Albizia Procera Research Articles

Screening indigenous tree species for suitable tree–crop combinations in the agroforestry system of Mizoram, India

The study was conducted in the northeastern state of Mizoram in India to find out the allelopathic effect of trees on agricultural crops. The study was conducted in a bioassay culture and a pot culture. The following results were received: • In the bioassay culture, the germination and radicle length of all food crops decreased in leaf and bark extracts of Aporosa octandra, Anthocephallus chinensis, and Albizzia procera compared with the control, except the radicle length of Glycine max in the bark extract of Anthocephallus chinensis. • In the pot culture, Glycine max was the most resistant crop (irrespective of trees and growth media), which showed the highest germination (75.28%) followed by Oryza sativa (68.33%) and Brassica campestris (54.44%). The length of crops (irrespective of growth media and crops) was the largest (86.39 cm) in combination with Anthocephallus chinensis, followed by Albizzia procera (83.85 cm) and Aporosa octandra (81.85 cm). • Dry matter production of crops was highest in Anthocephallus chinensis (1.06 g/plant) followed by Aporosa octandra (0.83 g/plant) and Albizzia procera (0.81 g/plant). Thus, we concluded that the order of tree suitability for crops was Anthocephallus chinensis > Albizzia procera > Aporosa octandra and that of crops to trees was Glycine max > Oryza sativa > Brassica campestris.

Effects of phosphorous fertilizer on seedlings growth and nodulation capabilities of some popular agroforestry tree species of Bangladesh

An experiment was conducted to assess the effect of Phosphorous (P) fertilizer (i.e. TSP or triple super phosphate @ 80 kg/hm2) on seedling growth and nodulation capabilities of three potentially important agroforestry tree species (Acacia auriculiformis, Albizia lebbeck and Albizia procera) of Bangladesh. The study was conducted in nursery beds with six-month-old polybag seedlings of A. auriculiformis, A. lebbeck and A. procera. The effects of P fertilizer on seedling growth and nodulation were compared with that of the seedlings grown in control (i.e. unfertilized soil). The observations revealed that the seedling growth was enhanced significantly with the application of P fertilizer. The growth was found more pronounced in A. auriculiformis, whereas it was not apparent and shows depressed growth in case of A. lebbeck. The study also suggests that the nodulation in terms of nodule number and size was also increased significantly with the application of P fertilizer.

Growth characteristics of multipurpose tree species, crop productivity and soil properties in agroforestry systems under subtropical humid climate in India

Multipurpose tree species (MPTs) were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m (2500 stems·hm−2) could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m3·hm−2 with mean annual increment (MAI) of 2.54×10−2·m3·tree1·a−1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m (1111 stems·hm−2) produced appreciably high timber volume of 315 m3·hm–2 and 165 m3·hm−2 with MAI of 1.77×10−2 m3·tree−1·a−1 and 0.92×10−2 m3·tree−1·a−1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m3·hm−2 with MAI of 1.47×10–2 m3·tree−1·a−1 followed by Samania saman (140 m3·hm−2), Albizzia procera (113 m3·hm−2) and Tectona grandis (79 m3·hm−2) with MAI of 1.40, 1.13 and 0.78 × 10−2 m3·tree−1·a−1, respectively in 4 m × 4 m spacing (625 stems·hm−2). Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice (Oryza sativa-variety, AR-11), groundnut (Arachis hypogaea-variety, JL-24) and sesamum (Sesamum indicum-variety, B-67) were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple (Ananas comosus-variety Queen), turmeric (Curcuma longa-variety RCT-1) and cowpea (Vigna sinensis-variety Pusa Barsati) as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil (0–15 cm) moisture availability were noted in soils under MPTs.

Inventory on non-timber forest products of Mizoram in North-East India

An inventory on Non-Timber Forest Product resources was made during 2005-2006 covering most forest types in Mizoram, N.E. India. A total of 272 species of NTFPs was made in the present study which included medicinal plants (85 families), fruit plants (23 families), food (20 families), fuelwood (18 families) and fodder plants (8 families). Among the various families, Poaceae contributed most (24) genera followed by Arecaceae 17 genera while the least by both Fabaceae and Verbenaceae 07 each. Albizia procera was the most preferred fuelwood species which was consumed by as high as 2075 households while the least preferred was Quercus pachyphylla (only 75 households) in the surveyed sites. A diverse variety of NTFPs were found from the different forest types among which the most important NTFP from utilization perspective was Broomstick. It has also been found a large variety of plants and fruits available to people were used for a variety of purposes. Such activities on one hand contributed to our knowledge of various uses of biodiversity and on the other have resulted in rapid depletion of natural resources.

Effect of Tannins in Acacia nilotica, Albizia procera and Sesbania acculeata Foliage Determined In vitro, In sacco, and In vivo

The nutritive value and the effect of tannins on the utilization of foliage from three commonly used legumes, Acacia nilotica, Albizia procera, and Sesbania acculeata, were determined. Three mature rumen-fistulated bullocks were used to study in sacco degradability and twelve adult sheep were randomly allocated on the basis of live weight to 4 groups of 3 in each to study the in vivo digestibility of the foliages. In all foliages, the contents of crude protein (17 to 24% of DM) were high. Fibre was especially high in Albizia (NDF 58.8% of DM vs. 21% in Sesbania and 15.4% in Acacia). Contents of both hydrolysable (4.4 to 0.05%) and condensed tannins (1.2 to 0.04%) varied from medium to low in the foliages. Acacia contained the highest level of total phenolics (20.1%), protein precipitable phenolics (13.2%) and had the highest capacity to precipitate protein (14.7%). Drying in shade reduced the tannin content in Acacia and Albizia by 48.6 and 69.3% respectively. The foliages ranked similarly for each of the different methods used to estimate tannin content and activity. Acacia and Sesbania foliage was highly degradable (85-87% potential degradability of DM in sacco), compared to Albizia (52%), indicating a minimal effect of tannins in Acacia and Sesbania. Yet, in vitro, the tannins in the Acacia inhibited microbial activity more than those in Albizia and Sesbania. Following the addition of polyethylene glycol to neutralise the tannins, gas production and microbial growth increased by 59% and 0.09 mg RNA equiv./dg microbial yield respectively in the Acacia, compared to 16-17% and 0.06 mg RNA equiv./dg microbial yield in the other foliages. There was a trend for low in vivo apparent digestibility of N in the Acacia (43.2%) and Albizia (44.2%) compared to the Sesbania (54.5%) supplemented groups. This was likely to be due to presence of tannins. Consistent with this was the low N retention (0.22 and 0.19 g N/g NI) in sheep supplemented with Acacia and Albizia compared to that for the Sesbania (0.32). Similarly, a trend for poor microbial N yield was observed in sheep fed these foliages. Across the foliages tested, an increase in tannin content was associated with a reduction in ruminal fermentation, N digestibility and N retention. For overall nutritive value, Sesbania proved to be the superior forage of the three tested.

Impact of life-history traits on response of seedlings of five tree species of tropical dry forest to shade

Seedling growth under three shade levels was studied at Varanasi, India, for five tree species of tropical dry forest, which differed in life-history traits. Three of these were small-seeded pioneer (Albizia procera, Acacia nilotica and Phyllanthus emblica) and the other two were large-seeded non-pioneer (Terminalia arjuna and Terminalia chebula) species. Seedlings of all the species were subjected to three light levels (80–100%, 20–30% and 3–7% of full sunlight) comparable to sunlit gaps and shaded microsites in the dry forest. After 4 mo of shade treatment, height, basal area, biomass and other growth traits, viz. RGR (relative growth rate), NAR (net assimilation rate), and SLA (specific leaf area) were determined. Etiolation and plasticity indices were calculated. Reduction in seedling height, biomass and relative growth rates and enhancement in SLA due to shade was greater for small-seeded pioneer species. Seedlings from large-seeded non-pioneer species exhibited a stronger etiolation response to shade than seedlings from small-seeded species. Phenotypic plasticity indices for basal area, plant biomass and relative growth rate were greater for the three small-seeded early successional species (A. procera, A. nilotica and P. emblica), indicating their specialization in a more favourable light environment such as large gaps and forest peripheries. The non-pioneer and pioneer species differed only in the degree of shade tolerance, and we suggest that dry forest species cannot be strictly categorized into two distinct groups (shade tolerant vs. intolerant), rather shade preference and gap preference would be the more expressive terms. Marked environmental heterogeneity in terms of irradiance and the phenology of dry tropical trees permits coexistence of species of varying ecological traits, contributing to the maintenance of diversity in the dry forest.

N and P resorption efficiency in certain young tropical tree species planted on mine spoil

N and P resorption efficiencies were studied in three years old eight tropical tree species planted on mine spoil. Of the eight species Albizia lebbeck, Albizia procera, Dalbergia sissoo and Pongamia pinnata were legumes while Azadirachta indica, Holoptelia integrifolia, Madhuca indica and Terminalia arjuna were non-legumes. Both groups of plants have shown higher resorpton efficiency for both nitrogen and phosphorus. But they potentially differed in terms of N and P resorption efficiency. Non-legumes have shown higher efficiency for N resorption and lower efficiency for P resorption while contrary to this, legumes have shown lower efficiency for N resorption and higher efficiency for P resorption.

The effect of calcium hydroxide treatment on the nutritive and feeding value of Albizia procera for growing goats

Albizia procera (Albizia) is widely planted in Bangladesh for timber and the leaves are also used as forage. In the dry season the leaves are less palatable than in the wet season and this may be a consequence of an excessive content of tannin. Albizia foliage was collected in the wet (June) and dry (January) seasons from six agro-ecological zones across Bangladesh and chemical composition, for tannins in particular, was determined. Variation in the tannin content across the six zones proved to be minimal. However, the concentration of tannins was almost two-fold higher in the dry compared to the wet season. To assess the potential for deactivating the tannins in Albizia so as to improve its nutritive value, leaves were treated with alkali (either calcium hydroxide or potassium carbonate) or polyethylene glycol (PEG). Alkali treatment reduced the concentrations of extractable tannin by as much as 92%. The ability of calcium hydroxide to deactivate tannin was then tested in vivo. Young goats, fed a basal diet of hay and wheat bran, were allocated to 4 equal groups ( n = 4 per group) and supplemented with fresh Albizia foliage (at 300 g/kg of the diet) that was either untreated, or treated with either PEG, calcium hydroxide or calcium hydroxide + PEG. The supplements were fed daily for 9 weeks to allow the effects of chemical treatment on intake and growth rate to be defined. In vivo digestibility, nitrogen (N) balance, and microbial N supply were measured over the 5th week. Intakes of feed dry matter (DM) and the digestibility of DM were similar across treatments (mean intake 32 g/(kg LW day), mean DM digestibility 0.63). However, both the PEG and the PEG + calcium hydroxide treatments, compared to the control and calcium hydroxide only treatments, increased N digestibility (0.72, 0.70 versus 0.60, 0.61), N retention (0.43, 0.48 mg N/mg versus 0.26, 0.27 mg N/mg N intake), and microbial N supply (23.7, 21.4 g/day versus 14.2, 12.4 g/day). These increases translated into a 35% improvement in growth rate (40, 36 g/day versus 26, 29 g/day). Calcium hydroxide alone did not improve the feeding value of Albizia. These data highlight the danger of assuming an assayable reduction in tannin, such as that observed in the calcium hydroxide treatment, will translate into an improvement in nutritive value and subsequent animal performance. Since the performance of the goats improved maximally when PEG was added to the calcium hydroxide-treated Albizia it was clear that the tannins were still as active as in the untreated Albizia. It was concluded that calcium hydroxide does not deactivate the tannins in Albizia.

Agroforestry on Small Landholdings in Bangladesh

The study was conducted in three sub-districts of Gazipur district in Bangladesh. It identified the diversity and distribution of tree species and which vegetable crops are grown beneath them, uses of different plants, to identify the problem faced by the farmers. Total of 43 tree plant species are used for fruit and timber were identified in the study area. Based on diversified uses, the major fruit species were jackfruit, mango and coconut. The major timber species were koroi (Albizia procera), raintree (Samanea saman), neem (Azadirachta indica), teak (Tectona grandis) and eucalyptus (Eucalyptus sp.). Total income was found to increase with increase of farm size. A large number of vegetables (32 species) are cultivated in the study area, largely for local consumption. The study showed that stem amaranthus, indian spinach, aroids, sweet gourd, chili pepper, turmeric, eggplant, and radish were grown under shade of jackfruit, mango, date palm, litchi, mahogany, and drumstick trees. The total income from trees in the last five years was higher in the large farm category than that in the tenant category. The major problems faced by the farmers in tree establishment were damage caused by animals which was reported by 68% of the respondents.

Germination and seedling growth of five tree species from tropical dry forest in relation to water stress: impact of seed size

The impact of seed size on germination and seedling growth, as affected by water stress, was studied for five tree species from tropical dry forest of India, viz. Albizia procera, Acacia nilotica, Phyllanthus emblica, Terminalia arjuna and Terminalia chebula. Germination tests were conducted under five osmotic potential levels. Seedlings from large (LS) and small (SS) seeds were grown at four soil moisture levels. Observations were made on height, leaf area, biomass and other growth traits such as relative growth rate (RGR), net assimilation rate (NAR), specific leaf area (SLA), and root:shoot (R:S) ratio. Seeds of pioneer species and large seeds, within species, germinated earlier, and with increasing water stress, per cent germination and germination velocity declined. RGR was inversely related with drought tolerance. R:S ratio increased, RGR and SLA declined, but NAR increased with water stress. Notwithstanding successional status, the slow-growing species registered minimum reduction in biomass due to water stress. The response of LS and SS seedlings also differed for some of the growth variables. Increase in NAR could be a compensatory response to water stress, and the marked allocational plasticity could help maximize capture of the limited resource. Seedlings from smaller seeds, particularly of fast-growing species, would be able to cope with mild drought by morphogenetic and physiological plastic response in a better way than those from large seeds. However, seedlings from large seeds had greater survival than those from smaller seeds under intense water stress.

Influencia de la vegetación sobre la calidad de un suelo tropical degradado.

Se evaluó la influencia de diferentes materiales vegetativos [dos leguminosas arbóreas (Andira inermes y Albizia procera), dos leguminosas coberturas (Arachis glabrata y Centrosema acutifolium) y dos gramíneas (Brachiaria humidicola y Hemarthria altissima)] sobre la biomasa microbiana y parámetros abióticos en un suelo altamente erodado de la serie Corozal (arcilloso, mixto isohipertérmico Aquic Haplohumults). Mensualmente se tomaron muestras de suelos a dos profundidades (0- a 5- y 5- a 15- cm) por un período de once meses. Los valores de la biomasa microbiana de carbono (BMC), la biomasa microbiana de nitrógeno (BMN), N extraíble, N total y la materia orgánica del suelo fueron mayores (P menor que 0.05) en suelos bajo gramíneas como grupo. La reserva microbiana de C y N y su actividad fue mayor a la profundidad de 0- a 5-cm. La respiración microbiana fue afectada significativamente por las especies y el tiempo, siendo los valores mayores en suelo bajo gramíneas. La biomasa microbiana de C y N fue un 2.8 y 1.4% de la totalidad del C y N orgánico del suelo, con valores mayores para C en suelos desnudos (control). El cociente de respiración (C mineralizable/BMC) disminuyó al aumentar la biomasa microbiana y los valores más bajos se obtuvieron en suelos bajo gramíneas. En este estudio, las propiedades que describen la salud del ecosistema del suelo exhiben una posible mejoría debido a la vegetación, con suelos bajo gramíneas manifestando mayor estabilidad debido a mayor contenido de materia orgánica, nitrógeno total, reservas biológicamente activas y pérdidas de C relativamente menores.

Comparative performance and restoration potential of two Albizia species planted on mine spoil in a dry tropical region, India

This study focussed on the comparative impact of young high density plantations of two Albizia species ( Albizia lebbeck and Albizia procera) on the soil redevelopment process during early phase of mine spoil restoration in a dry tropical environment. Plant-hostile features such as high levels of pyrites, etc. were not present. We compared vegetational (biomass, net primary production (NPP), production efficiency, litter fall and its decomposition rate) and soil characters (soil nutrients, microbial biomass and N-mineralization rate) for these plantations. The A. lebbeck plantation accumulated greater biomass and exhibited higher net primary production than the A. procera plantation. The tree layer NPP of A. lebbeck plantation at 6 years age (25.4 t ha −1 years −1) was even higher than that of native dry deciduous forest. The short-lived components (foliage, fine roots) accounted for a greater proportion of ecosystem function (productivity) than the long-lived component (stem). The efficiency of foliage for NPP was greater in A. lebbeck than in A. procera. Decomposition of leaf litter of A. lebbeck was faster than that of A. procera. Ninety five percent mass loss of leaf litter would require 922 days in A. lebbeck and 1328 days in A. procera. Amounts of N and P deposition through leaf fall and release of these nutrients increased with the age of plantation in both species but were higher for A. lebbeck plantation. There was a significant improvement in soil properties due to plantation of both species, but the organic C and kjeldahl N levels were higher in A. lebbeck plantation as were the N-mineralization rates and soil microbial biomass. The proportional increase in soil biomass was much higher than that in soil organic C. The study indicated that the restoration efficiency of A. lebbeck was greater than that of A. procera.

IBA promotes adventitious Rhizogenesis in juvenile shoot cuttings of Albizia procera

Albizia procera is a multipurpose tree of immense potential in forestry pursuits. In this very difficult-to-root species, lack of adventitious rhizogenesis in shoot cuttings creates problem in clonal propagation and mass multiplication. However, significant adventitious rooting has been achieved in softwood juvenile cuttings taken from seedlings. Low concentration (100 ppm) of IBA enhances induction and growth of adventitious roots. The technique would help in clonal propagation of Albizia procera especially in case of half-sib progenies of selected superior genotypes and hybrids of known parentage.

Regeneration and multiplication of Albizia procera Benth. through organogenesis

Vegetative propagation techniques are recognized as indispensable tools for mass multiplication of important multipurpose trees adopted in different agroforestry systems. Albizia procera, one among important species, is difficult to propagate commercially either by stem / root cuttings or layering. A study was undertaken to develop procedure for its in vitro regeneration through organogenesis. Explants collected from 15±2 yr-old mature plus trees and from 15 days old juvenile seedlings were regenerated with exogenous application of different hormones. Epicotyl and hypocotyl explants excised from juvenile seedlings showed higher callusing than axillary bud and shoot tip explants derived from mature trees. Benzylaminopurine (BA) at 3 µg/l was most effective, which induced hundred percent callusing in epicotyl and hypocotyl explants in 1/2 Murashige and Skoog (MS) medium. Callus originated from axillary buds and apical shoot tips of mature trees failed to form organs, however callus derived from epicotyl and hypocotyl explants proliferated and formed de novo shoots and leaflets. A concentration of 3 µg/l of BA was found effective for shoot proliferation. Shoots grew vigorously in 2 µg/l gibberellic acid (GA3) treatment and rooted in 1/2 MS medium supplemented with indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA). Rooting was most successful on medium supplemented with 6 µg/l IBA alone on which 93.3% of the shoots formed roots. Sand or vermiculite supplemented with 4 ml of yoshida solution proved as best hardening media, which recorded 70-80% survival of plantlets. One year old tissue culture raised plants had comparatively more height, collar diameter, biomass, and root shoot ratio than plants raised from cuttings and seeds of the same age. The procedures enumerated provide a basis for the development of in vitro techniques for rapid multiplication of A. procera.

Impact of elevated nitrogen inputs on seedling growth of five dry tropical tree species as affected by life-history traits

We examined whether the responses of dry tropical tree seedlings to elevated nitrogen (N) inputs were associated with functional types, and whether the growth traits of seedlings emerging from seeds of different size within a species were differentially affected by increased N inputs. The study comprised five dry tropical tree species: Albizia procera (Roxb.) Benth, Acacia nilotica (L.) Delile, Phyllanthus emblica L., Terminalia arjuna (Roxb.) Beddome, and Terminalia chebula Retz. Of these, Albizia procera, Acacia nilotica, and P. emblica are pioneer species. The former two are N-fixing legumes. Terminalia arjuna and T. chebula are nonpioneer, nonleguminous species. Albizia procera, P. emblica, and T. arjuna are fast growing, while the remaining two are slow-growing species. Seedlings of these species from large and small seeds were grown at four N input levels (0, 30, 60, and 120 kg N·ha–1). Height and leaf area were measured periodically. At the end of the experiment (after 4 months) biomass and other growth traits, namely relative growth rate, net assimilation rate, specific leaf area, and root/shoot ratio, were determined. Foliar N and net CO2 assimilation rates were also determined. The species responded differentially (66%–282% increase in biomass) to elevated N supply, but the response was not associated with between-species seed size variation. However, within species, small-seed seedlings exhibited a greater response. The elevated N input resulted in a greater enhancement in relative growth rate of the slow-growing species. The species response did not follow functional types such as pioneer versus nonpioneer, legumes versus nonlegumes, and deciduous versus evergreen, but rather was individualistic.Key words: Albizia procera, Acacia nilotica, Phyllanthus emblica, Terminalia arjuna, Terminalia chebula, elevated N input.

Response of five dry tropical tree seedlings to elevated CO 2 : impact of seed size and successional status

2 area, Stomatal conductance, Transpiration, Water use efficiency Abstract. The impact of seed size and successional status on seedling growth under elevated CO was 2 studied for five dry tropical tree species viz. Albizia procera, Acacia nilotica, Phyllanthus emblica, Terminalia arjuna and Terminalia chebula. Seedlings from large (LS) and small seeds (SS) were grown at two CO levels (ambient and elevated, 700-750 ppm). CO assimilation rate, stomatal conductance, 2 2 water use efficiency and foliar N were determined after 30 d exposure to elevated CO . Seedlings were 2 harvested after 30 d and 60 d exposure periods. Height, diameter, leaf area, biomass and other growth traits (RGR, NAR, SLA, R:S) were determined. Seedling biomass across species was positively related with seed mass. Within species, LS seedlings exhibited greater biomass than SS seedlings. Elevated CO2 enhanced plant biomass for all the species. The relative growth rate (RGR), net assimilation rate (NAR), CO assimilation rate, R:S ratio and water use efficiency increased under elevated CO . However, the 2 2 positive impact of elevated CO was down regulated beyond 30 d exposure. Specific leaf area (SLA), 2 transpiration rate, stomatal conductance declined due to exposure to elevated CO . Fast growing, early 2 successional species exhibited greater RGR, NAR and CO assimilation rate. Per cent enhancement in 2 such traits was greater for slow growing species. The responses of individual species did not follow functional types (viz. legumes, non-legumes). The enhancement in biomass and RGR was greater for large-seeded species and LS seedlings within species. This study revealed that elevated CO could cause 2 large seeded, slow growing and late successional species to grow more vigorously.

Impact of native tree plantations on mine spoil in a dry tropical environment

This study describes the impact of young high-density plantations of two native leguminous ( Albizia procera and A. lebbeck) and one non-leguminous timber tree ( Tectona grandis) species on the soil redevelopment process during the early phase of mine restoration in a dry tropical environment. There was a general improvement in soil properties due to establishment of plantations. Highest soil organic C values were found in A. lebbeck plantations and lowest in T. grandis plantations. Both A. lebbeck and A. procera substantially increased levels of nitrogen in soil. However, A. procera, with slow decomposing litter, was not as effective in raising N levels in the soil as A. lebbeck, indicating that all N fixers may not be equally efficient in raising soil N levels. Soil microbial biomass and N mineralization rates were always higher in plantations of N-fixer species. A continued increase with age in microbial C:total C ratio indicates these plantations have yet to reach steady state.

Fuelwood characteristics of indigenous tree species of north-east India

Fuelwood characteristics viz. moisture content, ash, silica, carbon, nitrogen, volatile matter, density and calorific value of 35 indigenous tree species of the age group of 10–15 years growing in their natural habitat in north-eastern region of India were determined and Fuel Value Index (FVI) of each of them was calculated. From the experimental data and the FVIs, it is found that Acacia nilotica, Acacia auriculiformis, Albizzia lebbeck, Albizzia procera, Pinus kesiya and Elaeognus umbellata possess better fuelwood characteristics and they may be considered for inclusion in energy plantation programme in the region.

STUDIES ON ROOTING PATTERNS OF 5-YEAR-OLD IMPORTANT AGROFORESTRY TREE SPECIES IN NORTH BIHAR, INDIA

ABSTRACT Studies on rooting patterns of eight important multipurpose tree species demonstrated large variation in root depth and horizontal root spread 5 year after planting. The root depth varied between 1.01m (Acacia lenticularis L.) and 2.71m (Acacia nilotica (L.) Willd ex. Del.). Variation in horizontal root spread was 1.69m in Syzygium cumini (L.) and 7.70m in Pithecellobium dulce (Roxb.) Benth…Root spread exceeded the crown cover in Acacia nilotica (L.) Willd ex. Del.; Dalbergia sissoo (Roxb), Pithecellobium dulce (Roxb.) Benth Cassia fistula (L.) and Syzygium cumini (L.) Skeels. The length and diameter of the main root were greatest in Acacia nilotica (L.) Willd ex. Del. The maximum length and diameter of lateral roots were recorded in Albizia procera (Roxb.) Benth and Acacia lenticularis (L.) respectively. Total root biomass among different species accounted for between 16 and 37% of the total tree biomass. Analyses of the soil in a comparable site suggest that all these species have potential for conserving moisture and improving the fertility status of the soil, but when grown with agricultural crops would need pruning of their lateral roots.

Influence of Seed Size on Seedling Growth of Albizia procera Under Different Soil Water Levels

Albizia procera Benth. is an early successional leguminous tree species that occurs naturally in dry tropical forests in India. The growth response of seedlings of A. procera from seeds of different sizes was studied under four soil water levels. Seeds were surface sterilized, germinated and grown in a glasshouse for 3 weeks under optimal water supply, and were subsequently maintained at four soil water levels for 4 months. Soil matric potentials for 1,<$>{\ extstyle\\raise1.3pt{1\\over 2}}<$>,<$>{\ extstyle\\raise1.3pt{1\\over 3}}<$>and<$>{\ extstyle\\raise1.3pt{1\\over 4}}<$>water holding capacity (WHC) were −0.01, −0.1, −0.61 and −1.20MPa, respectively. Plant height, stem diameter and leaf area were measured fortnightly. Seedlings were harvested at the end of the experiment. Biomass, relative growth rate (RGR), stem weight ratio (SWR), root:shoot ratio (R:S ratio) and net assimilation rate (NAR) were determined. Seedlings from large seeds had a higher biomass and leaf area and were more tolerant of long-term extreme water stress compared to those from small seeds which were more tolerant of moderate levels of water stress. Seedlings from small seeds did not survive beyond 75d at<$>{\ extstyle\\raise1.3pt{1\\over 4}}<$>WHC. Increase in the R:S ratio along with a decrease in SWR reflected a shift in biomass allocation from above- to below-ground parts as soil water level decreased. SLA declined sharply with increasing water stress, which in turn led to a decrease in RGR. NAR increased with water stress. The study revealed the ability of the species to acclimate to a wide range of moisture stress by morphogenetic (increased R:S ratio and decreased SWR) and physiological (increased NAR) plastic responses.