金沙江干热河谷银合欢人工林对土壤养分的影响

通过干热河谷银合欢人工林对土壤改良效应5年的研究,结果表明:银合欢林具有很好的土壤改良效应,土壤有机质明显高于CK,在0～20 cm,20～40cm和40～60cm的土层中,比CK分别高52.61%,51.09%和43.52%,土壤有机质随着土壤深度的增加而减少.pH在0～20cm,20～40cm和40～60cm的土层...     

红茶菌－嗜酸乳杆菌对银合欢叶的发酵脱毒效果

以银合欢叶含羞草素降解为单一指标.利用红茶菌液、嗜酸乳杆菌液、保加利亚乳杆菌液及植物乳杆菌液为发酵菌液,对银合欢叶的脱毒效果进行研究.以便选取有效的脱毒菌.结果表明,红茶菌液与嗜酸乳杆菌菌液等比例混合液对银合欢叶含羞草素降解效果最好.当菌液接种量为8%,固体密封发酵30d.银合欢叶中含羞草素降解率能达到82%左右,降解效果明显.这为拓宽银合欢的应用具有一定意义.     

Leaf chlorophyll readings as an indicator of nitrogen status and yield of spinach (Spinacia oleracea L.) grown in soils amended with Luecaena leucocephala prunings

A field study was conducted to evaluate the nitrogen status and yield of spinach grown in soils amended with prunings of Leucaena leucocephala, (applied at a rate of 3, 5, 7 or 11 t ha^?1). A ‘no fertilizer’ 0 nitrogen (N) and 150 kg N ha^?1 (recommended) were the control treatments. SPAD readings were recorded for the top six leaves. Nitrogen sufficiency indices were used to indicate the N status of plants. Application of L. leucocephala prunings increased spinach yields (8.98–13.86 t DM ha^?1) relative to the 0N treatment (1.35 t DM ha^?1) and yields increased with increasing rate of pruning application. SPAD readings showed a linear increase with the increase in applied prunings. There was preferential distribution of N to upper leaves. The relationship between shoot N concentration and SPAD readings was linear and strongest for the top three leaves (r² = 0.84–0.92). The results indicate the potential of chlorophyll meter readings in assessing N status of leafy vegetables grown on soils amended with different levels of legume tree prunings.     

银合欢硬实种子处理方法研究

采用7种不同方法对银合欢Leucaena leucocephala种子进行处理,结果表明,用98%的浓硫酸对银合欢种子进行处理5 min效果最好,发芽率达86%;其次是水温80℃浸种10 min,发芽率达74%;80℃高温干燥10 min和机械摩擦种皮效果比较差,发芽率仅19.3%和15.3%;酒精、40%的氢氧化钠、不同浓度萘乙酸(NAA)浸种对银合欢的发芽率没有影响,最佳处理的大田试验结果与实验室结果相吻合。     

不同经营模式下新银合欢的枝系特征差异分析

在中国科学院东川泥石流定位观测站附近,对不同经营模式下新银合欢的枝系特征进行了统计分析,结果表明：新银合欢在不同经营模式下的总体分枝率和逐步分枝率SBR1:2发生显著变化,逐步分枝率SBR2:3则未表现出显著差异;截干新银合欢二、三级枝长度,枝径比2：1及一、二、三级枝倾角显著大于未截干新银合欢;两种经营模式下叶片的分布特征未发生显著差异。通过对各种枝系特征综合分析,发现截干新银合欢的生长对策表现为向上拓展自身生长空间,保持其原有的生态位。     

Adoption potential of selected organic resources for improving soil fertility in the central highlands of Kenya

Soil fertility decline is the major cause of declining crop yields in the central highlands of Kenya and elsewhere within the African continent. This paper reports a study conducted to assess adoption potential of two leguminous trees, two herbaceous legumes, cattle manure, and Tithonia diversifolia either solely applied or combined with inorganic fertilizer, for replenishing soil fertility in the central highlands of Kenya. The study examined biophysical performance, profitability, feasibility and acceptability, and farmers experiences in managing and testing the inputs. The study was based on a series of studies incorporating both sociological and experimental approaches for two and a half years. Results of on farm trials showed that manure + fertilizer and tithonia + fertilizer treatments increased yields by more than 100% above the control. These treatments were the most profitable having highest net benefits and benefit cost ratios. They were also the most commonly preferred by farmers who used them on larger plots compared to the other inputs. In conclusion, cattle manure and tithonia were found to be the organic materials with the highest adoption potential for soil fertility improvement in this area. Calliandra calothyrsus and Leucaena trichandra, on the other hand, have potential for use as animal fodder. The herbaceous legumes had the least adoption potential due to poor performance recorded on the farms that possibly led to low preference by the farmers. However, issues of sustainable seed production could have played a role. This study recommends some policy issues for enhancing adoption and research issues focusing on exploring strategies for increasing biomass production and use efficiency on farms. Andre Bationo was formerly working for Tropical Soil Biology and Fertility Institute of CIAT (TSBF-CIAT) as the African network Coordinator.     

Tropical legume supplementation influences microbial protein synthesis and rumen ecology

Four rumen‐fistulated male swamp buffaloes, 5‐year‐old with initiated live weight at 360 ± 12 kg, were randomly assigned according to a 4 × 4 Latin square design to investigate the effect of feeding high level of dried Leucaena leaf (DLL) on feed intake, fermentation efficiency and microbial protein synthesis. The dietary treatments were the feeding levels of DLL at 0, 2, 4 and 6 kg/head/day. All buffaloes were supplemented with concentrate mixtures at 0.1% of body weight, and rice straw was fed ad libitum with the availability of water and mineral block at all time. The results revealed that the total feed intake and nutrient digestibility were significantly improved with the increasing levels of DLL feeding, and the highest was in the buffaloes consuming DLL at 6 kg/head/day. Feeding high levels of DLL did not affect on ruminal pH and temperature, while ammonia nitrogen, blood urea nitrogen and volatile fatty acid concentration were significantly enhanced. Moreover, methane production was dramatically reduced by increasing levels of DLL feeding. Total direct counts of the micro‐organism population were increased with the increasing levels of DLL feeding. According to the application of quantitative PCR to quantity cellulolytic bacteria (16S rRNA) targets, it was found that the population of total bacteria and Fibrobactor succinogenes was affected by treatments, while Ruminococcus flavefaciens and methanogen population were significantly decreased as buffaloes were fed with DLL. The nitrogen balance and microbial nitrogen supply were remarkably improved with the increasing levels of DLL feeding. Based on this study, it could be concluded that high levels of DLL feeding at 6 kg/head/day could enhance feed intake, nutrient digestibility, rumen fermentation efficiency and microbial protein synthesis in swamp buffaloes fed on rice straw without any adverse effect.     

银合欢AFLP分子标记体系的优化

以银合欢幼苗为材料,采用CTAB区室法和试剂盒法2种方法提取DNA,通过对影响AFLP反应关键因子,如DNA样品酶切时间、引物等进行优化,建立了适合银合欢AFLP分子标记的反应体系,为利用AFLP标记对银合欢进行分子生物学研究及分子育种奠定基础。     

泥石流频发区人工新银合欢林群落特征

采用植物群落学研究方法,对干热河谷泥石流频发区人工新银合欢林进行研究。结果表明：该人工林群落植物种类比较简单,科属组成极为分散,区系成分单调;科级地理成分热带性质较强（41.91%）,属级地理成分也以热带性质为主（45.16%）;群落物种组成以由中、小型叶面积、单叶、非全缘、纸质和革质的地面芽植物为主;垂直结构单调,虽可分为乔木层、灌木层、草本层,但乔灌层均以新银合欢占优势,草本层盖度低。群落处于不稳定的状态,应在人为干预的手段下进行分化和演替。