Production and use of maize seed for sowing in Bolívar,Ecuador

In the province of Bolívar in the Andean region 212 farmers, six salesmen and 14 technicians, involved in maize production, were interviewed. The majority of the farmers interviewed were small-holders; 64% of the farmers had a farm size of less than 4.5 ha. Maize is the most important crop and is often grown in association with beans. Most maize, 96%, is soft maize meant for human consumption. The cultivars grown are open pollinated ones. One cultivar, ‘Guagal’, was grown extensively. A few others, among which an improved version of Guagal were of some importance. In the production of maize the farmers consider damage due to insects, wind (lodging), diseases, drought and hail, the low prices for their surplus maize and the high costs of fertilizers, chemicals, sowing seed and labour as the most important constraints. The seed for sowing the next crop mainly came from seed kept from the last harvest. Farmers indicated that they select from the harvested ears the healthy looking larger ones. Kernel type also was a selection criterion. Selection for plant type in the field was rarely done. Of the farmers 71% stored the maize as kernels while 29% stored the seed kept on the ears. The storage was predominantly done somewhere in the house in plastic (56%) or cloth bags (14%), in a pile (13%), just on the floor (4%) or in cans (4%). Some farmers still had seed left from the last sowing and were willing to give a sample for testing. From 32 such samples the quality was assessed by INIAP, the Ecuadorean governmental research and breeding organisation. The samples were consistently of a low quality. Especially the vigour of the seedlings was poor and most of the seeds were infected or contaminated by fungi. In the region a few salesmen offer maize seed for sale of cultivar Guagal at prices affordable by the farmer. Of improved cultivars the prices were higher than most farmers are willing to pay. The technicians considered good seed quality and good maintenance of the cultivars effective methods in obtaining better yields. Many farmers do not have access to seed of INIAP and are not familiar with the improved cultivars.     

A rapid, seedling-based bioassay for identifying low cadmium-accumulating individuals of Durum wheat (Triticum turgidum L.).

We have developed a seedling-based bioassay that iscapable of identifying low Cd-accumulating phenotypes(homozygous and heterozygous) after 96–120 h ofexposure. Our experiments were conducted using¹⁰⁹Cd as a tracer at subtoxic concentrations tosimulate conditions that might be experienced in thefield. Supply of Cd (10^-11 M) to 4-d oldseedlings for 0–8 h resulted in no differences in rootand leaf Cd content between the low (TL05) and high(TL04) Cd-accumulating isolines. Increasing time ofexposure produced significant differences in leaf Cdaccumulation between isolines, with differencesbecoming most pronounced after the bulk of appliedcadmium ( 95%) was depleted from absorption solutions( 72 h). Similar results were obtained with8-d old seedlings, where differences between genotypeswere more pronounced in young leaves (2nd leaf) orshoot bases. Individuals from five low and highCd-accumulating near isogenic pairs (50individuals/isoline) were screened using Cdconcentration of shoot bases as the screeningcriterion. Mean scores within each isoline pair weresignificantly different, although overlap ofindividual scores was observed at intermediate foliarCd concentrations. The 2^nd leaf to root Cdcontent ratio, which reflects root to shoottranslocation, provided a better parameter todistinguish low from high Cd-accumulating isolines. Plants used for this bioassay could also be rescuedfor subsequent experimental crosses, providing a rapidand cost-effective tool for early detection of the lowCd-accumulating phenotype.     

Zur hydrologischen Bedeutung der organischen Auflage im Wald: Untersuchungsmethoden und erste Ergebnisse

About the hydrological role of organic layers in forest: methods and first results The forest floor (total organic matter above the surface of the mineral soil) is an important interception storage for throughfall. Therefore, it must be considered in detailed water balances of forest. The objective in this paper is to present a method for measuring the forest floor percolation. It was developed within the framework of the interdisciplinary project Ecosystem research in the Bornhöved lake region. A technique for permanent registration of mineral soil input and a vacuum control system for mini lysimeters and suction plates are described. The registration system has a resolution about 0,1 mm. Some figures illustrate the instrumentation, respectively measured row data and some results. Finally, the used materials, their properties and sources of supply are presented.     

Fumonisin B-glucose reaction products are less toxic when fed to swine

The effects of fumonisin B-glucose reaction products in swine diets was examined. Pigs were fed diets containing 528 micromol of total fumonisin B/kg (FB), 528 micromol of total FB-glucose adducts/kg (FB-G, 122 micromol of unreacted FB/kg), or 0 micromol of total FB/kg for 15 days to test the efficacy of the FB-G reaction products in detoxifying FB. Weight gain in FB pigs was lower than in FB-G or controls, which was correlated with feed intake reduction in FB pigs. Serum aspartate aminotransferase, gamma-glutamyltransferase, and total bilirubin in FB pigs were higher than in FB-G or control pigs. Serum sphinganine/shingosine ratios in FB pigs were higher than in FB-G or control pigs. Microscopic examination of tissues from FB pigs showed generalized liver necrosis and apoptosis with marked cellular pleomorphism and disorganized hepatic cords. The liver and kidneys in the FB-G group appeared to be normal. Tissues of controls were free of lesions. Results suggest that dietary FB-G products are less toxic to swine and may provide an detoxification approach in instances of widespread FB grain contamination (p < 0.05).     

The impact of gas extraction on landfill-generated methane gas levels

The changes measured in landfill-generated CH₄ gas levels in response to continuous pumping from an augered borehole in the refuse are described. The results of statistical analyses of concentration and pressure levels at a series of probes located radially outward from the gas extraction well are used to characterize the temporal and spatial variations. A drawdown curve arising from the continuous pumping is apparent and is quantified as a series of cones of varying impacts on percentages of CH₄. The results are indicative of a fairly free flow of gas through the landfill.     

Changes in volatile compounds of carrots (Daucus carota L.) during refrigerated and frozen storage

Carrots (Daucus carota L.) of cv. Bolero and cv. Carlo were processed into shreds and stored for up to 4 months at -24 degrees C (frozen storage), or the roots were stored for up to 4 months at 1 degrees C (refrigerated storage) followed by processing into shreds. Volatiles from the carrot shreds were collected by dynamic headspace technique and analyzed by GC-FID, GC-MS, GC-MS/MS, and GC-O to determine the volatile composition and aroma active components of carrots stored under different temperature conditions. A total of 52 compounds were quantified, of which mono- and sesquiterpenes accounted for approximately 99% of the total volatile mass. Major volatile compounds were (-)-alpha-pinene, beta-myrcene, (-)-limonene, (+)-limonene, (+)-sabinene, gamma-terpinene, p-cymene, terpinolene, beta-caryophyllene, alpha-humulene, and (E)- and (Z)-gamma-bisabolene. A considerable increase in the concentration of mono- and sesquiterpenes was observed during refrigerated storage, whereas the concentration of terpenoids was around the same level during frozen storage. GC-O revealed that the major volatiles together with (+)-alpha-pinene, (-)-beta-pinene, (+)-beta-pinene, 6-methyl-5-hepten-2-one, (-)-beta-bisabolene, beta-ionone, and myristicin had an odor sensation, which included notes of "carrot top", "terpene-like", "green", "earthy", "fruity", "citrus-like", "spicy", "woody", and "sweet".     

Secondary waste treatment: Aerobic bacterial activity,initial and residual respiratory phases

Secondary waste treatment is based on aerobic bacterial activity. Two fractions are involved, soluble, and insoluble organic matter. The basis of this study was to ascertain whether the major portion of bacterial activity was a function of specifically located aeration tank sites, of limited volume, or required the total aerated capacity and the longer detention times. To distinguish between these two possibilities, an aeration tank was partitioned into hypothetical subvolumes adjacent to the influent ports. These are the initial respiratory spaces, constituting the initial respiratory phase of secondary treatment. The remainder of the aerated systems activity occurs in the residual respiratory space or phase.     

Energy or nutrient regulation of decomposition: Implications for the mineralization-immobilization response to perturbations

A model developed previously to describe the turnover of forest soil nitrogen is modified here to explain the effects of carbon and nitrogen additions on their dynamics. The model, which is structurally very simple, seems to explain correctly, among other phenomena, the negative correlation between N mineralization and CO₂ evolution observed in many experimental situations. An important variable used to explain this behaviour is the deficiency factor, which is related to the critical C-to-nutrient ratio and which gives a measure of the C or nutrient deficiency in the substrate with respect to the needs of the decomposers. Ways are discussed in which the model output can be used to explain the observed retention in the soil of fertilizer N added to mature forest soils.     

Chemical changes of beech litter during passage through the gut of the lumbricid earthworm Eisenia fetida (SAV.)

Casts of the lumbricid earthworm species E. fetida were investigated by means of chemical analyses and ¹³C NMR spectroscopy and compared to the beech litter used as food. The casts are characterized by slightly reduced C-to-N ratios, higher ash contents and lower polysaccharide and lignin concentrations in comparison with the litter material. These differences between casts and litter are very small, ranging from 1 to 7%, and are not supported by any statistical evidence. In addition, NMR and Py-FIMS data complete the picture of E. fetida casts as almost exclusively physically altered (i.e. comminuted) plant residues.