Abstract: The main objective of this study was to investigate the effects of varying light intensities and different organic fertilizers on the growth performance of O. stamineus seedlings through measurement of Relative Height Growth Rate (RHGR) and biomass production. Randomized Complete Block Design (RCBD) was used. Orthosiphon stamineus was arranged accordingly into three blocks or replicates. The three blocks represented the percentage light intensity. Block 1 (30% of light), Block 2 (50% of light) and Block 3 (100% of light). Each Block had four treatments and 25 plants of O. stamineus. The treatments were chicken dung, cow dung, oil palm empty fruit bunch (EFB) and control. The four treatments were arranged randomly in each block. Growth parameters measured were plant height, biomass (aerial portion, root biomass and total biomass within sixth month’s period. The 50% Relative Light Intensity (RLI) was better than 30 and 100% RLI. The chicken dung is better than oil palm EFB and cow dung.
INTRODUCTION
Orthosiphon stamineus is believed to have anti-allergic, anti-hypertensive, anti-inflammatory and diuretic properties. Orthosiphon stamineus is used as a remedy for arteriosclerosis (capillary and circulatory disorders), kidney stones, diabetes and nephritis (Jaganath and Ng, 2000). According to traditional physiotherapy, Orthosiphon tea is used to remove uric acid stones from the kidneys and also used for treating diabetes and hypertension (Lee and Chan, 2004). The leaves have been introduced to Europe and Japan as a health tea that possess diuretic properties and used as a traditional herb for various ailments in Malaysia. Orthosiphon stamineus has been trusted traditionally as a diuretic and has been used in treating urinary lithiasis, edema, eruptive fever, influenza, rheumatism, hepatitis, jaundice and biliary lithiasis (Chew et al., 2003).
Orthosiphon stamineus shading needs is 30-40% for BRIS soil if planting is done in the dry season (January to June) due to high temperature. Shading can be achieved using shading net or intercrop under other trees. Manures and fertilizers are used in agriculture or forestry practices as nutrient source with the main objective of increasing the supply of plant nutrients already present in the soil (Onuh et al., 2008).
According to Taufik et al. (2007), the term organic refers to a material relating to or derived from living matter such as from an animal or vegetable origin; not involving or produced with chemical or artificial chemicals.
Plants have an optimal intensity of light. This is the point at which the process of photosynthesis is maximized and plant growth is at its greatest (Neri et al., 2003). If the level of light is less, growth is reduced. The point where an increase in light intensity will not increase photosynthesis any more is called light saturation. Light is generally recognized as the most influential environmental factor affecting the growth of trees (Karsai et al., 2008). Sufficient understanding on the influence of light on the survival, growth and regeneration of plant is needed for silvicultural guidelines for successful intercropping. A study on light requirement of O. stamineus especially for intercropping purposes has not been studied previously. It is a very crucial aspect for determining light intensity as a basic requirement for intercropping possibilities under the canopy of trees or any forest species. Therefore, the main objective of this experiment was to investigate the effects of varying light intensities and different organic fertilizers on the growth performance of O. stamineus seedlings through measurement of Relative Height Growth Rate (RHGR) and biomass production.
MATERIALS AND METHODS
Description of the Study Area
The study was carried out since May 2007 to November 2007 at the nursery
of School of International Tropical Forestry in Universiti Malaysia Sabah (UMS)
located at coordinates 06°02.191 N latitude and 116°07.121 E longitude.
According to the Malaysian Meteorological Department, the mean annual rainfall
for ten years from 1996 to 2007 for both sites was 2686.02 mm. The mean daily
temperature is 23.5 to 33°C.
Materials
A total of 2000 seedlings were established at the nursery through stem cuttings.
Each cutting was 6 to 8 inches or 20 cm in length. After one week in the sowing
beds, the seedlings were transplanted into perforated polyethylene bags sized
6x9 inches. The planting medium usually used in the preparation of planting
material is 3:1 (soil: sand) for regular preparation (Aminah
et al., 2002).
Experimental Design
In the nursery experiment, Randomized Complete Block Design (RCBD) was used.
Orthosiphon stamineus was arranged accordingly into three blocks or replicates.
The three blocks represented the percentage light intensity. Block 1 (30% of
light), Block 2 (50% of light) and Block 3 (100% of light). Each Block had four
treatments and 25 plants of O. stamineus. The treatments were chicken
dung, cow dung, oil palm Empty Fruit Bunch (EFB) and control. The four treatments
were arranged randomly in each block. In this study, the ratio that was used
in order to compare the growth of O. stamineus are 3:2:1.5 and 3:2:0.5
(topsoil: sand: organic manure) respectively as 3:2:1 ratio basis for potting
medium in the nursery (Vimala et al., 2004). The
two ratios used in this study were to investigate the most extreme and the least
extreme rate of fertilizer ratio. The experiment was carried out in order to
determine the best growth performance of O. stamineus under different
light intensities and ratios of potting medium in the nursery.
Data Collection
Growth parameters measured were plant height, biomass (aerial portion, root
biomass and total biomass) (Vimala et al., 2004).
The biomass measured using destructive sampling method. The data was collected
every week throughout the sixth months of the experiment. The formula for plant
height was based on Relative Height Growth Rate (RHGR) as an index of seedling
growth (Grotkopp and Rejmanek, 2007);
Where:
| Hi | = | Height of seedlings at initial reading. |
| Hf | = | Height of seedlings at the end of experiment |
| Ti | = | Time at initial reading (Week 0) |
| Tf | = | Time at end of experiment (Week n) |
| ln | = | Natural logarithm |
Statistical Analysis
The data were subjected to statistical analysis using Analysis of covariance
(ANCOVA) using Statistical Package Social Science (SPSS) software to find out
if there were any significant differences caused by light intensity and fertilizer
treatments on O. stamineus seedlings in the nursery.
RESULTS AND DISCUSSION
All the parameters showed that there were significant differences for light intensity especially for 50% of light intensity at p<0.05 (Table 1). The highest mean RHGR was 0.041 cm/cm/week. For root biomass, it was found that the mean value for 50% and 30% light intensity was 13.33 and 8.77 g for 100% light intensity. For aerial biomass, the mean values were 23.03 g. For total biomass, the highest mean weight was 41.99 g at 50% light intensity.
However, it was found that the mean values for all parameters under 100 and 30% of light intensity were lower compared to 50% light intensity. For example, the RHGR mean value for 100% light intensity was only 0.021 cm/cm/week.
| Table 1: | Mean results of parameters for different light intensities |
Mean values with different letter(s) were significantly different at the 5% level probability (p<0.05) using one way ANCOVA and DMRT | |
| Table 2: | Mean results of parameters for different fertilizer treatments |
Mean values with different letter(s) were significantly different at 5% level probability (p<0.05) using ANCOVA and DMRT | |
| Table 3: | Mean results of parameters for the two planting media in the nursery |
Mean values were significantly different at 5% level (p<0.05) using independent sample T-test | |
This is a similar trend for biomass which showed that 100% light intensity was lower compared to 50% light intensity with 8.77, 11.75 and 23.19 g, respectively.
Table 2 shows the results of the growth parameters studied for the fertilizer treatments. All the mean values were significantly different at 5% level probability (p<0.05). Mean value of RHGR for chicken dung was higher with a value of 0.051 cm. For root biomass, chicken dung treatment resulted in the highest mean value at 27.85 g. A similar trend was shown for root biomass aerial biomass and total biomass was highest mean value at 27.85, 41.78 and 69.64 g, respectively.
Table 3 shows the results of the parameters studied for the two planting media used in the nursery for O. stamineus. It was found that all mean values were significantly different at 5% level (p<0.05). The 3:2:1.5 ratio was higher compared to 3:2:05 ratio for every parameter tested.
In this study, the 50% RLI of growth O. stamineus was better than 30% and 100% RLI. The results of this study were supported by Renuka et al. (2007) which showed that the maximum survival obtained by Calamus thwaitesii and Calamus metzianus was under 50% light intensity. He also added that the number of shoots produced was also greater. The 30% RLI (70% shading) showed lower growth for O. stamineus. However, Morinda citrifolia under Acacia mangium (35% RLI) resulted in greater yield of fruits compared to other light intensity regimes (Ota et al. 2008). It was also concurred by Jalil et al. (2006) that Labisia pumila (Kacip Fatimah) under shade house (60-70% shade) produced 160 g per plant (22.1 t ha-1) fresh weight as compared to only 71 g per plant (9.8 t ha-1) under thinned jungle. A different trend of growth Polianthes tuberose L. (Harum Sundal Malam) under 75% shade (35% RLI) was found by Che Radziah et al. (2007) and that the rate of net photosynthesis is low, but chlorophyll content, plant height and leaf area were much higher compared to others. This is evidence that light intensity requirements differ with plant species.
Under full sunlight or 100% light intensity, Calamus hoookerianus and Calamus thwaitesii recorded low survival percentage (Renuka et al., 2007). This supported the present study that the growth height and biomass were lower under 100% light intensity rather than under 50% light intensity. Mori (1980) reported that the light requirements for rattan seedlings was about 33 to 50% relative light intensity in order to protect the plants from complete exposure which promotes scorching of leaves and finally death. Abdul Razak and Ismail (2006) found that Gigantochloa ligulata stands could be established by intercropping with 60% light intensity conditions and applying a mixture of organic and compound fertilizers.
There are two types of stands in order to determine the light intensity which includes heavy-shade and light-shade types. Kamo et al. (2007a) also stated that light-shade type in which the RLI was about 30-40% was much larger than in the tropical rainforests of Malaysia (0.3 to 0.4% RLI), broad leaved temperate forests (mostly less than 5% RLI) and deciduous broad-leaved temperate forests (3 to 5%) or the various types of closed forest. The reason is forest type has a smaller light canopy than light-shade type. In this view, the light-shade type stand expected to facilitate the growth of under planted indigenous seedlings or any cash crops.
However, a different cases with the tree species like dipterocarp species (Dryobalanops lanceolata, Shorea beccariana and Shorea pilosa) showed that optimum growth at about 20 to 30% light conditions for their initial establishment, above and below which growth rates were lower (Kamo et al., 2007b). According to Fenner (1992) light that penetrates through leaf can affect the germination of all species that need light for germination especially seeds that were more exposed to 100% RLI which caused the lower percentage of germination. Fruit yield was much higher at the open site than at the thinned A. mangium site. A comparison of the thinned A. mangium sites revealed that a relatively high yield was obtained at the 66% thinned treatment on an upper slope due to the relatively high light levels and good drainage (Miyamoto et al., 2007).
In terms of biomass production, it was also affected by relative light intensity. It is contradiction with the present study that shading reduced plant root biomass but had no effects on above ground biomass or leaf quality (Jackson and Ash, 2001). In addition, simulated under canopy plants or shading produced more biomass and had higher leaf N concentration than simulated ‘outside-canopy’ plants. However, Senevirathna et al. (2003) studied that shading of rubber reduced leaf expansion rate, plant height and stem diameter and vegetative growth of rubber.
From the experiment it was also supported with the present study that the chicken dung is better than the others due to its high nitrogen content (Zaharah and Vimala, 1987). Oil palm EFB can be used by smallholders as source of fertilizer because its nutrient content is high in Potassium (K) about 40% K2O based on dry weight of FFB and the rest is Phosphate (P2O5) and Magnesium (MgO) (Sumathi et al., 2008; Yusoff, 2006). Kasisira and Muyiiya (2009) contradicted with the result present study that cow dung is the best organic fertilizer because cows digest so little of their food. However, in this experiment, cow dung does not perform well. This might be due to the lower content of nutrient and nutrient leaching faster through soil.
CONCLUSION
Amongst the Relative Light Intensity (RLI) regime, 50% RLI was better than 30% and 100% RLI. The 50% RLI is very suitable and can give an optimum yield when planting under shade or intercrops under tree canopies. In addition to that, with an optimum light intensity regime it can produce a high number of leaves as higher biomass production for all portions whether root biomass or aerial portion. Light intensities had considerable effect on height increment of O. stamineus. This indicates that the effects of species vary with the change in period and light intensity. These shows that light greatly affect the growth performance of O. stamineus in terms of their height and biomass.
For all types of fertilizers used which can be compared with medium ratio, the chicken dung is better than oil palm EFB and cow dung. Different fertilizer ratio could be due to different content of nutrients. The different fertilizer ratio application affected the production of leaf, the number of stems, the green color of leaves and thickness of strip. In this regard, a combination of 50% relative of light intensity and medium soil ratio with chicken dung produces optimum growth performance.
ACKNOWLEDGMENTS
This study was funded by Ministry of Higher Education Malaysia (MOHE) through Fundamental Research Grant Scheme (FRGS)-FRG171-SSK-2008.