The African American experience in agriculture

Shrinking enrollments in the agricultural programs of the 1890 schools can be partly explained by negative attitudes of Blacks toward agriculture. This attitude has roots in the historical experiences of African Americans and has negative implications for the agricultural programs of the 1890 schools. A collection of data from a sample of Black Louisiana Farmers lends credence to the claim that Black Farmers are not encouraging their children to go into farming. To counter the impact on the 1890 schools, an active recruiting program should be undertaken, partly to show Black students that career openings in various agricultural fields offer excellent opportunities for Black students. These fields extend beyond the traditional farmgate.     

天府黑兔新品系与新西兰兔生长发育规律及饲料转率的比较研究

随机选择天府黑兔和新西兰兔各60只作为试验动物,对两个品种的家兔早期生长性能和饲料转化率进行比较研究。结果表明:天府黑兔和新西兰兔在30～75日龄阶段,其生长速度呈上升趋势,75日龄后生长速度呈下降趋势;天府黑兔生长强度比新西兰兔大,30～90日龄平均日增重天府黑兔35 5g,新西兰兔27 5g,差异极显著(P<0 01);饲料报酬和成活率天府黑兔高于新西兰兔,但差异不显著(P>0 05)。     

海南黑牛体型外貌测定与杂交效果初探

海南黑牛是利用良种日本黑毛和牛的冷冻精液与海南黄牛(雷琼黄牛)母牛进行人工授精所产的杂交后代.通过对海南黑牛进行外貌观察和体尺测量,研究其体型外貌与双亲的差异.结果表明,海南黑牛的多项体尺指标与母、父本相比都发生了变化.其外貌主要特征表现为头小颈短、面部清秀,体躯紧凑,背腰平直,无肩峰,毛呈黑色;而体尺测量除管围和管围指数外,体重、体高、胸围、体长等指标均比海南黄牛要小.即在外貌特征上,海南黑牛总体表现双亲的特性,毛色呈现日本和牛黑毛,体型接近海南黄牛小而清秀,但前期生长发育缓慢,表现出当地小型黄牛的特性.     

A history of black farm operators in Maryland

Since the turn of the century, the number of small-scale farmers in the U.S. and farmlands they owned have declined very sharply (structural change). Although the decrease in number is generally true for both white and Black farm operators, it has been more significant for Blackfarm operators than whites. The declining trend in the number of Blackfarm operators in the country is derived from individual state experiences that resulted from a combination of various political and economic factors. Using the census of agriculture data from 1900 to 1987, this paper gives a brief historical overview of Black farm operators in Maryland. The census data for the study period shows that at their peak number in 1910, there were 6,382 Blackfarmers in the state of Maryland. However, by 1987, only 371 of that number remained, representing a loss of 94 percent since 1910. According to the 1987 census data almost all Black operated farms in Maryland were not only small-scale but also in the lower sales class, less than $20,000 a year. Their household net family income is below that of non-metropolitan median household income. This concentration of Blacks in the lower economic class of farm operators in the state, for the most part, is closely related to their resource endowments, patterns of tenure, type of farm enterprises, and government farm programs and policies. On the average, Blackfarmers in Maryland have less land, capital and management skills than their white counterparts. Government policies and programs had, and continue to have, a devastating effect on Maryland Black farmers because they were tied to productive resources rather than farm income needs. Under conditions of low income, years of neglect by federal and state programs and policies, and limited resources Blackfarmers were unable to adopt capital intensive production practices and expand their farm operations. This resulted in most of them leaving agriculture, in the past and today, at a faster rate than whites. To avert or at least lessen the unfortunate situation of Black farm operators, projections and possible solutions are offered. This includes how the 1890 Land-Grant institutions because of their tradition, expertise and experience of research, teaching and outreach can take the leadership role in shaping the future direction of these farmers and their operations.Trained in agricultural economics, Ejigou Demissie is an Associate Professor in the Department of Agriculture at the University of Maryland Eastern Shore. His teaching areas include agricultural policy, farm business management, and agricultural marketing. Research interests center on small-scale agriculture and rural development. His recent book published by Westview Press is titledSmall-Scale Agriculture in America: Race, Economics, and the Future.     

甘蓝3种病害抗源筛选及抗病品种选育研究

选用不同区域带有 Tu MV、黑腐病、CMV3种病害的发病甘蓝植株 ,通过分离提纯获得病原物。利用 3种病原菌苗期室内人工接种鉴定和田间自然诱发鉴定相结合的方法 ,筛选出甘蓝 3种病害抗源材料 H85 0 1和B85 0 2。以抗源为亲本与其他 8份优良抗病自交系杂交 ,进行配合力测配和抗病性鉴定筛选育成经济性状优良 ,并抗 Tu MV、黑腐病和 CMV3种病害的甘蓝品种秦甘 70和秦甘 80。     

不同茄子品种植物学性状、产量性状以及销售情况的差异

为找到适宜本地早春大棚茄子的栽培品种,以8个茄子品种为试材,进行大棚栽培品比试验,结果表明：黑将军和黑珊瑚熟性早、果实色泽好、产量高,在扬州地区可作春大棚早熟栽培品种加以推广;黑龙长茄果形佳、产量高、熟性晚,可作露地栽培品种推广应用。     

和田黑鸡与三黄鸡血浆蛋白及血象指标的比较研究

应用常规的血液学指标测定方法,测定了和田黑鸡与三黄鸡血液学指标。结果表明:和田黑鸡雌雄个体之间血浆总蛋白、血浆白蛋白和血浆球蛋白无显著差异（P>0.05）,其中白蛋白与球蛋白之比小于1。和田黑鸡的血浆总蛋白、血浆白蛋白和血浆球蛋白极显著（P<0.01）高于三黄鸡。和田黑鸡WBC雄性高于雌性,但差异不显著（P>0.05）;而RBC、HGB表现为雌性高于雄性,其中HGB差异不显著（P>0.05）,RBC雌性为(4.52±0.041×10¹²/L,雄性为（3.78±0.12）×10¹²/L,雌性显著高于雄性（0.01相似文献   

Human X chromosome carries quantitative genes for immunoglobulin M

Concentrations of immunoglobulin M in serum were one-third higher in females than in males in the Black and White populations of Virginia. In family studies, a much closer correlation was shown between boys and their mothers than between boys and their fathers. The immunoglobulin M concentrations in girls were more closely correlated with those of their fathers than with those of their mothers. The higher mean values for IgM in females and the relative magnitudes of the correlation coefficients between parents and offspring support the hypothesis that the X chromosome of man carries genes with an effect on IgM concentration. These patterns were not demonstrated for immunoglobulins A or G.     

甘蓝多抗性抗源筛选及抗病品种选配鉴定分析

通过对甘蓝种质材料815份自交系的主要经济性状和抗病性的初步选择,入选了比较优良的自交系612份。然后利用研究建立的甘蓝室内苗期TuMV、Br、CMV抗性鉴定方法,结合田间自然抗病性鉴定方法,鉴定筛选出H8501、B8502、J8806、B9505等4个抗源。并以抗源为母本,以经济性状优良,配合力高和抗病的另5个自交系为父本杂交18个组合。经对组合抗病性和主要经济性状鉴定分析,结果表现组合均抗病,同时优质性和丰产性均优良的有8个组合,其中4个组合参加品种区域试验并通过了省级和国家品种审定。     

不同甜樱桃品种果实性状差异性比较

【目的】对8个甜樱桃品种的果实性状进行差异性研究,为徐淮地区甜樱桃优良品种的筛选提供依据。【方法】以红灯、桑提娜、黑珍珠、美早、早生凡、艳阳、萨米脱、砂蜜豆为试验材料,研究不同甜樱桃品种的果形指数、单果重、可溶性固形物含量、果柄长度、可食用率、果实硬度及果实色泽的差异。【结果】各品种果实形状表现不完全一致,大部分为心形;单果重以黑珍珠最高,美早最低;可溶性固形物含量以早生凡最高,美早最低;果柄长度以黑珍珠最长,桑提娜最短;各品种果实可食用率均在92.4%以上;果实硬度以艳阳最大,早生凡最小。【结论】黑珍珠在8个品种中综合表现最好,适宜在徐淮地区推广种植,萨米脱次之,其他品种可有选择的适当发展,以满足市场需求。     

“Raising among themselves”: Black educational advancement and the morrill act of 1890

Debate over the curricula of Black colleges and universities dates back to before the turn of the century and involved such noted Black leaders as Booker T. Washington and W.E.B. DuBois. The 1890 Land-Grant Colleges eventually established in 17 southern and border states were created to provide institutions for the teaching of the agricultural and mechanical arts to African-Americans. However, due to their being chronically underfunded and understaffed during the early decades of their existence, they focused mainly on teacher training and to a large extent became state normal schools or teacher colleges for Blacks. I argue that the improvements in public education of southern Blacks at the primary and secondary levels during the 1920s and 1930s induced many graduates of the 1890 institutions to become teachers. At the same time the growing numbers and higher quality of these individuals lead to an increase in the returns to time spent in school and induced increasing numbers of Black parents to send their children to school. During the 1930s expenditures per pupil in Black public schools increased, as did the real wages of Black teachers, while average classroom size fell. At the same time both literacy and school attendance of southern Blacks rose. In no small part these changes were due to 1890 colleges and their students.Lee A. Craig is Assistant Professor of Economics and Business, North Carolina State University, Raleigh, North Carolina 27695. He was co-winner of the 1989 Allan Nevins Prize, presented by the Economic History Association for the best Ph.D. thesis in American Economic History. He has published articles in journals such asAgricultural History and theJournal of Economic History, and his book,To Plant or Sow One Acre More: Farm Output, Productivity, and the Fall of Rural Birth Rates in the Northern United States is forthcoming from Johns Hopkins University Press.     

我国不同土壤Q/I特性及其供钾能力研究

用Ｑ／Ｉ方法对砖红壤、红壤、壏土、黑土和水稻土供钾特性进行了研究,结果表明,５ 种土壤对钾的缓冲性能（ＰＢＣＫ） 大小顺序为黑土＞ 壏土＞ 水稻土＞ 红壤＞ 砖红壤,５ 种土壤ＰＢＣＫ 和ＣＥＣ之间密切相关,可以用回归方程ｙ＝ －８ ．３２ ＋ ５．９２ｘ 表示,相关系数（ｒ） 为０．９８４ 。黑土和壏土以云母和蛭石２∶１ 型粘粒矿物为主,较多的楔形区域导致了较高钾特殊吸附（Ｋｘ） 值;而红壤和砖红壤具有较低Ｋｘ 归于粘粒矿物以高岭石为主。土壤的供钾强度指标（ＡＲＫｅ０） 大小顺序为砖红壤＞ 红壤＞ 壏土＞ 水稻土＞ 黑土,该值不仅取决于该土壤交换性钾含量,同时由粘粒矿物决定。     

Black farmers/farms: The search for equity

Black farmers are still Black farmers, yet now are considered a part of minority or small or limited resource farmers/ranchers (SLRF/R) by the Department of Agriculture. Except for a few Southern states, their numbers have fallen from a remnant to a fragment in recent years. They continue to leave agriculture at a faster rate than whites. What few programs the Department has for this category of producers (SLRF/R) show genuine promise, provided they are pursued diligently by the Congress and the Department. Also vigorous enforcement of civil rights laws and directives of the Secretary and the new initiatives by the Office of Civil Rights Enforcement (OCRE) have to be sustained.     

重庆本地山羊群体遗传关系的RAPD分析

采用RAPD技术分析了重庆本地的板角山羊、川东白山羊和重庆黑山羊基因组池DNA的多态性及其亲缘关系。通过100种随机引物扩增筛选。12种多态引物共获得了16个多态标记。各群体间的遗传距离指数和SPSS分层聚类树形图表明：板角山羊与川东白山羊之间的遗传距离较远;重庆黑山羊和板角山羊的遗传距离较近,2者有着密切的亲缘关系。结果还发现,板角山羊、川东白山羊和重庆黑山羊群体都具有一定的遗传稳定性。     

优质甘蓝三抗抗源J8806的选育及其利用

选用陕西、北京、四川、黑龙江等4个区域不同致病力的毒原和菌原,以品质优良的自交系为材料,筛选采用了室内苗期人工接种鉴定和结合自然诱发鉴定筛选方法.经过对材料反复筛选鉴定后育成了优质甘蓝对TuMV、Br和CMV 3种病害高抗自交系J8806(抗源).品种选育利用优质J8806抗源为亲本与其他5个优良抗病自交系杂交,育成了优质抗病符合育种目标的2个组合J8806×H13和J8806×H21,其中J8806×H13定名秦甘60.     

旧院黑鸡生产性能系统观察

引种观察表明，旧院黑鸡在中等营养水平和笼养条件下，１８周龄时体重达１２８３．２ｇ，料肉比为３．４２：１，５００日龄平均产蛋量为７６枚，比产区散养时提高了１９．８７％。成年公鸡体重２５３４．８ｇ，比散养时减少３．０８％，主要体尺变化不明显，胴体率，全净膛率分另为９１．５％和８１．４％，胸肌蛋白质含量为２６．０４％，１３种必需和半必需氨基酸占氨基酸的５８．４７％。旧院黑鸡在高温高湿笼养的条件下，生产性     

种衣剂包衣防治玉米丝黑穗病效果

用6种含有戊唑醇的种衣剂以供试剂量分别包衣高感丝黑穗病的玉米品种长单35号和感病品种潞玉13进行试验,结果表明,2个品种玉米发芽正常和出苗安全,发病率极显著低于对照。6.5%吡·高氯·戊唑、20%吡·福·戊醇、18%丁硫·福·戊醇对丝黑穗病的防治效果达80%以上,九兴黑虫搭档、黑虫双全的防治效果为70%左右,帅苗+戊唑醇的防治效果反差较大,有待进一步验证。     

海南猪杂交效果及海南猪H-FABP基因和MyoG基因5′上游区域的遗传变异研究

测定了海南猪、海南猪母猪与杜洛克公猪杂交后代的胴体性状、肉质性状,并对脂肪酸结合蛋白(H-FABP)和肌细胞生成素(MyoG)基因的5′上游区域的遗传变异进行了分析。结果表明:杂交黑猪与其母本海南猪相比,活体重、胴体重、屠宰率、胴体长、瘦肉率均有提高,且差异显著(P0.05),表现出较好的杂种优势;骨率、皮率降低,脂肪沉积性能提高,而眼肌面积、皮厚变化不大。另外,海南猪与杂交黑猪肉质均符合优良肉质标准,杂交黑猪肉在滴水损失、大理石纹、水分、粗蛋白含量等方面优于海南猪,表现出较好的杂种优势。海南猪H-FABP基因5′上游区域和MyoG基因5′上游区域遗传变异的基因型和等位基因频率,为海南猪优良肉质性状的形成提供了遗传学依据。     

圈养黇鹿对北方4种常见苗木叶片适口性浅析

为研究鹿科动物食性,探讨树叶用作鹿科动物饲料的可能性,以黇鹿为试验对象,选取北方常见榆树、刺槐、垂柳及毛白杨等4种树种新鲜叶片作为饲料,对其适口性进行分析。结果表明,黇鹿对4种叶片喜食程度依次为榆树叶、刺槐叶、垂柳叶和毛白杨叶;通过对叶片粗蛋白质含量(CP%)、酸洗纤维(ADF%)、中洗纤维(NDF%)等7种生化指标测定发现叶片中的CP含量(P=0.001)、ADF含量(P=0.025)及NDF含量(P=0.032)是影响其对叶片选择的关键因素。     

辽宁绒山羊和吕梁黑山羊及其F_3代若干生理生化指标的测定

本文测定了山西引入辽宁绒山羊和本地吕梁黑山羊及其 F_3代的7项生理指标和11项生化指标。上述三个品种山羊的多数指标为初次报道。