Ahmad Mustapha Mohamad Pazi

Increasing soil salinity led to a decline in rice yield, particularly in the coastal areas of West Aceh affected by the 2004 tsunami. This study aimed to examine the characteristics of soil salinity in the coastal rice fields of West Aceh during the rainy and dry growing seasons, and to evaluate its impact on rice yield. Soil sampling was conducted using purposive sampling during two growing seasons: the dry growing season (April-September 2024) and the rainy growing season (October 2024-March 2025). Clustering analysis showed that three clusters (sodic and saline-sodic) formed during the dry season, while two clusters (sodic and non-saline non-sodic) formed during the rainy season. The Suak Pante Breuh site changed cluster membership, being sodic in the dry season and non-saline non-sodic in the rainy season. Among all soil chemical properties, soil electrical conductivity (EC) and sodium adsorption ratio (SAR) showed the strongest negative correlations with rice yield, particularly during the dry growing season (r = -0.55; r = -0.50). This study found that rice yield was more affected by salinity than by sodicity. This was illustrated in the Suak Timah 5 site, which was classified as sodic during the rainy season but showed similar rice yields to non-saline and non-sodic sites. In contrast, during the dry season, this site was classified as saline–sodic and recorded lower rice yields than other locations that were classified as sodic.

Mangrove forests are vital coastal ecosystems that provide shoreline protection, support biodiversity, and sequester carbon. However, urbanization and industrial activities have led to the introduction of heavy metal contaminants, especially lead (Pb), posing significant threats to ecosystem...

Nutrients in sandy soil are limited due to low absorption capacity and are easily leached or evaporated. Biosilica and humic acid extracted from compost and husk ash can improve the soil structure and absorption capacity to optimize the availability and uptake of nutrients. Therefore, this research aims to examine the optimal application dose of biosilica and humic acid to improve the chemical properties of soil with a sandy texture. The experiment was structured based on a completely randomized design (CRD). Factor 1 consisted of biosilica doses of 0, 0.5, 1.0, and 1.5 tons ha-1, while factor 2 comprised humic acid doses of 0, 20, 40, and 60 kg ha-1. Data analysis was performed using ANOVA, followed by Tukey’s Honest Significant Difference (HSD) test, correlation, and determination analysis. The study results indicate that the combination of biosilica and humic acid contributes to the changes in nutrient availability. The impact of the treatment was observed 90 days after application on the parameters of soil pH, organic C, total N, and exchangeable K. The effects of the treatment were also evident in plant nutrient uptake, specifically in total N in the roots and total K in the stems. The optimal combination for improving soil nutrient availability and nutrient uptake in plant tissues was a biosilica dose of 1.0 tons ha-1 (S2) and humic acid at 40 kg ha-1 (H2).

Over the years, Eucalyptus plantations have rapidly expanded in Sarawak, Malaysia, accounting for 19% of the total forest plantation area. In a routine forest health surveillance conducted in 2022 at Sarawak, Malaysia, tree stands of Eucalyptus urograndis (Eucalyptus grandis × Eucalyptus urophylla hybrid) were detected with symptoms of stem canker disease caused by Chrysoporthe infection. Given the limited information on the chemical control of Chrysoporthe stem canker disease, there is a growing need to develop effective chemical control strategies to protect and cure Chrysoporthe infection on E. urograndis trees. Therefore, this study aimed to identify the causal pathogen of this stem canker disease in 7-year-old E. urograndis trees in Sarawak, Malaysia, and evaluate the efficacy of various fungicides as curative or protectant treatments on canker infection using artificial inoculation methods. Fungal isolates were first collected and subjected to molecular identification and pathogenicity analysis. Then, in vitro efficacy tests were evaluated using five licensed fungicides: thiram, prochloraz manganese chloride, copper hydroxide, dimethomorph, and mancozeb. Subsequently, the performance of these fungicides was assessed through preventive and curative field experiments on 10-year-old E. urograndis trees using the artificial inoculation technique. Based on the morphological and phylogenetic analysis of the ITS1/ITS4, β-tubulin 2 (BT2), and the combined ITS1/ITS4 and BT2 sequences extracted from 20 fungal isolates, Chrysoporthe deuterocubensis was identified as the causal pathogen of the canker disease, with isolate CHRY18 recording the highest virulence. The in vitro efficacy tests showed that prochloraz manganese chloride achieved 100% inhibition against C. deuterocubensis at 1.0 mg/mL. In the preventive experiment, thiram significantly inhibited C. deuterocubensis infection, yielding the shortest lesion length (19.40 mm) compared to the non-treated control (47.48 mm) at 20 weeks post-inoculation. In the curative experiment, a significant reduction of 54.7% in lesion length was observed in inoculated symptomatic trees after 20 weeks of post-fungicide treatment with copper hydroxide. In conclusion, this study demonstrated prochloraz manganese chloride, thiram, and copper hydroxide as effective chemical controls of C. deuterocubensis stem canker on E. urograndis.

Heavy metal concentrations have risen throughout Malaysia's coastline because of industrial wastewater discharge, affecting mangrove ecology significantly. Lead (Pb), Zinc (Zn), Chromium (Cr), and Nickel (Ni) were used to establish the Mangrove Sediment Quality Index (MSQi), which assesses and monitors the quality of mangrove sediment. This study was conducted at Matang Mangrove Forest Reserve (MFFR) in Perak, Malaysia to examine changes in MSQi features across seasons, mangrove zones, and sediment depths at three separate MMFR locations. Sediment samples were taken using auger in two different seasons (dry and wet seasons). After the silt was removed using aqua regia techniques, heavy metals were examined using an Atomic Absorption Spectrophotometer. According to MSQi criteria in various seasons at three different locations, the highest concentration of heavy metals (HMs) was detected in the dry season in the least disturbed region at three different locations. During dry seasons, only Cr and Ni levels are higher in moderately and highly disturbed areas. Pb and Zn levels in moderately and highly disturbed areas are higher than in least disturbed areas during the rainy season. MSQi parameters in different mangrove zones at three locations showed that most HMs content is highest in the landward zone and it can be concluded that HMs sources are anthropogenic. Furthermore, MSQi measurements at three locations revealed that heavy metals content is highest at 015 cm and lowest at other depths.

Sediment is an important part of heavy metal cycling in the coastal ecosystem, acting as a potential sink and source of inorganic and organic contaminants as environmental conditions change. The productivity of mangroves is utterly dependent on sediment enrichment. Moreover, mangrove sediment can trap pollutants discharged by households, industries, and agriculture activities. In this regard, it is essential to assess sediment quality in the presence–absence of heavy metals that are toxic to most living organisms. Thus, the question of how sediment quality is used as an index in the mangrove domain has arisen. Due to the many complex characteristics such as seasonal zones, tidal patterns, flora and fauna, and water, no specific method is used in Malaysia for assessing and monitoring mangrove sediment quality. Thus, the current study intended to develop a mangrove sediment quality index (MSQi) in the Matang mangrove forest in Perak, Malaysia. An area was selected based on the distinct level of mangrove disturbances. At 1.5 m depth, sediments were sampled in five segments (0–15, 15–30, 30–50, 50–100, and 100–150 cm). All the sediment physicochemical properties were then analysed. Fourteen variables were chosen and included in MSQi. This index categorises mangrove sediment levels as I = Very Bad, II = Bad, III = Moderate, IV = Good, and V = Excellent. MSQi will be used as a guideline in monitoring mangrove sediment pollution. In conclusion, the data analysis showed that the Sepetang River (SR) was highly disturbed, followed by the Tinggi River (TR) (moderately disturbed), and the Tiram Laut River (TLR) (least disturbed).

Low water availability predicted under climate change is a major abiotic factor limiting plants growth and productivity. In this study a greenhouse experiment was conducted on three important tree species of arid environment: Conocarpus erectus (CE), Acacia modesta (AM), and Salix tetrasperma (ST). Young saplings were subjected to control (C), medium (MWD) and severe soil water deficit (SWD) treatments and response was evaluated. Results showed that in all the three species leaf, stem and root dry weight production remained similar to C under MWD treatment but decreased significantly under SWD. The highest decrease in total dry weight was noticed in ST and the lowest was evidenced in AM under SWD. Root:shoot ratio increased significantly in both CE and AM under MWD and SWD. Furthermore, chlorophyll content decreased while proline content increased significantly in both MWD and SWD treatments. The production of oxidants (hydrogen peroxide and superoxide anions) and antioxidants (superoxide dismutase, catalase, peroxidase and ascorbate peroxidase) increased significantly under both MWD and SWD treatments and were the highest in AM in both MWD and SWD treatments. Therefore, we may conclude that all the three species can tolerate medium water stress due to increased root production and an effective antioxidant defense mechanism.

Matang Mangrove Forest Reserve (MMFR) is one of the most productive and managed forests in the world. On the other hand, it has become a concern whether MMFR is being degraded as a result of exposure to industrial pollution. Industries located around MMFR dispose effluents contaminated by heavy metals. This study was conducted to analyze heavy metal contamination and risk assessment status in MMFR sediments. Sediment samples from six compartments were collected based on age and location of the mangrove plantation. Total metal digestion and modified sequential extraction were performed to estimate the concentration of heavy metals. Based on the estimation, risk assessment code, geo-accumulation index, pollution load index, and contamination factor were computed to classify the compartments according to their contamination and pollution levels. Organic matter and sediment texture (silt, clay, and sand content) were also analyzed to find its correlation with heavy metals. According to the results, high concentrations for Copper, Nickel, and Cadmium were observed in Compartment 42, while Compartment 18 and Compartment 74 showed higher concentrations for Zinc and Lead. Heavy metals showed weak positive correlation with clay and silt, but weak negative correlation with sand. For organic matter, only Zinc showed statistically significant but weak negative correlation. Risk assessment code, geo-accumulation index, pollution load index, and contamination factor categorized the compartments into unpolluted to moderately polluted. Based on the study outcomes, it can be concluded that MMFR, although acquiring industrial discharge, is not with a high risk of heavy metal contamination.

Disposal of industrial wastewater has resulted in increased concentration of heavy metals (HMs) along the coastline of Malaysia. However, little is known about the accumulation capacity of HMs by Rhizophora apiculata in Matang Mangrove Forest Reserve (MMFR) Malaysia. The aim of this study is to measure the concentration of HMs in different ages of mangrove forests. In this study, 15 and 80-year old trees of Rhizophora apiculata were selected for experimentation. Thirty samples of leaves, roots and sediments were analyzed to measure the concentration of HMs in 15 and 80-year-old trees. The measured concentrations of copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) in leaves, roots and sediments were used to compare bio- concentration and translocation factor between the abovementioned two age groups. Concentration of Mn came out to be significantly higher in leaves than in sediment. This suggested that Rhizophora apiculata was an efficient Mn-extractor. On the other hand, it was found less efficient in extracting heavier metals (Fe, Cu and Zn) from the sediment, as their concentration was lower in leaves and roots as compared to sediments. The translocation factor was highest for Mn, indicating high mobility of Mn from roots towards the leaves. Bio-concentration factor was also found highest for Mn (3.52) followed by Zn (1.88), Cu (1.33) and Fe (0.26). Therefore, it can be concluded that Rhizophora apiculata is more efficient in extracting Mn as compared to Zn, Cu and Fe.

Mangroves are woody plants that grow at the interface between land and sea in tropical and subtropical latitudes where they exist in conditions of high salinity, extreme tides, strong winds, high temperature, and muddy anaerobic soils. The objectives of this study were to determine the selected heavy metals Copper (Cu), Zinc (Zn) and Lead (Pb) contamination in mangrove sediments at the Selangor River, Kampung Kuantan, Kuala Selangor, Selangor, Malaysia; and to compare heavy metals content in mangrove sediments between different plots and different sediment depths. Physical properties (sediment texture and sediment moisture) and chemical properties (pH water, electrical conductivity, and selected heavy metals) of sediments were determined by different plots and depths. The element of Pb was analyzed using the Inductively Coupled Plasma (ICP), whereas Cu and Zn using the Atomic Absorption Spectrometer (AAS). Data obtained were analyzed using the Statistical Analysis System (SAS) version 9.4 software. The results showed that the sediment texture was in the class of sandy clay, and soil moisture in all plots and at all depths were high. The contamination of sediment is affected by many factors, including soil pH and soil electrical conductivity. Cu, Zn and PB in sediment were determined around 1.00-10.60 mg/kg, 215.40-259.00 mg/kg and 18.83-28.59 mg/kg respectively, and were found to experience a significant difference between the plots, but not a significant difference between depths. The sediment in all plots and at all depths was contaminated with these heavy metals because of it being surrounded by residential and industrial areas, combined with particular recreational activities, agriculture and fishing along the Selangor River.