A field experiment was carried out to evaluate the responses of melon plants (Cucumis melo L.) under soil salinity (S1: 0.5 dS m-1, S2: 1.0 dS m-1 and S3: 2.5 dS m-1). The irrigation water was from a drainage water channel system following the traditional and sustainable irrigation system. Mineral nutrition, water content and chlorophyll in leaves were studied at flowering and harvesting periods. Nutrient and water content parameters were measured in leaf blades and petioles. Results evidenced significant differences in N, K and Na content. N significantly decreased in response to soil salinity in leaf blades. However, salinity significantly increased K and Na uptake. Macronutrients and micronutrients showed higher concentrations in leaf blades than petioles, except for Kand Na. K/Na ratio was higher in response to soil salinity. Higher K/Na ratio in leaf blades might indicate selectivity for K instead of Na as a strategy to combat salt stress. Significant differences were observed for the chlorophyll content with salinity, decreasing values at higher soil salinity.
This research was aimed at assessing the different tillage systems adopted in rural communities of Osun state with a view to estimating soil erodibility and to determine the prevalence of erosion in the sampled communities. Nine communities were selected and fifty questionnaires administered to farmers from the twelve LGA sampled, making a total of 5400 questionnaires. Ayedaade, Aiyedire, Atakunmosa west, Ede south, Ilesa west, Ife north, Ife south, Irewole, Oriade, Odo-Otin, Ejigbo and Ife central LGA.were used for this study. Result indicated that the slash and burn technique of land preparation is found to be predominantly adopted by the Farmers. Also, farmers percentage with erosion problems from the use of both conventional and traditional tillage techniques was highest in Ilesha west with a value of 44.56% (±8.12) and least in Irewole (12.11% ±1.45). Soils of Ife central and Ife south were highest in erodibility with values 0.65 and 0.53, respectively, while Oriade and Ede south had lowest erodibility with values 0.07 and 0.12, respectively. The practical implication of these findings is in the area of soil erodibility estimation for soil conservation planning.
Trichoderma constitute filamentous fungi which are frequently used as biocontrol agents against plant pathogenic fungi. The tolerance of these fungi to chemical fungicides is a prerequisite for biocontrol agents for their application to suppress the growth of some soil-borne pathogens. The objectives of this study were to evaluate tolerance of Trichoderma asperellum local isolates TK and TS from Batu-East Java, to mefenoxam fungicide, as well as to identify in-vitro the antagonistic activity of T. asperellum against the plant pathogen Phytophthora infestans by using dual-culture method. Thus, an integrated approach of chemical and biological methods was used to control the growth of P. infestans. This study was conducted at the Department of Biology, Faculty of Science and Technology Airlangga University, Indonesia, during March through December, 2012. T. asperellum isolates TK and TS were evaluated in-vitro for their efficacy against P. infestans and tolerance to 5000 ppm mefenoxam. The results showed that the growth of the two T. asperellum isolates on Potato Dextrose Agar (PDA) medium supplemented with 5 mL/L mefenoxam was up to 67%, while their antagonistic activity against P. infestans in dual-culture was 5,08% and 16,37%. The results are expected to help in selection of potential biocontrol agents.
Nucleic acid based technologies are useful tools in the investigation of microbial community composition. This study used three such methods – T-RFLP/PAT, clone library and metatranscriptome analyses – to probe changes in soil bacterial populations exposed to hydrogen gas. Total DNA and RNA were collected from both lab and greenhouse soil samples exposed to H2, with soil samples not treated with H2 used as controls. All three methods showed the same general trends, with members of Actinobacteria being suppressed by H2 exposure and populations of Proteobacteria, particularly β- and γ-proteobacteria, being stimulated by the presence of H2. These results agree with previous studies and show that all three techniques, either alone or in combination, are reliable methods for investigating shifts in soil microbial community composition when exposed to a selective pressure such as H2. This study also shows that H2has a marked effect on soil biology and microbial ecology. This soil bacterial community change explains the reported soil gas production switch and associated plant growth promotion.
Effectiveness of selected immersion-based seed pre-sowing treatments (cold water, hot water and concentrated sulphuric acid) on the germination of three Acacia species (A. tortilis, A. erioloba, and A. nigrescens) was studied between December 2012 and January 2013. For each species, four treatments (including the control) were replicated four times in a Completely Randomized Design. Percentage germination, germination mean time (GMT) and germination index (GRI) were calculated and the data were subjected to analysis of variance (ANOVA). Significant differences in germination were observed across the treatments. Concentrated sulphuric acid significantly (P < 0.01) increased the germination percentages of A. erioloba (87%) and A. nigrescens (30%) while the control, cold water and hot water treatments significantly (P < 0.01) reduced their germination percentages (5%). However, treating A. tortilis with hot water for 9 min significantly (P < 0.01) enhanced its germination percentage (30%) compared to the other treatments. As expected the control had the highest GMT, although this was not significant for A. tortilis. The GRI revealed similar trend as germination percentages across the treatments for the three Acacia species. Based on these results, we recommend concentrated sulphuric acid and hot water as suitable seed pre-treatments for enhancing the germination of the three Acacia species.
Phosphorus (P) fractions are important forms of P in the soil which determines P availability, an important ion in the soil for plant use. Incubation study was conducted in the laboratory for ten weeks to study the changes in selected P fractions in an Alfisol (Iwo soil series) in the southwestern region of Nigeria amended with poultry manure and single superphosphate (SSP). The soil was collected from the experimental field of the Institute of Agricultural Research and Training, Ibadan, Nigeria. Poultry manure at 0, 5, 10, 15 and 20 t ha-1 was applied in combination with single superphosphate (SSP) at 0, 15, 30, 45 and 60 kg P ha-1. The treatments were replicated three times and phosphorus fractions (Organic P, Fe-P, Al-P, occulded P and residual P) were determined before and at two weekly interval during the incubation studies using the Chang and Jackson method. Significant increases in Fe-P and Al-P fractions were observed to the 6th week of incubation after which it started decreasing when poultry manure was applied solely and in combination with SSP. The sole application of SSP i.e. at 30 kg P ha-1 of SSP increased the recalcitrant P fractions while poultry manure reduced it. When Fe-P extractable with NaOH i.e. NaOH-Pi builds up it acts as a sink for P and this is achieved more when the poultry manure was combined with SSP. Application of 20 t ha-1 of poultry manure in combination with 30 kg P ha-1 of SSP increased the Fe-P availability and therefore a potential sink for P.
Two pot experiments were conducted to examine the effect of arsenic (As) concentration both in irrigation water and in soil on the As content in vegetables grown in a glass greenhouse. In the first experiment, spinach (Spinacia oleracea), green amaranth (Amaranthus viridis) and gima kalmi (Ipomoea aquatica) were grown in soil containing 10 mgAskg-1, where the irrigation water contained two As levels (0.1 and 0.5 mg L-1). In the second experiment, gima kalmi (Ipomoea aquatica) was grown in As spiked soil at different levels [10 (control), 15, 20, 30, and 50 mgAskg-1 soil] and with irrigation water without As contamination. The As concentration (mg kg-1 DW) and As accumulation (µg plant-1) in the edible part of the plants increased significantly with increasing As concentrations in irrigation water and/or soil. When plants were irrigated with As contaminated water, the As concentration of the edible part exceeded its maximum limit (0.5 mg kg-1) in spinach and green amaranth at 0.5 mg L-1 of As, but gima kalmi had a smaller amount than the other vegetables. Gima kalmi had the characteristics of a lower As accumulation. Therefore, the risk level of As in irrigation water was suggested to be 0.1 mg L-1 for vegetables. When gima kalmi was grown in elevated levels of As contaminated soil, the As concentration of gima kalmi, even being a low As accumulator, exceeded the maximum limit at the level above 20 mgAskg-1 soil. The risk level of As in soil, therefore, was suggested to be 20 mg kg-1. The risk value of As concentration in irrigation water and/or in soil needs to be investigated in detail by using many vegetables and/or soils.
The research work was conducted at two locations in 2012, 100 meters away from mining pits to determine the effects of lead, slope position and depth on the variation of soil chemical properties. Random sampling method was used to collect soil samples from the study area. Samples were collected from upper-slope, middle-slope and bottom slope positions at depths 0 – 15 cm and 15 – 30 cm. Results indicated that the soils are generally clayey to clay loam and poorly drained in all the depths. The upper slope position in the two locations gave the highest contents of sand, while the highest percent of clay and silt were obtained from the bottom slope position in both Amaeze and Ihietutu locations. Results showed a significant difference among the chemical properties of upper, middle and bottom slope soils. Soil pH of the upper-slope (6.2) was the highest followed by middle (5.9) and bottom slopes (5.8). Soil pH in 15 – 30 cm depth gave the highest significant (P = 0.05) value (6.2) than the 0 – 15 cm depth (5.8).Exchangeable calcium and magnesium were highest at bottom slope followed by middle and upper-slopes. The results indicated that soil pH, CEC and available phosphorous increased as lead concentrations increases, total nitrogen decreases with increase in Pb, especially in Amaeze location. The soil in all the locations sampled is marginally fertile, as organic carbon and nitrogen of the fertility parameters are within the low- medium range when compared with the standard values. Exchangeable Mg, Ca and CEC are within medium and high range compared with the standard values.