Trophic fractionation (ΔN) in Collembola depends on nutritional status: A laboratory experiment and mini-review

Isotopic studies in temperate forest soils suggested that collembolans occupy a broad range of trophic niches. This notion is mainly based on the wide (up to 8-9‰) range of δ¹⁵N signatures of different species. The interpretation of these data depends strongly on the correct estimation of nitrogen isotope fractionation per trophic level. It is usually assumed that a consumer is on average enriched in ¹⁵N by about 3.4‰ relative to its diet. However, trophic fractionation is not uniform across different animal taxa and different tissues, and varies with a range of factors, including quality of the diet and the nutritional status of animals. We performed a laboratory experiment aiming to compare the trophic fractionation of nitrogen isotopes (Δ¹⁵N) in different Collembola species fed with three fungi of different palatability. Collembolans were fed with a single-species fungal diet for 75 days. There was a positive correlation between the whole body C:N ratio and reproduction rates of collembolans. We therefore used the C:N ratio as a proxy of nutritional status. In all species of collembolans, the trophic fractionation decreased with increased whole body C:N ratio, and this factor explained most of the within-species variation in Δ¹⁵N. The analysis of published data on the trophic fractionation of collembolans in laboratory experiments confirmed this conclusion. However, the mean trophic fractionation in most collembolan species studied in the laboratory was fairly similar. In contrast, field studies have documented a consistent difference in δ¹⁵N among different families of collembolans. In particular, in nearly all published cases Onychiuridae had δ¹⁵N higher than Isotomidae or Entomobryidae. A sharp contrast between laboratory-based estimates of the trophic fractionation (generally uniform in different species and families) and field data (which show a consistent difference in δ¹⁵N among different species and even families of collembolans) confirms that δ¹⁵N values of field-collected animals bear important information on the trophic position occupied by a particular species, and are not heavily affected by the species-specific differences in trophic fractionation. As the Δ¹⁵N in collembolans depends on their nutritional status, we suggest that the C:N values should be reported along with isotopic data to allow cross-study comparisons.     

Effects of iron nutritional status and time of day on concentrations of phytosiderophores and nico‐tianamine in different root and shoot zones of barley

The diurnal pattern in concentrations of phytosiderophores (PS) and its precursor nicotianamine (NA) was studied in different root and shoot zones of iron (Fe)‐sufficient and Fe‐deficient barley (Hordeum vulgare L. cv. Europa) grown in nutrient solution. Roots were separated into apical (0–3 cm) and basal zones (>3 cm) and shoots into young (3 cm basal zones of youngest two leaves) and old (remaining zones of youngest two leaves and oldest leaf) parts. The main PS in barley was identified as epi‐hydroxymugineic acid (epi‐HMA). Regardless of the sampling zone and time of day, epi‐HMA concentrations were several times higher in Fe‐deficient than in Fe‐sufficient plants and several times higher in the roots than in the shoots. In roots and shoots, epi‐HMA concentrations were always higher in the younger compared with the older zones. In both root zones of Fe‐deficient plants, an inverse diurnal rhythm occurred in epi‐HMA concentrations and in its release by the roots. In contrast, such a rhythm was absent in roots of Fe‐sufficient plants and in the shoots regardless of the Fe nutritional status. Nicotianamine concentrations in roots were not affected by the Fe nutritional status in apical zones but slightly enhanced under Fe deficiency in basal zones. In contrast to roots, NA concentrations in both shoot parts were lower in Fe‐deficient than in Fe‐sufficient plants. Regardless of the Fe nutritional status in roots and shoots, NA concentrations were higher in young than in old parts and no consistent diurnal variations were observed. The results suggest that PS are also synthesized in the shoot, although at much lower rates than in roots. As with roots, PS synthesis in the shoot is enhanced under Fe deficiency and is mainly localized in young growing tissue. The distinct diurnal rhythm in PS release in roots is apparently not regulated by variation in the rate of PS synthesis during the day.     

Can nutritional status of apple trees be determined by leaf analysis in early vegetation?

In this study, whether the nutritional status of apple trees can be predicted in the early stages of vegetation was determined by leaf analysis. For this purpose, from different districts of Isparta province in Turkey where apples are cultivated extensively, 150 apple orchards were assessed according to the production potential of districts. The leaf samples were collected at six different stages of vegetation from these orchards, and nitrogen, phosphorus, potassium calcium, magnesium, iron, copper, zinc, manganese, and boron (N, P, K, Ca, Mg, Fe, Cu, Zn, Mn and B) amounts were determined. Correlations were examined between the sixth period and the previous periods. The presence of significant correlations was interpreted, as leaf analysis can be used to determine the nutritional status of apples in the early growth period. Consequently, it was determined that leaf analysis can be carried out at any time from the beginning of vegetation for all elements except Fe and Cu.     

The nutritional status of asymptomatic HIV-infected Africans: directions for dietary intervention?

OBJECTIVE: To compare the relationships between food (nutrient) intakes and biochemical markers of nutritional status of asymptomatic HIV-infected with HIV-uninfected subjects, to gain more information on the appropriate diet for HIV-infected persons at an early stage of infection. DESIGN: Cross-sectional population-based survey. SETTING: North West Province, South Africa. SUBJECTS: Two hundred and sixteen asymptomatic HIV-infected and 1550 HIV-uninfected men and women volunteers aged 15 years and older, recruited as 'apparently healthy' subjects from 37 randomly selected sites. OUTCOME MEASURES: Food and nutrient intakes, measured with a validated food-frequency questionnaire, and nutritional status indicated by anthropometric and biochemical variables, measured by a standardised methodology. RESULTS: The prevalence of HIV infection in the study population was 11.9%. The anthropometric indices and nutrient intakes of HIV-infected and uninfected subjects did not differ significantly, indicating that these 216 HIV-infected subjects were at an early stage of infection. Of the biochemical nutritional status variables, high-density lipoprotein cholesterol and total cholesterol, haemoglobin, albumin and triglycerides were significantly lower in infected subjects. They also had higher globulin and liver enzyme levels than uninfected subjects. In infected subjects, serum albumin correlated significantly with serum lipids, serum vitamin A, serum vitamin E, serum iron, total iron-binding capacity and haemoglobin. The significant positive correlations of the liver enzymes with serum lipids, albumin, vitamin A and iron, observed in HIV-uninfected subjects, disappeared in the infected subjects. Polyunsaturated fat intake showed significant positive correlations with the increased liver enzymes in infected subjects. A principal components analysis indicated that, in infected subjects, increased liver enzymes correlated with higher consumption of maize meal and lower consumption of meat and vegetables. CONCLUSIONS AND RECOMMENDATIONS: This survey indicated that asymptomatic HIV-infected subjects who followed a diet rich in animal foods had smaller decreases in serum albumin, haemoglobin and lipid variables, and smaller increases in liver enzymes, than those who consumed a diet based on staple foods. This suggests that animal foods are associated with improved nutritional status in HIV-infected persons. These results should be confirmed with intervention studies before dietary recommendations for asymptomatic HIV-infected individuals can be made.     

Are research priorities in Latin America in line with the nutritional problems of the population?

OBJECTIVE: Concordance of nutritional research priorities with the related burden of disease is essential to develop cost-effective interventions to address the nutritional problems of populations. The present study aimed to evaluate whether nutrition research priorities are in agreement with the population's nutritional problems in Latin America. DESIGN: The epidemiological profile was contrasted with the research priorities and research produced by academic institutions for each country. Qualitative analysis of research production by type of contribution to problem solving was also conducted. SETTINGS: Nine Latin American countries. RESULTS: Obesity (high body mass index (BMI)) and micronutrient deficiencies (anaemia) emerged as key problems, followed by stunting, breast-feeding/lactation and low birth weight. Wasting in children and women (low BMI) was uncommon. Concordance of ranked research priorities with the epidemiological profile of the country was generally good for nutrition-related chronic diseases, micronutrients and low birth weight, but not for undernutrition, stunting and breast-feeding. Studies on the efficacy and effectiveness of interventions were uncommon. CONCLUSIONS: The present research agenda insufficiently supports the goal of public health nutrition, which is to ensure the implementation of cost-effective nutrition programmes and policies. A more rational approach to define research priorities is needed.     

Are dietary diversity scores related to the socio-economic and anthropometric status of women living in an urban area in Burkina Faso?

OBJECTIVES: To study dietary diversity and its relationship with socio-economic and nutritional characteristics of women in an urban Sahelian context. DESIGN: A qualitative dietary recall was performed over a 24-h period. Dietary diversity scores (DDS = number of food groups consumed) were calculated from a list of nine food groups (DDS-9) or from a list of 22 food groups (DDS-22) which detailed both micronutrient- and energy-dense foods more extensively. Body mass index (BMI), mid upper-arm circumference and body fat percentage were used to assess the nutritional status of the women. SETTING AND SUBJECTS: Five hundred and fifty-seven women randomly selected in two districts of Ouagadougou, the capital of Burkina Faso. RESULTS: The mean DDS-9 and DDS-22 were 4.9 +/- 1.0 and 6.5 +/- 1.8 food groups, respectively. In the high tertile of DDS-22, more women consumed fatty and sweetened foods, fresh fish, non-fatty meat and vitamin-A-rich fruits and vegetables. The DDS-9 was not associated with the women's socio-economic characteristics whereas the DDS-22 was higher when the women were younger, richer and had received at least a minimum education. Mean BMI of the women was 24.2 +/- 4.9 kg m-2 and 37% of them were overweight or obese (BMI > or = 25 kg m-2). Neither the DDS-9 nor the DDS-22 was associated with the women's anthropometric status, even though there was a trend towards fewer overweight women in the lowest tertile of DDS-22. CONCLUSION: In this urban area, the qualitative measurement of dietary diversity is not sufficient to identify women at risk of under- or overweight.     

Folate status and mood: is there a relationship?

OBJECTIVE: To explore the relationship between subjective mood, folate status and homocysteine in healthy individuals. DESIGN: Subjective mood assessments were completed twice daily over the course of one week using the Positive and Negative Affect Scale (PANAS). The PANAS is a validated scale which considers mood state on two distinct continua, one reflecting positive mood and the other negative mood, each requiring response to 10 adjectives on a Likert scale. A blood sample was taken on one occasion at the start of the week during which subjective mood was assessed and analysed for red-blood-cell (RBC) folate, serum folate and plasma homocysteine concentrations. SUBJECTS: Male volunteers aged 19-47 years (n = 58) were recruited from local industries. RESULTS: High concentrations of RBC folate were associated with less variability (lower standard deviation) in negative mood (P = 0.023). Subjective mood, however, was not related to serum folate or homocysteine. CONCLUSIONS: This study appears to be the first to uncover an association between long-term folate status and subjective mood (employing the PANAS) in healthy males. More research is needed to further explore the relationship between nutritional status and mood.     

Sulfur status of volcanic ash‐derived soils in Hawaii

Abstract

Several rainwater samples and 14 profiles of Hawaii's volcanic ash‐derived soils were analyzed for sulfur (S). Atmospheric deposition was an important S source at the coast (24 kg S/ha), but its contribution decreased with increasing distance from the sea (1 kg S/ha at 24‐km inland). The S concentration of rainwaters also decreased linearly with increasing rainfall.

Several thousand mg SO₄‐S/kg can be extracted from many volcanic ash‐derived soils of Hawaii, and it was often required at least four extractions [0.04 M Ca(H₂PO₄)₂, 1:10 soil to solution ratio] to completely desorb this SO₄. There was a close association of high SO₄ retention with high rainfall. This might have resulted from (1) the development of a solid phase with high SO₄ retention under intense weathering conditions, (2) more total SO₄ received by the soils from atmospheric deposition, and (3) past fertilization of sugarcane grown in high rainfall areas.

Low concentrations of soil solution SO₄‐S in relation to large amounts of P‐extractable SO₄ suggest that a S bearing mineral, such as basaluminite, may be controlling soil‐solution SO₄. Furthermore, SO₄ adsorption isotherms of these volcanic soils generally show a bi‐phasic property, and suggest that 40 to 80 mg SO₄‐S/kg is required to maintain 3 ‐ 6 mg SO₄‐S/L in the soil solution, a concentration range considered adequate for the growth of most crops.     

Lestes dryas kirby—a declining species of dragonfly (odonata) in need of conservation: Notes on its status and habitat in England and Ireland

A study of Lestes dryas was made in 1978. None was found in ten localities in south east England, which had held populations in the period 1940–1947. Major changes had occurred in eight of the localities, and these could readily account for the disappearance of the insect from them. A search for L. dryas was made in apparently suitable habitat in the Cambridgeshire Fens but none was found. L. dryas was found on three out of eighty waterbodies visited in the west and south of Ireland. Neutral or slightly acid waters with extensive emergent vegetation, notably Equisetum fluviatile, Scirpus lacustris and Typha sp., and supporting the dragonflies Sympertrum sanguineum and/or Coenagrion pulchellum, appear to indicate a suitable habitat for the species. The decline of L. dryas appears to have been caused by a combination of factors: loss of habitat, periods of drought and small population numbers.     

Effects of vesicular‐arbuscular mycorrhizas and phosphorus on water status and growth of apple

Apple (Malus hupehensis Rehd) seedlings were grown in sterilized and non‐sterilized soil with or without phosphorus (P) added and inoculated by VA mycorrhizal (VAM) fungi (Glomus versifome Daniels et Tappe and Glomus macrocarpum Tul et Tul). In sterilized soil, the VAM infection increased the transpiration rate (Tr.) of the leaves, reduced the stomatal resistance (Sr.) and the permanent wilting percentage (PWP) and enhanced the rate of recovery of the plant from the water stress and the plant growth (e.g. leaf number, stem diameter and dry weight). It also increased absorption of most minerals, especially Zn and Cu by the roots and weakened the P‐Cu and P‐Zn interactions. Phosphorus fertilization had some positive effects on the water status, P nutrition and growth, but it reduced the Cu concentration. VAM improved the water status and enhanced drought tolerance of the trees by enhancing absorption and translocation of water by the external hyphae. The efficiency of inoculation in nonsterile soil was not obvious.     

Differing N status and N retention processes of soils under old-growth lowland forest in Eastern Amazonia,Caxiuanã, Brazil

Indirect evidence of the nitrogen (N) status of tropical forests strongly suggests that in heavily weathered soils under old-growth lowland tropical forests nitrogen is in relative excess. However, within the lowland forests of the Amazon basin, there is substantial evidence that soil texture influences soil NH₄⁺ and NO₃^? concentrations and hence possibly N availability and retention in the soil. Here, we evaluate the soil N status of two heavily weathered soils which contrast in texture (sandy versus clay Oxisol). Using ¹⁵N pool dilution, we quantified gross rates of soil N cycling and retention. We also measured the δ¹⁵N signatures from the litter layer down to 50-cm depth mineral soil and calculated the overall ¹⁵N enrichment factor (ε) for each soil type. The clay soil showed high gross N mineralization and nitrification rates and a high overall ¹⁵N enrichment factor, signifying high N losses. The sandy soil had low gross rates of N cycling and ¹⁵N enrichment factor, manifesting a conservative soil N cycling. Faster turnover rates of NH₄⁺ compared to NO₃^? indicated that NH₄⁺ cycles faster through microorganisms than NO₃^?, possibly contributing to better retention of NH₄⁺ than NO₃^?. However this was opposite to abiotic retention processes, which showed higher conversion of NO₃^? to the organic N pool than NH₄⁺. Our combined results suggest that clay Oxisol in Amazonian forest have higher N availability than sandy Oxisol, which will have important consequences for changes in soil N cycling and losses when projected increase in anthropogenic N deposition will occur.     

Phytoindication of the water status and nutrient supply of oil-polluted soils in the middle reaches of the Ob’ River

The method of phytoindication of the soil water status and nutrient supply was applied to natural and oil-contaminated soils in the middle reaches of the Ob’ River. These soil characteristics were indirectly assessed using the ecological scales developed by L. G. Ramenskii. On this basis, changes in the soil water status and nutrient supply under the impact of soil contamination with oil and oil products were estimated for the particular soil and landscape conditions     

The status and ecology of the dama gazelle in the aïr and ténéré national nature reserve,Niger

As part of the biological survey of the recently proposed Aïr and Ténéré National Nature Reserve in Niger, information was gathered on the status and ecology of the dama gazelle Gazella dama. The population of the reserve was estimated at 150–250. Dama gazelle were most often in small harems or mixed groups, or singly. Average group size was 1·92±1·20. Dama gazelles were primarily browsers, with the leaves of Balanites aegyptiaca and Acacia tortilis forming the bulk of their diet. They were most often observed in temporary watercourses. The primary threats to dama gazelle in the reserve were hunting and habitat degradation, and conservation measures are proposed.     

Rice genotype differences in nutrient status under excessive ferric‐iron conditions

To investigate the relationship between rice genotypic variation in tolerance to iron (Fe) toxicity and nutrient element status, 10 rice genotypes with different growing performances under Fe toxicity were grown under normal culture solution and with excessive ferrous (Fe²⁺)‐Fe concentrations of 250 and 500 mg Fe²⁺ L^‐1. A close relationship was obtained between the relative ratio of symptomatic leaf numbers to total leaf numbers (SLN/TLN) and a relative decrease in dry matter under Fe²⁺‐toxicity conditions. The genotypic variations in nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) uptake were evaluated by the relative decrease in the N, P, K, and Mg content in the plants. Remarkable genotypic variation in tolerance to excessive Fe²⁺ was observed. The results indicated that excessive Fe²⁺ reduced N, P, K, and Mg uptake. The nutrient element concentrations, however, were still higher above deficient criteria even in severely affected plants, suggesting that the retardation of growth may not be intirely due to the deficiency of these elements in plants at the seedling stage. Significant correlations were found between the genotypic variation and the decrease in N, P, K, and Mg uptake and in their tolerance to Fe²⁺ toxicity, which suggests that the ability to maintain higher nutrient element uptake under a Fe²⁺‐toxic condition contributes the tolerance to Fe²⁺ toxicity.     

Phosphorus‐deficiency effects on response of symbiotic N2 fixation and carbohydrate status in soybean to atmospheric CO2 enrichment

The impact of phosphorus (P) deficiency on response of symbiotic N₂ fixation and carbohydrate accumulation in soybean (Glycine max [L.] Merr.) to atmospheric CO₂ enrichment was examined. Plants inoculated with Bradyrhizobium japonicum MN 110 were grown in growth chambers with controlled atmospheres of 400 and 800 μL CO₂ L^‐1 and supplied either 1.0 mM‐P (P‐sufficient) or 0.05 mM‐P (P‐deficient) nitrogen (N)‐free nutrient solution. When plants were supplied with sufficient P, CO₂ enrichment significantly increased whole plant dry mass (83%), nodule mass (67%), total nitrogenase activity (58%), and N (35%) and P (47%) accumulation at 35 days after transplanting (DAT). Under sufficient P supply, CO₂ enrichment significantly increased starch concentrations in nodules compared to the normal atmospheric CO₂ treatment. Under normal CO₂ levels (400 μL L^‐1) nonstructural carbohydrate concentration (starch plus soluble sugar) was significantly higher in leaves of P‐deficient plants than in leaves of P‐sufficient plants in which nonstructural carbohydrate concentration exhibited a strong diurnal pattern. Under deficient P supply whole plant dry mass, symbiotic N₂‐fixation parameters, and N and P accumulation were not enhanced by atmospheric CO₂ enrichment. Phosphorus deficiency decreased nonstructural carbohydrate accumulation in nodules at the end of a 10‐day period in which functional activity was developing by 86% relative to P‐sufficient controls. While P deficiency elicited significant increases in the nonstructural carbohydrate concentration in leaves, it caused significant decreases in the nonstructural carbohydrate concentration in nodules over the diurnal cycle from 30 to 31 DAT. Collectively, these results indicate that the lack of a symbiotic N₂‐fixation response to atmospheric CO₂ enrichment by P‐deficient plants may be related to the decreased carbohydrate status of nodules.     

Sulphur fertilizer effect on cotton: I. Nitrogen and sulphur status and petiole nitrate‐nitrogen

Abstract

The effect of S fertilization on S and N status and petiole NO₃ ^?‐N in cotton was observed during the growing seasons of 1980 and 1981. Four sites representing 2 soil subgroups were studied using a randomized complete block design with 4 replications. Leaf and petiole sampling began one week prior to bloom initiation and continued weekly for eight weeks. Leaf samples were analyzed for S and N and the petioles for NO₃ ^?‐N. Levels of leaf‐S varied directly with amounts of applied S. Leaf‐N and petiole NO₃ ^?‐N varied directly with amounts of applied N. Though not always significant, petiole NO₃ ^?‐N and leaf‐N showed negative correlations with leaf‐S. These results suggest that knowledge of the cotton plant S status may be necessary to interpret petiole NO₃ ^?‐N for N fertilization of cotton.     

Yield and nutritional evaluation of the banana hybrid ‘FHIA-18’ as influenced by phosphate fertilization

Abstract

The ‘FHIA-18’ hybrid banana is an alternative for producers as it is resistant to Black Sigatoka and Panama disease. However, few studies report the nutritional requirement of this hybrid, especially phosphorus. It is known that the efficiency of phosphorus use can be improved, reducing the need for application, depending on the genotype cultivated. Therefore, this study aimed to evaluate the yield and mineral nutrition of ‘FHIA-18’ hybrid banana on phosphate fertilization. A banana orchard with the cultivar ‘FHIA-18’ was conducted on a Typical Red Latosol. Then, triple superphosphate fertilizer was applied on plants at 0, 20, 30, 40, 50, and 60?kg ha^?1?year^?1, over three productive seasons. At the time of flowering the macro and micronutrient contents of the leaves were evaluated. Subsequently, the nutrient contents of the fruits were evaluated. For this, fruit pulp samples from the third and fourth hands were collected. In addition, yield was estimated considering cluster mass and plant density. The following dose 36?kg ha^?1 of P₂O₅ year^?1 increased the content of phosphorus in the leaf, despite that banana hybrid cultivar FHIA 18 demanded 50% of the recommended fertilizer to achieve its maximum yield (29.4 t ha^?1?year^?1). Phosphate fertilization promoted significant changes in P, Ca, Cu, and Zn contents of leaves and fruits. Therefore, it is concluded that the mineral nutrition of banana ‘FHIA-18’ is affected by phosphate fertilization, as well as requiring less P than recommended to achieve higher yield.