Leucaena Leucocephala

Phytoremediation is one of the low cost biotechnology technique for the reclamation of contaminated mined sites. This study investigated the use of Leucaena leucocephala as a potential plant species for phytoremediation of heavy metal contaminated soils. The phytoremediation capability of the plant was studied at the Nursery and Re-vegetation unit of AngloGold Ashanti in Obuasi. Tailings from the Sansu Tailings Dam was amended with top soil from Mampanhwe and three supplements to produce 10 treatments regimes, which were; T1 - Tailings alone, T2 - Tailings + chelator (EDTA), T3 - Tailings + Fertilizer (NPK), T4 - Tailings + Fertilizer (NPK) + chelator (EDTA), T5 - Tailings + PKC, T6 - Tailings + PKC + chelator (EDTA), T7 - Tailing + Topsoil (3:2), T8 - Tailing + Topsoil (2:3), T9 - Tailing + Topsoil (1:1) and T10 - Topsoil alone. Treatment soils of 5 kg were put in poly-pots. Each of the 10 treatments was replicated 6 times and harvesting was done twice at 45 and 75 days after transplanting. A total of 120 poly-pots were prepared. The concentrations of six heavy metals (As, Fe, Pb, Zn, Cd and Cu) were determined, in samples of shoots and roots from each harvest, using an Atomic Absorption Spectrometer. The levels of heavy metals were highest in the roots than in the shoot. The fertilizer (NPK) and the organic manure (PKC) did not have any effect on the biomass. The highest accumulation ratio (22.58 and 32.91) of heavy metals in shoots for both harvests was obtained in T2 for As. The highest accumulation ratio (35.76 and 51.39) of heavy metal in roots was obtained in T5 for As in both harvests. The highest percentage heavy metals reduction in soils was recorded for Zinc (Zn) for both harvests in T2 at 71.30% and 95.96% respectively. Except for As in T4, the amendment of treatment soils with chelator (EDTA) was not effective as the translocation of heavy metals into the shoots was not enhanced by its addition. T2 was the best treatment regime in enhancing the accumulation of heavy metals for both harvest in the order: (T2>T5>T6>T4>T3>T7>T9>T8). In general the levels of heavy metal accumulation increased with the addition of the supplements (Chelator, PKC and NPK) and performed much better than the tailings/soil mixtures. Between the tailings and soil mixtures ratios, T7 (3:2) was the best combination for increased heavy metal accumulation in the plant. Bioaccumulation ratios obtained were all less than 1 (<1) but increased from first to second harvests. Translocation factors greater than 1 (>1) was recorded for As in T4 (tailing + NPK + chelator) for both harvests and T9 (1:1) which was equal to 1 (=1) at the second harvest. Zn in the control also had TF greater than 1 (>1) in the second harvest. The results show that the plant is a phytoextractor and when aided with the addition of supplements, could be more effective in accumulation of heavy metals as a hyperaccumulator on long term cultivation.

Cellulose and microcrystalline cellulose (MCC) were isolated from waste Leucaena leucocephala seeds (LLS) by using acid hydrolysis method. Waste LLS are unused residues after extraction of oil for conversion to biodiesel. Cellulose from LLS (LLS-cellulose) has been isolated by using 80% acetic acid and 65% nitric acid to yield 33% cellulose. MCC was further prepared from the LLS-cellulose via the acid hydrolysis method and yield 71%. The obtained LLS-cellulose and LLS-MCC samples were comparatively investigated by Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy technique (FESEM). FTIR second derivative showed the presence of minor amounts of bound hemicellulose and relatively free of lignin compound. The crystallinity index of LLS-cellulose is higher than LLS-MCC, indicating higher crystallize size and thermal decomposition. FESEM image also showed that there is smooth surface of raw LLS after hot boiling extraction for 2 hours. Thus, this study revealed that the lignin and hemicelluloses can be removed efficiently by using hot water treatment. In addition, cellulose components produced from waste LLS could be used as precursors of other industrial applications.

The integration of leucaena into goat production systems in the tropics and subtropics is reviewed. Goats are well adapted to leucaena, and able to be productive on diets containing up to 100% leucaena as a result of bacterial and hepatic detoxification. Incorporation of leucaena into goat production systems can improve liveweight gains, milk production, worm control and reproduction. Successful feeding systems for goats can be based on both grazed silvopastoral systems and cut-and-carry intensive systems, although there is a lack of farming systems research examining the integration of leucaena into goat production systems, or documentation of the practicalities of these practices.
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Resumen La integración de leucaena en los sistemas de producción de caprinos en el trópico y subtrópico es revisado en este trabajo. Los caprinos están bien adaptados al consumo de leucaena y son capaces de ser productivos en dietas que contienen hasta un 100% de leucaena como resultado de la detoxificación bacteriana y hepática. La incorporación de leucaena en los sistemas de producción caprina tiene el potencial de mejorar las ganancias de peso vivo, la producción de leche, el control de parásitos internos y la reproducción. Sistemas de alimentación exitosos para caprinos pueden basarse tanto en pastoreo en sistemas silvopastoriles como en sistemas intensivos de corte y acarreo. Sin embargo, hay una escasa investigación sobre sistemas agropecuarios que examinen la integración de leucaena en los sistemas de producción caprina, y de documentación de aspectos prácticos de esta integración. Palabras clave: Caprus aegagrus hircus, corte y acarreo, leguminosas arbóreas, pastoreo, sistemas silvopastoriles.

The brood- and seed –size and seed packaging cost have been investigated in Leucaena leucocephala (Lam.) de Wit. From 300 pods belonging to three mother plants of L. leucocephala, a total of 5583 seeds were recovered. Of these seeds, 355 seeds were in waste class (4% in mother tree-A, and 7% in mother tree- B and C each). The largest class (51.0 ± 2.09%) of the seeds was that of the large seeds (> 40mg in weight. This class varied from 46 to 56% in the mother trees. The seeds lesser than 20mg in weight were 3.46 ± 0.33% of the total number of seeds. Pod based inter-tree similarity calculated according to Czekanowski (1913), on the basis of seed types, was not lesser than 91% and not more than 96%. The mean brood size for all pods from three mother plants (N = 300) averaged to 17.33 ± 0.203 varying from 6 to 25 (CV: 20.28%). Brood size distribution was negatively skewed and mesokurtic. The brood size in 90 healthy pods of Leucaena (pods with no waste seeds) varied around 19.80% and averaged to 18.37 ± 0.3869. The single seed weight averaged to 39.86 ± 0.188, 38.53 ± 0.197 and 39.17 ± 0.194 mg in three mother plants, respectively. The composite sample (N = 5228, excluding waste seeds) exhibited negatively-skewed and leptokurtic distribution with a mean seed weight of 39.21 ± 0.112mg (CV: 20.6%). The weight of seeds within pods varied with position of the seed in the pod. The first (proximal) seed of L. leucocephala pods averaged to 33.30 ± 0.0009mg and was lighter than the subsequent seeds (number II to 25) by a quantum of c 4 to 10.8mg. In the composite sample of ninety healthy pods, seed packaging costs, SPC1 = g.pericarp.g-1 seeds and SPC2 = g.pericarp.seed -1 averaged to 0.8265 ± 0.0366 and 0.0321 ± 0.0011g, respectively. SPC1 didn’t appear to follow normal distribution (positively skewed and highly leptokurtic, KS-z: 1.834, p < 0.002) where as SPC2 tended to be marginally away from the normalcy (KS-z: 1.258, p < 0.084). The results are discussed in view of available literature.

Abstract Balances between nutrients applied or mineralized and nutrients removed in maize grain and stover were calculated in a hedgerow intercropping experiment in which Leucaena leucocephala and L. pallida prunings and cattle manure were applied. Hedgerow intercropping (also called alley cropping) is an agroforestry system in which trees are grown in dense hedges between alleys where short-cycle crops are grown. The hedges are pruned periodically during the cropping period and the prunings are added to the soil as green manure. In control treatments, nutrient depletion per season was in the order of 7–19 kg N ha–1, 4–12 kg P ha–1, 10–26 kg K ha–1, 0–2 kg Ca ha–1 and 3–6 kg Mg ha–1. N fertilizer reversed the depletion of N, but it accelerated the depletion of the other nutrients. Manure and at least two applications of leucaena prunings resulted in net positive balances of N, K, and Ca between amounts applied or mineralized and amounts removed by maize. The amounts of P and Mg applied with, or mineralized from, prunings or manure were insufficient to offset the negative balances of these nutrients.

The brood-and seed –size and seed packaging cost have been investigated in Leucaena leucocephala (Lam.) de Wit. From 300 pods belonging to three mother plants of L. leucocephala, a total of 5583 seeds were recovered. Of these seeds, 355 seeds were in waste class (4% in mother tree-A, and 7% in mother tree-B and C each). The largest class (51.0 ± 2.09%) of the seeds was that of the large seeds (> 40mg in weight. This class varied from 46 to 56% in the mother trees. The seeds lesser than 20mg in weight were 3.46 ± 0.33% of the total number of seeds. Pod based inter-tree similarity calculated according to Czekanowski (1913), on the basis of seed types, was not lesser than 91% and not more than 96%. The mean brood size for all pods from three mother plants (N = 300) averaged to 17.33 ± 0.203 varying from 6 to 25 (CV: 20.28%). Brood size distribution was negatively skewed and mesokurtic. The brood size in 90 healthy pods of Leucaena (pods with no waste seeds) varied around 19.80% and averaged to 18.37 ± 0.3869. The single seed weight averaged to 39.86 ± 0.188, 38.53 ± 0.197 and 39.17 ± 0.194 mg in three mother plants, respectively. The composite sample (N = 5228, excluding waste seeds) exhibited negatively-skewed and leptokurtic distribution with a mean seed weight of 39.21 ± 0.112mg (CV: 20.6%). The weight of seeds within pods varied with position of the seed in the pod. The first (proximal) seed of L. leucocephala pods averaged to 33.30 ± 0.0009mg and was lighter than the subsequent seeds (number II to 25) by a quantum of c 4 to 10.8mg. In the composite sample of ninety healthy pods, seed packaging costs, SPC1 = g.pericarp.g-1 seeds and SPC2 = g.pericarp.seed-1 averaged to 0.8265 ± 0.0366 and 0.0321 ± 0.0011g, respectively. SPC1 didn't appear to follow normal distribution (positively skewed and highly leptokurtic, KS-z: 1.834, p < 0.002) where as SPC2 tended to be marginally away from the normalcy (KS-z: 1.258, p < 0.084). The results are discussed in view of available literature. INTRODUCTION Within-fruit allocation of phytomass, brood size (sensu Uma Shaanker, 1988), seed size and seed packaging cost vary from species to species, individual within species and even amongst fruits of an individual plant due to various reasons as genetic load manifestation, resource depletion, predation, pathogen infection or infestation, maternal regulation, sibling rivalry etc.

— The Jose Antonio Alzate dam is the main man-made reservoir along the Lerma River in central Mexico. The water in this dam is heavily contaminated with organic and inorganic residues including copper and other heavy metals. For many years, people living in the vicinity of the dam use sediments as fertilizers, resulting in heavy soil contamination. This study focuses on the use of native Leucadena leucocephala, a small, fast-growing mimosid tree cultivated under greenhouse conditions in an attempt to reduce the levels of copper. The plant was inoculated with a fungus of the Glomus sp. Zac-19 species that in a symbiotic manner increases the decontaminating properties of L. leucocephala. The study was carried out in three stages, starting with sequential extractions to assess the geochemical distribution of copper. Next, L. leucocephala was grown under controlled conditions using a factorial statistical model adding two known doses of Cu 2+ and a third plantlet grown under normal conditions to be used as control. The plant growth was followed at random during 30, 60, 90 and 180 days to assess the level of copper bioaccumulation in leaves, stem and in the whole plant. The bioaccumulation index was evaluated using the initial six fractions, with fraction five revealing a direct relationship between the levels of copper in plant and sediment. Due to the relation of fraction V with humic material, it was finally considered for the calculation of the bioaccumulation index. Copper accumulation in stems was greater than in leaves and the metal concentration decreased with time. The percentage of arbuscules, vesicles and complete colonization was affected by high doses of Cu 2+ ,inhibiting the growth of stem and leaves of L. leucocephala. These results suggest that the plant can be useful for the biological removal of copper in contaminated sediments or soils.

The objective of this study was to evaluate alternative methods to overcome dormancy in Leucena (Leucaena leucocephala) seeds. The seeds were collected from four different matrices and subsequently submitted to different treatments with mechanical scarification and immersion in water and soft drink at different times (0, 6, 24 and 48 h) at 25 ºC. A completely randomized design was used, consisting of 14 treatments composed of four replications containing 50 seeds each. The variables analyzed were:  Germination  at  the  first  count  (G);  Normal  Seedlings  (PN);  Hard or Dormant Seeds (SD); and Germination Speed Index (IVG). The results increased higher percentages of germination (G) in the T1 treatment (mechanical scarification) with 46.7 and 43.2% of normal seedlings (PN) with 43.2% and IVG of 41.9. However, when observing only the treatments submitted in different combinations, it was noted that the treatments T8 (Mechanical scarification and immersion in soda for 6h at 25 ºC) and T2 (Mechanical scarification and immersion in distilled water for 6h at 25 ºC) presented a germination of 44.7 and 39.7%, respectively. Thus, shorter water immersion times associated with mechanical scarification are required to obtain the highest percentage of germination and formation of normal seedlings.