Leucaena Species Research Articles

The Effects of Two Species of Leucaena on In Vitro Rumen Fermentation, Methane Production and Post-ruminal Protein Supply in Diets Based on Urochloa hybrid cv. Cayman

This study evaluates the effects of the inclusion of two different Leucaena species as a source of condensed tannins based on in vitro fermentation, methane production and post-ruminal protein supply in a diet based on Urochloa hybrid cv. Cayman CIAT BR02/1752 grass. Under in vitro conditions, Leucaena leucocephala CIAT 17263 and Leucaena diversifolia ILRI 15551 were incubated in two proportions (25% and 50% w/w) with Cayman grass and with/without polyethylene glycol as a tannin-binder. The results show that substrates with Leucaena diversifolia produced less gas and methane than those with Leucaena leucocephala with and without polyethylene glycol. The mass in undegraded feed + solid associated microbes fraction decreased linearly with increasing level of inclusion of both species of Leucaena, while increasing its nitrogen content. It is concluded that the condensed tannins of Leucaena diversifolia possess the superior activity and that the tannin content of both evaluated Leucaenas did not affect the diet degradation, and reductions in post-ruminal protein did not occur in the present study. Further studies are needed to differentiate the tannins present in different Leucaena species and their dietary effects.

Successful creation of seedless (sterile) leucaena germplasm developed from interspecific hybridisation for use as forage

Context The legume shrub/tree leucaena (Leucaena leucocephala (Lam.) de Wit.) is highly regarded as a cattle fodder, although it is considered an environmental weed in many parts of Australia. Aims We investigated the feasibility of developing a forage variety of triploid leucaena through interspecific hybridisation that is sterile (without seeds) as a strategy to mitigate its weed risk. Methods A conventional breeding strategy was used to create triploid hybrids from hand-crosses between tetraploid and diploid species of leucaena. Molecular markers were developed to confirm successful crosses and flow cytometry was used to confirm the ploidy level. The plants are being evaluated for flowering behaviour, seed and herbage production across two environmentally diverse sites at Carnarvon and Kununurra in northern Western Australia. Key results During 2018/19 and 2019/20, 2260 crosses between 45 different combinations of diploid females by tetraploid males and their reciprocals have created over 3000 putative triploid hybrid plants. This is the first time that triploids have successfully been created in Australia and 10 new parental combinations were created as a world-first. Conclusions A cohort of sterile triploid plants has been identified and selections will be made based on their edible biomass productivity, insect tolerance, capacity for regrowth after cutting, nutritive value and plant chemistry (including anti-methanogenic responses). A sterile leucaena variety will have application not only in Australian grazing systems but also in other tropical regions of the world. Implications A cost-effective technology for mass vegetative propagation of leucaena will be required for commercialisation of a sterile variety.

Methane Emissions from Ruminants in Australia: Mitigation Potential and Applicability of Mitigation Strategies.

Simple SummaryMethane is a potent greenhouse gas. It is 80-times more effective at heating the earth than carbon dioxide over the first 20 years following release into the atmosphere. Ruminant animals have diverse microbial populations in their stomachs that employ anaerobic fermentation to digest feed. Methane is belched into the atmosphere as a by-product of the digestive process. This gut, or enteric methane, primarily from cattle, but also sheep and goats, contributes 30% of the methane released into the earth’s atmosphere each day, and is more than any other single methane source. A major reduction in methane emissions from ruminants is crucial to preserve ecosystems on the planet. Various strategies to reduce enteric methane emissions in farm operations are reviewed to quantify their mitigation potential, determine their impact on animal productivity and likelihood of adoption. Two feed supplements, a commercial product, 3-NOP (Bovaer®), and the seaweed, Asparagopsis, can reduce methane emissions by 40+% and 90%, respectively, with associated increases in animal productivity and no adverse effects on animal health or product quality. The rumen microbial population can also be changed to provide long-term intergenerational reduction in methane emissions, if treated herds remain isolated from non-treated animals.Anthropomorphic greenhouse gases are raising the temperature of the earth and threatening ecosystems. Since 1950 atmospheric carbon dioxide has increased 28%, while methane has increased 70%. Methane, over the first 20 years after release, has 80-times more warming potential as a greenhouse gas than carbon dioxide. Enteric methane from microbial fermentation of plant material by ruminants contributes 30% of methane released into the atmosphere, which is more than any other single source. Numerous strategies were reviewed to quantify their methane mitigation potential, their impact on animal productivity and their likelihood of adoption. The supplements, 3-nitrooxypropanol and the seaweed, Asparagopsis, reduced methane emissions by 40+% and 90%, respectively, with increases in animal productivity and small effects on animal health or product quality. Manipulation of the rumen microbial population can potentially provide intergenerational reduction in methane emissions, if treated animals remain isolated. Genetic selection, vaccination, grape marc, nitrate or biochar reduced methane emissions by 10% or less. Best management practices and cattle browsing legumes, Desmanthus or Leucaena species, result in small levels of methane mitigation and improved animal productivity. Feeding large amounts daily of ground wheat reduced methane emissions by around 35% in dairy cows but was not sustained over time.

Leucaena leucocephala (Lam.) de Wit in Brazil: history of an invasive plant.

The purpose of this text is to provide a long-term record of occurrences of the species Leucaena leucocephala (Lam.) de Wit. in the Brazilian territory, in order to (i) determine if its introduction occurred before the earliest official record, (ii) identify points of occurrence in Brazil, and (iii) assess its status as a useful although invasive plant. The text is partly based on research done on the confirmed presence of this plant in the Brasília National Park, located in Brazil’s Federal District. Three databases available on the Internet containing information from several herbariums were accessed to obtain the location and the dates of the relevant records of the plant in Brazilian territory. We found that the species was rather widely present in the Brazilian territory before the official record of its earliest introduction. In addition, we found that the plant’s current geographic distribution indicates that it continues to have a strong invasive potential in Brazil, especially because there are social and technical incentives to cultivate it in rural properties.***Leucaena leucocephala (Lam.) de Wit no Brasil: história de uma planta invasora***O objetivo deste texto é oferecer um histórico de longo prazo das ocorrências da espécie Leucaena leucocephala (Lam.) de Wit. no território brasileiro, para (i) determinar se a sua introdução aconteceu antes da data oficial de seu primeiro registro, (ii) identificar os seus pontos de ocorrência no Brasil e (iii) avaliar o seu status como uma planta útil, mesmo que invasiva. O texto se baseia em parte em pesquisa conduzida sobre a presença confirmada dessa espécie de origem exótica no Parque Nacional de Brasília, Distrito Federal. Foram acessadas três bases de dados disponíveis na Internet para obter a localização e as datas dos registros relevantes da planta no território brasileiro. A pesquisa constatou que a espécie tinha uma presença relativamente abrangente no Brasil muito antes do primeiro registro oficial de sua introdução. Além disso, foi constatado que a atual distribuição geográfica da planta indica que ela continua a ter um forte potencial invasivo no Brasil, especialmente porque existem incentivos econômicos e técnicos para o seu cultivo em propriedades rurais.Palavras-chave: Leucaena leucocephala. ocorrência geográfica. espécies invasivas. Brasil.

Seed dormancy overcoming and seed coat structure change in Leucaena leucocephala and Acacia nilotica

Leucaena leucocephala and Acacia nilotica are two arboreal legumes with several uses in agriculture, nutritious forage and livelihoods, fence posts, wood production, biofuel production, charcoal, firewood, shading, hedges, windbreaks, and improvement of soil fertility. The seed dormancy is common in Leucaena and Acacia species, and it creates difficulties in seed testing and planting. The aim of this study is to determine the effective methods of sulfuric acid and hot water due to overcoming dormancy in seeds of those species. Most pretreatments significantly (p < 0.05) reduced hard seed content and enhanced germination percentage when compared to nontreated seeds. Effectiveness of water and acid pretreatments increased when increasing in duration time from 3 to 60 min. The best recommended time pretreatment of sulfuric acid 60 min for A. nilotica, and 3 min of hot water for Leucaena. These treatments all reduced hard seeds to 0% and did not cause damage to the seeds during the germination. Further, the lens and hilum both were identified as primary sites for water uptake into the seeds of Leucaena. Whereas, the lens was recognized as the original site of water intake in A. nilotica. In addition, the seed coat anatomy identified that the palisade epidermal layer was dense, and thickness tissue had been prevented imbibition of water in Leucaena and A. nilotica.

Environmental adaptation of leucaena in Western Australia – challenges and opportunities

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.There is considerable interest from Western Australian (WA) pastoralists on the potential role of leucaena (Leucaena leucocephala) in northern WA, where the potential area for dryland production of species of the genus Leucaena is high. Although it is highly regarded for animal production in other countries and in Queensland, leucaena is a contentious species since its status as an environmental weed precludes it from use on pastoral leases in the Kimberley and Pilbara regions of WA. Development of sterile/seedless forms would overcome risks of spread of the species as a weed. The key environmental constraints to growth of leucaena are likely to be the length of the dry season and low fertility of most soils other than the grey/black cracking clays (vertosols). Psyllid resistance and cool temperature tolerance are likely to be of secondary importance. Opportunities for irrigated production are also emerging and may allow leucaena species to be used in environments previously considered well outside their home-range. It is desirable now to re-examine the diversity of the wider leucaena genus for adaptation to WA conditions generally and for the purpose of selecting elite parent material for use in a sterile/seedless leucaena breeding program. These perennial species that can be under production for 30 to 40 years need to be evaluated in the target environments for at least 3‒5 years to fully understand their potential as adult plants.

Giant leucaena (Leucaena leucocephala subsp. glabrata): a versatile tree-legume for sustainable agroforestry

Leucaena leucocephala (leucaena) is one of the 22 Leucaena species that originated in Central America. There are two major subspecies of leucaena, L. leucocephala subsp. glabrata (giant leucaena) and L. leucocephala subsp. leucocephala (common leucaena). Giant leucaena is a medium size fast-growing tree important for agroforestry while common leucaena is a small bushy shrub that is considered to be an invasive weed. Giant leucaena can be grown as a woody tree of up to ~ 20 m in height or maintained as a bushy fodder legume by repeated harvest of its foliage several times a year. Giant leucaena grown for fodder can produce forage dry mater yield of up to 34 Mg ha−1 year−1. High forage yield together with high protein content makes leucaena an ideal fodder legume for the tropical and subtropical regions of the world. Although mimosine present in the leucaena foliage has toxicity, it should not be a big concern because ruminants can be successfully inoculated with the mimosine-metabolizing rumen bacterium Synergistis jonesii. Alternatively, mimosine present in the leucaena foliage can be removed easily and inexpensively through simple processing. Giant leucaena cultivars are generally free from diseases and are highly tolerant to drought. Although infestation by psyllids may be a problem, a number of psyllid-resistant cultivars of giant leucaena have been developed through interspecies hybridization. The wood of giant leucaena can be used for timber, paper pulp, or biofuel production. Leucaena foliage and wood may serve as raw materials for development of new industry for production of phytochemicals such as mimosine, tannins and anthocyanins, wood products, and high-protein animal feed for farm animals in the future.

Productivity Challenge of Soils Along the Slopes of Mount Oku in Cameroon

Soil fertility is the major determinant of output in Oku today. The objective of this study is based on the techniques used by rural farmers to maximize output on an advanced deteriorating soil. This phenomenon has not only impinged on output but limits the quality of food available to this agricultural dependent people. Over the years, soil constituents became exhausted as a result of continuous cultivation. The planting of Leucaena and Tephrosia tree species in farms played a challenging role in ameliorating output. The methodology adopted by this study centered on the administration of questionnaires, observation, interviews and field visits. A total of 38 Leucaena and Tephrosia trees were counted on four nearby farms. In these farms selected maize seeds were planted at regular ring distance around the trees. The results obtained revealed that, quality maize was harvested at closer perimeter to the soil fertilizer trees. This strategy maximized sustainable soil management and promoted agro forestry activities in Oku. The study concluded that soil fertility is improved upon by planting soil fertilizer trees in farms. At least one of these tree species is identified in farms in Oku.

PacBio-Based Mitochondrial Genome Assembly of Leucaena trichandra (Leguminosae) and an Intrageneric Assessment of Mitochondrial RNA Editing.

Reconstructions of vascular plant mitochondrial genomes (mt-genomes) are notoriously complicated by rampant recombination that has resulted in comparatively few plant mt-genomes being available. The dearth of plant mitochondrial resources has limited our understanding of mt-genome structural diversity, complex patterns of RNA editing, and the origins of novel mt-genome elements. Here, we use an efficient long read (PacBio) iterative assembly pipeline to generate mt-genome assemblies for Leucaena trichandra (Leguminosae: Caesalpinioideae: mimosoid clade), providing the first assessment of non-papilionoid legume mt-genome content and structure to date. The efficiency of the assembly approach facilitated the exploration of alternative structures that are common place among plant mitochondrial genomes. A compact version (729 kbp) of the recovered assemblies was used to investigate sources of mt-genome size variation among legumes and mt-genome sequence similarity to the legume associated root holoparasite Lophophytum. The genome and an associated suite of transcriptome data from select species of Leucaena permitted an in-depth exploration of RNA editing in a diverse clade of closely related species that includes hybrid lineages. RNA editing in the allotetraploid, Leucaena leucocephala, is consistent with co-option of nearly equal maternal and paternal C-to-U edit components, generating novel combinations of RNA edited sites. A preliminary investigation of L. leucocephala C-to-U edit frequencies identified the potential for a hybrid to generate unique pools of alleles from parental variation through edit frequencies shared with one parental lineage, those intermediate between parents, and transgressive patterns.

FORAGE PRODUCTION OF SOME LESSER-KNOWN LEUCAENA SPECIES GROWN ON ACID SOIL

Leucaena leucocephala leaves are nutritious and palatable for ruminants. However, the plant is poorly adapted on acid soil, water logged, and susceptible to psyllid (Heteropsylla cubana). Leucaena favours soils with pH &amp;gt;5. It performs best on calcareous soils. This study aimed to evaluate adaptability of several Leucaena species on acid soils. The study was conducted at the experimental field in Ciawi, Bogor, altitude 500 m above sea level, rainfall 1500-2000 mm year-1, on Latosol soil with pH 5.2. Leucaena species evaluated were L. leucocephala K28, L. leucocephala (local type), Leucaena KX2 hybrid, L. collinsii, L. trichandra, and L. diversifolia. Experiment was designed in a randomized complete block, four replications. All the seedlings were grown in the nursery for 2.5 months before being transplanted to the field. The plants were grown in row plots of 5 m x 1 m with planting distance 0.5 m and spacing between row plot was 3 m. One unit replicate was 5 m x 21 m. In wet season, the plants were pruned at 50 cm height every 3 months, whilst in dry season pruning was done every 5 months. Parameter measured were plant regrowth and forage production (edible part and non-edible part of the plant), as well as N and P content of the edible part. The result showed that Leucaena KX2 hybrid was superior to other leucaenas. Regrowth of KX2 hybrid was the fastest and produced highest forage. The highest fresh weight forage production for 1 year (four times harvests), i.e. 33.93 t ha-1 year-1 equal to 12.48 t ha- 1 year-1 of dry weight, was obtained from Leucaena KX2 hybrid, whereas the lowest was produced by L. diversifolia, i.e. 3.12 t ha-1 year-1 of fresh weight or 1.01 t ha-1 year-1 of dry weight. Production of non-edible part followed the pattern of production of edible part. N and P content in the edible part of all Leucaena species did not show any significant difference except for L. trichandra which contained the lowest. This study implies that Leucaena KX2 hybrid is adaptable to acid soil; therefore it can be grown in wider areas throughout Indonesia.

FORAGE PRODUCTION OF SOME LESSER-KNOWN LEUCAENA SPECIES GROWN ON ACID SOIL

Leucaena leucocephala leaves are nutritious and palatable for ruminants. However, the plant is poorly adapted on acid soil, water logged, and susceptible to psyllid (Heteropsylla cubana). Leucaena favours soils with pH &amp;gt;5. It performs best on calcareous soils. This study aimed to evaluate adaptability of several Leucaena species on acid soils. The study was conducted at the experimental field in Ciawi, Bogor, altitude 500 m above sea level, rainfall 1500-2000 mm year-1, on Latosol soil with pH 5.2. Leucaena species evaluated were L. leucocephala K28, L. leucocephala (local type), Leucaena KX2 hybrid, L. collinsii, L. trichandra, and L. diversifolia. Experiment was designed in a randomized complete block, four replications. All the seedlings were grown in the nursery for 2.5 months before being transplanted to the field. The plants were grown in row plots of 5 m x 1 m with planting distance 0.5 m and spacing between row plot was 3 m. One unit replicate was 5 m x 21 m. In wet season, the plants were pruned at 50 cm height every 3 months, whilst in dry season pruning was done every 5 months. Parameter measured were plant regrowth and forage production (edible part and non-edible part of the plant), as well as N and P content of the edible part. The result showed that Leucaena KX2 hybrid was superior to other leucaenas. Regrowth of KX2 hybrid was the fastest and produced highest forage. The highest fresh weight forage production for 1 year (four times harvests), i.e. 33.93 t ha-1 year-1 equal to 12.48 t ha- 1 year-1 of dry weight, was obtained from Leucaena KX2 hybrid, whereas the lowest was produced by L. diversifolia, i.e. 3.12 t ha-1 year-1 of fresh weight or 1.01 t ha-1 year-1 of dry weight. Production of non-edible part followed the pattern of production of edible part. N and P content in the edible part of all Leucaena species did not show any significant difference except for L. trichandra which contained the lowest. This study implies that Leucaena KX2 hybrid is adaptable to acid soil; therefore it can be grown in wider areas throughout Indonesia.

25 year results of a dryland tree trial, and an invasive risk assessment of introduced species

Tree species elimination trials were planted in 1988 and 1989 in Almeria, south-eastern Spain, and the driest part of mainland Europe. The aim was to test the adaptability of exotic species to local conditions and compare their performance with native species. Of the 50 species initially selected, 12 exotics failed to germinate or exhibited poor nursery establishment. Of the 38 species outplanted (574 trees in total, between 14 and 29 of each species), 11 exotics died within the first year, and a further 18 recorded 100% mortality after 24-25 years, when only 9 species remained with a total of only 40 surviving trees. The best performing species were the native/naturalised Pinus pinea and Pinus halepensis with 79% and 65% survival, respectively, followed by the exotic Acacia salicina with 38% survival, and most trees were 2.0-4.5 m tall. Apart from these dryland trials, trees were also planted on better terrace sites. Of these, Acacia salicina and Casuarina spp. were the largest (to 15 m tall), with an 11 m Prosopis chilensis and a Robinia pseudoacacia of 10 m. On the edge of the nationally recognised ‘Karst en Yesos de Sorbas’ Natural Area, special measures should be taken regarding potentially invasive alien species, and all non-native trees should be removed from the dryland site if further self-seeding is observed. This paper reports the first records of naturally regenerating Prosopis chilensis and P. velutina in Europe. On the terrace sites where natural regeneration were pronounced, it is strongly recommended that all exotic and potentially invasive species of Acacia, Casuarina, Leucaena, Gleditsia, Parkinsonia, Prosopis and Robinia are cut down immediately and stumps removed. On the irrigated ‘arboretum’ site, however, some stumps could be retain be retain for educational purposes, though regrowth must be cut as soon as they flower and before any further fruiting.

Biologia reprodutiva de L. leucocephala (Lam.) R. de Wit (Fabaceae: Mimosoideae): sucesso de uma espécie invasora

The species Leucaena leucocephala (Lam.) R. de Wit., known as leucaena, is originally from Central America. It has been considered a pioneer with high densities of individuals in its populations that could prevent the development of native species. The present study aims to understand the reproductive biology of L. leucocephala , synthetizing information about its reproductive success. The study was conducted in Trindade, central Brazil, from July to November 2012. All areas contained specimens in bloom. We selected four study areas containing populations of leucaena with at least six individuals with flowering. Observations were made of floral visitors and we did tests of first, second and third visit, and cross-pollination between plants, self-pollination and control group (without human intervention). There was a predominance of Apis mellifera and Trigona spinips as flower visitors in these areas. The flowers undergo senescence at the end of the day, however, there is a decrease in flower visiting by insects after 10 am. We found 342 visitors belonging to 12 insect species. After assessing the number of visits of pollinators and their influence on fruit production, we found that the number of visits of the main pollinator ( A. mellifera ) does not influence the production of fruits, showing the efficiency of this bee in its first visit to flowers. Leucaena leucocephala combines several attributes to be considered an invasive species, such as the efficient action of generalist pollinators as Apis mellifera , being able to produce considerable amounts of fruits and seeds that contribute to the potential dispersal and reproductive success of the plant. Keywords : pollination, Apis mellifera , reproductive success.

Germination, Vigor of Seeds and Emergence of Fabaceae Seedling in Bovine Faeces

This study was conducted to evaluate the physiological quality of forage seeds after passage through the gastrointestinal tract of cattle, as well as the emergence of seedlings derived from these seeds. Three Fabaceae species were used: tropical kudzu, leucaena and calopo. One hundred grams of seeds of each species were offered, separately, to five bovines. After the start of the dispersion, the faeces of the animals were collected every 6 hours, in a total of 72 hours, being taken to the greenhouse immediately after each collection. The study evaluated the total number of seedlings in the stool, the lengths of roots and aerial parts, as well as the natural and dry seedling weight thirty days after the disposal of the faeces in the greenhouse. The experimental design consisted of randomized blocks, with twelve treatments (sampling periods) and five replications (cattle). The best performance for the total number of seedlings in the faeces of cattle was observed in the kudzu species. The length of the root, length of the aerial part and dry matter seedling weight was observed in the leucaena species, followed by kudzu. The calopo showed low results for all variables due to the high degradation of the seeds.

Simulation of carbon pool changes in woodlots in eastern Zambia using the CO2FIX model

Agroforestry systems have the potential to contribute significantly to climate change mitigation and adaptation. However, data on tree and soil organic carbon (SOC) pools for most agroforestry systems are lacking because reliable methods for estimating ecosystem carbon (C) pools are scarce. This study quantified the effects of five Leucaena species (L. leucocephala, L. macrophylla, L. diversifolia, L. collinsii and L. pulverulenta) on vegetal and soil C stocks and on mean annual increment (MAI) in aboveground tree C stocks. Specifically, it tested the validity of the CO2FIX model using empirical data from 7 year-old woodlots at Msekera, Zambia, and assessed the impact of converting a degraded agricultural ecosystem to woodlots on C stocks. Measured above- and below-ground tree C stocks and MAI of aboveground biomass differed significantly among the Leucaena species. Measured stem and total aboveground tree C stocks in seven-year old woodlots ranged from 17.1 to 29.2 and from 24.5 to 55.9 Mg ha−1, respectively. Measured SOC stocks at 0–200 cm depth in Leucaena stands ranged from 106.9 (L. diversifolia) to 186.0 Mg ha−1 (L. leucocephala). Modeled stem and branch C stocks closely matched measured stocks, but the soil module of CO2FIX did not predict the soil C. The soil C data are inconclusive at this stage. We recommend that a fractionation and a soil aggregate hierarchy study backed by C dating is carried out to explain soil C dynamics in these soils. However, the model can be used only for estimating changes in aboveground tree C stocks in woodlots until soil C module is proven to predict SOC stocks.

A novel host shift and invaded range of a seed predator, Acanthoscelides macrophthalmus (Coleoptera: Chrysomelidae: Bruchinae), of an invasive weed, Leucaena leucocephala

AbstractAn endophagous seed predator, Acanthoscelides macrophthalmus (Coleoptera: Chrysomelidae: Bruchinae), utilizes Neotropical Leucaena (Fabaceae: Mimosoideae). One of its hosts, Leucaena leucocephala, is a fast‐growing nitrogen‐fixing tree that serves as a multipurpose beneficial plant but eventually becomes an aggressive invader where it was introduced. Herein, we report A. macrophthalmus invasion of the Far East, South Asian tropics and subtropics (Japanese Pacific Islands, Taiwan, Southern China, Northern Thailand and Southern India). Of other field‐collected mimosoid legumes, an introduced tree, Falcataria moluccana, in Taiwan was found to be used by the seed predator. Conversely, our published work review revealed that the seed predator had retained high host specificity to Leucaena species in its native and introduced regions. Acanthoscelides macrophthalmus was able to utilize aphagously postharvest mature seeds for oviposition and larval development, which is a trait of post‐dispersal seed predators. We confirmed that A. macrophthalmus that was reared on L. leucocephala was able to utilize F. moluccana as well. Although the relatively high host specificity of the oligophagous beetle is suitable for controlling the weedy L. leucocephala, the potential host range expansion confirmed by this study must be cautioned.

Thoraconaupactus, A New Brazilian Genus Of Broad Nosed Weevil (Coleoptera: Curculionidae: Entiminae) Associated With Leucaena (Fabaceae)

2 ABSTRACT: A new monotypic genus of Naupactini (Coleoptera: Curculionidae), Thoracon- aupactus del Rio and Lanteri is described based on the new species Thoraconaupactus vaninii del Rio and Lanteri (Type locality: Brazil, Bahia, Itaji). Two different morphotypes are distinguished by characters of the vestiture: one from Itaji, with integument brown, smooth, and vestiture mostly setose; the other from Ibiraba with integument black, rugose and vestiture mostly squamose. Thoraconaupactus is similar to Naupactus Dejean and Teratopactus Heller in several characters, and shows some unique features such as the strongly transverse pronotum with a sub-basal tooth-like pro- jection on each side. Specimens were collected in association with a species of Leucaena (Fabaceae). The paper includes habitus photographs and line drawings of genitalia, mouthparts, and other exter- nal features of taxonomic value.

Leucaena species valoration for biomass and paper production in 1 and 2 year harvest

In order to identify faster-growing non-woody species usable for biomass and paper production, four Leucaena species ( L. diversifolia, L. colinsii, L. salvadorensis and three varieties of L. leucocephala) were tested. All the Leucaena species showed a good soil and climatic adaptation to Spain Southwest except for L. salvadorensis. Studied Leucaena species showed biomass productivity ranges from 67.14 to 9.44 t ha −1 (o.d.b.) and 43.6 to 11.4 t ha −1 under Mediterranean conditions for the first and second year sprouts, respectively. The quantity of solubles and extractives shows similar values when compared with wood materials. Relatively lower lignin content in Leucaena (from 15.7% to 21.4%) species has been found with respect to other vegetal species. The α-cellulose contents (39.4–45.3%) are in the range of the normal values expected for the other non-wood raw materials. The study confirms the feasibility of organocell yield pulping process to Leucaena species. Organocell process provides an efficient delignification (kappa number 12.4 and pulp yield 42.2%) for L. leucocephala and suitably physical characteristics of paper sheet (tensile index 20.3 kNm/kg for L. diversifolia).

Mimosine Mitigates Oxidative Stress in Selenium Deficient Seedlings of Vigna radiata-Part I: Restoration of Mitochondrial Function

Mimosine, a non-protein plant amino acid found in Mimosa pudica and certain species of Leucaena, was beneficial for the growth of seedlings of Vigna radiata germinated under selenium-deficient stressed condition (-Se stressed) despite the recognized toxicity of the allelochemical. Exposure of mimosine at 0.1 mM (Mim-0.1) promoted the growth of the seedlings and significantly enhanced mitochondrial functional efficiency. Growth-related parameters including root and shoot lengths and dry weight were increased by 44-58% in the Mim-0.1 group compared to that of the -Se-stressed group. Oxygen uptake by mitochondria of Mim-0.1 group, studied with different substrates, revealed enhanced State 3 respiratory rates with regulated State 4 rates, resulting in high respiratory control ratio (RCR) of 3.4 to 3.9 indicative of a high degree of oxidative coupling. Specific activities of mitochondrial electron transport enzymes, nicotinamide adenine dinucleotide (reduced form) (NADH)-cytochrome (cyt) c oxidoreductase, succinate dehydrogenase, and cyt c oxidase in the Mim-0.1 group were enhanced by 53% to threefold over those of the Se-stressed group. Marked decreases in the extent of mitochondrial lipid peroxidation ensued upon mimosine exposure, indicative of its antioxidant function. Mitochondrial 45Ca2+ uptake was notably augmented twofold in the Mim-0.1 group, compared to the Se-stressed group. Detailed kinetic analyses of Ca2+ uptake revealed positive cooperative interactions in both -Se-stressed group and Mim-0.1 groups with Hill coefficient (nH) values of 1.7 and 2, respectively. The present study establishes the beneficial effects of mimosine exposure at 0.1 mM on the growth and mitochondrial function of the seedlings grown under selenium-deficient stressed condition and a significant physiological role can be ascribed to mimosine.

Vegetative Propagation of Leucaena Hybrids by Cuttings

Many interspecific hybrids have been produced among Leucaena species, some with great potential for high-value wood and forage production. Superior hybrids are often highly sterile, and vegetative propagation would be essential for their exploitation. Four experiments were conducted to investigate factors affecting the rooting of cuttings of Leucaena hybrids. Nine hybrids were studied that represented different ploidy levels (2x, 3x, and 4x), different levels of seedlessness, different ages (5–16 years) and varying leaflet sizes. Rooting ability basically depended on genotype, with only a few hybrids failing to root. Cuttings required leaflets to root, and half or more of a leaf led to higher frequencies of better roots. One-node cuttings had the same rooting ability as two-node cuttings. Rooting ability decreased dramatically in the cooler, low-light winter seasons of lowland Hawaii. Etiolation treatments increased rooting ability significantly for two difficult-to-root hybrids.