非洲罗勒提取的植物精油对须芒草人工瘤胃发酵的影响

在体外批次培养下,非洲罗勒提取的植物油能够调控瘤胃微生物发酵和降低甲烷产量。然而,随着研究的深入,植物油对瘤胃微生物发酵作用的影响尚不清楚。本试验旨在通过瘤胃模拟技术研究不同剂量的非洲罗勒油(0、100、200和400mg/L)对以须芒草为发酵底物的瘤胃微生物发酵和甲烷产量的影响。结果发现,非洲罗勒油对甲烷产量、产气量和发酵液pH呈二次方影响(P<0.05);随着丙酸产量的降低,乙酸和丁酸的产量增加,总挥发性脂肪酸产量呈线性降低(P<0.05);非洲罗勒油对须芒草干物质和中性洗涤纤维表观降解率、15 N标记的总微生物蛋白和微生物蛋白总产量呈二次方影响(P<0.05)。本研究结果证实:由于总须芒草降解率的降低,非洲罗勒油对甲烷产量呈二次方影响。

Preliminary Assessment of the Common Land Model Coupled with the IAP Dynamic Global Vegetation Model

The Common Land Model(CoLM) was coupled with the IAP Dynamic Global Vegetation Model(IAPDGVM), and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land Model(CoLM-LPJ) and CoLM-IAP were conducted. The CoLM-IAP coupled model showed a significant improvement over CoLMLPJ, as the deciduous tree distribution decreased over temperate and boreal regions, while the distribution of evergreen trees increased over the tropics. Some biases in CoLM-LPJ were preserved, including the overestimation of evergreen trees in tropical savanna, the underestimation of boreal evergreen trees, and the absence of boreal shrubs. However, most of these biases did not exist in a further coupled simulation of IAP-DGVM with the Community Land Model(CLM), for which the parameters of IAP-DGVM were optimized. This implies that further improvement is needed to deal with the differences between CoLM and CLM in parameterizations of landbased physical and biochemical processes.

Rice Yield and Yield Components as Influenced by Phosphorus and Nitrogen Application Rates in the Moist Savanna of West Africa

A two-year field experiment was conducted to evaluate the influence of nitrogen （0, 30, 60, and 120 kg N ha^-1） and phosphorus （0, 30, and 60 kg P2O5 ha^-1） application on grain yield and yield components of five New Rice for Africa （NERICA） cultivars, their parents, and a check on a degraded soil in the moist savanna of Nigeria. Nerica 14 recorded the highest grain yield of 1.3 mg halcompared to the other NERICA cultivars. It also produced significantly （P 〈 0.05） longer panicles （19.24 cm）, higher sink capacity as determined by thousand-kernel weight （30.3 g）, and a higher potential for partitioning photosynthates （45.15%） into grains than the other cultivars. N × P interaction effect on grain yield was significant （P 〈 0.05） with moderate P （60 kg P2O5 ha^1） and moderate N （60 kg N ha^-1） resulting in optimum grain yield （1.7 mg ha^-1）. Thus, moderate N and P were recommended for the production of NERICA varieties in low-input smallholder upland rice production systems of the moist savanna of Nigeria.

Fire temperature and residence time during dry season burning in a Sudanian savanna-woodland of West Africa with implication for seed germination

Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.

Contribution of Promiscuous Soybean （Glycine max L.） to Upland Rice-based Cropping Systems in West Africa

A two-year on-farm study was carried out at Eglime in the moist savanna （MS） and Ouake in the dry savanna （DS） of Benin to evaluate the contribution of inoculation of dual-purpose soybean varieties to grain yield of upland NERICA rice fertilized with low N level. In 2005, four dual-purpose, promiscuous soybean varieties （cv. TGx1440-IE; TG×1448-2E; TG×1019-2EB; and TG×1844-18E）, and a popular improved variety （cv. Jupiter） were sown in 12 farmer fields with and without Bradyrhizobium japonicum inoculation. There was also land which was left fallow that acted as the control. In 2006, upland interspecific rice （NERICA 1） was sown in all the plots and supplied with 15 kg N haL. Dry matter yield, N accumulation, and net N-balance were significantly enhanced by over 40% with inoculation of cv. TG× 1844-18E than non-inoculation in the DS in comparison to other cultivars. There were no significant effects of inoculation of previous soybean cultivars on soybean grain yield and on the succeeding NERICA rice yield. Averaged over inoculation, previous cv. TG× 1019-2EB plots supplied with only 15 kg N hal gave the highest grain yield, more than twice the yield of control plots in the DS, possibly because of significant production of higher tillers, panicles and harvest index than the other cultivars; and it could be recommended for upland rice-based system for NERICA production.

The Extension and Utilization of the Pasture in the Tropical Area of China

This paper summarized the research and development of pasture in the tropical areas,and simply generalized the problems and methods for improvement and expected the advancement of the tropical pasture.

Native Trees Forage Alternative Protein Feed for Cattle in Tropical ＂Mexico＂

The objective of this study was to find highly nutritious native plants to feed cattle in northern Veracruz （Mexico） as an alternative to avoid deforestation for pasture establishment. Six fodder tree species （Leucaena, Leucaenaleucocephala, Morera, Morus alba, Chacloco, rubiHamelia patents, Guficima, Guasumaulmifolia, Pichoco-bunting, Erythrinaamericana, Cocuite, Gliricidiasepium） were selected for their leave production, rapid growth and high nutritional quality. The plants were evaluated in the bud stage of senescence and flowering, restricting the fraction of mature foliage in the samples located under 2 meters height. Samples were collected from five plants per specie that were randomly selected. The nutritious parameters were evaluated through proximate analysis with the Van Soest technique. This study used a completely randomized design with five replicates. The nutritious composition showed PC （protein content） differences （P 〈 0.05） among species indicating that Leucaenaleucocephala （20%） had the lowest, Gliricidiasepium was （21%） intermediate and Morus alba （23%） had the highest. The FDN （neutral detergent fiber） and FDA （acid detergent） were lowest for Guasumaulmifolia （23.4%） and the other five species exceeded 40%. In conclusion, native foliage of fodder trees in northern, Veracruz are highly nutritious for cattle feeding and could alternative to avoid deforestation for pasture establishment to continue.

Evaluation of Neem-based Compound Fertilizer for Crop Production in Samaru, Moist Savanna of Nigeria

Nutrient mining is one of the major threats facing crop production in Africa and inputs of nutrients are required to overcome this constraint. Greenhouse and field trials were conducted to investigate the effect of sole and combined applications of neem-based and conventional compound （NPK 15-15-15） fertilizers on five crops. In another set of treatments, a factorial combination of the neem fertilizer and urea at 30, 60 and 90 kg N ha-1 was applied to maize, millet and sorghum in the field in a randomized complete block design. The results obtained on cowpea and soybean showed that application of 20 kg N hal from the neem-based compound fertilizer produced both grain and haulm yields that were comparable to what was obtained with the application of 30 kg N ha1 from the conventional fertilizer. Based on maize performance, combined application of neem-based and NPK in ratio 0.25：0.75 respectively gave significantly （P 〈 0.01） higher plant height, stem girth, shoot and dry weight compared to other treatment combinations. The causes of the interactions between the two fertilizer sources resulting in added benefits from their mixed rather than sole application could be attributed to improvement in phosphorus availability and other soil conditions.

Genotype x Environment Interaction of Carotene Content of Yellow-Fleshed Cassava Genotypes in Nigeria

Cassava is an important starchy root crop and a major staple for more than 70 million people in Nigeria. New yellow-fleshed genotypes are being developed to combat vitamin A deficiency. Trials of 18 yellow-fleshed genotypes and two officially released white-fleshed clones, used as checks for 2008/2009 and 2009/2010 seasons in five major cassava growing agroecological zones of Nigeria. The trial locations were Ikenne （humid forest）, Ibadan （forest-savanna transition）, Ubiaja （subhumid forest）, Mokwa （southern Guinea savanna） and Zaria （northern Guinea savanna）. At each location, the trial was established in a randomized complete block design with four replications. The objective of the study was to assess genotype performance and genotype ~ environment interaction for total carotene concentration （TCC）, total carotene content per root （TC-R）, and total carotene content per plant （TC-P）. Significant differences （P 〈 0.001） among genotypes, environments and genotype x environment interaction for all the traits evaluated were observed. For TCC, TC-R and TC-P, the best genotypes across the 10 environments were TMS I051601, TMS 1050311, and TMS 1050998. Variation among genotypes accounted for most of the Total Sum of Squares for TCC （67.9%）, TC-R （39.0%） and TC-P （35.9%）. These characteristics of total carotene were also highly correlated. This study revealed that cassava with total carotene concentration can be assessed using either the TCC, or the TC-R, or the TC-P.

Enhancing Rice Productivity and Soil Nitrogen Using Dual-Purpose Cowpea-NERICARice Sequence in Degraded Savanna

ISFM （integrated soil fertility management） involving annual sequencing of dual-purpose early-maturing first crop of cowpeas with biomass incorporation before seeding second crop of early-maturing NERICA （New Rice for Africa） was evaluated to enhance rice productivity and soil-nitrogen. Five dual-purpose early-maturing cowpea cultivars and local cultivar （Katche） were seeded early in the wet season in five farmers＇ fields at Ouake （9046＇ N, 1°35′ E, highly degraded-savanna）, Benin. After pod harvest, cowpea residues were minimally worked into the soil using minimum tillage with hand-hoe and seeded with early-maturing, resilient NERICA8 rice that received either 20 kg N/ha or zero-N. Cowpea grain yield averaged 0.1-0.3 Mg/ha, and mean aboveground cowpea biomass produced and recycled was 0.54-0.64 Mg/ha among best cultivars （IT97-568-11 and IT89KD-288）. NERICA8 seeded after cowpea cv. IT97-568-11 and supplied with 20N gave the greatest grain yield of about 2.0 Mg/ha, accounting for 500% heavier grains than fallow-rice rotation with zero-N. Mineral-N dynamics monitored under NERICA8 in year 2 showed that previous IT97-568-11 plots had the highest mineral-N at tillering which persisted till panicle initiation stage. The adoption of an ISFM comprising annual cowpea-NERICA sequence by smallholder rice farmers could enhance productivity and improve N-supply in fragile savannas.

Residual Effect of Long Term Application of Organic and Mineral Fertilizers on Selected Chemical Properties of a Savanna Alfisol

The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung （D）, nitrogen （N） and phosphorus （P） in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol.

Rainfall-Runoff Simulation in Part of Lower Niger Basin

Water resources assessment in poorly gauged and ungauged basins demand supportive rainfall-runoff estimation, while resolving practical water resource management and planning issues. In this study, the research method employed involves rainfall-runoff modeling and simulation with proper efficiency criteria evaluation using the MODMENS modeling platform, a numerical rainfall-runoff semi-distributed GR2M conceptual lumped model. The rainfall-runoff simulation was carried-out in three selected sub-basins of Lower River Niger Basin based on observable discharge dataset. Related error estimation was carried-out to estimate the runoff simulation uncertainty while model optimization approach entails use of Rosenbrock-Simplex method and model reliability evaluation entails the use of Nash and Sutcliffe efficiency criteria methods. Result shows a satisfactory model performance at Baro and Makurdi gauging stations （savannah ecological zone） while under-estimation characterizes simulated flow at Onitsha gauging station（Forest ecological region）. Seasonally, the model best fit the dry season flow but underestimate during the high flow periods （rainy seasons and wetter years）.

Macroalgae Blooms and their Effects on Seagrass Ecosystems

Seagrass decline caused by the macroalgae blooms is becoming a common phenomenon throughout temperate and tropical regions. We summarized the incidence of macroalgae blooms throughout the world and their impact on seagrass beds by direct and indirect ways. The competition for living space and using resources is the most direct effect on seagrass beds when macroalgae are blooming in an aquatic ecosystem. The consequence of macroalgae blooms(e.g., light reduction, hypoxia, and decomposition) can produce significant indirect effects on seagrass beds. Light reduction by the macroalgae can decrease the growth and recruitment of seagrasses, and decomposition of macroalgae mats can increase the anoxic and eutrophic conditions, which can further constrict the seagrass growth. Meanwhile, the presence of seagrass shoots can provide substrate for the macroalgae blooms. Controlling nutrient sources from the land to coastal waters is a general efficient way for coastal management. Researching into the synergistical effect of climate change and anthropognic nutrient loads on the interaction between searsasses and macroalgae can provide valuable information to decrease the negative effects of macroalgae blooms on seagrasses in eutrophic areas.

Effect of Seed Sizes on the Growth and Establishment of Seedlings of Sheanut Tree （Vitellaria paradoxa）

Seed size can influence germination, emergence and further development of plants to produce high yield. Therefore, pot trial was conducted to assess the effects of seed sizes on growth and establishment of sheanut tree seedlings （Vitellaria paradoxa） in tlae southern Guinea savanna of Nigeria. Seedlings produced from large sized seed had higher germination （80%） than those from medium （70%） and small （65%） sized seeds. Number of days to emergence of seedling from large-sized seed planting was 30 days, 49 days for small- and medium-sized seeds. Large sized seeds had higher N, P, K, Ca and Mg contents compared with small and medium sized seeds. Generally, seedlings from large sized seeds had about 1.5 times more leaves than medium sized seeds and about 2 times more leaves than small sized seeds at 8, 10, 12, 14 and 16 weeks after planting （WAP）. Seedlings from large sized seeds were taller and had larger stem girth （at 16WAP） than those from medium sized seeds. Variations in seedling growth from seed sizes could be of operational importance in nursery management as seeds can be sown according to size to improve uniformity. However, further studies to ascertain if the superior growth of seedlings from large sized seeds will lead to higher yield is recommended.

Microbial Biomass Dynamics in a Tropical Agroecosystem： Influence of Herbicide and Soil Amendments

The influences of herbicide alone and in combination with the soil amendments with contrasting resource qualities on dynamics of soil microbial biomass C （MBC）, N （MBN）, and P （MBP） were studied through two annual cycles in rice-wheat-summer fallow crop sequence in a tropical dryland agroecosystem. The experiment included application of herbicide （butachlor） alone or in combination with various soil amendments having equivalent amount of N in the forms of chemical fertilizer, wheat straw, Sesbania aculeata, and farm yard manure （FYM）. Soil microbial biomass showed distinct temporal variations in both crop cycles, decreased from vegetative to grain-forming stage, and then increased to maximum at crop maturity stage. Soil MBC was the highest in herbicide ＋ Sesbania aculeata treatment followed by herbicide ＋ FYM, herbicide ＋ wheat straw, herbicide ＋ chemical fertilizer, and herbicide alone treatments in decreasing order during the rice-growing period. During wheat-growing period and summer fallow, soil MBC attained maximum for herbicide ＋ wheat straw treatment whereas herbicide ＋ FYM, herbicide ＋ Sesbania, and herbicide ＋ chemical fertilizer treatments showed similar levels. The overall trend of soil MBN was similar to those of soil MBC and MBP except that soil MBN was higher in herbicide ＋ chemical fertilizer treatment over the herbicide ＋ wheat straw treatment during rice-growing period. In spite of the addition of equivalent amount of N through exogenous soil amendments in combination with the herbicide, soil microbial biomass responded differentially to the treatments. The resource quality of the amendments had more pronounced impact on the dynamics of soil microbial biomass, which may have implications for long-term sustainability of rainfed agroecosystems in dry tropics.

Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas

Aims Litterfall at a global scale is affected by climate,edaphic features and vegetation structure,with litter production increasing from grasslands to forests following the rise in standing biomass.However,at landscape scales,the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent,structurally distinct communities are lacking.Here,we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado.Methods We evaluated the woody vegetation structure and composition in 48 sites,equally distributed across four physiognomies and monitored the monthly litter production from April 2014 to March 2015.Important Findings Results showed that the density,basal area,cylindrical volume and aboveground biomass of woody vegetation differ among physiognomies,increasing consistently from cerrado ralo,cerrado típico,cerrado denso and cerradão.Indeed,we found a strong and positive relationship between aboveground biomass and annual litter production,with litter yield increasing from 0.9 to 8.4 Mg ha^(−1)across different physiognomies,following the increment in vegetation structure.Monthly production was seasonal and similar among vegetation types,increasing during the dry season.Leaves comprised the dominant fraction(approx.85%)and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months.However,the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types,likely following the decrease of deciduous species abundance in the plant community.Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies,which co-occur across the Cerrado landscape,with potential implications for the overall functioning of this ecosystem.Moreover,these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.