Increment In Growth Research Articles

Heterotrophic cultivation of mixed microalgae for lipid accumulation and wastewater treatment during sequential growth and starvation phases: Effect of nutrient supplementation

Microalgae are deemed to be a potential biocatalyst for the production of biodiesel along with other valuable products. An attempt was made to evaluate the effect of sequential growth phase (GP) and starvation phase (SP) on the lipid productivity of heterotrophically grown mixed microalgae using domestic wastewater as substrate/feed-stock. Effect of nutrients viz., nitrogen (N), phosphorus (P), carbon (C) and potassium (K) on biomass growth and lipid accumulation was elucidated. Due to good nutrients availability during GP operation, significant increment in biomass growth was observed. On the contrary, nutrients deprived condition during SP operation documented increment in lipid productivity due to acceleration of triacylglycerides formation. Higher biomass growth was observed in GP operation with maximum in N + P condition (1.69 mg/mL) while higher lipid productivity was observed in starvation phase with maximum in C condition (28.2%). Gross fatty acid composition depicted significant variations in the fatty acid profile with abundance in saturated fatty acids (SFAs). Relatively good wastewater treatment efficiency in terms of substrate degradation and nutrient removal was observed during the GP operation. Diversity studies visualized dominance of lipid accumulating microalgae such as Scenedesmus sp., Diatoms and Chlorella sp.

Effect of tungsten on growth, biochemical constituents, molybdenum and tungsten contents in wheat

  The effect of various concentrations (3, 9, 27, 81, and 243 mg/kg) of tungsten (W) on growth performance, biochemical constituents and tungsten and molybdenum (Mo) contents in wheat was observed. Lower doses (up to 9 mg/kg) of tungsten showed promotory effects whereas higher doses retarded. An increment in growth, biomass, chlorophyll and carbohydrate contents was observed. Tungsten contents in root and shoot showed a very strong linear dependence on the soil applied W contents. Mo contents in plant tissue showed an increase with an increase in the W contents in plant tissue up to a threshold after which it showed an abrupt decrease. The activity of peroxidase enzyme decreased with lower application of W. Higher administration of tungsten (27–243 mg/kg) resulted in increased total phenol, free proline and activity of enzyme peroxidase.

Influence of Yeast, Micronutrients, and Vitamins-B on Growth, Yield and Controlling Weeds of Flax (Linum usitatissimum L.)

The results of applying micronutrients, yeast, thiamine and riboflavin have shown great results in increasing growth and yield productivity of flax cv. Giza 5. Yet, the combined application of the two vitamins plus micronutrients has been much more effective. Applying riboflavin plus micronutrients precisely at the moderate concentration of riboflavin was the best method. Hand weeded was also good, causing significant increment in crop growth and yield productivity. Significant results increased the oil yield percentage of all crop treatments. On the opposite side of the activity, weeds growth was also affected and the most significant results were obtained by applying riboflavin plus micronutrients. The above results showed a significant decrease in the seed germination percentage and seedling root and shoot growth of the two seeds selected for the investigation, including Portulaca oleracea L. and Echinochloa crus-galli L. We may, therefore, recommend riboflavin plus micronutrients at 50+ 1.5 mg L−1 as the best treatment that could be chosen for obtaining the best results over the two sides of action; combating weeds and increasing crop productivity.

Under strong niche overlap conspecifics do not compete but help each other to survive: facilitation at the intraspecific level

Summary 1. Competition among conspecifics of the same cohort has been traditionally thought to be a main process driving population dynamics. In this classical view, however, the role of facilitation in stressful conditions has rarely been considered. Here, using a transplant experiment across a forest–prairie gradient, we test whether the stress gradient hypothesis (SGH) extends to individuals thought to be strongly competing. 2. We transplanted 2‐year‐old seedlings of Nothofagus pumilio at two different densities (clusters of 10 and isolated) and at different distances from the forest edge (from 30 m inside the forest up to 50 m outside the forest in the prairie). We further stem‐mapped all seedlings belonging to the clusters and computed a competition index (CI). After 3 years of growing, survival and increment growth in diameter and height were measured and analysed using mixed‐effects models. We conducted a nearest‐neighbour analysis using seedlings’ CI and growth and computed model fit using the area under the curve (AUC) method. 3. Seedlings planted in dense clusters had significantly higher survival than solitary seedlings at the stressful end of the gradient. This trend was reversed at the opposite end of the gradient, supporting the SGH at the intraspecific level. Pursuing this at the level of the individual, we found that higher CIs (more neighbours) in seedlings predicted higher probabilities of their survival (facilitation) in stressful conditions. 4. Seedlings diameter and height increment growth were not affected by planting density and only diameter varied along the stress gradient; seedlings had higher diameter increments in growth outside the forest. Finally, when compared with conceptual models, our results mostly support predictions of a higher facilitation at intermediate position along the gradient. 5. Synthesis. We showed that facilitation overrides competition among tree seedlings even at locations under moderate stress; the facilitation process occurs in resource‐mediated interactions (niche overlapping). These results represent an important shift in our way to understand the density‐dependent mortality process, and calls for a model reformulation including positive interactions even when competition is expected to be strongest (conspecifics of the same cohort).

Effect of arbuscular mycorrhizal fungi on growth of Gmelina arborea in arsenic-contaminated soil

Arsenic (As) in the soils of South-Eastern Bangladesh is not only a threat for the health of millions of people but also a problem for plant growth due to its higher concentration in soil. Gmelina arborea Linn. is a promising fast growing tree species in Bangladesh which has also a potential to be planted in arsenic contaminated areas. This study assessed the role of arbuscular mycorrhizal (AM) fungi on the growth of G. arborea in arsenic amended soils at nursery stage. Before sowing seeds, soils were treated with four different concentrations (10 mg·kg−1, 25 mg·kg−1, 50 mg·kg−1, and 100 mg·kg−1) of Arsenic. Growth parameters (length of shoot and root, collar diameter, fresh and dry weight of shoot and root) of the plant, and mycorrhizal root colonization and spore population in the rhizosphere soil of G. arborea were recorded. Mycorrhizal seedlings showed better growth than non-mycorrhizal seedlings. Mycorrhizal seedlings planted in soil with 10-mg·kg−1 arsenic showed best performance in terms of growth, biomass and mycorrhizal colonization, compared to other treatments with higher concentration of arsenic. With increasing arsenic concentration, growth of seedlings, mycorrhizal infection rate and spore population, all decreased significantly (p<0.05). The mycorrhizal seedlings had as much as 40% higher increment in total growth and 2.4 times higher increment in biomass compared to non-mycorrhizal seedlings. The study clearly indicated that mycorrhizal inoculation could reduce the harmful effects of arsenic on the initial growth of G. arborea Linn. in degraded soil at nursery stage.

Nursery fertilization enhances survival and physiological status in Canary Island pine (Pinus canariensis) seedlings planted in a semiarid environment

We tested the hypothesis that fertilized containerized Pinus canariensis seedlings increases survival when planted in semiarid sites through the improvement of their physiological status during the establishment phase by an increment in root growth. Seedlings were cultured under two different regimes: traditional (in non-fertilized natural soil) and alternative (in fertilized peat). Morphological attributes and nitrogen content were measured before planting. Measurements of survival and growth in the plantation were made periodically for 2 years and physiological plant responses (leaf water potential, gas exchange and chlorophyll fluorescence) during the third summer after planting were tested and finally a set of plants were excavated to measure the same parameters as before planting. Seedlings cultivated using fertilized peat achieved the highest values for all of evaluated parameters. During the third dry season, big seedlings exhibited better physiological status. Therefore, enhanced root growth can result in better water uptake during the dry period thereby increasing survival and growth in the next few years after planting. A feed-back physiological model is proposed to explain P. canariensis establishment in a semiarid environment.

Plant Growth-Promoting and Rhizosphere-Competent Acinetobacter rhizosphaerae Strain BIHB 723 from the Cold Deserts of the Himalayas

A phosphate-solubilizing bacterial strain BIHB 723 isolated from the rhizosphere of Hippophae rhamnoides was identified as Acinetobacter rhizosphaerae on the basis of phenotypic characteristics, carbon source utilization pattern, fatty acid methyl esters analysis, and 16S rRNA gene sequence. The strain exhibited the plant growth-promoting attributes of inorganic and organic phosphate solubilization, auxin production, 1-aminocyclopropane-1-carboxylate deaminase activity, ammonia generation, and siderophore production. A significant increase in the growth of pea, chickpea, maize, and barley was recorded for inoculations under controlled conditions. Field testing with the pea also showed a significant increment in plant growth and yield. The rifampicin mutant of the bacterial strain effectively colonized the pea rhizosphere without adversely affecting the resident microbial populations.

Radial variation of vessel lumen diameter in relation to stem increment in 30 hardwood species

Vessel lumen diameter (VLD) is one of the most important anatomical indicators for demarcating juvenile wood and mature wood in hardwoods. In several species, we previously found that the age at which VLD stabilizes (maturation age) and the age at which the mean annual increment in radial stem growth was maximal were approximately the same. In the current study, we investigated the extent to which this relationship is true for 30 species of hardwoods. We found that two types of relation exist between the maturation age of VLD and radial stem growth, i.e., the type in which the maturation age of VLD was similar to the age at which the current annual increment was maximal (Type-I), and the other type in which the maturation age of VLD was similar to the age at which the mean annual increment was maximal (Type-II). Where more than one species was studied for a given genus, the type was shared. Porosity (ring- or diffuse-porous) is not related with maturation type.

Optimizing conditions for poly(β-hydroxybutyrate) production by Halomonas boliviensis LC1 in batch culture with sucrose as carbon source

Halomonas boliviensis LC1 is able to accumulate poly(beta-hydroxybutyrate) (PHB) under conditions of excess carbon source and depletion of essential nutrients. This study was aimed at an efficient production of PHB by growing H. boliviensis to high cell concentrations in batch cultures. The effect of ammonium, phosphate, and yeast extract concentrations on cell concentration [cell dry weight (CDW)] and PHB content of H. boliviensis cultured in shake flasks was assayed using a factorial design. High concentrations of these nutrients led to increments in cell growth but reduced the PHB content to some extent. Cultivations of H. boliviensis under controlled conditions in a fermentor using 1.5% (w/v) yeast extract as N source, and intermittent addition of sucrose to provide excess C source, resulted in a polymer accumulation of 44 wt.% and 12 g l(-1) CDW after 24 h of cultivation. Batch cultures in a fermentor with initial concentrations of 2.5% (w/v) sucrose and 1.5% (w/v) yeast extract, and with induced oxygen limitation, resulted in an optimum PHB accumulation, PHB concentration and CDW of 54 wt.%, 7.7 g l(-1) and 14 g l(-1), respectively, after 19 h of cultivation. The addition of casaminoacids in the medium increased the CDW to 14.4 g l(-1) in 17 h but reduced the PHB content in the cells to 52 wt.%.

Metabolic markers in relation to nutrition and growth in healthy 4-y-old children in Sweden

The worldwide increase in overweight and obesity probably involves dietary factors, and early indicators of risk must be identified. We aimed to analyze metabolic markers in relation to dietary intake and anthropometry in healthy 4-y-old children. A cross-sectional study of nutritional intake was performed in 95 children by use of 7-d food records. Fasting blood samples were analyzed for glucose, insulin, and lipids. The study population was representative of Swedish children except that more parents than the average had a university education. The boys' mean energy intake was higher (6.6 +/- 0.75 MJ) than the girls' (5.7 +/- 0.79 MJ). Significant associations were found between the percentage of energy from carbohydrates and that from fat (r = -0.91) and sucrose (r = 0.59). High body mass index was associated with a low percentage of energy from fat (r = -0.32). Serum triacylglycerol, insulin, and the HOMA (homeostatic model assessment) index were higher in girls than in boys. In girls, HOMA beta-cell function was significantly negatively associated with fat intake and serum fasting insulin, and HOMA insulin resistance indexes were significantly associated with the increment in z scores for height and weight from birth to age 4 y. Compared with children with fasting insulin concentrations below the group mean + SD, the children with concentrations above that value were smaller as newborns and had larger increments in growth z scores from birth to age 4 y. In healthy Swedish 4-y-olds from well-educated families, low fat intake was related to high body mass index. Upward weight and height percentile crossings were related to insulin resistance, especially in girls.

Structure—biodegradation correlation of polyphenols for Thauera aromatica in anaerobic conditions

The anaerobic degradation of phenolic compounds depends greatly on their molecular structure. We have undertaken a systematic study on several phenol derivatives which are commonly found in industrial waters with the aim of investigating the structure–biodegradation relationship for bacteria in anaerobic conditions. The Thauera aromatica strain was used; this bacterium is able to use phenol as a sole carbon source in liquid cultures in the absence of molecular oxygen. Nitrate is the electron sink with complete reduction to N2. A systematic study has demonstrated the ability of this bacterial strain to use 3,4-dihydroxybenzoic acid, 4-hydroxycinnamic acid (p-coumaric acid), 4-hydroxy-3-methoxycinnamic acid (ferulic acid), 3,4-dimethoxybenzoic acid (veratric acid), and 3,4,5-trihydroxybenzoic acid (gallic acid) as substrate. The matching of the depletion of the concentration of such compounds with the increment in bacterial growth in the cultures demonstrates that the substrates are used as the sole carbon source. Also, a correlation between the rate of growth of bacteria and nitrite concentration has been observed. The progressive reduction in nitrate into nitrite and N2 is monitored through analyses. The protein pattern extracted from bacteria grown on methylated substrates is now being compared with that of bacteria grown on non-methylated polyphenols that are structurally analogous in order to identify specific enzymes for demethylation processes.

Cooperation and Conflict between Firms, Communities, New Social Movements and the Role of Government v. Cerro De San Pedro Case

The aim of this paper is to analyze relationships of cooperation and conflict between a mining company and the involved communities, New Social Movements and the three levels of government. The mining company begun operations for an open pit mine of gold and silver supported by officials from the local, state and federal government. The inhabitants of these communities supported by environmental groups and NGOs argue that the project will pollute sources of fresh water besides of perturbing the environment and the ecology of the region. The presence of the mining company (MSX) in Cerro de San Pedro has caused a severe social conflict among the inhabitants of San Pedro, Soledad y San Luis and has called the attention of all who are concerned by historic heritage, cultural and environmental issues. At the center of the controversy is the cheap and efficient technology. Federal and state Laws were violated. It is quite evident the lack of sensitivity of foreign mining companies toward the consequences of their activities upon the communities and environment. This case also shows the lack of negotiation between firms, communities, new social movements and governments. Information about externalities and future costs of company activities is crucial but more crucial is formulation and implementation of more sensitive policies to avoid damage of the environment, biodiversity and health of population. Governmental institutions must be aware that their decisions may affect the community quality of life of actual and future generations only for a small increment in economic growth and large increase in private benefits of a small group of investors. More informed citizens tend to be more active protestors, such as the case of the students in San Luis. Contact between informed individuals of diverse groups and organizations help to exchange experiences and create public opinion in favor of mobilizations. Community participation and involvement in decision making of community development planning is quite limited by the lack of critical information. This fact is critical when the local government cannot provide the right information because there are other interests affecting the process.

The effects of temperature and light integral on early vegetative growth and chlorophyll fluorescence of four contrasting genotypes of cacao (Theobroma cacao)

SummaryThe effect of temperature on early vegetative growth, leaf chlorophyll fluorescence and chlorophyll content was examined on four genotypes of cacao (Amelonado, AMAZ 15–15, SCA 6 and SPEC 54/1). A controlled environment glasshouse was used to simulate the temperature conditions of three cacao‐growing regions (Bahia, Brazil; Tafo, Ghana and Lower Perak, Malaysia) over the course of a year. Base temperatures calculated from increments in main stem growth varied from 18.6°C for AMAZ 15/15 to 20.8°C for SPEC 54/1. Temporal variation in Fv/Fm observed for two of the clones (SCA 6 and SPEC 54/1) in two of the compartments were correlated with temperature differences over time. Significant differences were also recorded between genotypes in leaf chlorophyll content. It was shown that variation over time in leaf chlorophyll content could be quantified accurately as a function of temperature and light integral. The results imply that genetic variability exists in cacao in response to temperature stress.

Autumn Fertilization in the Nursery Affects Growth of Picea abies Container Seedlings After Transplanting

Second-year Norway spruce seedlings [Picea abies (L.) Karst.] grown in containers were divided into three fertilization levels in August [5, 15 and 25 mg nitrogen (N) seedling−1]. The resulting foliar concentrations of N were 11.0, 13.1 and 15.8 g kg−1, respectively. Seedling height (mean 26.0 cm) did not differ among treatments. The next spring, the seedlings were tested in two experiments. (1) The seedlings were transplanted into pots containing sandy soil in the greenhouse, where they were fertilized with either pure water or nutrient solution (22 mg N l−1). (2) The outplanting performance of the autumn-fertilized seedlings was tested on a sandy field. In the greenhouse experiment, the autumn fertilization level affected height growth and root egress of the seedlings significantly, but less than fertilization with a nutrient solution after planting. In the field experiment, during the first season after transplanting shoot growth of the seedlings increased with the level of autumn fertilization. After the second and third seasons, the seedling stem volume was highest with the highest level of autumn fertilization. These results suggest that, by improving the preplanting nutrient status of seedlings, the growth of shoot, stem diameter and root biomass can be enhanced after planting, especially on nutrient-poor soils. However, heavier autumn fertilization than that used here may yield a greater and more persistent increment in growth.

Inoculum density of arbuscular mycorrhizal fungi needed to promote growth ofHancornia speciosaGomes seedlings

Introduction. Arbuscular Mycorrhizal Fungi (AMF) can promote host growth and, among other benefits, alleviate the stress produced by transplanting seedlings from the nursery to the field. The objective of this work was to evaluate the effect of the amount of AMF inoculum on growth of Hancornia speciosa (Mangaba tree). Materials and methods. A greenhouse experiment was performed using a randomized experimental design in a factorial arrangement of 3 × 3 corresponding to: two AMF (Gigaspora albida Schenck & Smith and Glomus etunicatum Becker & Gerdeman) treatments plus one control with plants without AMF × three inoculum densities ((50, 100 and 300) spores per plant), with five replicates, in a methyl bromide sterilized soil. Results. After 120 d, seedlings associated with G. albida had greater height, shoot diameter and dry biomass of the aerial part and leaf area than those associated with G. tunicatum, independent of inoculum density. G. etunicatum did not influ- ence growth of H. speciosa. Positive correlations occurred between plant growth parameters and root colonization promoted by G. albida. Regression analysis showed interaction between the inoculum density of G. albida and plant growth parameters. Discussion and conclusion. Increments in growth of H. speciosa can be obtained with inoculation of approximately 180 spores of G. albida per plant, which could reduce the necessary period of time for the transplanting of seedlings from the nursery to the field. Brazil / Hancornia speciosa / fruit trees / arbuscular mycorrhizae / Gigaspora albida / Glomus etunicatum / growth

Optimization of biomass, total carotenoids and astaxanthin production in Haematococcus pluvialis Flotow strain Steptoe (Nevada, USA) under laboratory conditions.

The microalga Haematococcus pluvialis Flotow is one of the natural sources of astaxanthin, a pigment widely used in salmon feed. This study was made to discover optimal conditions for biomass and astaxanthin production in H. pluvialis from Steptoe, Nevada (USA), cultured in batch mode. Growth was carried out under autotrophic (with NaNO3, NH4Cl and urea) and mixotrophic conditions (with 4, 8, 12 mM sodium acetate) under two photon flux densities (PFD) (35 and 85 mumol m-2 s-1). The carotenogenesis was induced by 1) addition of NaCl (0.2 and 0.8%), 2) N-deprivation and 3) high PFD (150 mumol m-2 s-1). Total carotenoids were estimated by spectrophotometry and total astaxanthin by HPLC. Ammonium chloride was the best N-source for growth (k = 0.7 div day-1, 228-258 mg l-1 and 2.0 x 10(5)-2.5 x 10(5) cells ml-1 at both PFD, respectively). With increasing acetate concentration, a slight increment in growth occurred only at 85 mumol m-2 s-1. Light was the best inductive carotenogenic factor, and the highest carotenoid production (4.9 mg l-1, 25.0 pg cell-1) was obtained in cultures pre-grown in nitrate at low light. The NaCl caused an increase in carotenoid content per cell at increasing salt concentrations, but resulted in a high cell mortality and did not produce any increment in carotenoid content per volume compared to cultures grown at 150 mumol m-2 s-1. The highest carotenoid content per cell (22 pg) and astaxanthin content per dry weight (10.3 mg g-1) (1% w/w) were obtained at 85 mumol m-2 s-1 with 0.8% NaCl.

Strontium as a marker for estimation of microscopic growth rates in a bivalve

Microscopic growth increaments in bivalve shells were measured by marking the shells of the short-necked clam Ruditapes philippinarum with the strontium chloride (strontium marking method, SMM). The results were com- pared with those achieved by the fluorescent marking method (FMM) using calcein. Because strontium has a higher atomic mass than calcium, strontium-enriched areas in the shells are visible as a bright band in the back-scattered electron image under the scanning electron microscope (SEM). R. philippi- narum were immersed in strontium chloride solutions of vary- ing concentrations, and the effects of immersion time (17 or 24 h) and concentration (0.72, 1.44 or 2.88 g l -1 ) were investi- gated. These shells exhibited clearly visible marks 19 or 20 d post-immersion. Using the SMM, a microscopic (single-digit µm) increment in shell growth could be detected under SEM with a magnification of at least 1200 × . Using the FMM, growth increaments of only tens of micrometers were de- tectable under fluorescence optical microscopy up to a mag- nification of 600 × . The SMM is thus superior to previous methods for detecting microscopic increases in shell growth. Marking methods should ideally be based on long-lasting markers that are easily detected and involve simple method- ologies. The SMM meets these requirements. It can be used to estimate growth in small bivalve specimens and growth rates in slow-growing species such as deep-sea and polar

Energy Absorption and Dissipation Characteristics of Pultruded Glass-Graphite/Epoxy Hybrid Composite Beams

The response of pultruded glass-graphite/epoxy hybrid composites has been evaluated under two different incident impact energy conditions. A high incident energy (HIE) and a low incident energy (LIE) of impact are chosen to cause either complete fracture or induce delamination, respectively, for assessing the energy absorption characteristics and delamination fracture toughness of these hybrid composites. From the HIE instrumented drop-weight impact tests, the energies required for damage initiation, propagation, as well as total absorbed energies and other parameters necessary for evaluating the impact performance of composites were derived from the load-deformation behavior of each sample. The influence of hybridization on the energy absorption characteristics of pultruded composites was investigated. A parametric study also was performed to correlate the energy absorption characteristics with the energy dissipative mechanisms attributed to the inherent material damping capacity of these composites. The qualitative assessment of the impact performance using inherent damping capacity as a non-destructive testing parameter is highlighted. The samples that were subjected to LIE impact testing were examined using ultrasonic C-scan tests to ascertain changes in the extent of delamination crack propagation as a result of hybridization. Finite element modeling was performed to simulate delamination crack propagation at various levels through the thickness. The strain energy release rate computed using the virtual crack closure technique was monitored to determine the likelihood of delamination crack propagation with increment in crack growth. The results obtained from LIE impact tests and ultrasonic C-scan tests were used to corroborate the predicted delamination fracture toughness of pultruded hybrids. Graphite-outside hybrids exhibited high flexural stiffness, propagation energy, ductility and failure index, but had lower initiation energy along with a greater tendency to delaminate.

Growth responses of excised radish cotyledons to meta-topolin

Meta-topolin (mT) has been established as an active aromatic cytokinin by Strnad et al. (1997). The present investigation assessed the effects of mT on radish cotyledon growth. The effect of mT on cotyledon growth, chlorophyll, N and soluble protein contents were measured. Peroxidase (POD) activity and polyamine (PA) contents were also determined. Treatment at 0.25, 0.5 and 1.0 mM mT concentrations resulted in 44, 50 and 57% increments in cotyledon growth, respectively, compared with control cotyledons. Increase in chlorophyll content per cotyledon was highest at low mT concentrations. Peroxidase activity was highest at 1.0 mM mT. Soluble protein content was reduced by the application of mT. Key words: Cotyledon growth, meta-topolin, polyamine, peroxidase, radish cotyledons

Dependência micorrízica de variedades comerciais de mamoeiro

O genótipo da planta é fator preponderante na resposta à micorriza. Avaliou-se, neste trabalho, a resposta a fósforo e o grau de dependência micorrízica de variedades de mamoeiro (Carica papaya L.). O experimento foi realizado em casa de vegetação da Embrapa-Centro Nacional de Pesquisa de Mandioca e Fruticultura, com quatro variedades, testando-se seis doses de P: 0, 20, 40, 80, 140, 280 mg dm-3 e três tratamentos fúngicos (um controle não-micorrizado e a inoculação de Glomus clarum ou Gigaspora margarita). Foram estimados os seguintes parâmetros: dose de P para máxima eficiência micorrízica; valor T'; benefício da aplicação do P; benefício micorrízico; eficiência simbiótica, e dependência micorrízica. Plantas não-micorrizadas apresentaram resposta quadrática ao P aplicado e as inoculadas seguiram modelo raiz-quadrático, com grande incremento de matéria seca da parte aérea nas doses baixas; o benefício de P foi maior nas variedades Sunrise Solo e Improved Sunrise Solo - Line 72/12, enquanto as variedades Baixinho de Santa Amália e Tainung nº 1 apresentaram benefício micorrízico proporcionalmente maior, resultando em maior eficiência simbiótica. As variedades de mamoeiro apresentaram a seguinte classificação quanto à dependência micorrízica: Baixinho de Santa Amália = Tainung nº 1 &gt; Sunrise Solo = Improved Sunrise Solo - Line 72/12. A maior ou menor dependência relacionou-se com a capacidade da variedade em produzir raízes.