3. Materials and Methods
3.1 Study Site
The experiments were carried out in the polybags in the nursery of the Institute of Forestry and Environmental Sciences, Chittagong University, Chittagong, Bangladesh. The university of Chittagong is situated in the south-eastern part of Bangladesh, which lies approximately at the intersection of 91050/ east latitude and 22030/ north longitude (Gafur et al., 1979). The average annual rainfall of this area is about 2500-3000 mm which mostly takes place between June and September. The climate is tropical monsoon with mean monthly maximum temperature of 29.750C and a monthly minimum of 21.140C. The highest temperature usually occurs on May as 32.60C and minimum in January as 14.10C (Ahmed, 1990).
3.2 Species Selection
There are three different types of experiments in this study. The potential agroforestry legumes are selected for the study as the species are used in agroforestry systems in Bangladesh to produce quality timber, fuel and fodder and are preferred by farmers.
For the first experiment, ten species were selected which were Albizia chinensis, A. saman, Albizia lebbeck Albizia. Procera, Acacia auriculiformis, Acacia tortilis, Acacia nilotica Gliricidia sepium Leucaena leucocephala, Sesbania sesban. For the second experiment six species were selected which were Albizia procera, A. lebbeck, A. saman, A. chinensis, Acacia auricoliformis and Pongamia pinnata. For the third experiment five species were selected which were Acacia auriculiformis, A. mangium, A. hybrid, Leucaena leucocephala and Albizia lebbeck.
3.3 Seed and seedling collection
Healthy and disease free seeds of all selected species were collected from the Seed Orchard Division of Bangladesh Forest Research Institute (BFRI), the plantation unit of Institute of Forestry and Environmental Sciences (IFES), Chittagong University and New Forest Project, USA. The seed were brought to the laboratory by using airtight polybag and they were kept in refrigerator until used. Six months old seedlings were collected from the IFES nursery.
3.4 Potting media and fertilizers
The following potting media are used for filling the polybags and the fertilizers used as treatment:
a. Forest top soil (up to 5 cm depth),
b. Pure sand,
c. Cowdung (decomposed),
d. Poly bag (6//x 4//),
e. Fertilizer (Urea and TSP)
Urea contains 46% of nitrogen; TSP (Triple Super Phosphate) contains 48% of P2O5 Cooke, 1970), which were collected from the market.
For these experiments the soils were collected from the forest floor of the University Campus. The soils were sieved well (<3mm)>
3.5 Experiments
3.5.1 Experiment: 1
3.5.1.1 Preparation and Seed Sowing
Polybags of 6//x4// in size used and the potting media used were forest top soil and sand in a ratio of 1:1. Forest top soils and sands were collected 3-4 weeks before filling the bags. Before filling the polybags, the soils and sands were also air-dried for few days, and the soil and sand were sieved to remove stones, roots and other inert debris. Then the polybags were filled in with soils and sand mixtures. The prefilled polybags were arranged in the nursery beds. The seeds were sown in polythene bags after pre-sowing treatment.
3.5.1.2 Experimental designs and Treatment rationale
A randomized complete block design with ten replicates was adopted for this study. Each species was subjected to seven different treatments. There were altogether 700 polybags involving seven treatments and ten species combinations. In addition, 10 seedlings having the same potting media (Soil: Sand : : 1: 1) and seedlings were maintained as control and were not given not any inorganic fertilizer treatment.
The experiment has the following treatments:
T0 : No Fertilizer (Control)
T1: 40 kg urea/ha/polybag
T2: 80 kg urea/ha/ polybag
T3: 40kg TSP/ha/ polybag
T4 : 80kg TSP/ha/ polybag
T5 : 40kg urea/ha+40kg TSP/ha/ polybag
T6 : 80kgurea/ha+80kgTSP/ha/ polybag
3.5.1.3 Application of fertilizers
After 5 weeks of germination, when the seedlings were established, the fertilizers were applied according to the doses (Table 3.1). Fertilizers were applied in 5 cm deep into the polybag.
Table 3.1: The level of inorganic fertilizers applied in the trial
| Commercial Fertilizer | Elements | Grams added per polybag | |
| Level 1(40kg/ha) | Level 2 (80kg/ha) | ||
| Urea (46% N) | N | 0.0817 | 0.1635 |
| TSP (48% P2O5) | P | 0.186 | 0.372 |
3.5.1.4 Care and Maintenance
Proper care and maintenance were done from the time of seed sowing as well as applying fertilizers up to the harvesting of seedling. During applying fertilizers care was taken so that they were not superficially applied on the top of the polybags. Otherwise, the fertilizers urea evaporated. Watering was done everyday morning and in a controlled way to avoid excess water. Weeding was done in every third day and in a controlled manner. The seedlings were kept under the nursery shade to protect strong sunlight and heavy rainfall.
3.5.1.5 Harvesting and data collection
The seedlings were allowed to grow altogether for three months from the time of seed sowing. Final harvesting was done after two month of fertilizer application. And seedlings from each treatment were measured for physical parameters. The recorded parameters were shoot and root length, collar dia, root dia, leaf no., number of nodules and their size, relative elongation ratio, etc. For the assessment of nodulation, the polybags were carefully torn and also soils were carefully separated from the root. Then the roots were thoroughly washed in water and the nodules were separated from roots of individual plants and were washed carefully to remove the soil particles (Solaiman, 1999).
3.5.2 Experiment: 2
Six months old healthy seedlings of six leguminous agroforestry tree species were collected from the nursery. Twenty-four seedlings of each species were collected. They were divided into four groups. Each of which consists three for control (No Fertilizer) and another three for treatment (Phosphate fertilizer (TSP) was applied at the rate of 80 kg /ha/polybag). Fertilizer was applied immediately after their collections and arrangement. There were altogether 144 sedlings/polybags involving four groups, 2 treatments (Control and Fertilizer), and three replicates of each treatment of six species. In this way four such groups of each species were arranged so that Plants were harvested every 20 days up to 80 days after fertilizer application, with almost the entire root system in-tact. Collar diameter, root length, root diameter, shoot length, nodule number, size, leaf no. of seedlings were assessed at every 20 days interval.
3.5.3 Experiment: 3
3.5.3.1 Preparation and Seed Sowing
Polybags of 6//x4// in size used and the potting media used were forest top soil, sand, soil and cowdung in a ratio of 1:1, 2:1, 3:1 respectively. Forest topsoils and sands were collected 3-4 weeks before filling the bags. Before filling the polybags, the soils, sands and cowdung were also air-dried for few days, and the soil, sand and cowdung were sieved to remove stones, roots and other inert debris. Then the polybags were filled in with soils, sand and soil and cowdung mixtures. The prefilled polybags were arranged in the nursery beds. The seeds were sown in polythene bags after pre-sowing treatment.
3.5.3.2 Experimental designs and Treatment combinations
Beneficial use of cowdung for improving growth of leguminous tree seedling is in aggrement with works of different authors (Das, 1984 and RAPA, 1987). A randomized complete block design with ten replicates for each treatment was followed. Each species was subjected to five different treatments. There were altogether 250 polybags involving five treatments and five species combinations.
The experiment has the following treatments:
To: Pure sand only
T1: Soil only
T2: Soil: Cowdung (1:1)
T3: Soil: Cowdung (2:1)
T4: Soil: Cowdung (3:1)
3.5.3.3 Maintenance and Care
Maintenance is the most essential operation to the nursery practice for proper management of planting stock.
Watering: Watering was carried regularly in the morning. This operation was done by the fine shower, which could not disturb the seedlings physically.
Weeding: Weeds make competition with the crops for nutrients, which is the ultimate result of poor performance of seedlings. So, regular removal of weeds, grasses etc.were done as far as possible.
3.5.3.3 Harvesting and data collection
Plants were harvested three months after seed emergence. The variable measured were shoot and root length, collar dia, root dia, leaf no., number of nodules and their dry weight and size, root and shoot dry weight etc.
3.6 Statistical Analysis
The data sets were statistically analysed by using the SPSS. They were subjected to a single factor analysis of variance/ one-way analysis of variance (ANOVA) to test for significant differences between treatment means were then compared with the control treatment using Dun-can's multiple range test (Bliss, 1967).
Relative ratios (Shoot length, root length, collar dia, nodulation and leaf no.) were calculated as suggested by Rho and Kil (1986):
Mean data of tested plant
Relative ratios = x 100
Mean data of control
3.7 Description of selected species
SPECIES NAME: Acacia auriculiformis A. Cunn. ex. Benth.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: Acacia auriculaeformis
COMMON NAMES: Tan wattle
ENVIRONMENT
CENTER OF ORIGIN: Australia, Papua New Guinea
MINIMEM RAINFALL REQUIREMENT: 1300mm
DRY SEASON ADAPTABILITY: 4 – 6 months
MEAN ANNUAL TEMPERATURE: 20 – 30+C
ELEVATION RANGE: 0 – 600m
SOIL REACTION: Strongly acid – highly alkaline
LIGHT REQUIREMENTS: Strongly demanding
OTHER KNOWN LIMITATIONS: Low wind tolerance
DESCRIPTION
HEIGHT AT MATURITY: 15 – 25m.
DBH AT MATURITY: 60 cm.
TREE FORM: Poor
LEAF TYPE: Alternate, simple flattened phyllodes
PESTS: Rose beetle
COPPICING ABILITY: Poor.
SPECIES NAME: Acacia mangium Willd.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: A. glaucescens Kanehira and Hatusima
COMMON NAMES: Mangium, brown salwood
ENVIRONMENT
CENTER OF ORIGIN: Australia
MINIMUM RAINFALL REQUIREMENT: 1000mm
DRY SEASON ADAPTABILITY: 2 – 4 months
MEAN ANNUAL TEMPERATURE: 22 - 250C
ELEVATION RANGE: <800m
SOIL REACTION: Moderately acid
LIGHT REQUIREMENTS: Shade intolerant
DESCRIPTION
HEIGHT AT MATURITY: 30m.
DBH AT MATURITY: 25 cm.
TREE FORM: Good
LEAF TYPE: Alternate, flattened phyllodes
PESTS: “Heart rot”, pinhole borers, scale
COPPICING ABILITY: Young trees only
SPECIES NAME: Albizia procera (Roxb.) Benth.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: Mimosa elata (Roxb.)
COMMON NAMES: White siris, akleng parang
ENVIRONMENT
CENTER OF ORIGIN: So. And S.E. Asia
MINIMEM RAINFALL REQUIREMENT: 1,000
DRY SEASON ADAPTABILITY: 6 – 8 months
MEAN ANNUAL TEMPERATURE: 20 – 250C
ELEVATION RANGE: 0 – 500m
SOIL REACTION: Moderately acid tolerant
LIGHT REQUIREMENTS: Moderately demanding
OTHER KNOWN LIMITATIONS: Frost susceptible
DESCRIPTION
HEIGHT AT MATURITY: 30m
TREE FORM: Straight bole, open crown
LEAF TYPE: Bipinnately compound
COPPICING ABILITY: Good.
SPECIES NAME: Leucaena leucocephala (Lam.) De Wit
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: Leucaena glauca
COMMON NAMES: Koa haole, ipil-ipil.
ENVIRONMENT
CENTER OF ORIGIN: Central America
MINIMEM RAINFALL REQUIREMENT: 600mm
DRY SEASON ADAPTABILITY: 4 – 8 months
MEAN ANNUAL TEMPERATURE: 20 - 300C
ELEVATION RANGE: 0 – 1000m
SOIL REACTION: Moderately acid – mod. alkaline
LIGHT REQUIREMENTS: Strongly demanding
OTHER KNOWN LIMITATIONS: Strongly acid soils, waterlogging
DESCRIPTION
HEIGHT AT MATURITY: 20m
DBH AT MATURITY: 50cm
TREE FORM: Fair
LEAF TYPE: Alternate, bipinnately compound
PESTS: Seed weevil
COPPICING ABILITY: Vigorous.
SPECIES NAME: Albizia saman (Jacq.) Merrill
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: Pithecellobium saman
COMMON NAMES: Raintree, monkeypod, acacia
ENVIRONMENT
CENTER OF ORIGIN: C. America, S. America
MINIMEM RAINFALL REQUIREMENT: 600mm
DRY SEASON ADAPTABILITY: 2 – 4 months
MEAN ANNUAL TEMPERATURE: 18 - 300C
ELEVATION RANGE: 0 – 700m
SOIL REACTION: Neutral to acid
LIGHT REQUIREMENTS: Strongly demanding
DESCRIPTION
HEIGHT AT MATURITY: 40m
DBH AT MATURITY: 200cm.
TREE FORM: Fair-poor
LEAF TYPE: Bipinnate
COPPICING ABILITY: Fair
SPECIES NAME: Acacia nilotica (L.) Willd. ex Del.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: A. arabica, A. scorpioides
COMMON NAMES: Egyptian thorn, kiker, babul
ENVIRONMENT
CENTER OF ORIGIN: Africa
MINIMEM RAINFALL REQUIREMENT: 500mm
DRY SEASON ADAPTABILITY: Extended
MEAN ANNUAL TEMPERATURE: >220C
ELEVATION RANGE: 0 – 500m
LIGHT REQUIREMENTS: Strongly demanding
OTHER KNOWN LIMITATIONS: Frost susceptible
DESCRIPTION
HEIGHT AT MATURITY: 20m
DBH AT MATURITY: 60 – 80cm
TREE FORM: Poor
LEAF TYPE: Alternate, bipinnately compound
PESTS: Wood borers, bruchid beetles
COPPICING ABILITY: Sporadic.
SPECIES NAME: Acacia tortilis (Forsk.) Hayne
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: A. raddiana, A. spirocarpa
COMMON NAMES: Umbrella thorn, seyal
ENVIRONMENT
CENTER OF ORIGIN: Africa
MINIMEM RAINFALL REQUIREMENT: 100mm
DRY SEASON ADAPTABILITY: Extended
MEAN ANNUAL TEMPERATURE: <500C
ELEVATION RANGE: Lowland
SOIL REACTION: Prefers alkaline soils
DESCRIPTION
HEIGHT AT MATURITY: 15m
TREE FORM: Poor, often shrubby
LEAF TYPE: Bipinnately compound
PESTS: Bruchid beetles
COPPICING ABILITY: Vigorously
SPECIES NAME: Albizia lebbek (L.) Benth.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Mimosoideae
SYNONYMS: Mimosa lebbek, Mimosa sirissa
COMMON NAMES: Sires, kokko, lebbek, kakko, sirisha
ENVIRONMENT
CENTER OF ORIGIN: S. Asia
MINIMEM RAINFALL REQUIREMENT: 500mm
DRY SEASON ADAPTABILITY: 2 – 6 months
MEAN ANNUAL TEMPERATURE: 20 - 360C
ELEVATION RANGE: 0 – 1600m
SOIL REACTION: Neutral to acid
LIGHT REQUIREMENTS: Moderately demanding
OTHER KNOWN LIMITATIONS: Fire susceptible
DESCRIPTION
HEIGHT AT MATURITY: 30m
DBH AT MATURITY: 100cm
TREE FORM: Fair to poor
LEAF TYPE: Bipinnately compound
PESTS: Wildlife, fungi attack leaves and pods
COPPICING ABILITY: Fair to good
SPECIES NAME: Gliricidia sepium (Jacq.) Steud.
TAXONOMY
FAMILY: Leguminosae
SUBFAMILY: Papilionoideae
SYNONYMS: Gliricidia maculata (H.B.K.) Steud.
COMMON NAMES: Madre de cacao
ENVIRONMENT
CENTER OF ORIGIN: S. America, C. America
MINIMEM RAINFALL REQUIREMENT: 1500mm
DRY SEASON ADAPTABILITY: 4 – 6 months
MEAN ANNUAL TEMPERATURE: 22 - 300C
ELEVATION RANGE: 0 – 1600m
DESCRIPTION
HEIGHT AT MATURITY: 10m
DBH AT MATURITY: 30cm
TREE FORM: Fair to poor
LEAF TYPE: Alternate, pinnately compound
PESTS: Aphids
COPPICING ABILITY: Vigorously.
