水杨酸和脱落酸浸种对低温下扁蓿豆种子萌发和幼苗生长的影响

为筛选出提高低温下扁蓿豆（Medicago ruthenica）种子发芽能力的处理措施,本研究选取水杨酸（salicylic acid,SA）和脱落酸（abscisic acid,ABA）分别对扁蓿豆进行了7种不同浓度的浸种处理,测定了2种外源物质对低温下扁蓿豆种子发芽势﹑发芽率﹑发芽指数﹑活力指数、根长和芽长的影响。结果表明,2种外源物质浸种处理下扁蓿豆种子的发芽势﹑发芽率﹑发芽指数﹑活力指数,根长和芽长均呈先升高后降低的趋势,初次发芽天数无变化。供试处理中,低浓度的SA（0.1～10 μmol·L^-1）和ABA（0.001～0.5 μmol·L^-1）对扁蓿豆种子萌发﹑根长和芽长均有促进作用,且对根长和芽长的促进效果较种子萌发好,高浓度的SA（>20 μmol·L^-1）和ABA（>1 μmol·L^-1）显著抑制了种子萌发及根和芽的伸长（P<0.05）。通过模糊数学隶属函数的综合评价,0.05 μmol·L^-1的ABA浸种处理是低温下促进扁蓿豆种子萌发和幼苗生长的最佳浓度。     

紫花苜蓿种子内生根瘤菌定位及灭菌方法研究

为探寻苜蓿种子内生根瘤菌的有效灭菌方法,试验以‘甘农9号’紫花苜蓿(Medicago sativa ‘Gannong No.9’)种子为材料,设置DF(碘伏浸泡6min),DS(碘伏浸泡5min→无菌水冲洗→ST液-0.9%无菌氯化钠溶液和0.5%吐温80浸1min),SH3(3%次氯酸钠浸泡6min)和SH10(10%次氯酸钠浸泡6min)4种灭菌方法,分别以完整种子、去皮种子、种皮、子叶、胚、子叶+胚、子叶-胚连接处、幼苗为研究材料,以无菌水浸泡相应时间处理为对照,分析4种灭菌方法对供试材料内生根瘤菌的灭菌情况以及对种子萌发能力及幼苗生长的影响。结果表明：内生根瘤菌主要分布于紫花苜蓿种子的子叶+胚(52.7个·粒^-1)中,种皮有少量分布(16个·粒^-1),而在子叶+胚组织中内生根瘤菌主要分布于子叶-胚连接处(38.33个·粒^-1),其余分布数量依次为子叶(9.67个·粒^-1)、胚(4.17个·粒^-1);DS处理可对种子完全灭菌,且DS处理下完整种子的发芽率、发芽势、发芽指数、胚芽长、胚根长和幼苗长与CK差异不显著。综上,子叶-胚连接处是紫花苜蓿种子内生根瘤菌的主要存在部位,DS处理是紫花苜蓿种子内生根瘤菌的最佳灭菌方法。     

Herder Observations of Rangeland Change in Mongolia: Indicators,Causes, and Application to Community-Based Management

Local observations of ecological change are important in developing tools for rangeland management and filling in gaps where quantitative data are lacking. Traditional ecological knowledge (TEK) is a potential source of information that can complement scientific knowledge. It may also allow policy makers and scientists to suggest responses that will be locally relevant, and therefore effective on the ground. We conducted 40 surveys with the use of closed-ended questionnaires followed by open-ended qualitative questions with herders in two soum (administrative districts), located in the steppe and forest steppe of Mongolia. Respondents were asked about their observations of rangeland change and its causes in the last 20 yr. Across the study areas, a strong majority (75%) of all herders reported that rangeland condition was much worse than 20 yr ago. Herders in both soum reported increases in undesirable plant species, declines in species richness, and the disappearance or decreasing abundance of specific desirable plant species. Comparing the two soum, more herders in the forest-steppe site (90%) reported that rangeland condition was much worse than reported by herders in the steppe site (65%). In qualitative responses to open-ended questions, herders identified multiple indicators of and causes behind degradation, including very heavy grazing. In a large, sparsely populated country like Mongolia, herders' observations may serve as an early warning of rangeland change, provide insights into causes of change, and identify key uncertainties. Community-based rangeland management organizations (CBRMs) could help to translate herder observations into action by participating in formal monitoring based on herder-identified indicators and implementing changes in management in response to observed change. However, herders cannot address all issues that might be contributing to troubling ecological trends without higher-level policy coordinating rangeland monitoring and herder movements at regional and national scales.     

A short-term mechanistic model of forage and livestock in the semi-arid Succulent Karoo: 1. Description of the model and sensitivity analyses

This series of two papers describes a mechanistic model that simulates within years the productivity of vegetation and livestock on the communal semi-arid rangeland of the Succulent Karoo of South Africa. The model enables users to evaluate short-term management decisions on the production of milk and meat and to develop sets of equations and rules for long-term models designed to examine the effects of different strategies on the sustainability of the ecosystem.A soil moisture module partitions daily rainfall between runoff, infiltration and drainage and also simulates the loss of soil moisture by evaporation and transpiration. Forage production by different types of plant is modelled in relation to soil moisture and the present potential for growth. Three factors are assumed to influence the animal’s preference for a specific type of plant or part of a plant: relative abundance, ease of harvesting and digestibility. The model combines three mechanisms of food intake regulation: the rate at which the animal is able to eat forage, physical capacity of the digestive system, and, in young animals, their growth potential. Metabolisable energy intake is partitioned between maintenance, accretion/depletion of body protein and fat, conceptus growth and milk production. Reproductive and survival rates are simulated in relation to predicted liveweight and liveweight changes for the different age classes of livestock.     

不同贮藏年限对燕麦种子活力的影响

对采自甘肃省通渭县华家岭镇、并在甘肃农业大学牧草实训基地种子室分别贮藏了0年(收获当年)、1年、2年、4年和8年。供试白燕2号、坝莜14号、坝莜9号3个燕麦品种进行了发芽试验,研究了其萌发特性、膜透性以及幼苗生长状况,以明确燕麦种子活力随贮藏年限的变化状况,结果表明:燕麦种子发芽势、发芽率、发芽指数、活力指数、幼苗芽长和根长均随贮藏年限的增加而显著下降,种子浸提液电导率则明显上升,膜透性增大。试验当年收获的燕麦种子含水量普遍高于贮藏后的,但均显著低于安全含水量。不同燕麦品种随贮藏年限的延长其种子活力变化不尽相同。白燕2号和坝莜14号种子在贮藏4年仍有90%发芽率,活力指数在66;而坝莜9号发芽率只有60%,活力指数降为48.45。贮藏8年后燕麦种子发芽率低于40%,丧失种用价值。3个品种中,坝莜9号耐贮性最差,安全贮藏期只有2年。     

青贮时间及添加剂对高寒牧区燕麦-箭筈豌豆混播捆裹青贮发酵品质的影响

为了探讨青藏高原高寒牧区燕麦与箭筈豌豆混播捆裹青贮的可行性,为该地区草产品加工提供技术依据,在甘南州夏河县研究了青贮时间与添加剂对燕麦与箭筈豌豆混播捆裹青贮品质的影响。在燕麦灌浆期、箭筈豌豆开花期刈割,添加玉米粉(4%)、尿素(0.4%)、Synlac Dry(0.002 g/kg)和Sila-Max 200 (0.0025 g/kg),以直接青贮为对照(CK),进行捆裹青贮。分别在青贮第40,80,120天开包取样,每处理各时间点3个重复,测定其营养指标、发酵指标和主要微生物类群数量。结果表明:青贮时间对燕麦与箭筈豌豆混播捆裹青贮品质影响显著。由于高寒牧区秋冬季气温很低,完成青贮发酵所需的时间明显增加,在青贮80 d左右发酵才能完成。添加尿素显著提高了青贮料的粗蛋白含量,但同时其氨态氮含量在青贮40,80和120 d时一直保持最高值,较对照分别增加了73.70%、189.60%和185.27%;pH值下降缓慢,青贮120 d后pH仍在4.2以上。添加玉米粉效果明显优于添加尿素。和非生物型添加剂相比,乳酸菌制剂的青贮效果更佳,不仅促进了发酵进程,而且提高了青贮发酵品质。添加Sila-Max 200青贮效果优于添加Synlac Dry,其LAB 数量在青贮40 d后较对照增加了9.88%,乳酸含量增加了110.77%,pH值显著(P<0.05)下降;在青贮80 d后乳酸含量仍为对照的2倍,显著(P<0.05)高于其他3个处理,pH已降至4.1以下。因此,在青藏高原高寒地区,燕麦与箭筈豌豆混播在燕麦灌浆期、箭筈豌豆开花期刈割,添加Sila-Max 200后捆裹青贮80 d即可获得优质的青贮料。     

5份燕麦材料苗期耐盐性综合评价

为明确不同燕麦材料苗期耐盐能力强弱和筛选出优异的燕麦种质,以前期试验筛选出的5份耐盐性较好的燕麦为材料,采用营养液沙培法,对3周龄幼苗进行0.9%NaCl连续处理7 d后,研究盐胁迫对供试燕麦幼苗生长特性、光合特性、叶绿素荧光参数、抗氧化酶活性、丙二醛含量和渗透调节物质含量等的影响,并通过主成分分析法和隶属函数法对5份燕麦苗期进行耐盐性综合评价。结果表明,盐胁迫下,供试材料各指标间差异显著(P<0.05)。青永久195相对白燕7号、青永久30、陇燕5号、陇燕4号有着较大的根表面积、根体积、较高的K⁺含量,较低的MDA含量,较高的P_n、qP、叶绿素含量以及POD活性;而青永久30的SOD、CAT活性大于其余材料;通过主成分分析筛选出无机渗透调节物质、膜脂过氧化性、抗氧化酶活性可作为燕麦苗期耐盐性评价的综合鉴定指标,根据耐盐综合评价值(D)得出材料耐盐性排序为青永久195>白燕7号>青永久30>陇燕5号>陇燕4号。     

成熟过程中细齿草木樨种子结构及产量和质量的变化

为了探索影响细齿草木樨(Melilotus dentatus Pers.)种子发芽力的主要因素，确定适宜的种子收获时间，本试验对不同成熟阶段细齿草木樨的种子结构、产量和质量进行了观察和测定。结果表明:随着细齿草木樨种子成熟，其栅栏细胞层厚度、骨状石细胞层厚度、硬实率、产量、千粒重和生活力呈上升的变化趋势，于完熟期达到最大值，其中硬实率与种皮栅栏细胞层厚度和骨状石细胞层厚度呈正相关；细齿草木樨种子的发芽势和发芽率呈先升后降的变化趋势，于黄熟前期后第5 d达到最大值；划痕后，细齿草木樨种子的发芽势和发芽率大幅提高，在完熟期分别由7.50%和8.00%增至96.00%和96.75%。综上所述，种皮硬实是影响细齿草木樨种子萌发的主要因素，其硬实程度可能取决于栅栏细胞层厚度和骨状石细胞层厚度。细齿草木樨在新疆阿拉尔市最适宜的种子收获时间为完熟期，用作播种材料时，必须先破除硬实。     

高寒牧区小黑麦与3种豆科牧草混播草地的土壤肥力特征

【目的】探究小黑麦与不同豆科牧草混播时草地土壤养分特征。【方法】研究了3个豆科牧草品种（青建1号饲用豌豆,青海箭筈豌豆和绿箭1号箭筈豌豆）与甘农2号小黑麦以不同混播比例（0∶100、20∶80、30∶70、40∶60、50∶50、60∶40、70∶30、80∶20、100∶0）混播对浅层土壤养分含量的影响。【结果】混播组合A1（小黑麦×青建1号）有利于提高土壤有机质、碱解氮含量和降低土壤pH值,A2（小黑麦×青海箭筈豌豆）和A3（小黑麦×绿箭1号）有利于提高土壤全磷、速效磷和速效钾的含量;混播比例随豆科牧草比例的增加,有机质、全氮、碱解氮和全磷含量显著升高（P<0.05）,土壤pH值和速效磷含量显著下降（P<0.05）;混播组合与混播比例的交互作用表明,混播比小黑麦单播的土壤pH值降低0.55%～1.52%,有机质含量提高13.07%～18.30%,全氮含量提高20.24%～44.05%,碱解氮含量提高5.44%～12.5%,全磷含量提高12.77%～29.79%,速效磷含量下降17.15%～44.62%,速效钾含量提高6.61%～19.06%。【结论】与小黑麦单播相比,小...     

Can Shallow Plowing and Harrowing Facilitate Restoration of Leymus chinensis Grassland? Results From a 24-Year Monitoring Program

Long-term effects of two mechanical interventions, shallow plowing and harrowing, on degraded Leymus chinensis (Trin.) Tzvel. grassland were studied. Species composition and standing biomass of the grassland were monitored at peak biomass each year for 24 yr after application of these two measures, together with grassland in natural recovery and that under public grazing. Results showed a high resilience of degraded grassland, which recovered naturally after excluding grazing animals to a structure similar to the intact L. chinensis community. In comparison with natural recovery, harrowing facilitated restoration of L. chinensis population and community structure and improved grassland production. Shallow plowing accelerated recovery of L. chinensis population to a larger extent than harrowing and led to a flourish of annual species and improvement of herbage production in the years following its application. But the production improvement was unsustainable and was associated with a decrease in grassland species richness and community complexity. We conclude that the best measure for restoring degraded grassland depends on the restoration objectives and severity of grassland degradation. Harrowing is a feasible technique to assist restoration of the degraded grassland. In contrast, shallow plowing is not appropriate for ecological restoration, but may be applied for quick restoration of herbage production.