Shamsiah Abdullah

Modelling of Carbon Sequestration in Rubber(Hevea brasiliensis) Plantations

The issues of global warming and climate change have been widely debated over the past few decades by researchers, managers and leaders. It was estimated that the annual global air temperature may increase by approximately 2.5 °C by the end of the century (NAST 2000). In 1992, the United Nations Framework on Climate Change (UNFCCC) produced an international environmental treaty at the United Nations Conference on Environment and Development (UNCED), held in Rio de Janeiro, Brazil. The objective of the treaty was to stabilize greenhouse gas (GHG) concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Carbon dioxide (CO2) is one of GHGs that contributes the highest emission (Dulal and Akhbar 2013). Malaysia remains committed to climate change agenda and recently introduced a new national policy on climate change and green technology. The country has recently passed a renewable energy act and reaffirms its commitment to a pledge during Rio Earth Summit and signed the UNFCCC and currently listed into non-Annex 1 countries.

Effects of natural and synthetic cytokinin hormone on shoot regeneration of rockmelon (Cucumis melo) Glamour cv. by using nodal explants

Rockmelon Glamour cv. belongs to Cucurbitaceae family and the fruit enriched with nutrients that can reduce the risk of cancer, heart disease and asthma. Using in vitro culture technique, rockmelon was able to mass propagate and commercially cultivated in order to meet rising market demand. The objectives of this study were to develop a micropropagation protocol for mass production of new Glamour cv. new plantlets and to acclimatize the plantlets to the ex vitro condition for further growth process. In this research, both natural (zeatin) and synthetic (kinetin) hormones were supplemented in MS media at different concentrations (0, 0.01, 0.1, 1 and 2 mg/L) for shoot proliferation from nodal explants of rockmelon Glamour cv. Shoots were successfully regenerated from node explant in all tested medium after 4 weeks. MS supplemented with 0.1 mg/L kinetin gave the highest number of shoots (1.83±1.89), nodes (4.33±3.31), and leaves (4.11±3.18). Regenerated shoots were transferred to the root induction medium containing IAA at different concentrations (0, 0.01, 0.1, 1 and 2 mg/L) and shoots was highly elongate and root proliferated in MSO. Healthy grown plantlets were acclimatized to three different growth media. In vermiculite growth media, plantlets were successfully survived (81±23.09%) after 6 weeks. In conclusion, kinetin synthetic hormone was able to give high number of shoots regenerated from nodal explants of rockmelon Glamour cv. compared to zeatin and plantlets were able to survive in the external condition in the vermiculite growth media.

Height-related changes in stomatal conductance, chlorophyll Content index and diameter of rubber tree (Hevea brasiliensis) saplings

This study aimed at investigating the influences of tree height on the physiology of rubber tree (Hevea brasiliensis) saplings specifically its relationships with stomatal conductance, chlorophyll content index and diameter. A total of 50 rubber tree saplings were sampled in five growth stages (i.e, 45, 90, 135, 180 and 225 days). The means of rubber tree saplings height were 19cm, 46cm, 81cm, 135cm and 194cm, respectively. Measurements for stomatal conductance and chlorophyll content index were taken from 07:30 to 13:00 hours with the recorded air temperature range from 25°C to 35°C. The stomatal conductance and chlorophyll content index were measured using leaf porometer and chlorophyll meter (SPAD 502 plus), respectively. Stem diameter was measured using a digital caliper while height was measured using a measuring tape. Correlation analysis indicated that there was a significant inverse relationship between the height and stomatal conductance (r=−0.47, p≤0.0001). In contrast, the chlorophyll content index showed a significant positive relationship with height (r=0.55, p≤0.0001) which suggests that the increase in chlorophyll content index contributes to the increment of height of tree saplings. Meanwhile, there was a strong positive relationship between height and diameter (r=0.903, p≤0.0001) which indicates the presence of development in apical and lateral growth in rubber plants. Future work will involve an evaluation of the three variables measured above as predictor variables for the development of carbon sequestration model.

Stomatal conductance, chlorophyll content, diameter and height in different growth stages of rubber tree (Hevea brasiliensis) saplings

This research reports results from preliminary data collection for carbon sequestration estimation of rubber plantations. The objective of this study is to determine the stomatal conductance, chlorophyll content, diameter and height at different growth stages of rubber tree saplings. Stomatal conductance, chlorophyll content, diameter and height were measured on the rubber tree (Hevea brasiliensis) saplings. The measurements were done in two weeks period on twenty saplings for each of two growth stages, i.e, 45, and 90 days respectively, and seventeenth saplings for growth stage of 135 days. Electronic devices were used to measure stomatal conductance, chlorophyll content and stem diameter, while measurement tape was used to measure the height of the samples to avoid destructive samplings. Results showed that stomatal conductance decreased with increased growth stages of rubber tree saplings. Chlorophyll content was highest at a growth stage of 90 days, followed by 45 days and 135 days. However, for diameter and height, results indicated the increase in both variables with increase growth stages of saplings. ANOVA of stomatal conductance, chlorophyll content, diameter and height within the growth stages of rubber trees saplings were analysed. From the analysis, the means of stomatal conductance, chlorophyll content, diameter and height were found to be significantly different within the growth stages of rubber tree saplings (P≤0.05). Since rubber plantation is one of the major plantations in Malaysia, the findings from this study may be useful as baseline information on the physiology of rubber trees.