桑园土壤芽孢杆菌分析

本文通过平皿分离培养及生理生化反应，对桑园土壤中的芽孢杆菌分布及种类进行了分析，结果表明，在上层土和下层土中的芽孢杆菌分布及种类存在较大的差异，在１～５ｃｍ、５～１０ｃｍ土层中，芽孢杆菌占细菌总数的百分比分别为１３．３７％和２．３２％。共检出芽孢杆菌１５种，并将其中１１种确定到种，在土壤分布中占优势的种为枯草芽孢杆菌、巨大芽孢杆菌、地衣芽孢杆菌、蜡样芽孢杆菌、蕈状芽孢杆菌和苏云金芽孢杆菌。     

豆科牧草化感作用初探

采用培养皿滤纸的生物检测方法对红三叶、白三叶和紫花苜蓿3种常用豆科牧草的化感作用进行了初步研究。结果表明：3种豆科牧草在一定的播量下，对萝卜、青菜、番茄等受体植物生长表现出明显的抑制作用，使发芽率、苗长、根长、苗干重、根干重明显比对照降低，且抑制作用的强弱与豆科牧草种子播量有关，说明3种豆科牧草均存在较大的化感作用潜势。     

中国肉牛业现状和发展对策

本文介绍了中国肉牛业的现状，分析了中国肉牛业生产中存在的3个方面的问题，提出了中国肉牛业发展的5个对策，即继续开展肉牛改良，加快肉牛良种培育和扩繁；提高肉牛饲养管理水平，促进优质肉牛生产；提高牛肉产品质量；实现产业化生产；实施牛肉品牌战略。     

秋季补播一年生豆科牧草对扁穗牛鞭草产量和质量的影响

本试验以光叶紫花苕、箭筈豌豆和豌豆为材料,秋季补播于扁穗牛鞭草草地上,通过对补播草种物候期的观察、草地产草量的测定和牧草化学成分的分析,研究其对扁穗牛鞭草牧草产量和质量的影响。结果表明,3个补播草种的出苗时间基本一致（6～7d）,成熟期相近,均在五月中旬;在整个试验过程中,补播处理的产草量均高于对照,补播箭筈豌豆对草地产草量提高最大;随着刈割次数的增加,牧草粗蛋白含量降低,中性洗涤纤维和酸性洗涤纤维含量增加,而光叶紫花苕和箭筈豌豆在提高牧草品质方面表现较好。综合分析,秋季在扁穗牛鞭草草地上补播光叶紫花苕、箭筈豌豆和豌豆后,全年干草产量分别为12.32、13.97、12.98t/hm2,与对照相比,分别提高了36.1%、54.4%、43.4%,并且补播一年生豆科牧草可明显提高春季牧草品质（P〈0.05）。     

A comparison of a number of annual cool season legumes under dryland conditions in the Dohne Sourveld

Abstract

Fifteen annual cool season legumes were compared under dryland conditions on two sites in the Dohne Sourveld. These sites were Dohne, with a mild but dry winter and an average rainfall of 743 mm per year, and Grasslands, a colder, wetter site.

Vicia spp were among the highest‐yielding cultivars at both sites. At Dohne the mean yield of the legumes that performed best was slightly more than that of the veld and their use does not seem worthwhile. At Grasslands, the mean yield of the highest‐yielding legumes was above 6 t/ha/year and their use does seem economical.

The high yield of the legumes during wet seasons suggests that their cultivation under irrigation should be profitable. Under these or high rainfall conditions seed production may be lucrative.     

Responses of yearling steers to different stocking rates on a subtropical grass-legume pasture

Despite potential benefits, limitations of individual tropical legumes have restricted development of sustainable grass-legume pastures in tropical and subtropical regions. Sowing mixtures of complementary legumes may overcome limitations of individual species. Responses of yearling steers grazing a mixture of three tropical legumes with bahiagrass (Paspalum notatum Flugge) were evaluated at three stocking rates under continuous grazing. Carpon desmodium (Desmodium heterocarpon [L.] DC.), which is persistent under grazing but often difficult to establish, was combined with the short-lived legumes aeschynomene (Aeschynomene americana L.) and phasey bean (Macroptilium lathyroides [L.] Urb.). Diet composition, as determined by microhistological analysis of fecal samples, and animal performance were evaluated in three grazing periods: summer 1987 and spring 1988 (2.0, 3.5, and 5.0 steers/ha) and summer 1988 (3.0, 5.3, and 7.5 steers/ha). Stocking rate did not affect percentage of the selectively grazed legumes, aeschynomene and phasey bean, in the diet. Average daily gain decreased linearly (P less than .05) with increased stocking rate, as is typical for grass pastures. Aeschynomene and phasey bean contributed to diets during the first summer, and carpon desmodium contribution was greater in the second summer. These results indicate that this pasture mixture can provide legume herbage from aeschynomene and phasey bean in the year of sowing and from carpon desmodium thereafter. Over the range of grazing pressures obtained, legume responses were generally consistent; thus, optimizing stocking rate for gain per hectare or for economic returns can be targeted without additional constraints to maintain the contribution of these legumes to grazing livestock.     

Exploratory trials on reinforcement of veld with legumes in the south‐eastern transvaal highveld

Abstract

The feasibility and potential of reinforcing veld with legumes in the south‐eastern Transvaal highveld was assessed in a number of trials during the period 1974–84. Experience was gained with regard to methods of establishment, adaptation of legumes to the local environment, responses to fertilization, especially with lime and superphosphate, and the reaction of legumes to fire and grazing. In all, 17 legumes were involved, including the genera Coronilla, Desmodium, Glycine, Lespedeza, Lotus, Macroptilium, Medicago, Neoto‐nonia, Trifolium and Vigna. Only Coronilla varia (crownvetch) showed a satisfactory degree of persistence. However, crownvetch is slow to establish, is intolerant of waterlogging and has a relatively high requirement for lime and phosphate. Considering these features, and the probability of undesirable changes in grass species composition in reinforced veld, it is recommended that intensification be achieved through development of improved pastures for use in conjunction with veld, rather than by means of veld reinforcement.     

桉树间作豆科牧草适应性筛选试验

研究13种豆科牧草与桉树(Eucalyptus spp.)间作的适应性筛选.结果表明:产草量以GC1581柱花草(Stylosanthes guianensis (Aubl.) Sw. cv. GC1581)最高(376.73 kg/hm²),与其他参试品种间差异极显著(P<0.01);大翼豆(Macroptilium atropurpureum (DC.) Urb.)、有钩柱花草(Stylosanthes hamata (L.) Taub. cv. Verano)和热研12号平托落花生(Arachis pintoi Krapov.et W.C. Greg.)不适合在桉树林间种植;参试品种的抗旱等级相差不大,其中以GC1581柱花草(Stylosanthes guianensis (Aubl.) Sw. cv. GC1581)最耐旱,抗旱等级为1.16;在6龄桉树林间种植豆科牧草,抗病性和抗虫性表现较好.     

豆科牧草研究进展

豆科牧草的属间、属内、种间与种内均存在着巨大的遗传变异，利用这种变异，通过育种与选择，已培育出可良好地适应广泛的环境与管理条件的品种，遗传操作为此提供了更为广阔的空间，在豆科牧草固氮方面，对固氮过程、氮向伴生禾草的传送途径及残余氮对后继农作物的价值均有了进一步的理解。对包括施氮、采摘策略和影响混播草地中禾本科－豆科牧草平衡的胁迫等相互作用因素均已给予了阐明。在禾草／白三叶草草地为基础的家畜生产系统中，氮素的损失及其对环境产生的不良作用低于大量施氮的禾草草地系统。与禾草相比，豆科牧草无是用作放牧、青贮或用作干草，其物理、化学和解剖学等方面的特性均可增加家畜的嗜食性和自由采食量。由于豆科牧草的营养价值、可利用营养成分和采食特征，在单一豆科牧草或豆科牧草比重较大的禾草－豆科牧草混播草地上采食的不同种类、不同类型家畜的个体生产性能均优于在禾草草地上采食者。值得注意的是浓缩单宁在动物营养中的有益作用，这类单宁存在于诸如百脉根（Lotus corniculatus）、红豆草（Onobrychis viciifolia）和冠状岩黄芪（Hedys-crum coroharium）等植物中，其防止家畜患膨胀病，通过使较多的氨态氮到达小肠而提高氮的利用，并减轻绵羊肠道中线虫的作用。显然，培育含浓缩单宁的转基因豆科牧草是植物育种者现阶段的主要目标之一。此外，豆科牧草亦有许多其他用途，例如，在葡萄园中用作保护性植被，禾谷类作物的下层植被和为制药业提供次生化合物等。豆科牧草以其植物多态性和花朵的颜色等亦在美化景观和自然保护区中发挥着作用。可以预见，豆科牧草的作用在温带可持续农业中的作用将会增加，充分发掘现有的知识和相关研究成果，及有效的技术将是未来豆科牧草利用的主要特色。     

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。