Influencing in vitro clonal propagation of Chonemorpha fragrans(moon) Alston by culture media strength,plant growth regulators,carbon source and photo periodic incubation

Chonemorpha fragrans is an endangered medicinal woody climber,regarded among alternative plant sources of camptothecin.Camptothecin is a monoterpene indole anti-cancer alkaloid with annual trade value of over three billion U.S.dollars in the recent,and is used in the production of its analog drugs approved for the chemotherapy of cancer of varied types.Effects of plant growth regulators,culture media strength and photoperi-odic duration on the micropropagation ef ciency of C.fragrans from nodal segment explants were studied on Murashige and Skoog(MS)medium amended with Thidiazuron(TDZ),Benzylaminopurine(BAP)or Kinetin(Kin).Thidiazuron was more ef cient over BAP and Kin when half basal MS medium was used over full or quarter strength.Results of carbon source experiment showed sucrose as the most effective over glucose,fructose,and maltose in the clonal production.Studies on the photope-riodic incubation duration showed 12 h as the best light period and sub or supra-optimal resulted in the production of abnormal and albino micro shoots.Experimental results on the evaluation of physiological,biochemical parameters showed the role of pigment molecules and antioxidant systems in the production of albino micro shoots.     

Effects of species and season on chemical composition and ruminal crude protein and organic matter degradability of some multi-purpose tree species by West African dwarf rams

Seasonal chemical composition and ruminal organic matter (OM) and crude protein (CP) degradabilities were determined in four tropical multi-purpose tree species (MPTS) namely; Pterocarpus santalinoides, Grewia pubescens, Enterolobium cyclocarpum and Leucaena leucocephala. Three West African dwarf (WAD) rams fitted with permanent rumen cannula were used for the degradability trials. Foliage samples were collected four times to represent seasonal variations as follows: January--mid dry; April--late dry; July--mid rainy and October--late rainy seasons. Leaf samples were randomly collected from the trees for estimation of dry matter (DM) and chemical composition. Ruminal in sacco OM and CP degradabilities were estimated from residues in nylon bags. All samples had high CP (161-259 g/kg DM) and moderate fibre concentrations [neutral detergent fibre (without residual ash], 300-501 g/kg DM; acid detergent fibre (without residual ash), 225-409 g/kg DM and acid detergent lignin, 87-179 g/kg DM across seasons. Interaction effects of species and season on chemical composition were highly significant (p = 0.001) except for trypsin inhibitor (p = 0.614). The MPTS recorded more than 60% OM and CP degradability at 24 h, which implied that they were all highly degradable in the rumen. Their incorporation into ruminant feeding systems as dry season forage supplements is therefore recommended.     

Seasonal trends in epidemiological and entomological profiles of malaria transmission in North Central Nigeria

The influence of seasonal changes on epidemiological and entomological indices of malaria transmission in North Central Nigeria was elucidated in a series of studies carried out between January 2004 and December 2009. The climate in the study area was divided into three seasonal periods namely, rainy (May-October), dry (December-March) and transitional (April and November), during which larval and adult anopheline mosquito collections were carried out and assessed for densities, sporozoite infection and parity rates and potentials for malaria transmission. The results indicated that the climate in the study area was clearly seasonal, with close similarities in the patterns of distribution of the climatic factors in the study sites. Mosquito densities, both at the adult and larval stages (i.e., 29.35 +/- 5.10 adult mosquitoes/man/night and 10.36 +/- 3.34 larvae/dip, respectively), were significantly (p<0.05) highest during the rainy season. However, while the former varied significantly in the three seasonal periods, the latter was not significantly different during the dry and transitional seasons. Malaria transmission risks, in terms of sporozoite rates and entomological inoculation rates, was significantly (p<0.05) least in the dry season (i.e., 2.89 +/- 1.25% and 0.37 +/- 0.21 infective bite/man/night, respectively) but the two variables were not significantly (p>0.05) different during the transitional and rainy seasons. Adult mosquito daily survival rate and adult longevity were least in the dry season (26.52 +/- 11.80% and 6.80 days, respectively) and significantly (p<0.05) highest during the rainy season (72.28 +/- 4.00% and 16.95 +/- 4.20 days, respectively). Parous rates of the mosquitoes and duration of sporogony had distinct distribution pattern from the other variables investigated. While, significantly highest parous rates were recorded in the transitional season (86.00 +/- 4.30%), duration of sporogony was not significantly (p>0.05) different during the three seasons. The epidemiology of urban malaria in North Central Nigeria was discussed from the view points of the these results and concluded that the findings should promote the development of informed temporally-targeted vector control programs for the area.     

有机肥与化肥配施对土壤微生物、土质及骏枣果实品质的影响

以10年生骏枣树作为研究对象,采用田间试验方法,研究有机肥与化肥配施对骏枣园土壤细菌、真菌和放线菌数量,土壤呼吸速率、容重和p H值以及骏枣果实品质和叶果比等指标的影响。结果表明:随着复混肥中有机肥和化肥使用量的增加,土壤中细菌、真菌和放线菌数量均呈现逐渐上升趋势,其中增加有机肥促进土壤微生物群落数量提升的效应明显高于化肥。土壤呼吸速率也随着复混肥施用量的增加缓慢增高,T12(有机肥:8 kg·株~(-1);N:450 g·株~(-1);P:300 g·株~(-1);K:300 g·株~(-1))处理的土壤呼吸速率最大,其在果实膨大期和成熟期的土壤呼吸速率分别为3.03±0.02、2.24±0.02μmol·m~(-2)·s~(-1),比对照分别高71.0%、86.2%。随着复混肥中有机肥施用量的增加,土壤容重表现出下降趋势,其中T4(有机肥:8 kg·株~(-1);N:150 g·株~(-1);P:100 g·株~(-1);K:100g·株~(-1))处理的土壤容重最低,为1.36±0.02 g·cm~(-3),比对照低0.11 g·cm~(-3)。土壤有机质含量随着有机肥比例的增加而上升,随着化肥施用比例的增加而下降,随着有机肥施用比例的增加碱性土壤的p H值有逐渐下降的趋势,而化肥增施对碱性土壤p H值的影响不显著。有机肥与化肥不同配施对骏枣果实可溶性糖含量的影响均不显著,对可滴定酸含量和糖酸比均有一定程度的影响;果实Vc含量随着复混肥中有机肥和化肥施用量的增加而上升,各施肥处理的果实Vc含量均显著高于CK。骏枣叶果比随着复混肥施用量的增加呈现逐渐上升趋势,各处理中T3与T5和T6,T4与T7,T8与T9和T10处理之间均无显著差异。总之,合理配比的有机-无机复混肥的施用对干旱、半干旱地区红枣产业的可持续发展具有较大应用前途。     

Spatial modelling indicates Striga seedbank density dependence on rainfall and soil traits in the savannas of northern Nigeria

Striga is one of most notorious weeds devastating crop production in the dry savannas of northern Nigeria. The weed attacks most cultivated cereals and legumes with crop losses as high as 100% when no control measure is employed. Studies conducted in the dry savannas of Nigeria indicated that Striga seedbank is strongly related to soil and climate properties. This study was conducted to model Striga hermonthica seedbank zones in the dry savannas of Nigeria based on soil and climate properties of the areas. Using multi-stage spatial sampling, 169 soil samples were collected at the centroids of 25 × 25 km grids across the study area and analysed for physico-chemical properties. The number of Striga seeds were counted from the soil samples using water elutriator and potassium bicarbonate method. Daily temperature, relative humidity and rainfall for each point were downloaded from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). Minimum and maximum temperatures, and relative humidity were accessed from National Aeronautics and Space Administration (NASA POWER). Thresholds of various soil and climate variables for optimum concentration of Striga seedbank were analysed using boundary line analysis (BLA). From the BLA, optimum amount of rainfall for high Striga seedbank was 549 mm per annum. While temperature has a wide suitability range for Striga seedbank development. Principal component analysis was used to reduce dimensionality of the dataset into principal components (PCs). Seven PCs which explained 75.6% variation in the data were retained and used in the weighed overlay modelling (WOM). The weighted overlay map produced five distinct Striga seedbank zones; very low, low, moderate, high and very high. More than 60% of the study area had moderate to high Striga seedbanks. The zones vary mostly based on soil, climate and Striga seed count. The establishment of the optimum levels of the environmental factors at which Striga seedbank is favoured will assist in designing a more site-specific Striga management. However, for scalability purpose, adoption of the Striga zoning approach can be useful.     

采前灌溉对骏枣落果、裂果及果实品质的影响

以8年生骏枣为材料,采用间隔灌水处理法,研究采前(8月1日至9月9日)不同灌溉次数对骏枣落果率、裂果率、叶片相对含水量及果实品质等指标的影响。结果表明:骏枣叶片相对含水量随着土壤含水量的增加而上升,T3(灌水5次)处理叶片相对含水量比CK高17.64%;随着灌水次数的增多,骏枣采前落果率和裂果率均显著下降,其中T3处理的采前落果率和裂果率分别为7.697%±0.724%、12.393%±0.290%,分别较CK低5.977%、9.987%;灌水次数的增多会导致果实中可溶性糖、可滴定酸、Ca和Zn含量减少,同时会促使其可溶性蛋白、糖酸比、黄酮、N、K、Mn、Fe和Cu含量显著提高,对P和Mg含量影响均不显著。增加采前灌水次数能够明显降低骏枣采前落果率和裂果率,灌水5次处理的效果较为显著。