Effects of biochar and poultry manure on soil properties,growth, yield and quality of cocoyam (Xanthosoma sagittifolium Schott) grown in sandy soil

ABSTRACT

Field experiments were conducted during the 2017 and 2018 cropping seasons, to evaluate the effects of biochar (B) and poultry manure (PM) on soil physical and chemical properties, leaf nutrient concentrations, growth, mineral composition and corm and cormel yield of cocoyam. The experiment each year consisted of 4 × 2 factorial combinations of B (0, 10, 20 and 30 t ha^?1) and PM (0 and 7.5 t ha^?1). Results of the study indicated that in both years, the application of B and PM alone, and in combination, improved soil physical and chemical properties, leaf nutrient concentrations, growth, mineral composition and corm and cormel yield of cocoyam. There was a significant interaction effect of B and PM (B x PM) which was adduced to the ability of the B to increase PM-use efficiency and promote better use of the nutrients in the PM. It was found that combination of 30 t ha^?1 B and 7.5 t ha^?1 PM (B₃₀+ PM_7.5) gave the highest corm and cormel yield of cocoyam compared with other treatments. The combination of 30 t ha^?1 B and 7.5 t ha^?1 PM (B₃₀+ PM_7.5) exhibited the highest impact and is therefore recommended for soil sustainability and cocoyam productivity on sandy soil.     

Influence of nitrogen forms and levels on the growth and nutrition of cacao

Ammonium and nitrate are the major forms of nitrogen (N) present in tropical soils. An experiment was conducted to assess the influence of nitrate and ammonium forms (NO₃^?, NH₄⁺, and mix of NO₃^? + NH₄⁺), and levels (1.5–12.0 mM) of N on the growth and nutrition of cacao (Theobroma cacao L). Growth parameters were significantly influenced by N forms, and nitrogen supplied as NH₄⁺ proved better for the growth of cacao compared with NO₃^? form and mixtures of these two forms. Irrespective of the forms of N, levels of N had no significant effect on plant growth parameters. Nutrient efficiency ratios (NERs) (shoot dry matter produced per unit of nutrient uptake) for macronutrients were sulfur>phosphorus>calcium>magnesium>nitrogen>potassium (S>P>Ca>Mg>N>K) and for micronutrients NERs were in the order of copper>boron>zinc>iron>manganese (Cu>B>Zn>Fe>Mn).     

Recruitment of sympatric vendace (Coregonus albula) and whitefish (C. lavaretus) is affected by different environmental factors

Vendace and whitefish in Lake Osensjøen (boreal south‐east Norway) were studied by means of gillnet test fishing (1976–2013) and hydro acoustic acquisition (1986–2011). Vendace increased in number between 1998 and 2009 while growth and size at maturity decreased. The relative density of whitefish decreased in the pelagic habitat, whereas growth and size remained the same. Both species exhibited varying year‐class strength. Whereas strong year‐classes of both species became less frequent after 1980 than before this, this seemed to change after 2000, especially for vendace. Generalised additive models suggested a strong positive relationship between July/August mean air temperature and year‐class strength of both vendace and whitefish. Whitefish recruitment was also negatively affected by the new regulation regime implemented since 1981, and positively correlated with water level after hatching and by late ice off. The reason for the diverging impacts of environmental factors on the two species may be that vendace spawn in deeper waters that whitefish do. The results indicate that increasing summer temperatures benefit recruitment of both species, whereas low water level and early ice off will harm whitefish recruitment. Both trends are caused by climate warming. It may be speculated that increased density of the specialised plankton feeding vendace may affect the algal community through increased predation on herbivorous zooplankton and potentially affect the trophic state of the lake.     

速生杨硫酸盐浆中木素的存在对纤维素水解反应性能及其产物结构的影响(英文)

对木素含量为0.9％～8.3％的速生杨硫酸盐浆进行了X-射线分析研究。利用多相水解方法测定了其反应性能。研究确定,浆中结晶纤维素含量取决于木素脱出程度并随着木素含量的降低而增加。木屑和浆中的纤维素结晶度相当高,而在脱木素过程中只呈微小变化。木素存在于多相水解反应过程中起着阻碍纤维素水解的作用,降低其反应速度常数。基于研究结果还提出了木素与纤维素结晶部分外表面联结的结论,并探讨了这种联结键的可能方式.     

Axial and radial water flow in the trunks of oak trees: a quantitative and qualitative analysis

Axial water flow in the trunks of mature oak trees (Quercus petraea (Matt.) Liebl. and Q. robur L.) was studied by four independent techniques: water absorption from a cut trunk, sap flowmeters, heat pulse velocity (HPV) and thermoimaging. Estimation of the total water flow with sap flowmeters, HPV and water absorption yielded comparable results. We concluded from dye colorations, thermograms and axial profiles of sap flow and heat pulse velocity that, in intact trunks, most of the flow occurred in the current-year ring, where early-wood vessels in the outermost ring were still functional. Nevertheless, there was significant flow in the older rings of the xylem. Total water flow through the trunk was only slightly reduced when air embolisms were artificially induced in early-wood vessels, probably because there was little change in hydraulic conductance in the root-leaf sap pathway. Embolization of the current-year vessels reactivated transport in the older rings.     

The role of shelter in Australia for protecting soils,plants and livestock

The purpose of this review is to examine the current knowledge of the role of trees in providing shelter for pastures, crops, and livestock, for controlling erosion of soils and improving productivity and sustainability of agricultural production in Australia — and the extent to which this knowledge has been applied.Land degradation — tree loss and associated soil salinity, water and wind erosion, soil acidification, soil structural decline and nutrient degradation — is evidence that our primary production systems are not sustainable. We have sought increased production without proper consideration of the ecological context of that system. About half of Victoria's crop and pasture lands are affected or at risk, and in Western Australia about 25% of the cleared agricultural land is wind-eroded and 60% is potentially susceptible, salinity affects 0.43 m ha and half of the divertible surface water is affected by salinity. Similar problems occur in other States. At least 43 m ha or 13% of our rangelands are seriously degraded by wind erosion caused by overgrazing, often coinciding with drought or a run of drier years.Minimum tillage and stubble management for erosion control in cropping has been a major extension and research activity in Australian agriculture. Severe weather, combined with imperfect adoption of appropriate grazing and crop management systems, shows the weakness of complete reliance on these methods of erosion control. An effective system must accommodate the impact of extreme events, which are the most damaging. However, the complementary use of windbreaks to reduce soil erosion is rare, and their establishment has not been promoted, despite the wide-spread adoption of this technology by other countries.In the cropping and higher rainfall grazing areas, the systematic planting of 10% of the land in a net of shelterbelts/timberbelts/clusters could achieve a 50% windspeed reduction; this would substantially improve livestock and pasture production in the short and long-term. Wind erosion could be dramatically reduced and crop production probably increased by the use of windbreaks. Wheat and oat yield at Rutherglen (Victoria), and lupin yield at Esperance (Western Australia), were increased in the sheltered zone by 22% and 47%, and 30%, respectively.In semi-arid and dry temperate areas, planting of 5% of the land to shelter could reduce windspeed by 30–50% and soil loss by up to 80%. This planting would also contribute substantially to achieving other objectives of sustainable agriculture. Agroforestry — particularly timberbelts applications — will be important in the long-term strategy for achieving revegetation. If some of the trees yield a marketable product then the adoption of the system will be more readily achieved.In the arid (pastoral) areas there is an urgent need to promote the ethic that preservation and improvement of the perennial grass and shrub vegetation is critical for the protection of the soil and maintenance of land capability. Control of animal grazing remains the sole means of preventing erosion in much of this zone. While satellite imagery allows us to assess the condition of leasehold lands, we have failed to achieve stocking policies that will halt the degradation of our rangelands.     

Time and method of floral initiation and effect of paclobutrazol on flower and fruit development in Shorea stenoptera (Dipterocarpaceae)

Small Shorea stenoptera Burck. (Dipterocarpaceae) trees of reproductive age growing in an arboretum in west Java were studied to determine the pattern of vegetative shoot development, the time and method of floral initiation and the effect of paclobutrazol on floral enhancement. Vegetative buds were enclosed by two stipules between which was a leaf primordium, a small axillary vegetative bud and another pair of stipules. This sequence was reiterated five to seven times before the vegetative apex was visible. At the time of floral initiation, axillary buds developed into floral spikes and compound inflorescences formed at the end of drooping branches. A compound inflorescence might bear many floral spikes and each floral spike bore many flowers. The compound inflorescence was a modification of the reiterative developmental pattern observed in vegetative shoots. The time of floral initiation began in late June or early July and continued until about November. Floral enhancement using paclobutrazol as a soil drench was attempted in mid-July, but this was later found to be after the onset of floral initiation, and the treatment failed to enhance flowering; however, it appeared to enhance the rate of floral and fruit development. The similarity in vegetative bud development among dipterocarp genera suggests that the time of floral initiation may be easily determined in many species based on simple dissection techniques.     

Studies on the allelopathic effects of some agroforestry tree crops of Garhwal Himalaya

The allelopathic effects of Adina cordifolia, Alnus nepalensis, Celtis australis and Prunus cerasoides were tested by growing crops of Eleusine coracana, Glycine max and Hordeum vulgare on top soil, rhizosphere soil from the plantation of these trees, and on field soil either mulched with dry leaves or irrigated with aqueous leaf extracts of the agroforestry tree species. Germination percentage, shoot length, root length and dry matter production and pigment contents of crops were depressed by agroforestry tree crops. Maximum reduction in germination percentage, root-shoot length and dry matter production was obtained with experimental garden soil mulched with dry leaves of trees and by the effect of Adina cordifolia followed by P. cerasoides, H. vulgare proved most susceptible and E. coracana highly resistant to these tree-top interactions.     

Control ofAgrotis ypsilon (Hufn.) (Lep., Noctuidae) on some vegetable crops in Egypt using the microbial agentBacillus thuringiensis

The effective threshold rate of application of Dipel 2X was 250g/f. Incorporation of some chemical additives such as calcium sulphate (CaSO₄) or calcium oxide (CaO) significantly potentiated the effectiveness of Dipel 2X on larval population. The addition of calcium carbonate (CaCO₃) and zinc sulphate (ZnSO₄) to Dipel 2X greatly reduced the larval population and led to a significant increase in the yield of some vegetable crops. Dipel 2X baits at 250g/f were almost as effective as the chemical insecticide Hostathion when used at 1.5l/f in controllingA. ypsilon larvae attacking vegetable crops. Control of the greasy cutwormAgrotis ypsilon population was better achieved when the biological control agent Dipel 2X was used as baits.     

基于反馈回归法的用电量预测模型研究

多元线性回归法是用电量预测中常用的一种方法,带反馈的多元线性回归法是一种改进的回归方法,具有更高的精度.本文在此基础上进行了多次反馈,即利用带多次反馈的多元线性回归法,结合SPSS软件进行统计分析,并以陕西省用电量为例探究分析多次反馈的多元线性回归法在用电量预测中的应用,从而得到更精准的用电量预测模型.最后以四川省的用电量数据对模型进行了验证,体现出了该模型的优越之处.