Field Application Strategies for the Inoculant Biofertilizer Biogro Supplementing Fertilizer Nitrogen Application in Rice Production

Biofertilizer research for rice in Vietnam has focused on the isolation and selection of strains that can fix nitrogen, solubilize inorganic phosphates, stimulate plant growth, and breakdown soil organic matter. This paper assesses the consistent positive effect of BioGro on grain yield and agronomic parameters, including the rates and times for its application, the need for continued inoculation of crops grown in the same site, varietal differences, and nitrogen (N), phosphorus (P), and potassium (K) combinations on the effectiveness of BioGro. The commercial biofertilizer, BioGro, consists of four strains, one formerly considered as nitrogen fixing, Pseudomonas fluorescens, a soil yeast strain, Candida tropicalis is P-solubilizing, and two other bacilli, Bacillus amyloliquefaciens and Bacillus subtilis, potentially breaking down cellulose, protein, and starch. All four strains contribute to plant growth promoting rhizobacteria (PGPR) effect as shown by enhanced root growth. BioGro can be produced in local factories providing there is technical backup in the supply of starter culture and quality control of the final product.     

The nutrient and glycoalkaloid content of a new potato meal

The nutrient and glycoalkaloid content of a new potato meal produced as a by-product of starch manufacture using low temperature dehydration was determined. Comparisons were made between the new potato meal and the previously manufactured meal which was prepared by high temperature dehydration. The glycoalkaloid content of the new potato meal was 15.53mg α-chaconine and 4.75mg α-solanine per 100g meal compared to 15.79mg α-chaconine and 7.83mg α-solanine in the potato meal produced by high temperature dehydration. The new potato meal contained 2% more protein and 1.9, 3.4 and 1.2 times more niacin, riboflavin and thiamin, respectively than the previous by-product. The potassium and phosphorus concentrations were approximately 2.0 and 0.2%, respectively. Other minerals were found in lesser concentrations with the sodium content being only 7.4mg/100g potato meal. A 28g serving would provide approximately 5, 7 and 4% of the RDA for protein, niacin and thiamin, respectively.     

Influence of water table levels on CO2 emissions in a Colorado subalpine fen: an in situ microcosm study

We quantified the relationship between water table position and CO₂ emissions by manipulating water table levels for two summers in microcosms installed in a Colorado subalpine fen. Water levels were manipulated in the microcosms by either adding water or removing water and ranged from +10 cm above the soil surface to 40 cm below the soil surface, with ambient water levels in the fen averaging +3 and +2 cm above the soil surface during 1998 and 1999, respectively. Microcosm installation had no significant effect on CO₂ efflux; the 2 year means of natural and reference CO₂ efflux were 205.4 and 213.9 mg CO₂-C m⁻² h⁻¹, respectively (p=0.80). Mean CO₂ emissions were lowest at the highest water tables (water +6 to +10 cm above the soil surface), averaging 133.8 mg CO₂-C m⁻² h⁻¹, increased to 231.3 mg CO₂-C m⁻² h⁻¹ when the water table was +1 to +5 cm above the soil surface and doubled to 453.7 mg CO₂-C m⁻² h⁻¹, when the water table was 0-5 cm below the soil surface. However, further lowering of the water table had little additional effect on CO₂ emissions, which averaged 470.3 and 401.1 mg CO₂-C m⁻² h⁻¹ when the water table was 6-10 cm, and 11-40 cm beneath the soil surface, respectively. The large increase in CO₂ emissions as we experimentally lowered the water table beneath the soil surface, coupled with no increase in CO₂ emissions as we furthered lowered water tables beneath the soil surface, suggest the presence of an easily oxidized labile carbon pool near the soil surface.     

Ascorbic acid and glycoalkaloid content of Atlantic and Superior potato tubers as affected by supplemental irrigation and soil amendments

Atlantic and Superior potato (Solanum tuberosum L.) tubers were collected at harvest from two field experiments in Maine during 1993 and 1994. Tubers were analyzed for ascorbic acid (ASC) and total glycoalkaloid (TGA) concentration within one month of harvest and after 4 to 5 months of storage at 10 C. ASC concentration was significantly higher in Superior than Atlantic at harvest and after storage. TGA concentration was consistently higher in Atlantic than Superior. Irrigation tended to slightly reduce ASC and increase α-solanine concentrations when applied too late in the season for yield benefits. Storage decreased tuber ASC content, but no specific pattern was observed for TGA changes. Soil amendment programs using compost and manure (22 Mg ha^?1 potato compost + 45 Mg ha^?1 manure) did not dramatically affect tuber ASC or TGA concentrations. ASC content of the tubers declined dramatically in storage, but no consistent pattern was found for tuber TGA changes. We conclude that genotype, growing environment, and storage time play much stronger roles in determining tuber ASC and TGA levels than do irrigation and soil management programs. We observed a negative relationship between the average tuber size of the assayed samples and ASC concentration in fall samplings; however, this relationship was not observed from storage. Average tuber size and TGA content generally displayed a negative relationship.     

The Contribution of Naturally Occurring Food Items to the Diet of Bidyanus bidyanus When Fed Differing Formulated Diets

Fish raised in ponds and fed formulated feed also have access to naturally occurring food items. The contribution of these food items to growth of Bidyanus bidyanus was investigated by assigning fish to four treatments: in diet 1, caged fish were fed a high protein feed (52% CP); in diet 2, caged fish were fed a medium protein feed (30% CP); in diet 3, caged fish received no feed; and in diet 4, uncaged fish received no feed. Survival between caged treatments was similar (88%–96%), and fish performed best when fed a high-protein feed. Modelling of C and N stable isotope ratios showed formulated pellets provided 12% to 84% of the growth of fish fed diet 1 or 2, while invertebrates provided between 4% and 74%. The majority of growth of fish in diet 3 was from zooplankton (54%–76%) and invertebrates for fish in diet 4 (6%–94%). Implications for low intensity production of B. bidyanus are discussed.     

Sea cucumbers in the Seychelles: effects of marine protected areas on high‐value species

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Role of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter solanacearum’ and <Emphasis Type="Italic">Bactericera cockerelli</Emphasis> Haplotypes in Zebra Chip Incidence and Symptom Severity

Two haplotypes of the pathogen, ‘Candidatus Liberibacter solanacearum,’ (Lso) and four haplotypes of the insect vector, Bactericera cockerelli, are associated with zebra chip disease of potato. Whether disease severity or incidence is influenced by pathogen or insect haplotype is poorly understood. The role of Lso ‘A’ and ‘B,’ transmitted by three haplotypes of B. cockerelli, on disease severity and incidence in eight potato cultivars was analyzed. Both haplotypes of Lso induced tuber symptoms. In general, Lso B caused higher incidence of symptoms, and greater reduction in tubers compared with Lso A. Lso B was associated with more severe tuber symptoms, producing fewer mild or moderate tuber symptoms. Lso A was associated with less severe tuber symptoms, despite being able to induce severe symptoms. Disease incidence, tuber yield, and symptom severity ratings were not dependent upon the psyllid haplotype transmitting the pathogen, suggesting that pathogen, not insect haplotype affects Lso transmission.