Slow-release and organic fertilizers on early growth of Rangpur lime

Slow-release and organic fertilizers are promising alternatives to conventional fertilizers, as both reduce losses by leaching, volatilization and problems of toxicity and/or salinity to plants. The objective of this work was to evaluate the effect of different rates of the organic fertilizer Humato-Macota® compared with the slow-release fertilizer Osmocote® on the growth and nitrogen content in the dry matter of Rangpur lime. A field experiment was conducted in a factorial completely randomized design with an additional treatment (4 x 4 +1). The first factor consisted of four Humato­Macota® rates (0, 1, 2, and 3%) applied to the substrate; the second factor consisted of the same Humato-Macota® concentrations, but applied as fortnightly foliar sprays; the additional treatment consisted of application of 5 kgm-3 Osmocote® 18-05-09. Means of all growth characteristics (plant height, total dry matter, root/shoot ratio and leaf area) and the potential quantum yield of photosystem II (Fv/Fm) were higher when plants were fertilized with the slow-release fertilizer. The organic fertilizer applied alone did not meet the N requirement of Rangpur lime.

Growth and nutrient uptake of coffee seedlings cultivated in nutrient solution with and without silicon addition

In recent years, the application of silicon (Si) in crops, including coffee, has become a common practice. The objective of this study was to assess the silicon uptake by coffee seedlings and its effects on plant growth, water and macro and micronutrient uptake. The research was conducted using nutrient solution in a greenhouse at the Departamento de Fitotecnia da Universidade Federal de Viçosa, in a completely randomized design with two treatments (with and without silicon) and three replications. Each plot consisted of three plants grown in a 800 mL vessel containing the treatment solutions. At every three days, water consumption, the concentration of OH - and the depletion of Si and K were assessed in the nutrient solutions. After 33 days, the plants were assessed with regard to their fresh and dry weight of leaves, roots and stem, shoot height and total length of the plant (shoot and root). Number of leaves and internodes, and the content and accumulation of silicon, macro, and micronutrients were also determined. The consumption of water, the amount of potassium uptake and, biomass accumulation were greater in plants grown in solution without silicon addition. However, the concentration of OH- in the solution and the amount of silicon uptake were greater in plants grown in solution with added silicon. Silicon accumulation was greater in leaves than in stem and roots. Silicon decreased coffee plant accumulation of phosphorus, potassium, calcium, zinc, copper and iron.

Growth and physiological characteristics of the weed false johnsongrass ( Sorghum arundinaceum (Desv.) Stapf)

ABSTRACT Sorghum arundinaceum (Desv.) Stapf is a weed that belongs to the Poaceae family and is widespread throughout Brazil. Despite the frequent occurrence, infesting cultivated areas, there is little research concerning the biology and physiology of this species. The objective of this research was to evaluate the growth, carbon partitioning and physiological characteristics of the weed Sorghum arundinaceum in greenhouse. Plants were collected at regular intervals of seven days, from 22 to 113 days after transplanting (DAT). In each sample, we determined plant height, root volume, leaf area and dry matter, and subsequently we perfomed the growth analysis, we have determined the dry matter partitioning among organs, the accumulation of dry matter, the specific leaf area, the relative growth rate and leaf weight ratio. At 36, 78 and 113 DAT, the photosynthetic and transpiration rates, stomatal conductance, CO2 concentration and chlorophyll fluorescence were evaluated. The Sorghum arundinaceum reached 1.91 in height, with slow initial growth and allocated much of the biomass in the roots. The photosynthetic rate and the maximum quantum yield of FSII are similar throughout the growth cycle. At maturity the Sorghum arundinaceum presents higher values of transpiration rate, stomatal conductance and non-photochemical quenching coefficient (NPQ).

Growth and nutrient accumulation in mycorrhized papaya seedlings cultivated in a phosphorus-fertilized substrate

ABSTRACT The indiscriminate use of mineral fertilizers in papaya orchards has increased production costs, and the use of arbuscular mycorrhizal fungi is a promising alternative to reduce such expenses. Therefore, the present research aimed at studying the efficiency of arbuscular mycorrhizal fungi (AMF) on dry matter and nutrient accumulation in Sunrise Solo papaya seedlings, by applying doses of P2O5 (triple superphosphate) that are harmful to the symbiosis. The experiment was carried out in a protected environment and was set up in a randomized block design with four replications, and consisted of four P2O5 doses (0, 672, 1386 and 2100 mg dm-3), three mycorrhizal fungi species (Gigaspora margarita, Entrophospora colombiana and Scutellospora heterogama) and the control treatment (mycorrhiza-free). Shoot and root dry matter as well as nitrogen, phosphorus and potassium contents in leaf and root tissues were assessed. Mycorrhizal inoculation promoted a 30% increase in shoot dry matter in relation to the control treatment. Mycorrhizal fungi promoted increases in leaf and root nitrogen content up to 672 mg dm-3 P2O5. Inoculation of E. colombiana favored the highest gains in root and shoot dry matter. P2O5 fertilization increased foliar and root phosphorus content.

Growth and plant mass of radish fertirrigated with different doses nitrogen

ABSTRACT The objective of the present study was to evaluate the effect of nitrogen doses applied via fertigation and associated with different types of crop establishment fertilization on growth and biomass of radish. The experiment was conducted in a greenhouse of the Academic Unit of Agricultural Engineering, Federal University of Campina Grande, from April to May 2014. Treatments consisted of five doses of nitrogen fertilizer applied by fertigation (0, 0.7, 1.4, 2.1 and 2.8g per pot) and three types of crop establishment fertilization (humus 2:2; NPK and control), arranged in a 5 x 3 factor design with four repetitions. The 15 treatments were arranged in 60 plots. The nitrogen source used in the study was urea, divided in three applications: the first application was carried out eight days after transplanting, the second, on day 15, and the third, on day 22. The crop establishment fertilization significantly influenced the growth variables and plant mass of the radish on day 35 after transplanting. The highest values of the variables (number of leaves, plant height, bulb diameter, leaf area, fresh mass of the aerial part, dry mass of the aerial part and root/aerial part were observed in the treatment with humus on day 35 after transplanting. The dose of 2.8g nitrogen per pot corresponding to 6.22g of urea per plant provided the highest yield for the variable number of leafs, leaf area and root length on day 35 after transplanting.

Effect of plant-biostimulant on cassava initial growth

ABSTRACT Biostimulants are complex substances that promote hormonal balance in plants, favor the genetic potential expression, and enhance growth of shoots and root system. The use of these plant growth promoters in crops can increase quantitatively and qualitatively crop production. Therefore, the aim of this study was to evaluate the effect of a commercial biostimulant on the initial growth of cassava. The experiment was arranged in a 2 x 5 factorial design, corresponding to two cassava cultivars (Cacau-UFV and Coimbra) and five biostimulant concentrations (0, 4, 8, 12 and 16 mL L-1). At 90 days after planting, the characteristics leaf area, plant height, stem diameter, leaf number, total dry matter and dry matter of roots, stems and leaves were evaluated. The biostimulant promoted linear increases in plant height, leaf number, leaf area, total dry matter, dry matter of stems, leaves and roots. The cultivar Cacau-UFV had a higher growth rate than the cultivar Coimbra. The growth promoter stimulated the early growth of the cassava crop.

Absorption of primary macronutrients and soybean growth at different compactation densities and moisture levels in a silt loam soil

ABSTRACT Soybean cultivation is increasing rapidly in the region of Alto Vale do Itajaí, State of Santa Catarina, where there is a predominance of silt soils. The objective of this work was to evaluate the content of primary macronutrients in shoots and shoot and root vegetative growth of soybean (Glicine max L. Merrill) grown in a silt-loam soil under different compactation densities and moisture levels. A randomized block design in a 4x4 factorial arrangement was used, with four compactation densities: 1.00; 1.20; 1.40 and 1.60 Mg m-3, and four soil moisture levels: 0.130; 0.160; 0.190 and 0.220 kg kg-1 and four replications. Each pot consisted of the overlapping of three 150-mm PVC rings, where soil was maintained in the higher and lower part of the pot with a density of 1.00 Mg m-3 and in the intermediate ring, the compactation densities were increased. Values of soil density higher than 120 Mg m-3 negatively affected N, P and K uptake by soybean plants, as well as the plant mass of the shoots and roots. The higher levels of soil moisture reduced the compaction effect and promoted better absorption of P and K.

Integrated analysis of climate, soil, topography and vegetative growth in Iberian viticultural regions

The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate.

Molecular regulation of secondary gorwth: searching for SHORT-ROOT function in cork formation

The analysis of molecular regulators involved in controlling the maintenance and function of plant meristems has been the subject of many studies. Some master regulators of these processes have been identified in Arabidopsis benefiting from the array of tools available for genetic and molecular analysis in this model plant. However, aspects such as secondary growth that are more extensively observed in woody plants, have been less studied. Secondary growth is responsible for the enlargement of the plant stems and roots and results from the activity of the lateral (secondary) meristems, vascular cambium and cork cambium (phellogen), which produce two important renewable natural resources, wood and cork, respectively.(...)

Influence of boron on growth and mineral composition of bean (Phaseolus vulgaris L.)

Nine cultivars of Phaseolus vulgaris L. were grown in nutrient solution to study the effect of boron on growth and mineral composition. Data obtained in thie study allowed for the following conclusions: (1) high levels of boron affected plant height, root length, dry weight of tops, dry weight of root, and total dry weight; (2) regression analysis was used to point out differential behaviour among cultivars in relation to boron concentration in nutrient solution; (3) the best mineral concentration in the plant tissue was obtained with application of 0,5 ppm of boron in the nutrient solution.

Influence of aluminum on growth and mineral composition of bean (Phaseolus vulgaris L.)

Seven cultivars of Phaseolus vulgaris L. were grown in nutrient solution in the presence and absence of aluminum. Da ta obtained herewith allowed for the following conclusions to be drawn: (1) plant height, root lenght and total dry weight decreased with increase of aluminum levels in the nutrient solution; (2) aluminum concentration in plant tissue increased with higher levels of aluminum in the substrate; decreases pf calcium and magnesium concentration in the dry matter in the presence of higher aluminum concentration in the nutrient solution were observed.

Promise for plant pest control: root-associated pseudomonads with insecticidal activities.

Insects are an important and probably the most challenging pest to control in agriculture, in particular when they feed on belowground parts of plants. The application of synthetic pesticides is problematic owing to side effects on the environment, concerns for public health and the rapid development of resistance. Entomopathogenic bacteria, notably Bacillus thuringiensis and Photorhabdus/Xenorhabdus species, are promising alternatives to chemical insecticides, for they are able to efficiently kill insects and are considered to be environmentally sound and harmless to mammals. However, they have the handicap of showing limited environmental persistence or of depending on a nematode vector for insect infection. Intriguingly, certain strains of plant root-colonizing Pseudomonas bacteria display insect pathogenicity and thus could be formulated to extend the present range of bioinsecticides for protection of plants against root-feeding insects. These entomopathogenic pseudomonads belong to a group of plant-beneficial rhizobacteria that have the remarkable ability to suppress soil-borne plant pathogens, promote plant growth, and induce systemic plant defenses. Here we review for the first time the current knowledge about the occurrence and the molecular basis of insecticidal activity in pseudomonads with an emphasis on plant-beneficial and prominent pathogenic species. We discuss how this fascinating Pseudomonas trait may be exploited for novel root-based approaches to insect control in an integrated pest management framework.

Growth Rate Estimation in the presence of Unit Roots

This study addresses the issue of the presence of a unit root on the growth rate estimation by the least-squares approach. We argue that when the log of a variable contains a unit root, i.e., it is not stationary then the growth rate estimate from the log-linear trend model is not a valid representation of the actual growth of the series. In fact, under such a situation, we show that the growth of the series is the cumulative impact of a stochastic process. As such the growth estimate from such a model is just a spurious representation of the actual growth of the series, which we refer to as a “pseudo growth rate”. Hence such an estimate should be interpreted with caution. On the other hand, we highlight that the statistical representation of a series as containing a unit root is not easy to separate from an alternative description which represents the series as fundamentally deterministic (no unit root) but containing a structural break. In search of a way around this, our study presents a survey of both the theoretical and empirical literature on unit root tests that takes into account possible structural breaks. We show that when a series is trendstationary with breaks, it is possible to use the log-linear trend model to obtain well defined estimates of growth rates for sub-periods which are valid representations of the actual growth of the series. Finally, to highlight the above issues, we carry out an empirical application whereby we estimate meaningful growth rates of real wages per worker for 51 industries from the organised manufacturing sector in India for the period 1973-2003, which are not only unbiased but also asymptotically efficient. We use these growth rate estimates to highlight the evolving inter-industry wage structure in India.

Glomus intraradices induces changes in root system architecture of rice independently of common symbiosis signaling

? Arbuscular mycorrhizal fungi colonize the roots of most monocotyledons and dicotyledons despite their different root architecture and cell patterning. Among the cereal hosts of arbuscular mycorrhizal fungi, Oryza sativa (rice) possesses a peculiar root system composed of three different types of roots: crown roots; large lateral roots; and fine lateral roots. Characteristic is the constitutive formation of aerenchyma in crown roots and large lateral roots and the absence of cortex from fine lateral roots. Here, we assessed the distribution of colonization by Glomus intraradices within this root system and determined its effect on root system architecture. ? Large lateral roots are preferentially colonized, and fine lateral roots are immune to arbuscular mycorrhizal colonization. Fungal preference for large lateral roots also occurred in sym mutants that block colonization of the root beyond rhizodermal penetration. ? Initiation of large lateral roots is significantly induced by G. intraradices colonization and does not require a functional common symbiosis signaling pathway from which some components are known to be needed for symbiosis-mediated lateral root induction in Medicago truncatula. ? Our results suggest variation of symbiotic properties among the different rice root-types and induction of the preferred tissue by arbuscular mycorrhizal fungi. Furthermore, signaling for arbuscular mycorrhizal-elicited alterations of the root system differs between rice and M. truncatula.

Natural Arabidopsis brx loss-of-function alleles confer root adaptation to acidic soil.

Soil acidification is a major agricultural problem that negatively affects crop yield. Root systems counteract detrimental passive proton influx from acidic soil through increased proton pumping into the apoplast, which is presumably also required for cell elongation and stimulated by auxin. Here, we found an unexpected impact of extracellular pH on auxin activity and cell proliferation rate in the root meristem of two Arabidopsis mutants with impaired auxin perception, axr3 and brx. Surprisingly, neutral to slightly alkaline media rescued their severely reduced root (meristem) growth by stimulating auxin signaling, independent of auxin uptake. The finding that proton pumps are hyperactive in brx roots could explain this phenomenon and is consistent with more robust growth and increased fitness of brx mutants on overly acidic media or soil. Interestingly, the original brx allele was isolated from a natural stock center accession collected from acidic soil. Our discovery of a novel brx allele in accessions recently collected from another acidic sampling site demonstrates the existence of independently maintained brx loss-of-function alleles in nature and supports the notion that they are advantageous in acidic soil pH conditions, a finding that might be exploited for crop breeding.