桉树人工林间作禾本科牧草适应性筛选与评价

桉树人工林单一种植引起植被多样性减少、生物多样性下降是普遍存在的问题,间作成为恢复与重建桉树林下植被多样性的重要途径。桉树人工林下间作禾本科牧草综合评价结果表明,热研14号网脉臂形草、热研8号坚尼草、热研9号坚尼草、热研6号珊状臂形草等牧草产草量达215.89～475.42 kg/hm2,旱季牧草产量占年产草量的14.08%～17.51%,在极端干旱条件下仍保持一定的生长和生物量的积累,植株存活率达53.6%～76.6%,覆盖度达62.71%～90.42%。间作牧草在桉树行间形成良好的覆盖层,提高了林地植被覆盖度,植株存活率较高,促进植被多样性的形成,对增加桉树人工林的群落组成、形成多层次片层结构有积极意义。     

桉树林草间作系统根层结构的研究

试验对6 a树龄桉树人工林12个牧草间作3 a后间作系统根层结构进行研究，结果表明：间作牧草3 a后桉树根系主要分布在距树基50～100 cm的行间，间作禾本科牧草限制了桉树根系向行间（4 m）伸展，而间作豆科牧草促进了桉树根系向行间伸展。桉树根系主要集中在10～50 cm的土层，占总根量的74.81％，间作禾本科牧草抑制了桉树根系向浅层分布的可能，而间作豆科牧草后桉树根系向土壤中上层扩展，且更加集中在20～40 cm土层。     

桉树人工林间作豆科牧草适应性评价

桉树人工林单一种植引起植被多样性减少是普遍存在的问题,间作成为恢复与重建桉树林下植被多样性的重要途径。桉树人工林下间作豆科牧草综合评价结果表明GC1581、GC1517、热研10号和热研2号柱花草牧草产草量达296.54~852.08 kg/hm2,耐干旱,旱季牧草产量占年产草量的18.42%~23.95%,在极端干旱条件下仍保持一定的生长和生物量的积累,植株存活率达50.2%~61.9%,间作牧草在桉树行间形成良好的覆盖层,覆盖度达47.083%~79.252%,适应性强。间作可促进林下植被的恢复,进而促进植被多样性的形成,这对增加桉树人工林的群落组成、形成多层次片层结构有积极意义。     

椰园/牧草间作:主间作物之间相互的影响

进行了椰园间作牧草生态系统的研究。通过不同类型椰园间作不同品种牧草的适应性试验,观测了不同主间作物栽培方式中椰园根系分布、土壤养分与温度、主间作物生长及产量等方面的变化。结果表明:(1)在种植密度为10m×6m的椰园(相对光照强度约在50%以上)中,禾本科和豆科牧草均能正常生长;在8m×6m的椰园(相对光照强度约在30%左右)中,多数牧草品种能正常生长;在6m×6m的椰园(相对光照强度不足30%)中,只有少数禾本科牧草能基本正常生长。(2)禾本科牧草与椰树组成的系统稳定性比豆科牧草的好。(3)间作物一般应距幼树1m、成龄树2m以外的地方种植。(4)合理压青培肥与科学防治金龟子害虫,有利于加强主间作物生态系统的稳定性。      

茶园间种桉树对茶叶品质的影响研究

调查发现云南昌宁、云县等地部分茶园间种了桉树。本研究采集了间作和未间作桉树的茶鲜叶分别烘干和阴干制备茶样,应用分光光度法、高效液相色谱法等测定了茶叶水浸出物、茶多酚、儿茶素、黄酮醇、茶氨酸等41种成分含量,结合感官审评分析了间种桉树对茶叶品质的影响。茶样内含生化成分经主成分、正交偏最小二乘法判别分析发现,与对照相比,间作桉树茶样的没食子儿茶素、山奈酚、槲皮素、甘氨酸、鞣花酸、木犀草素、花旗松素、表没食子儿茶素没食子酸酯、表没食子儿茶素等9种成分含量显著升高（VIP> 1,p <0.05,FC> 1.2）,而谷氨酸含量显著降低（VIP> 1,p <0.05,FC <0.83）。感官审评发现,间作桉树的阴制茶样香气与滋味都辛辣,品质降低。研究结果表明,云南昌宁、云县等茶区茶园间种桉树会降低茶叶品质,不宜在茶园间种。     

植物促生菌对桉树幼苗生长及其氮素来源的影响

利用~(15)N稳定性同位素示踪法,研究施氮水平对接种或不接种植物促生菌的桉树幼苗生物量、N和P吸收量及其吸收氮素来源的影响。结果表明:随着施氮量的增加,桉树幼苗植株生物量、N和P吸收量均显著增加。接种PGPR SZ7-1植物促生菌能显著促进桉树幼苗生物量的增加和养分量的吸收。未接种植物促生菌的桉树幼苗,其植株吸收氮素主要来源于土壤,其次是肥料;而接种PGPR SZ7-1植物促生菌的桉树幼苗,其植株吸收的氮素则主要来源于生物固氮。PGPR SZ7-1植物促生菌具有较好的固氮能力,固氮率达40%以上。结果还显示,随着施氮量的增加,接种植物促生菌的桉树幼苗生物固氮能力下降,植株氮素主要来源于土壤氮,其次为生物固氮和肥料氮。在较低的氮素水平下,接种植物促生菌能有效促进桉树植株的生长发育和养分吸收,是一种减少肥料施用、保护生态环境的农业措施之一。     

胡椒与槟榔间作对群体养分吸收利用的影响

选用胡椒与槟榔种子苗为材料,比较胡椒与槟榔间作和二者单作条件下,胡椒与槟榔的根系形态、地上部和根系的养分浓度和含量、养分吸收和利用效率、地上部和根系生物量的差异。结果表明:胡椒与槟榔间作显著提高了胡椒根系有效形态及地上部氮、磷、钾、钙和镁的养分含量,胡椒对磷的利用效率和地上部生物量均表现出明显的间作优势。分析胡椒根系形态参数与养分效率相关关系,发现胡椒的根长密度、比根长和比表面积与磷的利用效率显著正相关,其中比根长对磷利用效率提升的贡献率达94%,胡椒/槟榔体系显著提高了胡椒的这3个根形态参数和生物量,所以,胡椒/槟榔体系通过改变胡椒根系形态,增加了对养分的吸收量和利用效率,从而提升了胡椒的生物量。间作还提高了槟榔根系氮和磷的养分含量,提高了槟榔对氮和磷的利用效率。间作体系中槟榔对氮和磷的利用效率增加,有利于提高槟榔抵抗病虫的能力,还可以改善槟榔黄化现状和防止其发生。可见,间作体系通过改变胡椒和槟榔的根形态,提升了二者对养分的吸收利用效率和胡椒生物量。     

桉树人工林的若干生态问题及其研究进展

综述了国内外关于桉树人工林对养分、水分过度消耗，减少生物多样性和生态稳定性差等生态问题的研究进展。     

连栽桉树人工林不同代次土壤养分与酶活性的分析

探讨桉树不同连栽代次、不同土层土壤养分与土壤酶活性的变化,为人工林的持续经营和生产实践提供参考依据。对广西东门林场连栽巨尾桉人工林不同栽植世代：一代林（G1）、二代林（G2）、三代林（G3）、四代林（G4）林地及对照林马尾松林（G0）的0~5、5~20、20~60 cm土层土壤养分与酶活性进行分析。结果表明：将马尾松林换种桉树后一代林地,其土壤pH、全氮、全磷、全钾、磷酸酶、脲酶和过氧化氢酶均不同程度降低了,且0~5 cm表层土下降较明显。随着桉树连栽代次的增加林地土壤土壤全氮、全磷和全钾都呈现先增后减趋势,且在0~5 cm表层土中二、三代林都出现停滞现象;随着桉树连栽代次的增加林地土壤磷酸酶、过氧化氢酶和脲酶活性也呈现先增后减的趋势,其中脲酶在0~5 cm表层土中二、三代林也出现停滞现象。随着土层的加深,土壤pH、全氮、磷酸酶和脲酶逐渐降低,而土层加深对土壤全磷、全钾和过氧化酶影响不大。     

热带地区桉树林地与农用地土壤肥力现状研究初报

在不同的土壤类型上,针对不同的利用方式(桉树林地和农业用地),自2000年起,开始长期的定点定位肥力对比观测,并进行了海南桉树林地和农业用地土壤肥力变化规律研究.研究结果表明:与农业用地相比,桉树林地土壤有机质较高,土壤容重较小,土壤的阳离子代换量增加。海南发展桉树生产只要合理的利用,注意地表覆盖,防止水土流失,就可以不断地提高土壤肥力。     

豫北优质大豆产业发展策略

针对豫北地区的大豆生产现状，从气候、土壤、品种、生态因素及市场需求等方面提出了优质大豆的发展策略与途径。     

湖南沅陵4种绿茶品质成分分析

以长沙县高桥相同嫩度茶鲜叶原料采用卷曲形毛尖茶加工工艺制绿茶为对照,分别对沅陵县齐眉翠峰、凤娇碣滩茶、干发茶和军大坪茶4种绿茶的主要生化成分与感官品质进行初步分析。结果表明,沅陵4种绿茶的茶多酚总量28.76%~30.34%,游离氨基酸总量2.35%~3.22%,咖啡碱含量3.00%~3.63%,水浸出物含量37.26%~40.07%,可溶性糖总量5.46%~5.65%,可溶性蛋白含量1.50%~1.74%,类黄酮化合物总量1.16%~1.79%,叶绿素总量1.36%~2.01%,儿茶素总量13.53%~16.20%。与对照相比,4种绿茶的茶多酚、可溶性糖和儿茶素总量均高于对照,除齐眉翠峰外其余3种茶样水浸出物和叶绿素总量均高于对照,除干发茶外其余3种茶样类黄酮化合物总量均高于对照。     

Comparisons of methods of scheduling irrigations of potatoes

Irrigation of Netted Gem potatoes was scheduled during three growing seasons by three methods: (a) when plants displayed first visual symptoms of moisture stress, (b) when indicated by a soil moisture budget involving estimated evapotranspiration, and (c) on the basis of tensiometer readings of soil moisture suction. When the tensiometer method of scheduling was used, the mean yields of tubers were 55.0 and 25.8 cwt/acre (6160 and 2890 kg/ha) higher than those obtained with the other two scheduling methods. Methods did not affect the specific gravity of potatoes. Method (a) scheduled irrigations least frequently. Scheduling by the budget method was not always adequate because it was based on the assumption that the crop extracted water from a constant 4 ft (1.2 m) profile from planting to full vegetative growth. In one year the budget method scheduled the first irrigation earlier than necessary and delayed the second irrigation during a critical period of crop growth. From full vegetative cover to harvest the irrigation schedules were alike for both the budget and tensiometer methods.     

Analysis of nutritional components of eight famine foods of the Republic of Niger

In the western Sahel, indigenous plants become important staples when cereal harvests are inadequate to support populations inhabiting that region of Africa. The purpose of this study was to assess the nutrient content of several of these edible wild plants. The leaves of the following seven plant foods were analyzed: Ziziphus mauritiana, Cerathotheca sesamoides, Moringa oleifera, Leptadenia hastata, Hibiscus sabdarifa, Amaranthus viridi, and Adansonia digitata. The fatty acid, vitamin E, carotenoid, selected mineral and amino acid contents of these plant foods were determined. These same analyses were performed on the fruit of the Adansonia digitata. In quantitative and qualitative terms, Amaranthus viridis was found to be an excellent source of protein. Its amino acid composition compared favorably to that of a World Health Organization (WHO) protein standard. It also contained considerable amounts of the two fatty acids that are essential in humans (linoleic and -linolenic) and a number of minerals including iron, magnesium, calcium and zinc. The leaves of Hibiscus sabdarifa contained an appreciable quantity of protein the composition of which was comparable to the WHO standard. The mineral content of the leaves of this plant was also exceptionally high; noteworthy was its high zinc content. H. sabdarifa also contained significant quantities of the two essential fatty acids. Ziziphus mauritiana was an excellent source of the essential fatty acid linoleic acid and several of the metals including iron, calcium, magnesium and zinc. Its content of other essential nutrients, however, was rather low. In general, Adansonia digitata leaves were nutritionally superior to the fruit of the tree; however, the fruit did contain useful quantities of potassium, phosphorus, zinc and -linolenic acid. The Leptadenia hastata leaves were an especially good source of lutein and -carotene. These data should be useful to the people who inhabit the western Sahel in helping them devise healthy diets during times when cereal staples are in short supply.     

狗牙根诱变后代抗寒性评价

通过电解质外渗法和匍匐茎恢复试验对‘阳江’狗牙根及其12个通过形态鉴定选出的坪用价值高且花序密度低的诱变后代进行抗寒性鉴定。电解质外渗法结果表明:诱变后代间的抗寒性具有较大差异,其叶片半致死温度(LT₅₀)的变异范围为-7.6～-0.2℃(最低值与最大值相差7.4℃);参试材料抗寒性由强到弱依次为M18>M4>M26>M28> M22>阳江>M29>M31>M10>M37>M16>M1>M25,其中,有5个诱变后代抗寒性优于亲本,分别是M18、M4、M26、M28、M22。匍匐茎恢复实验结果表明:诱变后代M1、M22、M26、M31、M25在0℃和-5℃低温胁迫后的恢复生长率都高于亲本,恢复能力均优于亲本;M10、M37、M28在-5℃低温胁迫下,恢复生长能力低于亲本,抗寒性相对较弱,M16和M4在0℃和-5℃低温胁迫下,恢复生长率都低于亲本,抗寒性明显弱于亲本。综合2种方法鉴定结果显示:诱变后代M1、M25的恢复能力较强;M4、M28的叶片抗寒性较好,青绿期较长;M22、M18、M26的叶片抗寒性和匍匐茎恢复能力均较强;M29,M31的叶片抗寒性和匍匐茎恢复能力与亲本相似;M10、M16、M37的叶片抗寒性和匍匐茎恢复能力均较弱,整体抗寒性较弱。     

吉林省平安农业科学院大豆所大豆研究工作报告

1　吉林省平安农业科学院大豆研究工作简介吉林省平安农业科学院大豆研究所 ,设在吉林省长春市西安大路种子大厦内。现有科技人员 6人 ,其中研究员 2人 ,农艺师 2人 ,技术员 2人 ,定向培养研究生 2人。大豆研究所的主要任务是选育稳产、高产、优质及抗病虫大豆新品种 ;同时密切     

巴西橡胶树MADS-box基因家族6个成员的染色体物理定位

MADS-box基因家族广泛分布于真核生物中,巴西橡胶树的MADS-box基因家族主要参与花形态建成,对生殖生长起到重要的调节作用。目前,MADS-box基因家族的26个相关基因已被克隆分析,但它们在染色体上的具体位置还未确定。本研究以巴西橡胶树‘热研7-33-97’品种为材料,将MADS-box基因家族的6个成员（HbAGL8、HbAG15、HbAGL30、HbTT16、HbAP1和HbSVP1）定位在细胞核染色体上,通过双探针荧光原位杂交技术（FISH）对巴西橡胶树MADS-box基因家族的这6个成员在细胞核染色体上进行物理定位分析。结果表明：MADS-box基因家族的6个基因分别位于不同的染色体上,其中HbAGL15、HbAG8、HbAG30和HbSVP1基因定位在第4、5、7和8号染色体长臂上,其信号位点到着丝粒的平均百分距离是11.85、39.71、48.94和6.70;HbTT16和HbAP1基因定位在第1和13号染色体短臂上,其信号位点到着丝粒的平均百分距离是22.19和18.01。本研究结果揭示了巴西橡胶树MADS-box基因家族的6个成员在细胞核染色体上的实际位置,展现家族基因之间的分布特点和连锁遗传关系,不仅丰富了橡胶树分子细胞遗传学信息,也为橡胶树的分子辅助育种和比较基因组学研究提供了分子细胞遗传学的科学理论依据。     

Comparison of two methods of PCNB application for control of Rhizoctonia infection of potatoes

A broadcast application of PCNB (Terraclor) resulted in a reasonably uniform distribution of the chemical in the soil with the concentration decreasing in a linear fashion with increasing depth in the soil profile. A banded application resuluted in a considerably higher chemical concentration at the 4–6 inch depth than at the 0–2 or the 2–4 inch depths. The problem of the lack of uniformity of chemical distribution could probably be solved by altering nozzle placement and size and allow use of the band method of application to minimize grower cost. More complete disking in the case of the broadcast treatment would probably result in a relatively uniform distribution of the chemical but at higher cost to the grower. PCNB application rates of 10, 15 and 25 lbs per acre broadcast and 71/2, 10 and 121/2 lbs per acre in a band significantly reduced the severity ofRhizoctonia infection of Russet Burbank potatoes but did not increase potato yields significantly.     

Prediction of the digestibility of the diet of horses: evaluation of faecal indices

Data from in vivo digestibility trial with four to six horses fed twenty-seven forage-based diets are used to calculate prediction equations for the digestibility of dry and organic matter, based on the crude ash (CA), crude protein (CP) and crude fibre (CF) contents of diets and faeces. The most precise prediction of dry-matter digestibility (r.s.d. = 0.032, R²= 0.80) was derived from a multiple regression including faecal (CP, CF) and dietary parameters (CF). Among faecal parameters, CP was the best single predictor of both digestibility (r.s.d) = 0.040, r²= 0.63) and dietary CP content (r.s.d = 0.028, r²= 0.59). For biological reasons we propose a non-linear model that allows prediction of dry- and organic-matter digestibility from faecal CP Content with reasonable Precision (r.s.d = 0.038, 0.036, r²= 0.65, 0.74, respectively). This will be adequate for many studies, especially for free-living animals in rangelands.