Temperature and Saline Stress on Seedlings of Swietenia macrophylla: A Comparative Study
M. Siddiqur Rahman,
Physical responses of plants to change in climatic factors
like temperature, precipitation and abiotic factors like salinity intrusion
may lead positive or negative effects. Some factor may promulgate growth while
other may stunts their vigour. Present study seeks growth of a plantation species
at its early stage of life towards elevated temperature and saline water stresses.
Growth records of Swietenia macrophylla seedlings were enumerated by
measuring height, collar diameter and leaf number development of the replicates
growing at an environment-controlled plant growth chamber. One experimented
with merely elevated temperature while other tries to find results of combined
effect of elevated temperature (30, 32 and 34°C) and saline (0.5, 1.5 and
2.5 g L-1 NaCl) to said species seedlings. Seedling replicates showed
diverse response to elevated temperature and saline irrigation at height, collar
diameter and leaf number development. Results depict that elevated temperature
alone might be positive for S. macrophylla seedlings, rather most favourable
for its growth in height, however, collar diameter and leaf number may remain
unaffected. Saline treatment along with higher temperature stresses may lead
seedlings toward stunted or very low growth. As saline intensity increases,
species growth tends to decrease proportionally. Elevated temperature aided
with higher salinity may direct further under development of S. macrophylla
seedlings which is distressing to plantation establishment of this species in
sites which are vulnerable to salinity intrusion due to climate change. However,
S. macrophylla may be a promising plantation species in drier part of
the globe in near future.
Received: January 15, 2013;
Accepted: March 30, 2013;
Published: May 16, 2013
According to the Intergovernmental Panel on Climate Change (IPCC,
2007), there would be four climate change responses on the earth viz. temperature
change, precipitation change, sea level rise and extreme events. MEF
(2009) identified that all these three responses are happening and will
happen in Bangladesh due to climate change phenomenon as Bangladesh is the worst
affected due to climate change impacts (MEF, 2008). When
climate of any region or as a whole being changed, it affects everywhere (Rahman
et al., 2012). Like any other natural resources, forest flora may
experience the extreme threat of elevated temperature and saline water submergence
at different stages of their lives i.e. from germination to maturity due to
climate change effects (Rahman et al., 2012).
Bangladesh would face 3.4°C temperature increase within the year 2100 as
the country is a poor one with limited resources but contribute less to global
emission (IPCC, 2007). Where national estimations prove
that the country would face an additional 2.4°C temperature increase and
an 88 cm sea level rise by 2100 (MEF, 2009).
Response of elevated temperature to forest flora depends on the climatic conditions
such as temperature, precipitation, humidity and light intensity. Several studies
pointed out that temperature increase may lead the forest ecosystem to change
considerably in forest growth over the next century (Kellomaki
et al., 1997). Response to elevated temperature and precipitation
change, forest flora might experience greater survivability challenge in a climate
change prone country like Bangladesh. Mahtab (1992) identified
that if there would temperature rise there will be salinity intrusion in southern
part of Bangladesh. Due to climate change effects, forest growth may be stunted
due to salinity intrusion in coastal and offshore areas of Bangladesh (Rahman,
2012b). Moreover, the combined effect of elevated temperature and salinity
intrusion might affect forest trees at their early stages of life (Rahman
et al., 2012).
Swietenia macrophylla King (big-leaf mahogany) is one of the most economically
important tree species (Morris et al., 1999).
The species is found in elevations that range from 50 to 1400 m with precipitation
from 1500 to 4000 mm and temperatures of 23 to 28°C (Lamb,
1966). Annual temperature averages of greater than or equal to 24° C
and 1000-2000 mm annual precipitation (Holdridge, 1967).
Mean maximum and mean minimum tolerable temperature for optimum growth of Swietenia
macrophylla is 32 and 16°C, respectively (Troup,
1921, 1986; Das and Alam, 2001;
Luna, 1996), however, literature for salinity acceptance
was not found. Considering silvicultural requirements and changing climate scenarios
for future in Bangladesh the potential suitable lands for indigenous species
like Swietenia mahagony may decrease significantly by 22.07% than present
by the year 2100 (Al-Amin and Rahman, 2011; Rahman,
2012a). For this, temperature-humidity-light controlled plant growth chamber
was used to enunciate stated seedling growth. Using environment controlled plant
growth chamber is helpful in analysing responses to environmental factors to
plants like temperature, humidity and also to salinity. Olszyk
et al. (1998) reported that responses to elevated atmospheric temperature
over several years in controlled-environment chamber facility shows plant morphological
The aim of present study was to enunciate this species ability to withstand higher temperature (30-34°C) than its normal range (20-30°C) along with saline water treatment (0.5, 1.5 and 2.5 g L-1 NaCl concentrations). This experiment might be helpful in asking the answer whether Swietenia macrophylla would be tenable to elevated temperature and saline stress in future or not.
MATERIALS AND METHODS
Materials: Initial growth performance of S. macrophylla at three different parameters viz. height, collar diameter and number of leaves were measured by meter scale, slide callipers and manual reading, respectively. For temperature, light and humidity control the seedlings were reared in the Weiss Gallenkamp fitotron Plant Growth Chamber (Tree propagation laboratory, IFES, University of Chittagong). Temperature records were taken by atmospheric thermometer placed at outdoor condition to measure existing temperature.
Study site and period: The experiment was conducted in the nursery and
Tree Propagation laboratory of Institute of Forestry and Environmental Sciences,
University of Chittagong, Bangladesh. Study conducted during the month of January,
February and March 2009. The mean monthly temperature varies from 19.44°C
in January to 28.88°C in May (UNEP (Islam et al.,
Samples: Healthy seedlings of same age and origin were used for treatments.
For elevated temperature treatment, forty seedlings were taken, where replication
was ten for each. While for combined experiment, thirty samples taken where
replicates were three for each. A two-factor split-plot design with ten and
three randomly assigned complete replications was used (Morris
et al., 1999).
Methods: Two types of experiments were conducted with different treatment to seedlings.
Experiment 1: Temperature elevation at 30, 32 and 34°C compared with existing temperature (26.31°C).
Experiment 2: Temperature elevation at 30, 32 and 34°C along with NaCl concentrations of 0.5, 1.5 and 2.5 g L-1 in each of the three elevated temperature compared with existing temperature (26.31°C) and fresh water irrigation.
Seedlings were reared in the Weiss Gallenkamp Plant Growth Chamber where the
temperature, light intensity and relative humidity were controlled strictly.
The growth chamber was programmed with a pick temperature of 30, 32 and 34°C
and with relative humidity 80% at pick point. Ramping increase of temperature
was 0.02 and for humidity it was 0.01. Day light was considered at maximum twelve
hours a day because Mejia et al. (2008) showed
that seedlings growth of this species depends largely on light availability.
The study was conducted with heating the seedlings at day and night time both.
Therefore, programming was done according to this context. Un-purified salt
from salt bed of coastal areas of Chittagong district was collected and packed
in vacuum packet to protect them from moisture intrusion. Solution of NaCl with
water according to predetermined amount was irrigated to each seedling as treatment
at every day. Data collected about the height, collar diameter and number of
leaves of the seedlings recorded at every fourth day. After three months observation
the data were analyzed. Growth data of height, collar diameter and leaf number
were measured by subtracting final measurement with initial measurement during
Statistical analysis: Statistical software used to analyze the growth
measurements was Minitab 2002 version 13.2. Analysis of variance (ANOVA) was
used to analyze both responses (Morris et al., 1999).
Growing seedlings in a controlled Plant Growth Chamber and observing their performances
is supported by Rahman et al. (2012); Al-Amin
and Afrin (2011); Ullah and Al-Amin (2008) and Kotoky
et al. (2000).
Plant seedlings grown at elevated temperature shows a positive response. or
increment within stipulated study period.
||Mean height growth comparison of Swietenia macrophylla
under different temperature scenarios (T) compared with existing study site
||Mean height growth of S. macrophylla under different
Temperatures (T) and Saline Concentrations (SC) comparing to existing temperature-
no saline treatment
||Collar diameter growth of Swietenia macrophylla under
different Temperatures (T) compared with existing study site temperature
The study seeks to find effects of higher temperature in one experiment and
another with elevated temperature along with saline treatment. Figure
1-5 show mean height collar diameter and leaf number development
growth after treatments given to same origin and same age seedlings was increased
due to elevated temperature in a controlled plant growth chamber.
||Collar diameter growth of Swietenia macrophylla under
different Temperatures (T) and Saline Concentrations (SC) comparing to existing
temperature- no saline treatment
||Comparison of leaf number of Swietenia macrophylla
under different temperature scenarios (T)
This denotes that after elevated temperature treatment, seedlings might find
suitable condition rather than stunted growth. However, different situations
occur when elevated temperature associated with saline water treatment affects
seedlings drastically (Fig. 2-6). Plants
height growth was decreased due to mostly salinity treatment. Only elevated
temperature can have less effect on seedling mortality or stunted growth. Seedling
s grow at collar diameter and leaf number development at decreasing rate.
Table 1 illustrates that number of days and higher temperature had significantly affected the height and collar diameter growth but number of leaf development was only affected by varying temperature. However, accept collar diameter growth, higher temperature and saline treatment affect plant growth significantly. Collar diameter can be in responsive to higher temperature effect.
Climate change can pose both positive and negative effects on forests and its
components (Rahman, 2012a).
|| Leaf number of Swietenia macrophylla under different
Temperatures (T) and Saline Concentrations (SC)
||Statistical analysis of the effect of growing period and treatments
on growth performance of Swietenia macrophylla
|F means mean value obtained at fishers test, P means probability
Thus, these responses are noted as following several example as the present study indicates that several areas are there at which tree seedlings may alter their normal growth rate, whether this may be positive or negative.
Positive response: Increased CO2 concentrations in the atmosphere
and favourable elevated temperature may grow floral species positively. Reported
that seedling survival and growth increased both under the future climate regime
in USA for black spruce (Picea mariana) (Wang et
al., 1994). With increased temperature and CO2, forest ecosystems
may grow faster, mature earlier and die younger (Ryan,
1991). Several studies pointed out that temperature increase may lead the
forest ecosystem to change considerably in forest growth over the next century
(Kellomaki et al., 1997). Some examples are
here. Lagerstroemia speciosa showed tolerance with high temperature when
grown at elevated temperature in controlled growth chamber conditions and initial
growth was better in existing temperature comparison to mid and high temperatures
for Albizia procera (Ullah, 2008). Ahmed
(2007) found positive response at elevated temperature between 31.580
and 39.60C for germination and initial growth performance of Shorea
robusta. Also for Gmelina arborea grown in growth chambers there
showed a positive response to elevated temperature (Rahman,
2009). Leaf number may promulgate or decrease due to salinity impacts with
sharp changes. For Anthocephalus chinensis, mean number of leaves per
seedlings at 28°C (4.1) and 32°C (3.2) was found significantly higher
than that at 24°C (Kotoky et al., 2000).
Negative response: The combined effect of high salinity and higher
elevated temperature results in seedling mortality to Artocarpus chaplasha.
This happens with chronological increase of temperature and saline intensity.
At extreme stage i.e. with higher most temperature and maximum saline water
treatment, Artocarpus chaplasha tend to die rather than increase in height,
collar diameter and leaves number (Rahman et al.,
Height growth of Taxadium distichum and Sapium sebiferum seedlings
were affected by salinity with 0 and 2 ppt (parts per ton) water, but heights
of plants watered with 10 ppt water were significantly lower. Diameter growth
was much more variable (Corner, 1994).
Leaf and height growth were significantly reduced after 3 and 5 days following
exposure to salinity, respectively for all four experimented poplar clones (Fung
et al., 1998).
Average number of leaf developed during the observation period showed that
as temperature rises and salinity increases, seedlings of Artocarpus chaplasha
shed their leaves. This condition led to total leaflessness of the seedlings
with respect to succeeding thermal and salinity condition (Rahman
et al., 2012).
Leaf, stem and root of sunflower and maize showed an almost similar growth
reduction due to salinity. The higher the salinity, the lower the leaf area
and dry matter production of trees (Katerji et al.,
1994). During early growth under field-like soil moisture and fertility
conditions, elevated temperatures associated with global warming effects (salinity)
may reduce shoot height, but not necessarily stem diameter (Olszyk
et al., 1998).
Out of several climate change affects, raise in temperature and salinity intrusion in forest arenas may hamper their actual undisturbed growth. Elevated temperature has reported to be suitable for several species while some species tend to response negatively. Swietenia macrophylla is a common plantation species that grows all over the country. It has proved to be potential at future elevated atmospheric temperature condition. Nonetheless, this species might face a drastic situation at saline water intrusion in its plantation at their early stage of life. Therefore, plantations might be raised or planned in sites where there would be a salinity intrusion in near future. On the other hand, plantations might be raised in drier places facing or will face atmospheric temperature raise within 2050 or 2100.
This study indebt to IFESU-USDA project run in the Institute of Forestry and Environmental Sciences, University of Chittagong as grant number BG-ARS 124.
1: Ahmed, S., 2007. Germination and initial growth of arjun and sal under different temperatures. B.Sc. (Honours) Thesis, Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh.
2: Al-Amin, M. and M.S. Rahman, 2011. Sketching future forest of Bangladesh considering climate change scenarios, silviculture and productivity of species using GIS. Proceedings of the IUFRO International Conference on Research Priorities in Tropical Silviculture: Towards New Paradigms? November 15-18, 2011, Montpellier, France, pp: 70-.
3: Al-Amin, M. and S. Afrin, 2011. Adaptive responses of Artocarpus chaplasha to stresses induced by changing climate. Proceedings of the 1st Bangladesh Forestry Congress, April 19-21, 2011, Forest Department, Bangladesh, pp: 11-15.
4: Corner, W.H., 1994. The effects of salinity and water logging on growth and survival of baldcypress and Chinese tallow seedlings. J. Coastal Res., 10: 1045-1049.
Direct Link |
5: Das, D.K. and M.K. Alam, 2001. Trees of Bangladesh. Bangladesh Forest Research Institute, Chittagong, Bangladesh, Pages: 224.
6: Fung, L.F., S.S. Wang, A. Altman and A. Hutterman, 1998. Effect of NaCl on growth, photosynthesis, ion and water relations of four poplar genotypes. Forest Ecol. Manage., 107: 135-146.
7: Holdridge, L., 1967. Life Zone Ecology. 1st Edn., Tropical Science Center, San Jose, Costa Rica.
8: IPCC., 2007. Climate change 2007: The physical science basis summary for policy makers. Contribution of Working Group І to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Geneva, Switzerland, pp: 21. http://www.slvwd.com/agendas/Full/2007/06-07-07/Item%2010b.pdf.
9: Islam, A.T.M.T., M.S. Chowdhury, A.K.M.M. Hoque and S.A. Malek, 1979. Detailed soil survey. Chittagong University Campus, Hathazari, Chittagong, Bangladesh, pp: 4-10.
10: Katerji, N., J.W. Von Hoorn, A. Hamdy, F. Karam and M. Mastrorilli, 1994. Effect of salinity on emergence and on water stress and early seedling growth of sunflower and maize. Agric. Water Manage., 26: 81-91.
Direct Link |
11: Kellomaki, S., T. Karjalainen and H. Vaisanen, 1997. More timber from boreal forests under changing climate? For. Ecol. Manage., 94: 195-208.
CrossRef | Direct Link |
12: Kotoky, A., J. Devi and P.C. Deka, 2000. Effect of different temperatures and substrates on the germination of kadam (Anthocephalus chinensis walp.) seeds. Indian J. For., 23: 139-141.
Direct Link |
13: Lamb, F.B., 1966. Mahogany of Tropical America: Its Ecology and Management. 1st Edn., University of Michigan Press, Ann. Arbor, Michigan Pages: 220.
14: Luna, R.K., 1996. Plantation Trees. International Book Distributors, Dehradun, India.
15: Mahtab, F.U., 1992. Climate Change and Sea Level Rise due to Green House Effect: Its Consequences on Bangladesh. In: Training Manual on Environmental Management in Bangladesh, Rezauddin, M. and L. Khan (Eds.). Department of Environment, Dhaka, Bangladesh, pp: 148-172.
16: Mejia, E., X. Buitron, M. Pena-Claros and J. Grogan, 2008. Big-leaf mahogany (Swietenia macrophylla) in peru, Bolivia and Brazil. NDF Workshop Case Studies, WG 1-Trees, Case Study 4, pp: 1-36.
17: MoEF., 2008. Bangladesh climate change strategy and action plan 2008. Ministry of Environment and Forests, Government of the People's Republic of Bangladesh, Dhaka, Bangladesh, pp: 1-86. http://www.sdnbd.org/moef.pdf.
18: MoEF., 2009. National adaptation programme for Action (NAPA). Ministry of Environment and Forests, Government of the People's Republic of Bangladesh, Dhaka, Bangladesh.
19: Morris, M.H., P. Negreros-Castillo and C. Mize, 1999. Sowing date, shade and irrigation affect big-leaf mahogany (Swietenia macrophylla King). For. Ecol. Manage., 132: 173-181.
20: Rahman, M.S., 2009. Elevated temperature and saline stress on selected indigenous and introduced exotic tree species of Bangladesh. B.Sc. (Honours) Thesis, Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh.
21: Rahman, M.S., 2012. Future Forest of Bangladesh: How Climate Change Alter Spatial and Temporal Distribution of Species. LAP Lambert Academic Publishers, Saarsbrucken, Germany, ISBN-13: 9783659135750, Pages: 52.
22: Rahman, M.S., 2012. Climate Change and Forest in Bangladesh: Growth, Survivability, Stress Adoption and Spatial Shift to Forest Species Due to Climate Change. LAP Lambert Academic Publishers, Saarsbrucken, Germany, ISBN-13: 9783659247347, Pages: 60.
23: Rahman, M.S., M. Al-Amin and S. Akter, 2012. Artocarpus chaplasha: Establishment and initial growth performance at elevated temperature and saline stresses. J. For. Sci., 28: 12-18.
Direct Link |
24: Ryan, M.G., 1991. Effects of climate change on plant respiration. Ecol. Appl., 1: 157-167.
CrossRef | Direct Link |
25: Olszyk, D., C. Wise, E. VanEss and D. Tingey, 1998. Elevated temperature but not elevated CO2 affects long-term patterns of stem diameter and height of Douglas-fir seedlings. Can. J. For. Res., 28: 1046-1054.
CrossRef | Direct Link |
26: Troup, R.S., 1921. The Silviculture of Indian Trees. Clarendon Press, Oxford, UK., Pages: 1195.
27: Troup, R.S., 1986. The Silviculture of Indian Trees. Clarendon Press, Oxford, UK., Pages: 833.
28: Ullah, M.R. and M. Al-Amin, 2008. Seedling growth performance of Cassia fistula (Linn.) using climate change scenarios for Bangladesh. Forestry Nepal Publications, Nepal.
29: Ullah, M.R., 2008. Tree composition, regeneration and initial organic carbon stock of slected trees using climate change scenarios. B.Sc. (Honours) Thesis, Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh.
30: Wang, Z.M., M.J. Lechowicz and C. Potvin, 1994. Early selection of black spruce seedlings and global change: Which genotypes should we favour? Ecol. Appl., 4: 604-616.
Direct Link |