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Rubber seedlings raised in the soil-polybag system experience root coiling and restriction and the overhead sprinkler results in much water wastage. The objective of the study was to determine the influence of root trainers and three irrigation systems on rubber seedlings grown in a peat-based medium. The irrigation systems were the overhead sprinkler (SPR), drip (DRP) and capillary wick (WCK). The fourth treatment was the control (CTRL), which required growing rubber seedlings in conventional soil-polybags that were then irrigated using the wick system. The treatments were compared with one another in terms of their influence on nutrient loss, crop water productivity and water use efficiency, plant growth parameters and plant nutrient content of the rubber seedlings. A field experiment was carried out in a rain shelter for eight months, and data collection was carried out once per month. The experimental layout was the completely randomised block design. The results showed that WCK had the lowest cumulative leachate volume and the least cumulative nutrients leached. Both DRP and WCK had the highest plant growth parameters such as total fresh and dry weight, total leaf area and girth size, water productivity and leaf nutrient content. WCK was the best irrigation system together with the peat-based growing medium for raising rubber nursery seedlings.

Coronary reactive hyperemia (CRH) protects the heart against ischemia. Adenosine A 2A AR–deficient (A 2A AR −/− ) mice have increased expression of soluble epoxide hydrolase (sEH); the enzyme responsible for breaking down the cardioprotective epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). sEH–inhibition enhances CRH, increases EETs, and modulates oxylipin profiles. We investigated the changes of oxylipins and their impact on CRH in A 2A AR −/− and wild type (WT) mice. We hypothesized that the attenuated CRH in A 2A AR −/− mice is mediated by changes in oxylipin profiles, and that it can be reversed by either sEH- or ω-hydroxylases–inhibition. Compared to WT mice, A 2A AR −/− mice had attenuated CRH and changed oxylipin profiles, which were consistent between plasma and heart perfusate samples, including decreased EET/DHET ratios, and increased hydroxyeicosatetraenoic acids (HETEs). Plasma oxylipns in A 2A AR −/− mice indicated an increased proinflammatory state including increased ω-terminal HETEs, decreased epoxyoctadecaenoic/dihydroxyoctadecaenoic acids (EpOMEs/DiHOMEs) ratios, increased 9-hydroxyoctadecadienoic acid, and increased prostanoids. Inhibition of either sEH or ω-hydroxylases reversed the reduced CRH in A 2A AR −/− mice. In WT and sEH −/− mice, blocking A 2A AR decreased CRH. These data demonstrate that A 2A AR–deletion was associated with changes in oxylipin profiles, which may contribute to the attenuated CRH. Also, inhibition of sEH and ω-hydroxylases reversed the reduction in CRH., SCOPUS: ar.j, info:eu-repo/semantics/published

Determination of plant stress factors is often challenging as it can be a compound result of water deficit, nutrient deficiency and disease infection. Symptoms arising from these stress factors may also be similar. Hence, visual observation alone could result in flawed diagnosis which would eventually disrupt remedial action for the affected plant/crop. Spectral reflectance measurements can help identify and select wavelengths sensitive to different types plant stress. Previous studies have found that plant stress will change spectral reflectance pattern in the visible range (380-720 nm or F380-F720) and the infrared range (720-1500 nm or F720-F1500). Typically, the magnitude of change will vary at different wavelengths. Such information facilitates early detection of plant stress, particularly nutrient deficiency. This approach can potentially lower operating cost in fertilization and minimize acute loss of productivity. This review examines a range of spectral techniques that deploy remote sensing for detecting plant nutrient stress and monitoring plant nutritional status.

This study was conducted to understand the effects of fertiliser type (straights, compounds and controlled-release fertilisers) on N, P, K and Mg losses by surface runoff. The study was conducted in a mature oil palm field using three 20 m by 6 m erosion plots containing two palms per plot with the soil type being Typic Kandiudults and slopes ranging from 5.5° to 7.5°. Nutrient losses were measured in the eroded sediment and runoff water for every rainfall event over a period of 24 months. Nutrient losses were higher in the runoff water than in the eroded sediments. Broadcast application of controlled-release fertilisers and its slow dissolving nature made it prone to washing down the slope. Hence, higher nutrient losses were observed in the controlled-release fertilisers compared to other treatments. Compound fertilisers showed lower total losses for N (4.96%), K (3.95%) and Mg (0.65%) compared to straight fertilisers. Lower P losses were observed in the straights compared to the compound fertilisers due to higher percentage of soluble P in the compound fertilisers. Controlled- release fertilisers recorded high nutrient losses in the sediments caused by the washout Except for nitrogen, controlled-release fertilisers recorded higher losses for P (56.56%), K (19.83%) and Mg (10.36%) compared to straight fertilisers. Nitrogen losses were 18.15% lower in the controlled-release fertilisers compared to straights. Compound fertilisers showed lowest losses for N and K compared to straight fertilisers. Based on the data, it is postulated that compound fertilisers can lead to better nutrient uptake compared to straight fertilisers. However, this hypothesis needs to be tested through field experiments measuring nutrient uptake and its effect on oil palm productivity.

Natural zeolite has been widely used as an ion exchanger since the 1950s. The purpose of this study was to quantify the cation exchange capacity (CEC) of natural zeolite from different locations (Bayah and Cikembar in West Java, Indonesia) based on particle sizes of 0.15 and 0.079 mm, using different displacement solutions of 0.5M cesium chloride (CsCl) and 0.5 M potassium chloride (KCl). Higher CEC was observed in Cikembar100 compared to Bayah100 due to its higher surface area (31%) and total pore volume (11%) compared to Bayah100. Cikembar100 had 11% higher clinoptilolite mineral content compared to Bayah 100. The low CEC measured for Bayah100 and Bayah200 may be due to the lower percentage purity of the clinoptilolite mineral content in those samples. The natural zeolite samples displaced with 0.5M CsCl had 6% higher CEC compared to 0.5M KCl, which means that Cs+ had more strength compared to K+ in displacing NH4+ into the solution from the nanocavity site of the zeolitic framework into the solution. In both displacement solutions (0.5M CsCl and KCl), Cikembar100 had 10% more net negative charge compared to Bayah100 due to its isomorphous substitution properties in natural zeolite. Isomorphous substitution in natural zeolite affects its negative charge and the capacity to retain NH4+ in the zeolitic framework, thus increasing its CEC and making natural zeolite with the particle size of 0.079 mm (Cikembar100) a promising material for cation removal, particularly Cs from aqueous solution.

The use of compost in the produced from oil palm empty fruit bunch and palm oil mill effluent anaerobic sludge mix media was tested to evaluate the plant growth in oil palm main nursery. Even Conventional inorganic fertilizer increased production but consumption and excessive application that eventually led to environmental pollution. This study was carried out to evaluate of the reduction of applied inorganic fertilizer and effect compost as mixed media from oil palm waste. Mixed media containing 50% compost in soil with soil and chemical fertilizer as the control composition of 25%, 50%, 75% and 100% chemical fertilisers were tested for the plant growth and root structure. All the treatment with compost with compost showed significantly improved plant growth compared to the control corresponded directly to the enhanced secondary root structure. Interestingly, the plant growth and secondary root structure in the mixed media with 50% chemical fertilizer composition was not significantly different to that with 100% and 75%inorganic fertilizer. Therefore it is concluded that application of 50% compost in the mixed media resulted enhance secondary root structure which helped to reduce the chemical fertilizer requirement by 50% in oil palm main nursery.

Spatial variations of forest floor thickness in tropical montane forest influences carbon stocks estimates in forest floor and soil, microbial decomposition and soil conservation. Delineation of forest floor thickness according to decomposing layers (litter, hemic, sapric) and total forest floor will provide refined measurements of forest floor carbon stocks to improve site-specific carbon management. This study was aimed at determining spatial variability of the depths of decomposing forest floor layers in a tropical montane forest at varying topography. Sampling grids (10 m × 10 m) were established along three slope positions (summit, sideslope and toeslope) with 120 quadrants and their depths measured. Forest floor samples were georeferenced using a global positioning system. Variables were first explored using univariate statistics, including normality check, non-spatial outlier detection and data transformation. Variography and kriging analyses were used to quantify spatial variability of forest floor depths. Results showed that spatial structure of test variables differed across topographic positions. The coefficient of variation for test variables ranged from 27 to 64%. Surface maps displayed distinct spatial clustering and acceptable accuracy of interpolated values. Hemic and total forest floor were highest at the toeslope where hemic constituted approximately 80% of total forest floor. Site-specific management of forest floor carbon stocks in tropical montane forest should be based on topographic delineation.

This study was undertaken to compare the chemical characteristics of pineapple leave residues (PLRs) char generated by controlled combustion and by open burning. The properties of char generated by control combustion (CC) and open burning (OB) varied, due to differences in the production process. The total N, K and surface area of the char generated by CC were significantly higher than the OB. The results indicate that the CC process was better to be applied as a soil amendment than was the OB process.

A waste by-product of local rice mill namely rice husk biocharcoal (RHC) was investigated for its effects in minimising nutrient losses and retaining nutrients during composting of poultry manure. Treated poultry manure was co-composted with RHC at two rates (10% and 5%) and determined for their composting nutrient content, leaching rates through laboratory column leaching test and the leached composts were viewed under SEM/EDX. RHC was quantified to minimise nitrogen loss during composting where 10% and 9% of N was retained in compost treated with RHC 10% and RHC 5% correspondingly as compared to control. Meanwhile laboratory leaching tests and SEM micrograph on RHC-compost at both rates have proven that RHC does physically trapped and chemically sorb organic and inorganic molecules such as C, N, P, K, NO3 Ca and P and retained them against leaching losses.

Water in the paddy field covered by acid sulfate soils having very low pH contains high amount of Al and Fe that affects rice growth. A laboratory study was conducted to qualify rice grown under the adverse conditions can withstand the stresses. Two rice varieties, MR 219 and MR 253, were grown hydroponically at various pH (3, 4, 5, 6, 7), Al (0, 20, 40, 60, 80, 100 µM) and Fe (0, 20, 40, 60, 80, 100 µM) concentrations. After 14 days, rice root length and surface area were determined using a root scanner. Thereafter, organic acids released by the roots of rice were determined by high performance liquid chromatography. Results showed that the root length decreased with increasing Al and/or Fe concentration. On the contrary, the root length increased linearly as the pH of the solution increased. This phenomenon was probably in part related to the exudation of oxalic, citric and malic acids by the rice roots. It was observed that the amount of organic acids released was increased with increasing Al and/or Fe concentration in the solution culture. Hence, it is believed that these organic acids were responsible for chelating some of the Al and/or Fe in the solution, rendering them unavailable for their uptake by rice. In this way, rice plants can withstand some degree of Al3+ and/or Fe2+ toxicity.

Leaf litter decomposition and soil respiration are of great interest in climate change studies due to their roles in recycling carbon and nutrients. These processes can be markedly different in tropical montane and lowland forests. Litterbag technique was used to determine the decomposition and nutrient dynamics of leaf litter in two different tropical forest types in Pahang, Malaysia for 480 days. Soil CO2 fluxes were measured periodically for up to 360 days. Mass loss, total C, N, S, P, K, Mn, lignin, cellulose as well as C:N and lignin:N dynamics of decaying leaves were quantified. Various mathematical models and regression analysis were used to describe litter mass loss trends. Rapid decomposition (k: -0.004 day-1) and weight loss (> 80%) took place in the lowland forest compared with the montane forest. Significant linear regression relationships between mass loss and litter quality were obtained for all sites except for cellulose (montane forest). Low soil CO2 fluxes (two to three folds) and 38% slower decomposition due to reduced soil and air temperatures were found in the montane forest, suggesting its role as potential temporary C sink. Decomposition rate, C:N, lignin:N and soil respiration can be used as potential indicators to predict C balance in forests.

Mulching materials from oil palm residues such as pruned palm fronds (OPF), empty fruit bunches (EFB), and Eco-mat (ECO; a compressed EFB mat) are often the recommended soil and water conservation practices (CP) for oil palm plantations on hill slopes. Another recommended CP is the construction of silt pits or trenches (SIL) across the hill slope to capture runoff and then return the water and nutrients into the surrounding soil. Although these four CP are recommended practices, their relative effects on improving soil physical properties and on increasing the soil water content have never been compared with one another. Consequently, the objective of this study was to fill in this knowledge gap. A three-year field experiment was conducted in a non-terraced oil palm plantation, and soil samples from 0 to 0.15, 0.15 to 0.30, and 0.30 to 0.45 m depths were collected every three months and analyzed for their soil physical properties. Soil water content up to 0.75 m depth was also measured daily. EFB released the highest amount of organic matter and nutrients into the soil compared to OPF, ECO, and SIL. Hence, EFB was most effective to increase soil aggregation, aggregate stability, soil water retention at field capacity, available soil water content, and the relative proportion of soil mesopores. Due to these improved soil physical properties, EFB also gave the highest soil water content. Unlike ECO that concentrated more water in the upper soil layers, EFB distributed the soil water more uniformly throughout the whole soil profile, but SIL concentrated more soil water in the lower soil layers (>0.30 m) because the water levels in the pits were often below 0.30 m from the soil surface. The large opening area of the silt pits could have also caused large evaporative water losses from the pits. EFB mulching is recommended as the best CP, particularly for oil palm plantations on hill slopes.