排序方式: 共有32条查询结果,搜索用时 15 毫秒
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在荒漠草原采用两因素完全随机区组设计,分析了不同载畜率下降水变化对植物物种多样性的影响。结果表明:(1)低载畜率放牧下增加50%的降水植物物种数最多,增加100%的降水反而降低了植物物种的多样性。(2)在低载畜率放牧下,减少50%降水Shannon-wiener指数显著低于自然降水、增加50%、100%降水(P0.05)。(3)中载畜率处理下,Margalef指数在减少50%降水下显著低于其他3个降水处理(P0.05)。(4)Pielou指数在中、高载畜率放牧处理下,减少50%降水显著低于增加50%降水(P0.05)。由上述结果可知,在中等载畜率放牧下减少降水有降低植物物种多样性的趋势。 相似文献
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通过Rusitec-s体外发酵系统研究不同粒度猫尾草对羔羊体外发酵参数与微生物数量的影响,选取6种不同粒度(1.00、2.36、3.35、4.75、8.00和12.50 mm)的猫尾草作为试验饲粮的纤维来源,按照猫尾草的粒度将试验分为6个处理组,每个处理4个重复,利用Rusitec-s型人工瘤胃模拟装置进行48 h体外发酵,测定养分降解率、发酵参数及发酵液中6种微生物菌群的拷贝数。结果表明:与其他处理组相比,2.36 mm组显著提高了体外中性洗涤纤维降解率(IVNDFD)、丁酸、异丁酸、戊酸、异戊酸摩尔比和溶纤维丁酸弧菌(B. f)数量(P<0.05),且显著降低总产甲烷菌(TMe)数量(P<0.05)。总菌(TB)与氨态氮(NH3-N)浓度、乙酸摩尔比呈正相关(R2=0.84,P=0.038;R2=0.88,P=0.021);B. f数量与丙酸摩尔比呈正相关(R2=0.82,P=0.045),且与pH呈负相关(R2=-0.98,P=0.001);TMe数量与体外粗蛋白质降解率(IVCP... 相似文献
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用正常产酶培养基和流加氨水产酶培养基培养Aspergillus niger J506,测定木聚糖酶的活性、酸性蛋白酶的活性和pH值。结果表明,用正常培养基培养时,木聚糖酶的活性在78~82 h达到产酶高峰,酶活力为226 U/mL。流加氨水培养,发酵液的pH值控制在4.0以上,木聚糖酶活力在86~90 h达到产酶高峰,活力为319 U/mL,比正常发酵提高了41.15%;而流加氨水条件下酸性蛋白酶活性从64 h开始比正常培养有明显降低。蛋白酶活力的降低和木聚糖酶活力的提高可能有一定关系。 相似文献
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为揭示短花针茅(Stipa breviflora)荒漠草原物种多样性季节性动态变化对长期放牧强度的响应机制,本研究以内蒙古四子王旗短花针茅荒漠草原为研究对象,2018年5月至9月对围封14年(2004-2018)不同放牧处理下的物种组成、植物高度、盖度和密度进行观测,并对物种多样性、丰富度和均匀度分析。结果表明:5次观测对照区物种Shannon-Wiener多样性指数、Margalef丰富度指数均显著大于中度放牧区和重度放牧区;所有处理均是7月和8月的物种Shannon-Wiener多样性指数、Margalef丰富度指数较高,6月和9月观测值较小;Pielou均匀度指数变化差异由大到小排序为:重度放牧区 > 中度放牧区 > 轻度放牧区 > 对照样地;月份和放牧对短花针茅荒漠草原物种α多样性指数影响均达到极显著水平,且放牧处理对物种α多样性指数影响效应大于月份。研究认为,长期重度放牧对短花针茅荒漠草原物种多样性的影响在6月和9月表现最为明显,且会威胁草地生态系统的稳定性。 相似文献
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荧光假单胞菌岩藻多糖酶的生产和酶学性质研究 总被引:1,自引:1,他引:0
[目的]研究了荧光假单胞菌HNTO1液态发酵产岩藻多糖酶的条件,并对酶学性质进行初步探索。[方法]采用单因子试验。[结果]HNT01产酶的最适培养基组成为:海带粉2%、尿素2%、葡萄糖0.06%、磷酸氢二钾0.1%,发酵起始pH值6.0,250 ml三角瓶装液量为100 ml,30℃、160 r/min条件下培养76 h。该菌所产岩藻多糖酶最适反应温度为50℃,最适反应pH值为6.0。[结论]为进一步开发高附加值的褐藻类保健食品和医药产品提供必要的科学基础。 相似文献
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Four common inducers, salicylic acid (SA), 1-aminocyclopropane-1-carboxylic acid (ACC), benzothiadiazole (BTH) and methyl jasmonate (MeJA), were selected to evaluate the effects of inducers on the resistance of adzuki bean to rust by investigating urediospores germination and the adzuki bean resistance to Uromyces vignae. The results showed that four inducers had no effects on the urediospores germination. However, they can significantly induce adzuki bean resistance to U. vignae. Among these four inducers, 0.25 mg·mL-1 ACC can significantly reduce the disease index, which was 45.06% lower than the control. Aditionally, seedlings treated with ACC exhibited a typical "triple reaction", which indicated that this induced resistance may relate with the endogenous ethylene biosynthesis in adzuki bean. Then the adzuki bean seedlings were treated with an ethylene receptor inhibitor, 1-methylcyclopropene (1-MCP) alone or combined with ACC. The results showed that 1-MCP alone had no significant effect on the growth and rust resistance of adzuki bean. However, 1-MCP could eliminate the "triple reaction" and did not affect the induced resistance caused by ACC when it used combined with ACC. Results obtained in current study suggested that ACC can significantly induce the resistance of adzuki bean to the rust. Moreover, we speculate that ACC-induced rust resistance of adzuki bean may not depend on ethylene signaling pathway. 相似文献
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