The Phytotoxicity of Palm Oil Mill Effluent, its Degradation and Effect on Plant Growth

The presence of abundant agricultural residues in Malaysia prompted the need to utilize these wastes to overcome environmental pollution. A large portion of these wastes comes from the oil palm effluent. Palm oil meal (POMeal) has been used as an organic fertilizer to increase growth and yield of several crops. However, application of raw or undecomposed POMeal can also be detrimental to the growth of certain plants. In view of this, the project conducted aimed to study the following aspects: the inhibitory effect of different levels of raw POMeal on growth of vegetables, the effect of decomposition on POMeal phytotoxicity and the degradation of p-coumaric and vanillic acids by Pseudomonas sp. and Penicillium sp. In this study the water-soluble phytotoxic compounds present in raw POMeal will be identified. Results of the glasshouse experiment showed that growth of tomato and spinach was strongly affected by the type (raw or decomposed) and amount of POMeal applied. Growth of both plants was inhibited by application of > 1% raw POMeal. In contrast, application of 1% - 21% decomposed POMeal increased the plant's growth, with maximum dry matter production at 6% POMeal. Increase in shoot dry weight of tomato and spinach given decomposed POMeal was 7 and 178 times respectively. Increase in root dry weights was 1.6 and 62 times respectively, compared to plants given raw POMeal. Soil N, P and K contents, pH and electrical conductivity also increase with increase in PO Meal levels. The phytotoxicity of raw POMeal was reduced when POMeal was decomposed for > 4 weeks

Growth of Sesbania rostrata on Different Components of Tin Tailings

Two field experiments were conducted to evaluate the growth of Sesbania rostrata on sandy, sandy loam and slime components of a tin tailing area treated with inorganic fertilizer, and on the sandy component amended with an organic mixture. Inorganic fertilizer was applied at a rate of30 kg N, 90 kg P20sand 120 kg K20 ha -1. The organic mixture used consisted of50% palm oil mill cake (POMC) and 50% chicken dung at a total equivalent rate of10 t ha -1. Plants were harvested after 24, 42 and 63 days of growth. The results showed that S. rostrata grew best on the slime and poorest on the sandy tailings. Inorganic fertilization increased plant growth on the slime and sandy loam but not on the sandy tailings. Plant tops, roots and nodules in sandy soil amended with organic mixture were 29,27and 2.5 times bette'i than those with the inorganic fertilizer. Plant growth on sandy tailing was equivalent to 56% of plant tops and 200% of roots from plants grown on slime supplied with inorganic fertilizers

Effect of kaempferol on the establishment of arbuscular mycorrhizal fungi on oil palm seedlings roots

Arbuscular mycorrhizal fungi (AMF) could associate beneficially with more than 80% of terrestrial plants roots including oil palm roots and as an alternative to reduce chemical fertilizer applications. Oil palm root exudate such as flavonoid is important in the interaction between the crop and AMF. Flavonoids exhibit a strong stimulatory effect on AMF hyphal growth, hyphal differentiation and root colonization, plus improving plant-microbe interactions. The present studies were conducted with the following objective to determine the flavonoid efficiency on AMF establishment in oil palm roots. Exogenous kaempferol as one of the flavonoid types was applied at four concentrations (0, 2.5, 5.0 and 10.0 ppm) with three AMF sources (Glomus mosseae, mixed AMF and non-inoculated) with complete fertilizer. Each pot contained sand mixture with one-month-old oil palm seedling. The planting time is twelve weeks in the net shelter house. The oil palm growth and root development significantly affected by the treatment (G. mosseae*10 ppm kaempferol) since plant height, root length and phosphorus uptake showed significant interactions between the treatments with 20.91%, 27.24%, and 102.33% difference, compared to non-inoculated plant at the same concentration, respectively. The results for shoot biomass, root biomass, root volume, root diameter, phosphorus in soil and root infection showed the highest value compared to AM mixed species and non-inoculated plants

Phytotoxicity of phenolic acids extracted from palm oil dry solids

A study on the extraction of palm oil dry solids (PODS) was conducted to identify the water-soluble compounds involved in the phytotoxicity of PODS. The aqueous extract of PODS was sequentially partitioned using various organic solvents. Each of the dried extracts was bio assayed for inhibitory activity on the growth of tomato radicles. Maximum inhibition of radicle growth was observed in the diethyl ether extract, resulting in 53.3% growth compared with control. Further separation of the ether fraction using column chromatography resulted in a single toxic fraction, RM10, which caused only 30% radicle growth. The fraction was compared with 14 synthetic phenolic compounds using thin-layer chromatography and was observed to be similar to four of the compounds. Further analysis by high performance liquid chromatography revealed that the RM10 fraction comprised vanillic acid. However, the RM10 fraction was more inhibitory to the growth of tomato radicles than synthetic vanillic acid

Bio-compartmental in vitro system for Glomus mosseae and Ralstonia solanacearum interaction.

The life cycle of arbuscular mycorrhizal fungi (AMF) is initiated by spore germination. The interaction between Glomus mosseae and Ralstonia solanacearum was achieved by following the bio-compartmental in vitro system. The system was modified to be useful for different microbes with different types of medium. Mycorrhizal fungi spores were germinated using water agar, nutrient agar and soil media, while casamino acid-peptone-glucose (CPG) media was used for R. solanacearum.all medium. All medium were mixed with different volumes of tomato and corn root exudates. The hyphal length of G. mosseae greatly affected by the exudates particularly, mycorrhizal tomato root exudates (MTRE) and mycorrhizal corn root exudates (MCRE). The growth of R. solanacearum was suppressed due to G. mosseae spores germination which can produce different volatile and non volatiles substances. The aim of this experiment was to investigate the influence of root exudates volatiles on R. solanacearum and the hyphal of G. mosseae growth under laboratory conditions using a new modified technique

The phytotoxic effects of palm oil dry solids on plant growth

Glasshouse and laboratory experiments were conducted to evaluate the phytotoxicity of palm oil dry solids (PODS) on growth of vegetables and the effect of decomposition on the reduction of PODS phytotoxicity. Raw and decomposed PODS was applied to sandy tailing soil at the levels of 0, 1, 3, 6, 9, 15 and 21 % (w/w) and planted with tomato and spinach seedlings. Samples of raw PODS were incubated at 30'C for 1, 2, 3, 4, 6 and 8 weeks and the aqueous extract of each sample was bioassayed for growth inhibition of tomato radicles. Results from the glasshouse experiment showed that growth of tomato and spinach was strongly affected by the type (raw or decomposed) and amount of PODS applied. Growth of both plants was inhibited by application of >1%raw PODS. In contrast, application of 1- 21 % decomposed PODS increased plant growth, with maximum dry matter production at 6% level. At this level, shoot dry weights of tomato and spinach increased 7 and 178 times, respectively, while root dry weights increased 1.6 and 62 times, respectively, compared to plants in raw PODS. Soil N, P and K contents, pH and electrical conductivity also increased with increase in PODS levels. The incubation study showed that the phytotoxicity of raw PODS was reduced when PODS was decomposed for > 4 weeks

The potential of endomycorrhizal fungi in controlling tomato bacterial wilt Ralstonia solanacearum under glasshouse conditions

The impact of colonization by three mycorrhizal fungi on tomato bacterial wilt caused by Ralstonia solanaceraum was investigated. Three species of arbuscular mycorrhizal fungal (AMF) were tested (Glomus mosseae, Scutellospora sp. and Gigaspora margarita). Siginificant differences in tomato growth based on plant hieght was recorded between G. mosseae (125.25 cm) and all treatments. The combination of G. mosseae and R. solanacearum resulted in significantly taller tomato plants than G. margarita + R. solanacearum and Scutelospora sp.+ R. solanacearum. Shoot fresh and dry weight was higher in G. mosseae inoculated plants. No disease symptoms were observed in the combination treatment of G. mosseae and R. solanacearum. The plants treated with Scutellospora sp. showed low incidence of infection (105, 15%) at 15 and 20 days after inoculation, respectively. The combination of G. mosseae and R. solanacearum resulted in more increase in root morphology (root tips (434.75), root length (267.00 cm), root surface area (149.31 cm2), root volume (3.77 cm3), root fresh weight (4.75 g) and root dry weight (2.5 g). The treatment of G. mosseae + R. solanacearum was different significantly when compared to G. margarita and Scutellospora sp. + R. solanacearum treatments in all parameters considered. The highest number of AMF spores was recorded in G. mosseae treatment followed by Scutellospora sp. The concentration of N, P and K in G. mosseae + R. solanacearum treatment was significantly higher (N: 1.69; P: 0.51 and K: 1.65%) compared to G. margarita (N: 1.06 ; P: 0.11 and K: 1.02%) and Scutellospora sp., treatment (N: 1.48; P: 0.44 and K: 1.47%). Generally, the current findings has provided an evedance about the ability of AMF species to control bacterial wilt causal agents with significant differences between the species used.Keywords: Bio-control, wilt disease, tomato, Glomus mossea

Labile carbon and carbon management index in peat planted with various crops.

Changes in soil carbon (C) from forest to agriculture land in Mukah, Sarawak, and Simpang Renggam (SR) Johor were studied. The changes in labile C (CL) (Mukah, 0.7–43%; SR, 0.2–20%) were greater than changes in the total C (CT) (Mukah, 0.5–9%; SR, 0.3–7%) as compared to the forest. In Mukah, oil palm and pineapple ecosystems showed approximately 18% and 6% increases in CL at a soil depth of 0–15 cm, respectively, as compared to the forest, and thus had greater C management index (CMI) values. In the sago ecosystem, the decline in CL was approximately 26% at the soil depth of 0–15 cm as compared to the forest. In SR, oil palm and pineapple ecosystems showed approximately 0.2% and 19% decreases in CL, respectively, at soil depths of 0–15 cm, resulting in low CMI value. The CL and the CMI can be used to monitor the rate of changes in soil C for different land uses on peat

Effect of urea-N on growth and indoleacetic acid production of Stenotrophomonas maltophilia (Sb16) isolated from rice growing soils in Malaysia

Growth and activity of N2-fixing bacteria can be affected by N fertilizer application. A study was conducted at Universiti Putra Malaysia, Malaysia, to determine the effect of urea-N on the growth and indoleacetic acid (IAA) production of diazotrophic Stenotrophomonas maltophilia strain Sb16 (accession number, JQ820255), previously isolated from rice (Oryza sativa L.) growing soils of Malaysia. Five rates of N from urea fertilizer were applied (0, 50, 100, 150, and 200 kg ha-1) to the flooded rice soil and incubated in the control environment for 6 wk. Results showed that the population growth increased with increased N rates and highest population (8.2 log10 cfu mL-1) recorded in soil-standing water at the second week of incubation. The population decreased with the reduction of total N. Soil and soil water pH increased from 7.1 to 8.4 at the first week of incubation. Production of indoleacetic acid was significantly reduced with N fertilizer application. The highest indoleacetic acid (2.6 mg mL-1) was produced in the control treatment. Application of high rates of N fertilizer increased the population of diazotrophic strain Sb16 but significantly reduced indoleacetic acid production