大兴安岭北部草本沼泽的基本特征

大兴安岭北部草本沼泽30个群系共含维管植物99种,分属于37科73属。多年生草本占绝对优势,共66种。区系地理成分以北温带种、旧大陆温带种和东亚种占优势。群落类型多样,区系组成单纯,种类贫乏,群落结构简单,生产力高。     

西藏主要栽培牧草、作物秸秆营养价值评价

通过对西藏4种栽培牧草和6种作物秸秆的6种营养成分的测定,应用随意采食量、净能估测模型计算了栽培牧草和作物秸秆的分级指数,对其进行了综合评价。结果表明:品质较好的栽培牧草为隆孜紫花苜蓿Medicagosativa、黄花苜蓿M.falcata和江孜紫花苜蓿。作物秸秆品质较好的为土豆Solanumtu-berosum、玉米Zea mays和燕麦Avena sativa。同时运用灰色关联度分析法对其营养价值进行了综合评价,结果表明:栽培牧草营养价值高的为紫花苜蓿和隆孜黄花苜蓿;作物秸秆营养价值较高的有土豆和玉米。运用粗饲料分级指数和灰色关联度分析法对栽培牧草、作物秸秆营养价值的评定结果较为一致。     

亚高山草甸十种多年生植物种间非同步性生长

本文以亚高山草甸群落中较常见的１０个种群为材料，通过定株定期测定，研究了种间单株生物量动态在时间上的差异。研究结果表明，此１０个种群在到达最大生物量的时间上有差异，且同一时间内，１０个种群间单株生物量相对增长率显著不同。这一结果揭示了草本植物群落中一些常见组分，种间通过在诸如土壤矿物质等资源消费时间上的错位，缓冲了种间竞争，从而得以共存。     

Decomposition of cattle dung on grazed signalgrass (Brachiaria decumbens Stapf) pastures in monoculture or intercropped with tree legumes

Livestock excreta is one of the major nutrient sources in natural grasslands. Understanding how livestock diet and season affects the decomposition dynamics is critical to nutrient cycling models. We hypothesised that livestock diet and season of the year affect dung decomposition. This study evaluated the decomposition and release of N, P, K, Ca, Mg, and Na from faeces of cattle collected in dry and wet seasons. Treatments were signalgrass (Brachiaria decumbens Stapf) in monoculture or mixed with sabiá (Mimosa caesalpiniifolia Benth.) or gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.). Excreta samples were incubated in nylon bags for 0, 2, 4, 8, 16, 32, 64, 128 and 256 d. The single negative exponential mathematical model was adequate (P < 0.0001) to explain the decomposition. The relative rate of dung decomposition (k) was greater for samples that originated from cattle grazed on signalgrass (k = 0.00284 g g^?1 d^?1), followed by sabiá (k = 0.00233 g g^?1 d^?1), and gliricidia (k = 0.00200 g g^?1 d^?1) pastures. The rate of nutrient release showed a time effect for all variables and interaction between time and season for Ca (P = 0.0042) and Mg (P = 0.0013). Faeces collected from cattle grazing/browsing intercropped pastures tended to have lower decomposition rates.     

Compost addition,but not tillage,affects establishment of urban highway plantings

Establishment of roadside plantings is often limited by adverse site conditions, particularly poor soil physical and chemical properties. We compared plant establishment of shrubs, herbaceous perennials, and grasses in response to addition of compost and/or tillage before planting in replicated plots at two locations along an interstate highway near Detroit, MI, USA. Plots at each location received one of four site preparation treatments: control (no treatment), compost only (top-dressed with 8 cm of municipal compost), tillage only (soil tilled to 20 cm) or compost + tillage (8 cm of compost added and tilled to 20 cm). Within each site preparation plot, we established sub-plots of 16 selections of shrubs, perennials, and ornamental grasses. Compost addition, plant selection, and location affected (P ≤ 0.05) plant survival, height growth, and % plant cover two years after planting. Tillage did not affect (P > 0.05) plant establishment. Similarly, the interaction of tillage × compost was not significant, indicating that surface application of compost was as effective as tilling compost into the soil. Improved plant establishment with the addition of compost was associated with improved soil and plant nutrition and reduced soil pH and soil bulk density. Within each plant group (i.e., shrubs, perennials, grasses) plant establishment varied widely. Overall, the results indicate that compost addition can improve establishment of diverse roadside plantings, which was associated with improved soil fertility. In contrast, tillage provided comparatively little benefit to plant performance in this trial.     

大学校园野生草本植物的绿化结构有待优化——内蒙古农业大学职业技术学院调查研究

对内蒙古农业大学职业技术学院校园野生草本植物进行调查,根据初步调查和统计,共有野生草本植物27科70属95种。对植物区系优势科和优势属的分析,可知有6个优势科构成该区系植物的主体,即菊科、禾本科、蓼科、藜科、毛茛科、蔷薇科,分别占该区系总属数的55.71%,占该区系总种数的63.16%。     

Comparative molybdenum concentrations in some tropical pasture legumes

Abstract

The relation between Mo concentration of several tropical pasture legumes and their growth response to Mo application has been compared. Lotononis had the greatest ability to take up Mo and its growth was least responsive to Mo application. There were no consistent differences between Mo concentrations in Siratro, desmodium and glycine, even though their growth responses differed.

The concentrations of Mo in plant shoots required for maximum growth were about 0.02 ppm or less for all species. By contrast, critical Mo concentrations in shoots of temperate pasture legumes usually exceed 0.1 ppm.

When Mo was annually applied to soil on which no growth response to Mo occured, Mo concentrations in the shoots of plants reached levels that could be toxic to cattle.     

Visual Colour Shades in Pelts from Brown Mink (Mustela vison) Explained Colourimetrically

Microspectrophotometric methods were used to provide objective correlates to the visually judged colour shade (CS) of the underfur in scanbrown mink pelts. The study included 21 scanbrown mink pelts (winter coat), representing a larger group of 87 mink pelts coming from a feeding trial with experimental and control animals. The pelts were visually graded from 1 (blue-greyish) to 5 (reddish), primarily in respect of the CS (in auction classification=clarity of colour) of the underfur seen on the edge of the pelt. Prepared samples of underfur fibres showed in visual inspection a gliding change of colour from paler to darker in a proximal-distal direction and were consequently examined at three levels above the skin surface. The means of the dominant wavelengths (hues) were 589.40, 588.00 and 586.70 nm, respectively, indicating that the variation between levels was small. Investigation of the small pelt material concerned showed that CS was significantly correlated with the measured lightness (L*) and with the yellow chromaticity coordinate (b*) of the underfur samples. In this investigation it was also shown that the underfur fibres with a visually blue-greyish colour shade were relatively dark and less yellow compared with underfur fibres with a reddish colour shade. However, data and the model estimating the colour shade demonstrated that, for the material concerned, visually very reddish underfur colour shades were not found in the lightest coloured pelts.     

华东地区豆科树种根瘤菌多样性的研究

华东地区５１个豆科树种（含羞草亚科５属,蝶形花亚科１８属）根瘤中分离获得的６６个菌株经形态、生理生化、抗逆性等性状测定,对４２个性状进行了聚类分析,除９２７８２菌株外,６５个菌株在０７５的相似水平上可划分为６个菌群。根据菌株的生长速度,６个菌群可以分为快生和慢生两个类群,但两类群的某些性状与目前根瘤菌分类系统中的分属辨别特征不完全符合,如部分菌株能利用其淀粉。聚类分析结果还表明,菌群划分的主要依据是表型特征,与寄主的种类、来源没有相关性。６６个菌株在形态、生理生化、抗逆性以及交叉结瘤试验结果存在明显差异,表明了豆科树种根瘤菌的多样性。     

The Effects of Timing of an Interim Harvest on the Yield and Composition of Lablab purpureus

Lablab purpureus was grown in two field experiments in consecutive years to evaluate the effects of the timing of an interim harvest on the yield and nutritive value of the harvested material and the subsequent regrowth, which was determined from the second and final harvest. Delaying the first harvest to 50–70 days post-sowing increased the total (first plus second harvests) dry matter (DM) yield, with a greater first harvest and reduced second harvest DM yield. The delay also reduced the crude protein concentration of the first harvest and tended to increase its modified acid-detergent (MAD) fibre concentrations. The delay increased the crude protein concentration and decreased the MAD fibre concentration of the second harvest. The total crude protein yield of both harvests increased with late interim harvesting. The first harvest plant calcium concentration increased and phosphorus concentration decreased with a delay in the interim harvest. It is concluded that, in the difficult growing conditions of the Sahelian zone of sub-Saharan Africa, delaying the interim harvest of Lablab purpureus until 50–70 days post-sowing will have beneficial effects on total dry matter and crude protein yields.