Nutritional Amendments Research Articles

Willow growth in response to nutrients and moisture on a clay landfill cap soil. I. Growth and biomass production

The growth and biomass production by willow ( Salix viminalis L.) was studied in lysimeters containing Oxford clay landfill cap soil with different amendments, bulk densities and watering regimes. Three years from planting, stem biomass in well-watered plants was least (0.28 kg plant −1) with high bulk density soil (1480 kg m −3) and no nutritional amendment but was increased 10-fold (2.53 kg plant −1) by reducing soil bulk density (1200 kg m 3) and adding amendments. In comparison, on a sandy loam soil it was 6.23 kg plant −1. There were similar differences in number of stems plant −1, stem basal area plant −1 and plant leaf area which can be attributed to low nitrogen and phosphorus levels in Oxford clay. Water stress reduced stem biomass production by 26–37% and caused higher root:stem ratios. These were also higher on Oxford clay than on the sandy loam. Successful biomass production from willow on Oxford clay landfill caps will therefore require nutritional amendment.

Ethanolic fermentation of acid pre-treated starch industry effluents by recombinant Saccharomyces cerevisiae strains

Two industrial effluents, a pre-fermentation effluent and a post-fermentation effluent from a wheat starch production plant, were used as substrates for fuel ethanol production in anaerobic batch cultures using minimal nutritional amendment. The performances of three metabolically engineered xylose-utilizing Saccharomyces cerevisiae strains: TMB 3001 expressing XYL1, XYL2 and XKS1, redox metabolism modulated CPB.CR1 and glucose de-repressed CPB.CR2, as well as a reference strain CEN.PK 113-7D not fermenting xylose, were evaluated. For the recombinant strains a glucose consumption phase preceded the xylose consumption phase. In both effluents, biomass and ethanol production occurred predominantly during the glucose consumption phase, whereas xylitol and glycerol formation were predominant in the xylose consumption phase. Total specific ethanol productivities on glucose were 6-fold higher than on xylose in the pre-fermentation effluent and 15-fold higher than on xylose in the post-fermentation effluent. CPB.CR1 showed impaired growth compared to the two other xylose-utilizing strains, but displayed 18% increased ethanol yield in the post-fermentation effluent.

Economic Impact of Pecan Integrated Pest Management Implementation in Texas

The Texas pecan integrated pest management (IPM) program, begun in the early 1970s, was evaluated using research and demonstration IPM trial data and producer survey responses. The initial survey conducted in 1981 was chosen as the base line against which later surveys were compared to measure the economic impact of an IPM program. Producers in Texas reduced fungicide use 30%, insecticide use 35%, and the overall number of spray applications per season 9% from 1980 to the present. Producers practicing an IPM program realized contemporaneous benefits of $3.93 million annually from 1994 to 1996 compared with conventional program producers, and the overall economic benefits to pecan producers were estimated to be $6.06 million per year during 1990-1996 from the pecan IPM program in Texas. Needed nutritional amendments of zinc were identified as the current principal spray component applied to improved pecans that prevents further substantial reductions in management costs.

Pathogenicity and Formulation of Typhula phacorrhiza, a Biocontrol Agent of Gray Snow Mold.

In previous testing, we found that gray snow mold, caused by Typhula ishikariensis or T. incarnata, could be controlled by applying T. phacorrhiza onto turf grass prior to snowfall. To test for phytopathogenicity of this biocontrol agent, the five most disease-suppressive isolates were cultured on mixed grains and applied to 12 turfgrass cultivars and 2 winter wheat cultivars in December 1995 and 1996. After snow melt in April 1996 and 1997, significantly greater winter injury was visible on plots treated with the pathogens compared to T. phacorrhiza-treated plots or untreated plots. Except for one cultivar in 1996, there were no significant differences between T. phacorrhiza-treated plots and untreated plots. Pelletized alginate formulations of T. phacorrhiza containing kaolin clay with various nutritional amendments were tested for viability and efficacy. After 64 weeks of storage, viability remained >85% at -15°C and >70% at 4°C, but <30% at 10°C and 25°C. Significant control of gray snow mold by T. phacorrhiza using small numbers of pellets (20 g/m2) was equivalent to using larger amounts of mixed grain inoculum (200 g/m2) or wheat bran inoculum (100 g/m2) in 2 years of field testing.

Survival of Bacillus subtilis NB22 and its transformant in soil

Bacillus subtilis NB22 is an anti fungal-antibiotic (iturin) producer that expresses broad suppressibility of phytopathogenic fungi and bacteriaand is considered as a potential biological pesticide. The survival of B. subtilis NB22-1, which is a spontaneous streptomycin-resistant mutant of NB22 and its transformants with plasmid DNA, was investigated in soil, The number of vegetative cells of the host strain NB22-1 declined initially in soil at 15°C, but the population was stabilized at the level of spores which were formed during incubation in soil. Neither nutritional amendment nor the raising of temperature were effective for the higher induction of spore formation in soil, However, simultaneous treatment of increasing the temperature and nutritional amendment was effective for the rapid induction of spores in the soil, which led to stabilization of the population at the level of 10 7 spores g −1 dry soil of the initially added cell number. Vegetative cells of the transformants NB22-1 (pC 194) and NB22-1(pUB1 10) also sporulated efficiently in soil under these conditions and were stable for 50 days, but died out within 10 days without such treatment. The stability of plasmid pUB110 was high (around 90%), but pC194 was quickly cured and its stability declined to about 50%. The stability of the two plasmids was similar to that in liquid culture using sporulation medium. When spores of NB22-1 or its transformants were introduced into the soil, they persisted at high level and showed no loss in their viability until the end of the experiment at 50 days.

Biodegradation of Ethylene Glycol in Simulated Subsurface Environments

Ethylene glycol is regularly used as an industrial solvent and in vehicular anti-freeze and de-icing compounds. Significant quantities of it are released into treatment streams and onto land. The aim of this study was to establish rates of biodegradation of ethylene glycol in simulated subsurface environments. The utilization of ethylene glycol as substrate by microorganisms naturally occurring in soil and groundwater was monitored over time while substrate concentration, soil type, temperature and nutrient level were varied. Batch studies at 100 and 1000-ppm ethylene glycol demonstrated that increasing substrate concentration decreased the rate of its biotransformation as the first-order kinetic rate constant decreased from 1.01 to 0.95 days−1. Further increase in initial concentration to 10,000-ppm resulted in minimal substrate disappearance from solution which was likely due to oxygen limitation. Studies with two different soils under identical environmental conditions and substrate concentrations indicated soil type had a clear effect on biodegradation rate. Lowering the temperature from 25° to 10°C for a given soil retarded the degradation rate by a factor of 2.44, but at each temperature greater than 99% removal was achieved in less than 7 days. Removal of nutritional amendments from the microbial population had only a slight impact on biotransformation rate. Unamended microcosms still exhibited nearly complete ethylene glycol transformation in 3 days as compared to 2 days for amended microcosms. Groundwater served as a satisfactory bacterial inoculum and generated a rate constant only slightly lower (0.76 days−1) than that found for the soils. All results were comparable to those found by others for the biotransformation of linear alkylbenzene sulfonates (LAS) or of ethylene glycol by activated sludge.

Effects of Nutritional Amendments on Conidial Production of Fusarium solani f. sp. cucurbitae on Sodium Alginate Granules and on Control of Texas Gourd

Effects of Nutritional Amendments on Conidial Production of Fusarium solani f. sp. cucurbitae on Sodium Alginate Granules and on Control of Texas Gourd

Survival of Bacillus thuringiensis Spores in Soil

Bacillus thuringiensis spores and parasporal crystals were incubated in natural soil, both in the laboratory and in nature. During the first 2 weeks, the spore count decreased by approximately 1 log. Thereafter, the number of spore CFU remained constant for at least 8 months. B. thuringiensis did not lose its ability to make the parasporal crystals during its residence in soil. Spore survival was similar for a commercial spore-crystal preparation (the insecticide) and for laboratory-grown spores. In contrast to these results, spores that were produced in situ in soil through multiplication of added vegetative cells survived for only a short time. For spore additions to soil, variations in soil pH had little effect on survival for those spores that survived the first 2 weeks of incubation. Also without effect were various pretreatments of the spores before incubation in soil or nutritional amendment or desiccation of the soil. Remoistening of a desiccated soil, however, caused a decrease in spore numbers. Spores incubated in soil in the field did not show this, but the degree of soil desiccation in nature probably never reached that for the laboratory samples. The good survival of B. thuringiensis spores after the first 2 weeks in soil seemed to be a result of their inability to germinate in soil. We found no evidence for the hypothesis that rapid germination ability for spores in soil conferred a survival advantage.

Effect of nutrition on the interaction of viruses andFusarium oxysporum in tomato seedlings

The effect of different nutritional amendments on the growth of tomato seedlings subjected to combined infection byFusarium oxysporum f.sp.lycopersici (Fol) and either Tomato Bushy Stunt Virus (TBSV) or Tomato Mosaic Virus (ToMV) was investigated. The growth of healthy or infected tomato seedlings was repressed more when they were maintained under conditions of nitrogen deficiency than in nutrient solutions devoid of potassium or phosphorus. Plants infected with the fungus and either virus had lower fresh weights and smaller leaf areas than those infected by any of these pathogens alone. With the exception of seedlings grown in potassium-deficient solutions, co-infection resulted in no fundamental differences in virus concentration per plant. The concentration of both TBSV and ToMV was higher per unit fresh weight of leaf in co-infected plants maintained in all types of nutrient. It is suggested that the presence of the fungus in the plant tissues may be a more important factor than nutrition in promoting virus replication.