Nitrogen fixation of and N transfer from cowpea, mungbean and groundnut when intercropped with maize

Grain legumes are used widely in intercropping systems. However, quantitative and comparative data available as to their N₂ fixation and N beneficial effect on the companion crop in intercropping systems are scarce. Hence, studies were conducted to ascertain the above when cowpea (Vigna unguiculata L.), mungbean (Vigna radiata L.) and groundnut (Arachis hypogaea L.) were intercropped with maize. The study was¹⁵N-aided and made outdoors in basins (30 L) filled with 38 kg of soil.¹⁵N labelling was effected by incorporating¹⁵N-tagged plant material or applying¹⁵N-labelled fertilizer along with sucrose to stabilize¹⁵N enrichment in the soil during the experimental period. Intercropped groundnut fixed the highest amount of nitrogen from the atmosphere (i.e. 552 mg plant^–1), deriving 85% of its N from the atmosphere. Intercropped cowpea and mungbean fixed 161 and 197 mg N plant^–1, obtaining 81% and 78% of their N content from the atmosphere, respectively. The proportion of N derived by maize from the associated legume varied from 7-11% for mungbean, 11–20% for cowpea and 12–26% for groundnut which amounted to about 19–22, 29–45 and 33–60 mg N maize plant^–1, respectively. The high nitrogen fixation potential of groundnut in dual stands and its relatively low harvest index for N have apparently contributed to greater N-benefical effect on the associated crop.     

眉豆油的测定

利用GC／MDS分析了眉豆油的成分组成,共检出14种成分,眉豆油主要由豆油酸（含量53．93％）,棕榈油（14．44％）,α－亚麻酸（9．59％）,油酸（9．43％）,硬脂酸（3．66％）和长碳链脂肪酸组成,眉豆油还含甾二烯（0．92％）,角鲨烯（2．23％）和丰富的维生素E（420mg/100g油）,同时测定了眉豆油理性质,结果表明眉豆油是一种性能优良,极具营养价值和保健功能的油脂。     

Fire performance of wood (Pinus radiata) treated with fire retardants and a wood preservative

In this work, we co‐formulated an oil‐borne copper naphthenate/permethrin wood preservative system with synthetic polymer‐based fire‐retardant additives prior to the impregnation of Pinus radiata sapwood. We evaluated what effect, if any, the preservative had upon the fire performance properties of the fire retardants and whether the fire retardants impacted on the fungicidal and termiticidal efficacy of the preservative. The fire retardants included halogenated and phosphorus‐based systems. A mass loss calorimeter, in conjunction with a thermopile, was used to measure the time to ignition and the peak heat release rate (PHRR) from which the fire performance index (FPI) was determined. The preservative properties were evaluated using termite and soil‐block decay bioassays. In summary, we found that the rate of fire growth was reduced when the fire retardants were used in combination with the wood preservative. We also found that the PHRR was a better determinant of fire performance than the FPI. The performance of the wood preservative was enhanced against fungal decay and termite attack when used in combination with the fire retardants. The fire retardants also demonstrated some wood preservative properties of their own. Copyright © 2008 John Wiley & Sons, Ltd.     

Nutritional management ofPinus radiata at Gurnang State Forest,New South Wales

A survey of foliage and soil nutrients and productivity in post first-thinned stands (15 years +) ofP. radiata showed high variability on uniform soil parent material. Site index was significantly related to stand age and soil P. Nutritional monitoring plots in pre-crown closure stands showed P and B deficiency in the foliage and declining concentrations with age. High accumulations of Al and Mn in the foliage in both surveys were unrelated to stand age or site index. A 14-year-old once-thinned stand responded to N and P but not to K, Mg, Ca, B, Cu or Zn. The requirement for P in foliage appears to increase with age, though assessing the critical level is difficult. Nutritional monitoring, supported by fertilizer trials, appears essential to assess nutritional needs and to maintain productivity.     

EFFECTS OF SAWING PATTERN ON LUMBER DRYING: MODEL SIMULATION AND EXPERIMENTAL INVESTIGATION

ABSTRACT

The sawing pattern of lumber affects the drying rate due to transverse permeability differences. These permeability differences are considered in a single board drying model which is able to investigate the drying rates for boards with varying growth ring angles. For the drying of Pinus radiata lumber, the model predicts that the quartersawn boards need longer drying time than the flatsawn boards. The drying time difference was 10–15% of the total drying time for conventional temperature (CT) drying and accelerated conventional temperature (ACT) drying, but was less significant for high temperature (HT) drying. In the simulation of a kiln stack drying, a sawing pattern factor was introduced to the relative drying rate function, which reflected the effects of the growth ring angle and the drying temperatures. The modified kiln wide drying model was used to predict the drying rates for a kiln stack consisting of entirely flatsawn boards and a kiln stack consisting of entirely quartersawn boards. Drying tests were conducted using stacks of mixed flatsawn and quartersawn Pinus radiata sapwood boards. In the tests, three drying schedules were used which included CT, ACT and HT drying. The experimental results agree closely with the model predictions and thus, after further validation, the drying models can be used to predict commercial kiln drying of boards with different sawing patterns.     

MATHEMATICAL MODELLING OF MDF FIBRE DRYING: DRYING OPTIMISATION

In the production of MDF, wet resinated fibre must be dried to its target moisture content, normally 9 to 11%, before compaction into a board by hot pressing. Fibre drying can be interpreted as an incorporated process involving gas-solid two phase-flow, inter-component transfer, and heat and mass transfer within the fibre. Based on these mechanisms, a mathematical model has been developed to simulate the MDF fibre drying process. From the model, fibre moisture content, air temperature and air humidity along the dryer length can be predicted and factors affecting the drying rate examined. The model can be employed to optimise drying conditions and to evaluate improvements in dryer design. A case study of drying improvement in reduction of dryer emissions and heat consumption is given to demonstrate the potential application of the developed dryer model.     

Seed coat tannins and bruchid resistance in stored cowpea seeds

Seeds of wild species and varieties of Vigna were screened for their tannins and α‐amylase inhibitor contents as defensive compounds against cowpea weevil. Seed coats contained condensed tannins that were positively correlated to their colour but not to their resistance against the insect. The α‐amylase inhibitors were present in different amount in cotyledons of all species analysed. Amongst the cultivated lines assayed, Vigna unguiculata TVu 2027, an accession identified as moderately resistant, was found to contain the higher amount of α‐amylase inhibitor. When wild species were considered, V luteola and V vexillata (two resistant species) showed the highest content of α‐amylase inhibitors. In addition, two cultivated accessions (Vita 7 and IT 84E‐1‐108) of cowpea seeds, both classified as susceptible accessions, showing a different degree of bruchid damage in storage, were also analysed. No α‐amylase inhibitory activity was found in cotyledons of undamaged Vita 7 seeds, while the seed coat tannin content was found to be 13 times higher in undamaged Vita 7 seeds than in IT 84E‐1‐108 infested seeds. These latter results support the hypothesis that seed coat tannins must also be considered in biochemical defence mechanisms, which can deter, poison or starve bruchid larvae that feed on cowpea seeds. Copyright © 2004 Society of Chemical Industry     

赤豆双歧杆菌发酵饮料生产工艺的探讨

本文以赤豆为主要原料,经液化、糖化后进行调配,然后接种双歧杆菌发酵,然后再与嗜热链球菌、保加利亚乳杆菌进行混合发酵,调配后获得较高品质的产品。通过正交试验等实验方法进行优化,确定出最佳配方和工艺条件。     

Angiotensin‐I converting enzyme inhibitory and antioxidant activities of peptide fractions extracted by ultrafiltration of cowpea Vigna unguiculata hydrolysates

BACKGROUND: Enzymatic proteolysis of food proteins is used to produce peptide fractions with the potential to act as physiological modulators. Fractionation of these proteins by ultrafiltration results in fractions rich in small peptides with the potential to act as functional food ingredients. The present study investigated the angiotensin‐I converting enzyme (ACE‐I) inhibitory and antioxidant activities for hydrolysates produced by hydrolyzing Vigna unguiculata protein extract as well as ultrafiltered peptide fractions from these hydrolysates. RESULTS: Alcalase^®, Flavourzyme^® and pepsin–pancreatin were used to produce extensively hydrolyzed V. unguiculata protein extract. Degree of hydrolysis (DH) differed between the enzymatic systems and ranged from 35.7% to 58.8%. Fractionation increased in vitro biological activities in the peptide fractions, with IC₅₀ (hydrolysate concentration in µg protein mL^?1 required to produce 50% ACE inhibition) value ranges of 24.3–123 (Alcalase hydrolysate, AH), 0.04–170.6 (Flavourzyme hydrolysate; FH) and 44.7–112 (pepsin–pancreatin hydrolysate, PPH) µg mL^?1, and TEAC (Trolox equivalent antioxidant coefficient) value ranges of 303.2–1457 (AH), 357.4–10 211 (FH) and 267.1–2830.4 (PPH) mmol L^?1 mg^?1 protein. CONCLUSION: The results indicate the possibility of obtaining bioactive peptides from V. unguiculata proteins by means of a controlled protein hydrolysis using Alcalase^®, Flavourzyme^® and pepsin–pancreatin. The V. unguiculata protein hydrolysates and their corresponding ultrafiltered peptide fractions might be utilized for physiologically functional foods with antihypertensive and antioxidant activities. Copyright © 2010 Society of Chemical Industry