Decomposition and Nutrient Release from Litter Fall in the Semi‐arid Tropics of Sudan

In Sudan, tree plantations remain the first choice and are widely used in protecting arable lands from sand movement. Decomposition and nutrient changes from leaves of some agroforestry trees (Eucalyptus microtheca, Ficus spp., and Leucaena leucocephala) and litter fall from guava (Psidium guajava) and mango (Magnifera indica) were monitored (in a 12‐week litter‐bag experiment). Rate of dry‐matter weight loss from guava (0.098 wk^?1) was significantly (P < 0.01) faster than from mango residues (0.04 wk^?1). Corresponding values for Leucaena, Eucalyptus, and Ficus were 0.0533, 0.0524, and 0.0438 wk^?1, respectively. In general, micronutrients tend to accummulate during a decomposition period. Potassium (K) was the only element found to be consistently lost by leaching very rapidly from all litters. Nitrogen (N) was released at a significantly (P < 0.03) higher rate from Leucaena (0.0558 wk^?1) compared to Ficus (0.0399 wk^?1) and Eucalyptus (0.0301 wk^?1). Mobility of nutrients from the litters was in the order of K > phosphorus (P) = N > calcium (Ca) > magnesium (Mg). It is concluded that ficus and mango leaves are suitable for improving quality of arid soils through buildup of soil organic matter and supplying easily released organic sulfur (S) (environmentally sound management practice) whereas litter from guava is suitable for temporary nutrient correction. Mixing of guava and mango residues may slow fast decomposition of the former.     

浅析奇台苏丹草的种籽产量

奇台苏丹草是一种优势高产牧草,由于建立起以提纯复状为目标的三级良种繁育体系,分三次采种,对灾害性大风的预防措施,播种前的选、浸、拌种工作和贯彻执行了种籽管理的各项法令,使种籽产量突破3000kg/ha增产34％,在加强管理的基础上,达到3750～4200kg/ha是可行的。     

Evaluation of ELISA in the serodiagnosis of bovine farcy

Mycobacterium farcinogenes is the causal agent of bovine farcy, a chronic infectious disease of zebu cattle in some parts of tropical Africa. Whole cell homologous antigen of M. farcinogenes was used in the standardization and evaluation of an enzyme linked immunosorbent assay (ELISA) for the detection of circulating antibodies against bovine farcy using sera from confirmed bovine farcy and from bovine farcy-free cattle. The cut-off optical density (OD) value was decided at 1.8 using filter 405nm after one hour of incubation at 37°C. Accordingly, 115 out of 124 (92.7%) serum samples from clinically proven bovine farcy cattle were reported sero-positive. Sera from cattle infected with M. avium and M. paratuberculosis revealed OD value <1.8, indicating the differential diagnostic ability of M. farcinogenes antigen. Our test sensitivity was 92.7% and specificity was 97%, therefore could be routinely employed to support early clinical diagnosis, epidemiological surveys and for screening animals before exportation to farcy-free regions.     

Variations in nitrogen uptake and nitrate-nitrogen concentration among sorghum groups

Nitrogen uptake and nitrate-N concentration in forage sorghums, which are related to ground water pollution or feed quality under conditions of crop fertilization by only animal wastes, were examined. Seventy-four genotypes of sorghum and Sudan grass were tested. They were classified into 4 groups; grain type and dual purpose type sorghums (6 and 13 genotypes, respectively, Sorghum bicolor Moench), sorgo type sorghum (21, S. bicolor), Sudan type sorghum (22, S. bicolor × S. sudanense (Piper) Stapf), Sudan grass (12, S. sudanense). There was a strong correlation between dry matter (DM) yield and N uptake, with the sorgo type producing the highest DM matter yield and showing the highest N uptake. Nitrate-N, which causes nitrate poisoning of ruminants, was detected mostly in the stem of all the genotypes. The nitrate-N concentration based on DM could be calculated accurately by multiplying the nitrate-N concentration of stem on a fresh matter basis by the DM partitioning ratio of stem divided by the DM concentration of stem. The grain type and the dual purpose type of sorghums with dry stem showed the lowest nitrate-N concentration because these plants had a lower DM partitioning ratio of stem and higher DM concentration of stem. Sudan grass and Sudan type sorghum with the genetic background of Sudan grass showed higher nitrate-N concentrations owing to their ability to accumulate nitrate-N.     

苏丹红Ⅲ对泥鳅胚胎发育的毒性研究

为研究水体中苏丹红Ⅲ的毒性作用,以苏丹红Ⅲ为诱变剂,以泥鳅胚胎为试验材料,选择泥鳅胚胎发育的4个不同时期(胚胎隆起期、原肠胚中期、神经胚期、尾芽期)为开始处理时间,用0.085g/L(1/12LC50,24h)、0.057g/L(1/18LC50,24h)、0.038g/L(1/27LC50,24h)、0.025g/L(2/81LC50,24h)、0.017g/L(4/243LC50,24h)等5个质量浓度梯度,探讨了苏丹红Ⅲ对泥鳅胚胎发育的影响。结果表明:苏丹红Ⅲ对泥鳅各发育时期的孵化率均产生影响;最低质量浓度组(0.017g/L)的孵化率与对照组(自来水处理)相比无明显差异;原肠胚中期和神经胚期对苏丹红Ⅲ最为敏感,在次低质量浓度组(0.025g/L)即开始表现出差异。尾芽期时,在中质量浓度组即0.038g/L时即开始表现出差异。苏丹红Ⅲ对泥鳅胚胎具有明显的致畸作用,胚胎的主要致畸症状包括体态异常、胚体浑浊或解体等。苏丹红Ⅲ对尾芽期胚胎的致畸作用表现最为明显,在最低质量浓度组(0.017g/L)时即与对照组具有极显著差异;胚胎隆起期,在中质量浓度组(0.038g/L)时,开始与对照组产生差异;原肠胚中期和神经胚期,只有最低质量浓度组(0.017g/L)与对照组无差异,其余组与对照组有极显著差异。4个不同处理时期的半数有效致畸质量浓度(EC50)分别为0.056、0.044、0.039、0.049g/L。苏丹红Ⅲ对泥鳅胚胎的发育有明显的抑制、致畸、致死作用,表现出明显的毒性,这可为苏丹红Ⅲ的合理使用提供依据。     

苏丹草与高粱杂交后代特征及其主要经济性状

以黑颖苏丹草作母本与父本同杂2号高粱杂交。通过 4代选育,结果表明,杂种后代表现抗倒伏、耐旱、抗病、植株粗壮、高大、叶片宽而长,适应性较广。其形态特征与父母本相比具有明显差异。     

Yield,N Uptake and N Utilization of Early Maturing,Drought and Striga-Tolerant Maize Varieties under Low N Conditions

Performance under sub-optimal nitrogen (N) conditions, of early maturing maize cultivars bred for tolerance to drought and Striga parasitism in the Nigerian savanna is not known. This study evaluated the tolerance of selected early maturing drought and Striga-tolerant maize cultivars to low N conditions in Northern Nigeria. The cultivars were evaluated at 30 and 100 kg N ha^?1. The varieties were compared with an improved maize cultivar that is not tolerant to drought and Striga. Maize grain yield was 26% higher at 100 kg N ha^?1 than at 30 kg N ha^?1 in 2010 and 161% higher100 kg Nha^?1 than at 30 kg Nha^?1 in 2011. The drought and Striga-tolerant varieties produced consistently higher yields than the non-drought-tolerant variety particularly at 30 kg Nha^?1. These cultivars also accumulated higher amount of N, had higher N-uptake efficiency or N-utilization efficiency than the non-drought-tolerant variety ACR 95 TZE-COMP4 C3. Grains yield at low nitrogen rate was associated with high ears m^?2, high dry matter accumulation, high grains m^?2, suggesting that these traits are linked to low-N tolerance. The good performance of the drought-tolerant maize varieties under low N suggests that varieties developed for drought tolerance may be tolerant to low-N conditions.     

凝胶渗透色谱净化-HPLC同时检测麻油中苏丹红Ⅰ-Ⅳ

采用LabTech PrepElite GV全自动凝胶渗透色谱净化-定量浓缩系统对麻油样品进行净化并采用HPLC分析其中的苏丹红Ⅰ-Ⅳ,回收率在93.1%～107.7%,RSD不大于3.7%,该方法灵敏可靠,适合于麻油中苏丹红Ⅰ-Ⅳ的同时检测。      

草鱼肠道微生物对食物改变适应性变化的研究

对草鱼(Ctenopharyngodon idellus)先饲喂人工饲料再饲喂苏丹草,运用PCR-DGGE的方法,比较了食物改变引起的草鱼肠道微生物菌群结构的变化过程。结果显示,饲喂同种饲料的草鱼后肠与前、中肠样品间菌群结构存在显著差异(TH0-F0=-2.268,P0.05;TH0-M0=-2.470,P0.05),饲喂不同种食物的相同肠段样品间菌群结构也存在着显著差异(P0.05)。微生物多样性指数显示,后肠样品Shannon指数H'一般不低于4.25,而前、中肠样品H'均未超过4.25。对后肠样品进一步研究发现,食物改变11 d之后,后肠微生物菌群基本达到稳定。结果表明,草鱼肠道不同部位内容物菌群结构不同,后肠样品具有更高的微生物多样性,并且食物的改变会对草鱼肠道微生物菌群产生快速而显著的影响。     

苏丹Ⅲ在有机溶剂中的光催化降解研究

苏丹Ⅲ作为一种偶氮染料不溶于水,微溶于乙醇,易溶于氯仿、油脂、矿物油、丙酮和苯等,属于难挥发、难生物降解性有机物。以纳米TiO2为催化剂,考察了苏丹Ⅲ在3种不同光源2种不同溶剂条件下的光催化降解,讨论了光源种类、溶剂体系和催化剂时间对其降解的影响,并利用紫外吸收光谱等和质谱的手段,考察了苏丹Ⅲ的光解动态和光解产物。结果表明,苏丹Ⅲ的光催化降解符合一级动力学方程,在乙醇溶液中的光解半衰期为58 min,在三氯甲烷/乙醇中的半衰期约为17.2 min。