Leucaena (Leucaena leucocephala (Lam) de Wit) prunings as nitrogen source for maize (Zea mays L.)

The effectiveness ofLeucaena leucocephala (Lam.) de Wit, prunings as N source for maize (Zea mays L.) was evaluated in field and pot trials at Ibadan, southern Nigeria. An N deficient, sandy Apomu soil (Psammentic Usthorthent) was used. The prunings significantly increased N uptake of seedlings and N percentage in ear leaves of maize. High maize gain yield was obtained with application of 10 tons fresh prunings or a combination of 5 tons fresh prunings and N at 50 kg ha^–1. The prunings as N source, appeared to be more effective when incorporated in the soil than when applied as mulch. In the pot trial, prunings applied two weeks before planting was more effective than when applied at time of planting maize. Under screen house conditions, the apparent N recovery from prunings with early incorporation about equals that of fertilizer N.     

Use ofLeucaena leucocephala (Lam. de Wit) leaves as a nitrogen source for crop production

Field and pot trials were conducted to determine optimum management practices for usingLeucaena leucocephala (Lam. de Wit) leaves as a N source for crop production. Field trials with maize showed no benefit from split application of leucaena leaves or from application of fresh as opposed to dried material. Field trials also failed to show any difference between incorporation as opposed to surface application of leucaena leaves. This may be attributed to the low nitrogen response observed. Pot trials however, showed that soil incorporation of leucaena leaves was more effective than surface application in increasing plant dry weight.Leucaena leaves were not as effective as inorganic N in increasing maize grain yield (field trials) or dry matter production (pot trial). Unlike inorganic N, leucaena leaves had a significant residual effect on the succeeding maize crop. In decomposition studies, buried leucaena leaves decomposed more quickly than surface-applied leaves, and fresh leaves decomposed more rapidly than dried leaves.     

银合欢种子多糖微结构的原子力显微镜观察

目的：通过对银合欢种子多糖的形貌观察,研究其微结构。方法：采用热水浸提法提取银合欢种子多糖,通过改变溶液的质量浓度、云母基底表面的化学修饰等不同制样方式,用原子力显微镜(AFM)可视化不同样品制备条件形成的聚集体和非聚集体银合欢半乳甘露聚糖结构形貌。结果：样品在不同制备条件下得到膜状、颗粒状的聚集体结构和非聚集体单糖分子结构。结论：银合欢种子多糖的单个糖分子呈线形螺旋状,并具有短的分枝结构,分子链间互相缠绕,而形成网格状。     

Chemical composition and nutritive value of leaf protein concentrate from leucaena leucocephala

Leaf protein concentrate (LPC) was prepared from Leucaena leucocephala leaf meal (LLM). The recovery of LPC was 7.6 % and analysis showed that the LPC contained 65.91 % crude protein compared with 29.15 % of the LLM, ash content was 17.56% while levels of essential amino acids-lysine, histidine, arginine, isoleucine and leucine—were 5.57, 2.34, 5.88, 5.42 and 10.8% on a dry matter basis, respectively. The LPC had higher in-vivo digestibility than the LLM with values being 63.20 and 48.82%, respectively. The LPC diet supported growth in rats but gave lower nutritive indices than the control diet of soya bean and Guinea corn.     

Accounting for co‐extractable compounds (blank correction) in spectrophotometric measurement of extractable and total‐bound proanthocyanidin in Leucaena spp

Methods to account for the spectral interference of co‐extractable compounds (blank correction) in the spectrophotometric analysis of both extractable and bound proanthocyanidin (PA) using the proanthocyanidin (butanol/HCl) assay were evaluated. Crude extractable and bound PA sample matrices of PA‐free Leucaena magnifica were used. Extractable PA blanks generated in heated 95% butanol/5% H₂O reagent underestimated the optical density (absorbance) of co‐extractable compounds by 24% (P < 0.01), whereas unheated 95% butanol/5% HCl blanks, incubated at room temperature, accurately measured the absorbance of the background matrix (P < 0.01). Current procedures that estimate bound PA concentrations using the proanthocyanidin assay produce intensely coloured background matrices. Recovery measurements from total‐bound PA extracts spiked with 1071 and 2142 µg anthocyanidin per tube indicated that existing analytical procedures that do not account for the spectral interference of co‐extractable compounds overestimated (P < 0.01) bound PA concentrations by 69 and 38% respectively. An innovative technique that generated an internal correction factor for each sample, using wavelength‐scanning spectrophotometry and non‐linear curve‐fitting computer software, was developed. This procedure recovered 100% of added anthocyanidins from bound PA matrices. © 2002 Society of Chemical Industry     

银合欢种子多糖提取工艺优化

对银合欢种子中可溶性粗多糖的提取工艺进行研究。采用单因素试验和L9（3^3）正交试验研究浸取温度、处理时间和料液比对多糖提取率的影响。结果表明,是影响银合欢种子多糖提取的主要因素为提取时间,其次是料液比,再次是提取温度;最佳工艺为浸提温度60℃、浸提时间5h、料液比1：35、醇沉浓度95％vol。在此提取条件下,银合欢种子多糖提取率为12．16％。采用紫外检测和茚三酮法检测未见多糖含有核酸、蛋白质。     

Valorization of Leucaena leucocephala for energy and chemicals from autohydrolysis

In this work, Leucaena leucocephala K366 was characterized chemical and energy terms, and assessed its potential as a lignocellulosic raw material and energetic and industrial crop specie, and its integral fractionation by autohydrolysis by evaluating its calorific value, holocellulose, glucan, xylan, arabinan, lignin and oligomers and monomers contents in autohydrolysis liquor and solid phase. Also, this paper will consider the influence of the temperature and time of autohydrolysis process from L. leucocephala K366 to obtain valuable liquor and a suitable solid phase to produce energy by combustion.Valuable liquor was obtained from the autohydrolysis of L. leucocephala by simultaneously using operating temperatures and times in the medium-high ranges studied, namely: 172-184 °C and 15-30 min. The optimum processing conditions provided an acceptable yield (16-26%), and high xylose and xylo-oligomer contents in the liquor (10.0 and 58.6%, respectively, of the amounts present in the starting raw material when operating at 184 °C for 30 min) in comparison with other raw materials. The arabinan fraction was extracted virtually completely —only 8.3% remained in the solid fraction—, and the acetyl group fraction was recovered in full. In addition, these conditions reduced the glucose content of the liquor to 2.9% of the amount present in the raw material while largely preserving the integrity of cellulose fibers.Klason lignin was scarcely dissolved under the operating conditions of the autohydrolysis process. This increased the calorific value of the solid phase by 9% (under the most drastic operating conditions) with respect to the starting raw material.     

Comparative evaluation of weaning foods from Glyricidia and Leucaena leaf protein concentrates and some commercial brands in Nigeria

Three studies were conducted to evaluate the nutritive potential of Glyricidia leaf protein concentrate (GLPC) and Leucaena leaf protein concentrate (LLPC) in infant weaning foods. The first two trials evaluated 10 laboratory‐formulated weaning foods, in which soybean meal (SBM) was replaced at levels of 0, 25, 50, 75 and 100% with either GLPC or LLPC, and subsequently compared them nutritionally with three commercial weaning foods (coded CFB, CFC and CFN) currently on sale in Nigeria in a 28 day feeding trial using weanling albino rats. Thereafter the best GLPC‐ and LLPC‐based weaning foods, in terms of animal performance consistent with low cost of the foods (designated GL50 and LL25 respectively), were compared with the best commercial weaning food (CFB) in a 14 day rehabilitative potential trial using rats that had previously been protein depleted. In the first trial the final weight was highest in rats fed the 50% GLPC‐based food (159.8 ± 9.5 g) and lowest in rats fed CFN (114.7 ± 9.7 g), while the feed efficiency was best in rats fed the 50% GLPC‐based food and CFC and worst in rats fed the 100% GLPC‐based food and CFN. The nitrogen retention (NR) did not differ significantly (P ≥ 0.05), while the apparent nitrogen digestibility (AND) and ‘operative’ protein efficiency ratio (PER) decreased with increasing level of replacement of SBM with GLPC (R² = 0.61, P ≤ 0.05 and R² = 0.67, P ≤ 0.05 respectively). In the second trial the highest weight gain was observed in rats fed the 25% LLPC‐based food (3.4 ± 0.5 g day^?1). Feed consumption was not significantly (P ≥ 0.05) influenced by dietary treatment, but rats fed the laboratory‐formulated diets containing 0 and 25% LLPC utilised their food more efficiently (3.0 ± 0.4/0.2 respectively) than rats fed the other diets, including the commercial foods. While NR did not differ significantly (P ≥ 0.05), there was a decrease in AND and PER with increasing level of SBM replacement with LLPC (R² = 0.96, P ≤ 0.01 and R² = 0.89, P ≤ 0.05 respectively). Among all the organs weighed in the first two trials, only the relative weight of the lungs was significantly (P ≤ 0.05) affected. Neither the haematological variables nor the serum metabolites were significantly influenced by dietary treatment, except for the packed cell volume of rats fed the LLPC‐based foods. The economics of food production showed that all the laboratory‐formulated foods were cheaper than the commercial foods, with the 50% SBM + 50% GLPC (GL50) and 75% SBM + 25% LLPC (LL25) formulae proving to be the most nutritious. On rehabilitation, rats fed LL25 recovered lost weight faster than those fed GL50, followed by rats fed the best commercial diet (CFB), while the whole‐body and liver protein contents were identical. The incorporation of LPC/SBM mixtures into local food formulae is suggested as a valid intervention strategy for tackling the endemic protein under‐nutrition, especially among vulnerable groups, in sub‐Saharan Africa. Copyright © 2003 Society of Chemical Industry     

Degradation of mimosine during ensiling of leucaena

The causes of the degradation of the toxic component, mimosine, during ensiling of leucaena leaves were investigated in small-scale laboratory preparations. Degradation of mimosine to 3-hydroxy-4(1H)-pyridone was shown to be caused almost entirely by endogenous enzymes in the leaf and not by fermentation during ensiling.     

Mineral deficiencies and fertilization of coastal reforestations in Benin,West Africa

In the coastal zone of Benin K and P deficiencies are a common phenomena in reforestated Eucalyptus camaldulensis as well as in young stands of Casuarina equisetifolia (filao) even with initial fertilization during planting. Mineral disorders (N/K-ratios of about 10) were also described for Leucaena leucocephala used in alley cropping trials. Special attention was focused on the development of deficiency symptoms of young filao, on which red leaves are an advanced stage of leaf yellowing. This phenomenon is induced by N-, P- and K-deficiency.Due to the small CEC of the sandy soils fertilization with (NP)K may quickly enhance Mg-deficiency, as shown for coconut with foliar levels of only 0.03–0.05% Mg. To get a better understanding of these relationships fertilization trials were started.