【作者】 曹仲华；

【导师】 呼天明；

【作者基本信息】 西北农林科技大学 ， 草业科学， 2011， 博士

【摘要】 披碱草属牧草是青藏高原天然草地上重要的牧草品种之一。本文从三个方面对披碱草属牧草进行了研究:(1)利用AFLP分子标记对搜集的9份西藏披碱草属野生牧草进行了遗传多样性的研究,从分子水平上评价西藏地区野生披碱草属种质资源的遗传多样性;(2)分析比较了两种披碱草属牧草在不同的氮肥施用量上,籽粒产量、氮肥利用率和氮素籽粒生产效率的差异;(3)选用6只装有永久瘤胃瘘管的‘澎波’西藏半细毛羊,采用尼龙袋法评价了15种西藏天然牧草的营养价值。主要结果如下:1.遗传多样性研究(1)在参考前人在其他植物上建立的AFLP反应体系和反应程序的基础上,首次建立了披碱草属牧草的AFLP银染体系。(2) AFLP标记:筛选了16对引物组合,其中有3对引物组合扩增效果较好,每对引物组合可扩增出70～83个位点,共扩增出232个位点。其中206个位点有多态性,标记产生的位点多态性达88.79%,平均每个引物产生68.67个多态性位点。17个披碱草属牧草居群的遗传相似性指数在0.284～0.955之间,UPGMA聚类分析结果表明,当相似系数为0.59时,17个牧草居群可明显划分为4类。2.氮肥利用研究(1)两种披碱草属牧草地上生物量随着氮肥施用量的增加而增加(P < 0.01)。施氮量在240 kg/ha时获得了最大的籽粒产量,施氮量在320 kg/ha时籽粒产量呈下降趋势。(2)两种披碱草属牧草的氮肥利用率受施氮量的影响较大(P < 0.05),并随着施氮量的增加呈逐渐下降的线性关系。在成熟期时两个品种的氮肥利用率无显著差异(p > 0.05),但品种和氮肥处理之间的相关性显著(P < 0.05)。(3)氮素籽粒生产效率受施氮量的影响较大(P < 0.01),并随着氮肥用量的增加而呈线性下降。垂穗披碱草(28.47 kg DM kg-1 N)呈现出一个比老芒麦(24.82 kg DM kg-1 N)高的氮素籽粒生产效率,并且在成熟期时两个品种之间的差异显著(P < 0.01)。综合籽粒产量及氮肥利用率等因素考虑,垂穗披碱草是比老芒麦更经济的一个牧草品种。3.饲用价值评定研究(1)牧草干物质、有机物、蛋白质、中性洗涤纤维和酸性洗涤纤维在瘤胃中的降解率随着时间的延长而提高,在48h左右基本稳定。(2)15种天然牧草在瘤胃流通速度k=0.02时,干物质有效降解率在29.23%-52.46%,有机物有效降解率在30.37%-51.78%,蛋白质有效降解率在32.28%-55.81%,中性洗涤纤维有效降解率在27.59%-52.61%,酸性洗涤纤维有效降解率在24.51%-48.65%。综合15种牧草的干物质、有机物和蛋白质在瘤胃中的快速降解部分(a)、潜在降解部分(b)和有效降解率看,披碱草属牧草表现较好,优于一般的禾本科牧草。(3)不同海拔的披碱草属牧草相比较,海拔较高的牧草粗蛋白含量较高,中性洗涤纤维较低,相应地,各营养成分在瘤胃中的降解率也较高。更多还原

【Abstract】 Wildrye is one of the most important forage plants on the Qinghai-Tibet plateau. This paper were studied Elymus from three aspects (1) Genetic diversity of 9 Tibet Elymus populations with 8 control groups was studied by amplified fragment length polymorphism (AFLP) in order to evaluate the genetic diversity, quantity and distribution of germplasm resources of the Tibet wild Elymus L. on molecular level and utilization in the evaluation of the genetic diversity of Elymus L., (2) quantify the seed yield, apparent N recovery efficiency (ANRE), and N utilization efficiency (NUE) in response to the rate of the applied N, and (3) evaluate the rumen degradation characteristics of main nutrients (DM, CP, OM, NDF, ADF) of 15 forages in Tibet using six rumen-cannulated‘Pengbo’semi-wool rams. The main results were as follows:1. Genetic Diversity(1) Based on the previous research on AFLP reaction system and reaction procedure, the AFLP silver-staining analysis system suitable for genomic DNA of Elymus L.was established for the first time.(2)AFLP marker: 16 primer combinations were used for polymorphism selection and 3 primer combinations produced specifically polymorphism products. Each primer combination amplified 70-83 loci. A total of 232 sites were observed, among them 206 sites are polymorphism sites. Polymorphism markers generated percentage of 88.79%, the average number of polymorphism site produced by each primer combination was 68.67. Genetic identity ranged from 0.284 to 0.955 among the 17 populations. The cluster analysis with UPGMA showed that when genetic identity is 0.59, the 17 populations could be divided into 4 groups.2. Nitrogen Utilization(1)Variation in total above-ground plant biomass was associated with N treatment, and was increased by N fertilization with a larger N effect (P < 0.01). The best seed yield response was obtained in the 240 kg N ha-1 treatment. Seed yield in plants receiving 320 kg N ha-1 was slightly lower, although straw yield increased significantly.(2)Nitrogen application rate had a significant effect on ANRE (P < 0.05), and a general decrease in ANRE was observed as N fertilization rate increased in both species. In both species ANRE showed a linear response to N fertilization. ES showed a higher mean ANRE than EN, but the difference in ANRE between ES and EN at maturity was not significant (p > 0.05). However, the interaction between N treatment and species on ANRE was significant (P < 0.05).(3)The N treatment significantly affected wildrye NUE (P < 0.01), which tended to decline linearly with increasing N rate. At maturity, both species had a significant effect on NUE (P < 0.01). Variation in NUE existed due to observed differences in plant N concentrations; EN showed a higher NUE (28.47 kg DM kg-1 N) than ES (24.82 kg DM kg-1 N), and the difference between ES and EN at maturity was significant (P < 0.01). There was also a significant interaction (P < 0.01) between N treatment and species on NUE at maturity. Compared with E. nutans (EN), E. sibiricus (ES), achieved higher total biomass, N concentration and N uptake, but a lower NUE, which indicated that E. nutans is an N-efficient species.3. Assessment of feeding value(1) The degradability of DM, OM, CP, NDF and ADF in rumen of the forages increased as incubation time and stabled within 48h.(2)When the k is 0.02, the effective degradation of DM were range from 29.23 to 52.46%, the effective degradation of OM were range from 30.37 to 51.78%, the effective degradation of CP were range from 32.28 to 55.81%, the effective degradation of NDF were range from 27.59 to 52.61%, the effective degradation of ADF were range from 24.51 to 48.65%. From the point of view of the rapidly solube fraction, potential degradable fraction and effective degradable fraction for DM, OM and CP, wildrye performed better than other grass forages.(3)The content of crude protein of Elymus increased as the altitude increasing, while the content of neutral detergent fibre was decreased. Accordingly, the forage with high nutritional value had high degradability in sheep.更多还原