Decomposition of Roots and Nodules of Centrosema Pubescens Benth

A modified technique involving incubation of moistened Serdang Series soil samples with segments of radicle and lateral roots as well as portions of nodules of Centrosema was used to study release of nitrogen into the soil as well as the biology of decompositon of roots and nodules of this legume. The samples were incubated for various lengths of time under optimum temperature and moisture content. At weeks 0, 1, 2, 4 , 8, 12 and 16, the respective soil samples were cleared of undecomposed legume tissues and analysed for total N, ammonium, nitrate, organic carbon and soil pH. At the same time the extracted laterals, radicle and nodule tissues were respectively plated on Czapek-Dox and potato dextrose agar media for isolation and enumeration of the decomposer mycoflora. The amount of ammonium nitrogen released from the different soil treatments was much higher than the levels of nitrate nitrogen released throughout the experiment. This could probably be due to the slightly acidic nature of the soil media used. The organic carbon content however decreased with increase in incubation time. This ultimately reSUlted in the narrowing of the C/N ratio to < 10 for all treatments under study. Accumulation of the ammonium nitrogen in the soil apparently resulted in the slight increase in soil pH. Soils amended with nodules varied significantly for all analyses when compared to the other treatments. The number of decomposer mycoflora isolated from the three tissue types increased with advanced tissue decay. For all the three tissue types used: laterals, radicles and nodules, five fungal genera were isolated frequently throughout the sampling period. The different gen era isolated were Fusarium, Trichoderma, Curvularia, Gliocladium and Penicillium. Total number of fungal genera and total isolates from decaying nodules were significantly higher when compared to results obtained from either decaying laterals or radicles

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

Kajian Awal terhadap Sistem Pemilihan Somaklon CUi Yang Resistans kepada Colletotrichum capsici (Syd.) Butler & Bisby

Toxin treatment from the anthracnose pathogen, Colletotrichum capsici on chilli tissue culture was utilised as the selection mechanism for variants which are resistant to this pathogen. The crude toxin preparation was sterilised and then added to the MS medium at the concentration of 0, 10, 20, 30 or 40% (v/v). At concentrations higher than 20 %, the toxin prevented the formation of calli from hypocotyl explants, and at 10% and 20 %, the formation of calli was strongly inhibited. The calli which survived the toxin treatment did not regenerate. Conversely, calli which were cultured on MS medium suplemented with VB juice or on the control MS medium, were able to regenerate at 37.6% and 62.7%, respectively. Induction of resistant variants was attempted by inoculating the calli with the konidia from the anthracnose pathogen. The antibiotic which had been extracted from an antagonistic fungus, Chaetomium trilaterale, was added to the MS medium to limit the spread of the pathogen to the medium from the chilli calli. From the antibiotic assay, the developement of the pathogen was dependent on the antibiotic concentration used in the media. The minimum antibiotic concentration which successfully prevented the growth of the fungal pathogen was 100 mg/ml. At that concentration, the fungus was only observed on the calli but not on the medium. However, the calli turned brown after 2 weeks of inoculation. In addition, the calli that survived became compacted and failed to regenerate

Responses of winged bean (Psophocarpus Tetragonolobus) to Mycorrhiza Inoculation in pot and field trials

Two greenhouse experiments and one field trial were conducted to provide information on the possibility of exploiting the beneficial effects of vesicular-arbuscular mycorrhizal fungi in Malaysian agriculture. In the first study, winged bean (Psophocarpus tetragonolobus) was grown in steam-sterilized Serdang soils and the development of the endophytes evaluated fortnightly. The second experiment was conducted in unsterilized Serdang and Munchong soils respectively with three levels ofP and/or inoculated with Acaulospora laevis, Glomus macrocarpum, Glomus mosseae, a mixture of Glomus species and Scutellospora calospora. All inocula, except for S. calospora, significantly enhanced growth throughout the course of the experiments and increased N, P and K concentrations in the plant tissues. G. mosseae was superior to the rest. In the field trial, Acaulospora laevis, Scutellospora calospora and Glomus mosseae were inoculated into winged bean grown in unsterilized field soil, with or without phosphate fertilizer. Inoculation of winged bean with G. mosseae significantly (P < 0.05) increased inflorescence formation (4.5/plant) , particularly at an intermediate level (60 kg ha-1 ) of P fertilizer

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

Variability and predictability of Malaysian export-grade starfruit properties

The properties of commercially-graded B10 cultivar starfruit (Averrhoa carambola) namely length, diameter, mass, volume, the five colours values (L, a*, b*, C, h°), firmness, total soluble solids (TSS), titratable acidity (TA) and pH were measured. Coefficients of variation (CV), correlation and property tolerances were evaluated to develop a relationship between the non-destructively measurable external properties and the non-destructively immeasurable internal properties. The length, diameter, mass and hue were found to have low CV levels. Mass appears to have a very strong correlation with volume while hue has a strong correlation with firmness

Distribution of VA Mycorrhizal Spores in Sandy Beach Soils under Cashew

Surface horizons (0-15 em) of sandy beach soils from Besut and Kuantan, (Malaysia) under cashew (Anacardium occidentale L) were sampled for Vesicular-Arbuscular Mycorrhizal (VAM) spores. Isolation of VAM spores were made from both the Rudua and Jambu series in Besut as well as the Rudua and Baging series in Kuantan. There were more spores isolated from the Kuantan than the Besut areas. The results also indiate a positive relationship between spore number to percent organic matter present in the topsoil. The abundant spores isolated from the Kuantan areas (in contrast to Besut) could have some significance in the P nutrition of cashew and probably explain the yield differences existing between these two areas

The effectiveness of two arbuscular mycorrhiza species on growth of cocoa (Theobroma cacao L.) seedlings

A pot experiment was conducted to study the effectiveness of two arbuscular mycorrhiza (AM) species in enhancing growth of cocoa seedlings. Cocoa seedlings of hybrid UITI X Na32 inoculated with Glomus mosseae and Seutellospora ealospora either as a single inoculum or as a mixed inoculum and an uninoculated control were grown in 2 kg sterilized Tai Tak series soil. The experiment was a single factor experiment arranged in a completely randomized design, with type of inoculum as a factor with four replications. Of the four treatment used, plants inoculated with mixed inoculum Glomus mosseae and Seutellospora ealospora gave more pronounced and significant vegetative growth and higher percentage of root colonization than the other treatments. Maximum plant height and total leaf area of43.7 cm and 1819.2 cm2 respectively were obtained from seedlings inoculated with mixed inoculum compared to seedlings given either G. mosseae (37.9 cm dan 1007.2 cm2 ) , or S. ealospora (32.3 cm and 1316 cm2 ) and control (28.5 cm and 736.7 cm2 ). The highest percentage of root colonization (72%) was aslo recorded from seedlings inoculated with mixed inoculum followed by those given S. ealospora (54%) and single inoculum G. mosseae (43%)