunflower could significantly increase the DBH, plant height, biomass of sunflower anddecrease the parasitic number of O. cumana, and improved the yield of sunflower indirectly.更多还原