Soil Nutritional Status Research Articles

English

Lack of indigenous soil rhizobia that colonize and nodulate soybean (Glycine max L. Merrill) roots is a common problem of South African soils. Bradyrhizobium japonicum strain WB74 has long been used as an effective commercial inoculant strain for soybean since its introduction in 1998. This paper investigates the major limiting factors involved in the nodulation efficiency of B. japonicum WB74 that affect soybean growth and yield in South Africa. Methods including analysis of soil physicochemical properties, farmers’ management practices and quality control tests of locally manufactured inoculant products were employed. Inoculant’s strain verification was conducted using phylogenetic analysis of the 16S ribosomal RNA of the Bradyrhizobium strains in each of the inoculant product. The major findings of this study is that nodulation failure of introduced B. japonicum is caused by a combination of several limiting factors such as acidic nature of the soils as well as poor soil nutrition status especially that of phosphorous. Nodulation failure was also prominent in the soybean farms where there was no proper soil management practice. Results of the viability and shelf life studies also indicate that nodulation failure is caused by using sub-standard soybean inoculants products available on the market. Key words: Bradyrhizobium japonicum WB74, inoculants, nodulation, quality control.

Phosphorus and Potassium Fertilizer Effects on Alfalfa and Soil in a Non‐Limited Soil

Fertilization strategies for high‐yielding alfalfa (Medicago sativa L.) should take in account the increase in soil nutritional status that occurred during the last decades in areas with intensive agricultural use. A field study was conducted at the University of Padova, northeastern Italy, to determine the response of alfalfa yield and nutritive value to various combinations of P and K rates in a soil lacking nutrient deficiency. Alfalfa cultivar Delta was seeded in March 2005 on a silt loam soil having 38 mg kg–1 available P and 178 mg kg–1 exchangeable K. Nine treatments deriving from the combination of three P fertilization rates (0, 100, and 200 kg ha–1 P2O5) and three K rates (0, 300, and 600 kg ha–1 K2O) were compared in a randomized complete block design. Plots were harvested at bud stage during three growing seasons (2005–2007) and dry matter (DM) yield, forage nutritive value, P and K contents, canopy height, and stem density were measured at each harvest. Soil samples were collected at the end of the research period for determination of available P and exchangeable K. The results demonstrated that P application had no impact on yield and did not interact with K in determining productivity, while K had a positive effect on yield. However, the 300 kg ha–1 K2O rate appeared sufficient to maximize yield, without adverse effects on the forage nutritive value. Data from soil analyses showed that alfalfa has a high K uptake even when it is fertilized at high rates.

Fertilization Affects Biomass Production of Suaeda salsa and Soil Organic Carbon Pool in East Coastal Region of China

Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon (SOC) is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon (LOC) concentration, SOC pool and carbon management index (CMI) as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates (0 (N0), 60 (N1), 120 (N2) and 180 kg ha−1 (N3)), three P-fertilization rates (0 (P0), 70 (P1) and 105 kg ha−1 (P2)) and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production (above-ground biomass and roots), bulk density (ρb), available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased ρb at the 0–20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0–20 and 20–40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass (above-ground biomass and roots) and SOC as well as LOC in 2010 and 2011 across all soil depth, respectively. The treatment with N at 180 kg ha−1 and P at 105 kg ha−1 was superior to the other treatments. The results from the 2-yr continuous experiments indicated that, in short-term, there were a few accumulation of SOC and LOC concentrations by means of N and P application to S. salsa, whereas in the long run, S. salsa with N and P application was recommended for coastal tidal lands because of its great potential of carbon sequestration, improvements of soil nutrition status and promotion of soil quality.

Soil nutritional status, not inoculum identity, primarily determines the effect of arbuscular mycorrhizal fungi on the growth of Knautia arvensis plants

Arbuscular mycorrhizal (AM) symbiosis is among the factors contributing to plant survival in serpentine soils characterised by unfavourable physicochemical properties. However, AM fungi show a considerable functional diversity, which is further modified by host plant identity and edaphic conditions. To determine the variability among serpentine AM fungal isolates in their effects on plant growth and nutrition, a greenhouse experiment was conducted involving two serpentine and two non-serpentine populations of Knautia arvensis plants grown in their native substrates. The plants were inoculated with one of the four serpentine AM fungal isolates or with a complex AM fungal community native to the respective plant population. At harvest after 6-month cultivation, intraradical fungal development was assessed, AM fungal taxa established from native fungal communities were determined and plant growth and element uptake evaluated. AM symbiosis significantly improved the performance of all the K. arvensis populations. The extent of mycorrhizal growth promotion was mainly governed by nutritional status of the substrate, while the effect of AM fungal identity was negligible. Inoculation with the native AM fungal communities was not more efficient than inoculation with single AM fungal isolates in any plant population. Contrary to the growth effects, a certain variation among AM fungal isolates was revealed in terms of their effects on plant nutrient uptake, especially P, Mg and Ca, with none of the AM fungi being generally superior in this respect. Regardless of AM symbiosis, K. arvensis populations significantly differed in their relative nutrient accumulation ratios, clearly showing the plant's ability to adapt to nutrient deficiency/excess.

Coffee is highly tolerant to cadmium, nickel and zinc: Plant and soil nutritional status, metal distribution and bean yield

Sewage sludge has been used to fertilize coffee, increasing the risk of metal contamination in this crop. The aim of this work was to study the effects of Cd, Zn and Ni in adult coffee plants growing under field conditions. Seven-year-old coffee plants growing in the field received one of three doses of Cd, Zn or Ni: 15, 45 and 90 g Cd plant −1; 35, 105 and 210 g Ni plant −1; and 100, 300 and 600 g Zn plant −1, with all three metals in the form of sulphate salts. After three months, we noticed good penetration of the three metals into the soil, especially in the first 50 cm, which is the region where most coffee plant roots are concentrated. Leaf concentrations of K, Ca, Mg, S, B, Cu, Fe and Mn were not affected. N levels did not change with the application of Ni or Zn but were reduced with either 45 or 90 g Cd plant −1. Foliar P concentrations decreased with the addition of 45 and 90 g Cd plant −1 and 600 g Zn plant −1. Zn levels in leaves were not affected by the application of Cd or Ni. The highest concentrations of Zn were found in branches (30–230 mg kg −1), leaves (7–35 mg kg −1) and bean (4–6.5 mg kg −1); Ni was found in leaves (4–45 mg kg −1), branches (3–18 mg kg −1) and beans (1–5 mg kg −1); and Cd was found in branches (0–6.2 mg kg −1) and beans (0–1.5 mg kg −1) but was absent in leaves. The mean yield of two harvests was not affected by Ni, but it decreased at the highest dose of Zn (600 g plant −1) and the two higher doses of Cd (45 and 90 g plant −1). Plants died when treated with the highest dose of Cd and showed symptoms of toxicity with the highest dose of Zn. Nevertheless, based on the amounts of metal used and the results obtained, we conclude that coffee plants are highly tolerant to the three metals tested. Moreover, even at high doses, there was very little transport to the beans, which is the part consumed by humans.

Plasticity in the expression of direct and indirect defence traits of young plants of Mallotus japonicus in relation to soil nutritional conditions

Although soil nutrients can influence the defence strategy of plants that have multiple defence traits, to date, there have been few studies to examine this. To evaluate the effect of soil nutrients on multiple plant defences, we cultivated Mallotus japonicus under three soil nutritional conditions in the field, and experimentally examined the expression of a physical defence trait (trichomes), chemical traits (pellucid dots), and biotic traits (extrafloral nectaries (EFNs) and pearl bodies) of the plants, and the number of ants visiting them. Under the low soil nutritional condition, plants strongly expressed the physical defence by trichomes and chemical defence by pellucid dots, meaning that the young plants adopted direct defences under the poor soil nutritional condition. Under the high soil nutritional condition, in contrast, the plants strongly expressed the indirect defence traits. They produced abundant EFNs and pearl bodies, and attracted many ants. These results suggest that young plants of M. japonicus use different defence modes in response to different soil nutritional conditions.

GIS-based modeling of potential yield distributions for different oat varieties in China

Cultivation of the common oat ( Avena sativa L.) and the naked oat ( Avena nuda L.) can be highly productive in many types of environments because these species are tolerant to infertile, dry and salty environments. In this study, we modeled the distribution of potential yields for different varieties of oat in China based on GIS assessments. We analyzed the yield of three oat varieties under different environmental conditions and created a model of factors significantly correlated with yield. Stepwise regression models were constructed for each oat variety, and the potential yield distributions were calculated for each variety. Correlating oat variety yield with environmental factors showed that precipitation and soil nutrition content were the most important factors in oat production. Precipitation and soil nutrition during the month of April were positively correlated with yield, while temperature and wind speed in July were negatively correlated with yield. The common oat variety “Qingyj444” was capable of producing a fresh grass yield of 30,000 kg/hm 2 in western Sichuan, the southwest of Gansu, and certain parts of Qinghai and Heilongjiang province. The naked oat varieties “Bayou3” and “Pin5” produced high yields of 3000 kg/hm 2 in Heilongjiang, the regions north of Shanxi, east of Neimenggu and the southern Gansu province, areas with high quality rain and soil nutrition conditions. We constructed a “China Crop Mapping Decision System” based on our findings, and this system is accessible through the internet and will facilitate informed agricultural decision-making.

Production, nutritional status and chemical properties of soils with addition of cattle manure, reactive natural phosphate and biotite schist in Massai cultivar

The objective of this work was to evaluate the effects of cattle manure, reactive natural phosphate and biotite schist on the soil fertility, yield and nutritional status of Megathyrsus spp. cv. Massai. The experiment was conducted under field conditions, in a dystrophic Red Yellow Latosol (Oxisol). It was used a randomized block experimental design with the following treatments: three natural reactive rock phosphate from Algeria (Djebel-Onk) doses (0, 100 and 200 kg ha-1 of P2O5), three biotite schist doses (0, 150 and 300 kg ha-1 of K2O) and three cattle manure doses (0, 20 and 40 t ha-1). The application of natural phosphate increased dry matter yield, however, application of cattle manure and biotite schist did not influence this variable. Foliar levels of nitrogen, potassium and magnesium (cattle manure), phosphorous and boron (natural rock phosphate) and potassium (biotite schist) were influenced by the applied fertilizer doses. Only the levels of phosphorous in the soil and in the plant and levels of magnesium and boron in the plant show interaction with dry matter yield of Massai cultivar.

SOIL NUTRITIONAL STATUS OF APRICOT (PRUNUS ARMENIACA L.) ORCHARDS IN MALATYA PROVINCE

Apricot (Prunus armeniaca L.) is one of the most important fruits in Malatya province. Nutritional status of soils is an important factor that affects yield and fruit quality. In this study, some physical and chemical properties of soil samples collected from 30 cm depth from different apricot orchards in Malatya region between 2003-2007 were investigated in the Soil and Plant Analysis Laboratory of the Fruit Research Institute. Organic matter, pH, CaC0 3 , EC, texture, available P, exchangeable K of soil samples were determined and compared to standard limits given for soils. Most soil samples were highly calcareous, low in organic matter contents. There was no salinity problem. The pH of soil samples was alkaline and slightly alkaline. Available P, exchangeable K were generally found in high levels.

An evolutionary perspective on morphological and ecological characters in the mushroom family Inocybaceae ( Agaricomycotina, Fungi)

Inocybaceae is one of the larger families among the gilled mushrooms ( Agaricales) but their morphology-based taxonomy is still not fully settled considering molecular-based phylogenetic insights. Here we investigate the evolution of five morphological and four ecological characters using ancestral state reconstruction methods. All the morphological characters are correlated with the phylogeny, but we find spore shape and presence of cortina, to have the greatest taxonomic potential, as they are the most evolutionarily conserved. None of the five characters have, however, evolved in a way that easily delimits inclusive monophyletic groups and the section level taxonomy needs revision. Host preference, preference for calcareous soil, and soil nutritional status preference are shown to be reflective of the evolutionary history of the species at the scale investigated here while soil moisture preference is not. The states of three of the four ecological characters can therefore be predicted in a phylogenetic framework for species where they are unknown.

Repeated application of diluted olive mill wastewater induces changes in the structure of the soil microbial community

Repeated application of diluted olive mill wastewater (OMW) is a common disposal method which allows the application of large amounts of OMW and improves the organic matter and nutrient status of Mediterranean soils. However, there is lack of information regarding the effects of this practice on the soil microbial community. A study was carried out to investigate these effects on the structure of the bacterial and fungal community of a loamy sand (LS) and a sandy loam (SL) soil, using denaturating gradient gel electrophoresis (DGGE) fingerprinting. OMW was daily applied as aqueous solutions of 0, 2 and 4%, in the presence or absence of nitrogen fertilization, for a three-month period. Multivariate analysis of the DGGE profiles showed that OMW applications resulted in marked changes in the fungal community in both soils, while nitrogen fertilization diminished these effects. Small effects were evident for the bacteria only in the LS soil and this was attributed to the higher availability of OMW-derived phenolics in this soil which resulted in a direct impact on bacteria. Nitrogen fertilization alleviated the effects of OMW on the bacterial community. We suggest that the impact of OMW on the structure of the soil microbial communities was mostly a result of its indirect effect on the soil nutritional status, which becomes enriched in organic substrates and poor in available nitrogen.

Effects of soil application of olive mill wastewaters on the structure and function of the community of arbuscular mycorrhizal fungi

Recycling of olive mill wastewaters (OMW) into agricultural soils is a controversial issue since benefits to soil fertility should counterbalance potential short-term toxicity effects. We investigated the short-term effects of OMW on the soil–plant system, regarding the diversity, structure and root colonization capacity of arbuscular mycorrhizal (AM) fungi and the respective growth response of Vicia faba L, commonly used as green manure in olive-tree plantations. A compartmentalized pot system was used that allowed the establishment of an AM fungal community in one compartment (feeder) and the application of three OMW dose levels in an adjacent second compartment (receiver). At 0, 10, and 30 days after OMW treatment (DAT), V. faba pre-germinated seeds were seeded in the receiver compartment. At harvest, shoot and root dry weights, AM fungal root colonization, soil hyphal length and P availability were recorded in the receiver compartment. In addition, OMW effects on AM fungal diversity in plant roots were studied by DGGE. A transient effect of OMW application was observed; plant growth and AM fungal colonization were initially inhibited, whereas soil hyphal length was stimulated, but in most cases differences were absent when seeding was performed 30 DAT. Similarly, changes induced in the structure of the root AM fungal community were of transient nature. Cloning and sequencing of all the major DGGE bands showed that roots were colonized by Glomus spp. The transient effects of OMW on the structure and function of AM fungi could be attributed to OMW-derived phytoxicity to V. faba plants or to an indirect effect via alteration of soil nutritional status. The high OMW dose significantly increased soil P availability in the presence of AM fungi, suggesting efficient involvement of AM fungi in organic-P minerilization. Overall our results indicate that soil application of OMW would cause transient changes in the AM fungal colonization of V. faba plants, which, would not impair their long-term plant growth promoting ability.

Canopy of three forest species and their relation to adaptation to by erosion degraded soils

During 30 months an experiment was carried out at the locality of Firavitoba - Boyaca, to evaluate and analyze the canopy changes and the adaptive capacity of three cold climate forest species, Alnus acuminata H. B. K., Escallonia pendula Pers. and Quercus humboldtii Bompl., in a by water eroded degraded soil. All three species were planted in two spatial arrangements tres bolillo and square methods. The species were situated in distinct treatments of simple and compound mixtures. Plant height, leaf emission, leaf area index (LAI), crown diameter expansionaand fallen leaf litter were measured. It was determined that A. acuminata is a high sensible plant to drought stress, presenting high losses of planted trees, while, E. pendula showed the major survival index. However, A. acuminata had the best elongation index, a major leaf rate emission and a constant growth of LAI, even though it showed periods of massive leaf fall. Q. humboldtii demonstrated to be a species that needs shading during the first 24 months after transplanting, since, when sown in monoculture, the plant growth was slow and the development of few leaf structures was observed. The three species improved the soil nutrition conditions due to the litter incorporation. The research established the planting conditions for the three species and concluded that it is possible to use them in order to promote reforestation programs, preferably in mixtures, on soils with high erosion levels.

Soil and plant nutritional status in fruit orchards in Syria

A study was conducted over 15 years in apple, peach, pear, citrus, grapevine and olive orchards in different locations in Syria. The study aimed at monitoring and evaluating the long-term nutrient behaviour in plants and soil in order to suggest measures for nutrient management improvement. Leaf and soil samples were collected in the years 1982, 1987, 1990 and 1997. The soils were characterized by high pH values, high CaCO 3 and low to medium organic matter contents. Due to the unfavourable soil conditions and ill-chosen fertilizer use, the nutrient balance in the plant tissues was disturbed. To correct the situation, the application of improved nutrient management practices was suggested.

Sensitivity and uncertainty analysis from a coupled 3-PG and soil organic matter decomposition model

3-PG [Landsberg, J.J., Waring, R.H., 1997. A generalised model of forest productivity using simplified concepts of radiation-use efficiency, carbon balance and partitioning. Forest Ecol. Manage. 95, 209–228] is a process-based model using simplified physiological concepts such as light use efficiency, a constant ratio between net and gross primary production and a simple stand nutritional status parameter. This last parameter is commonly adjusted manually to fit observations, based on data from field surveys. It has been shown that nutritional status has a significant effect on estimated gross and net productivity and it has been suggested that the introduction of a soil sub-model could overcome such problems. This paper introduces a soil organic matter decomposition model within the routines of 3-PG. ICBM/2N (Introductory Carbon Balance Model [Andrén, O., Kätterer, T., 1997. ICBM: the introductory carbon balance model for exploration of soil carbon balance. Ecol. Appl. 7, 1226–1236]) was chosen because it operates at a level of complexity similar to 3-PG. The new model 3-PGN (3-PG Nitrogen) includes three soil carbon and three soil nitrogen pools with eleven additional parameters. This approach provides a new way to account for soil nutritional status within 3-PGN by introducing a fertility rating that varies over the life of a stand. We present the integrated model and describe the basic concepts of the integration. The model has been calibrated and tested for commercial plantations of Scots pine ( Pinus sylvestris L.) in Scotland. An uncertainty analysis was performed based on a Bayesian framework using Monte Carlo simulations and a sensitivity analysis to understand the model’s feedbacks and interactions between parameters and outputs. The results show that the least uncertain parameters were the most sensitive, having the greatest effect on many of 3-PGN’s outputs, including quantum yield efficiency, specific leaf area and foliage:stem biomass partitioning ratio. Although the soil sub-model had no direct effect on productivity, strong non-linear relationships were found between many of the soil parameters and 3-PGN outputs. Root turnover rate was found to be the most uncertain parameter, whereas the ratio of net to gross primary production was the least. Finally, through the validation procedure it was shown that 3-PG’s self-thinning routine may cause problems when predicting the number of stems in stands with low fertility.

Efeitos do substrato, bordas e proximidade espacial na estrutura da comunidade arbórea de um fragmento florestal em Lavras, MG

The present study aimed at detecting the influence of both edge effects and space substrate-related variables on the structural variations of the tree community in a small (4.0 ha) forest fragment in Lavras, Minas Gerais state, SE Brazil. Trees with diameter at breast height (dbh) > 5 cm were identified and measured in 29 (20 ×20 m), systematically distributed plots over the fragment. Substrate-related variables were obtained for each plot from the topography, laboratory analyses of soil samples and soil compaction measures. An 'edge factor' was calculated per plot from the fragment morphometry. Spatial variables were derived from the Cartesian coordinates of plot center. A canonical correspondence analysis of the species distribution abundance indicated significant correlations with some variables of the environmental and spatial matrices. The first ones were drainage classes, mean elevation, and saturation of bases, which explained 22.4% of the total variance. The spatial variables, x and x2*y, explained 12.7%, but the two sets shared, indistinctly, 4.6% of the total variance. Therefore, apart from the unexplained and stochastic variations (69.5%), the species distribution on the fragment is primarily influenced by spatial proximity, soil nutritional status and ground water regime.

Organic banana production in Ecuador: Its implications on black Sigatoka development and plant–soil nutritional status

AbstractBlack Sigatoka, caused by the leaf fungus Mycosphaerella fijiensis Morelet, is a major constraint to banana production around the world. In Ecuador, the biggest banana-exporting country in the world, this disease has become increasingly aggressive. This has resulted in more fungicide applications, which have significantly increased costs in production and for the environment. Consequently, many banana growers have shifted to organic production, which produces greater economic returns as a result of higher sale prices. In addition, production costs are lower as no fungicides are applied. These organic bananas receive substantial amounts of organic products. This study describes the black Sigatoka disease and nutrient status in an organic banana plantation and compares it with a conventionally fertilized and fungicide-treated plantation. Black Sigatoka symptoms were evaluated in the vegetative and flowering stages under both production conditions and in vitro conditions. Univariate and multivariate descriptive statistics were used to analyze the parameters. Disease symptoms were more severe in leaves from the organic field than in leaves from the inorganic field, but the nutrient status (soil and foliar) did not differ between the two farms. Banana plants from the organic farm had 12 functional leaves at flowering and eight functional leaves at harvest. Average banana yields were over 40% lower for organic versus inorganic management; however, the average price received for organic bananas was over two times higher. Profit–cost analysis has shown that the organic banana farm was substantially more profitable than the inorganic one during the time period analyzed. These results indicated that bananas can be grown commercially without fungicides, and the lower productivity levels are compensated by higher prices of organic fruits in international markets. In addition, organic production has beneficial impacts on social and environmental issues.

Soil-to-plant transfer of 137Cs and 40K in an Atlantic blanket bog ecosystem

The transfer of 137Cs and 40K from soil to vegetation was studied in an Atlantic blanket bog ecosystem along the Atlantic coast of Ireland where the dominant vegetation is a mixture of Calluna vulgaris, Eriophorum vaginatum and Sphagnum mosses. The impact of soil chemistry and nutritional status of vegetation on the uptake of both radionuclides was also examined. Cesium-137 transfer factors values ranged from 1.9 to 9.6 and accumulation of 137Cs was higher in the leaves of C. vulgaris than in the stems. Transfer factors values for 137Cs in both C. vulgaris and E. vaginatum were similar indicating that for the vegetation studied, uptake is not dependent on plant species. The uptake of 137Cs in bog vegetation was found to be positively correlated with the nutrient status of vegetation, in particular the secondary nutrients, calcium and magnesium. Potassium-40 transfer factors ranged from 0.9 to 13.8 and uptake was higher in E. vaginatum than in C. vulgaris, however, unlike 137Cs, the concentrations of 40K within the leaves and stems of C. vulgaris were similar. The concentration of both 137Cs and 40K found in moss samples were in general lower than those found in vascular plants.

Fertility Influence of the U.S. Midwestern Soils on Yellow Shoulder Disorder in Processing Tomatoes

The economics of processing tomato production are driven by soluble solids content, viscosity, color, and color uniformity of the fruit. Ripening disorders that affect color are a major limitation to the economic success of processing whole-peel and diced products. The causes of ripening disorders are not completely understood, although it is clear that soil nutritional status, weather, plant genetics, and interactions among these variables are important factors. We sampled both soil and fruit from fields in Michigan, Ohio, and Indiana and were able to correlate soil fertility properties and fruit color. The correlation between soil properties and fruit color was different for fine- and coarse-textured soils. Fine-textured soils presented more frequent, but weaker, correlations with absolute color and within-fruit color differences when compared with coarse-textured soils. For fine-textured soils, exchangeable K correlated with a measure of within-fruit variation, L* difference (L*diff; r = −0.21, P < 0.01). Other measurements of K nutrition, K·Mg−½ ratio, Kact, and K%CEC, all correlated to the same extent (r = −0.29, P < 0.01). The highest correlations were identified between soil-available P and L* (r = −0.33, P < 0.01) and L*diff (r = −0.31, P < 0.01). In coarse-textured soils, exchangeable K correlated with L* (r = −0.373, P < 0.05), b* (r = −0.49, P < 0.01) and Hue° (r = −0.37, P < 0.05). K·Mg−½ ratio and Kact yielded higher correlation coefficients with absolute color measurements when compared with fine-textured soils. Soil-available P was correlated with L* (r = −0.375, P < 0.05), a* (r = 0.49, P < 0.01), Hue° (r = −0.46, P < 0.01), and C* (r = 0.40, P < 0.01). For coarse soils, K·Mg−½ ratio, Kact, and available P were important properties when the color of tomato fruit is of value. In all cases, higher exchangeable K and P nutrient status had a positive correlation with fruit color. Our sampling could not detect interactions among weather, genetics, and soil, and further work will be necessary to clearly describe the role of interactions in determining fruit quality in tomatoes.

Quantitative prediction of the distribution and abundance of Vaccinium myrtillus with climatic and edaphic factors

AbstractQuestion: Can the distribution and abundance of Vaccinium myrtillus be reasonably predicted with soil nutritional and climatic factors?Location: Forests of France.Methods: We used Braun‐Blanquet abundance/dominance information for Vaccinium myrtillus on 2905 forest sites extracted from the phyto‐ecological database EcoPlant, to characterize the species ecological response to climatic and edaphic factors and to predict its cover/abundance at the national scale. The link between cover/abundance of the species and climatic (65 monthly and annual predictors concerning temperature, precipitation, radiation, potential evapotranspiration, water balance) and edaphic (two predictors: soil pH and C:N ratio) factors was investigated with proportional odds models. We evaluated the quality of our model with 9830 independent relevés extracted from Sophy, a large phytosociological database for France.Results: In France, Vaccinium myrtillus is at the southern limit of its European geographic range and three environmental factors (mean annual temperature, soil pH and C:N ratio) allow prediction of its distribution and abundance in forests with high success rates. The species reveals a preference for colder sites (especially mountains) and nutritionally poor soils (low pH and high C:N ratio). A predictive map of its geographic range reveals that the main potential habitats are mountains and northwestern France. The potential habitats with maximal expected abundance are the Vosges and the Massif central mountains, which are both acidic mountains.Conclusions: Complete niche models including climate and soil nutritional conditions allow an improvement of the spatial prediction of plant species abundance at a broad scale. The use of soil nutritional variables in distribution models further leads to an improvement in the prediction of plant species habitats within their geographical range.