Sensitivity of yellow passion fruit plants to ultraviolet-B radiation

The objective of this work was to evaluate the effects of UV-B radiation on the vegetative growth and on the gas exchange characteristics of passion fruit plants (Passiflora edulis) grown in greenhouse. The average unweighted UV-B radiation near the apex of the plants was 8 W m-2 for the UV-B treatment (high UV-B), and 0.8 W m-2 for the control plants (low UV-B). Plants were irradiated with UV-B for 7 hours per day, centered on solar noon, during 16 days. High UV-B radiation resulted in lower shoot dry matter accumulation per plant. The content of UV-B absorbing compounds and anthocyanins was increased in the plants exposed to high UV-B radiation, when compared with the control. UV-B radiation did not affect stomatal conductance or transpiration rate, but reduced photosynthesis and instantaneous water‑use efficiency, and increased intercellular CO2 concentration. The accumulation of UV-B-absorbing compounds and anthocyanins did not effectively shield plants from supplementary UV-B radiation, since the growth and photosynthetic processes were significantly reduced.

Allelopathic potential of Equisetum giganteum L. and Nephrolepis exaltata L. on germination and growth of cucumber and lettuce

Nephrolepis exaltata L. Schott "Bostoniensis" family Davalliaceae and Equisetum giganteum L. family Equisetaceae, Phylum Pteridophyta, exhibit a strong mechanism of dominance in the areas in which they live. Have secondary compounds with allelopathic activity. The objective of this article was evaluate allelopathic potential of two ferns species, using bioassay applying aqueous extracts of dried fronds, in cucumber and lettuce seeds, and observing germination and initial development. To observe the influence on germination was analyze the percentage of germinated seeds and germination speed index (GSI). To observe initial development was analyzed shoot and root growth of the seedlings. The bioassays revealed that no concentration significantly inhibited the germination, but germination speed was delayed gradually in two species tested, as increased the extract concentration. In initial development, all the extracts showed a tendency to inhibit the growth, and an increase in extract concentration decreasing growth of radicle and hypocotyl axis. We conclude that the aqueous extract has inhibitory activity more pronounced in early development than in seed germination, affecting the primary structures of the tested plants, corroborating with the observations of occurrences of the species in natural places where dominate and suppress the growth of other species.

Synergism of crude extracts and essential oils from medicinal plants with antimicrobial drugs

The emergence of resistant strains to conventional antimicrobial drugs has been constant as well as research aimed new alternatives of antibacterial agents. Therefore, considering that natural products have been an important potential source of new antimicrobial drugs, aim to verify the synergism by disk and time kill curve method between antimicrobials (extracts-Ext. and essential oils-EO) from four plant and eight antimicrobial drugs against Staphylococcus aureus and Escherichia coli strains from human specimens. The S. aures strains were highly susceptible with all plant antimicrobials (eg., 1.24 mg/ml with Vernonia polyanthes Ext. and 2.21 mg/ml with Eugenia uniflora EO for the Minimal Inhibitory Concentration-MIC). According disk method, the Bacharis dracunculifolia and V. polyanthes EO had synergism with all eight tested drugs while only Matricaria chamomilla Ext. showed synergism against S. aureus. The synergism was found with V. polyanthes and E. uniflora Ext. while M. chamomilla Ext. had antagonism against E. coli strains. By time kill curve, the bacterial growth inhibition was superior when drugs were tested alone and the synergism effect also was verified. The antagonism effect was detected only for E. coli strains and only with Ext. Results indicated the potential use of these products as coadjutants during treatment of infectious diseases.

Carbohydrates, growth and production of -roxo de valinhos- fig tree in initial development under irrigation management

The carbohydrates translocation and consequently growth and production of fig tree (Ficuscarica L.) vary according to the different management on cultivation conditions. The aim of this study was to evaluate the changes in the levels and total carbohydrates accumulation together with growth and “Roxo de Valinhos” fig trees production onimplementation of orchards in initial phase, cultivated with and without irrigation. We adopted a factorial arrangement (2 x 7) with four repetitions distributed in installments (with and without irrigation) subdivided in time (collect time). Destructive analyzes were performed at 40, 80, 120, 160, 200, 240 and 280 days after pruning (DAP) and are measured: stem diameter and branch, stem length and branch, number of leaves, internodes and fruit. Subsequently, the plant parts were sectioned to obtain the leaf area, length and roots volume, fresh and dry matter weight. The number, weight and total productivity of fruits were evaluated. The media of all growth attributes and production characteristics were higher in treatments with water irrigation. The total carbohydrate content was higher at 120 and 160 DAP and the carbohydrates accumulation was increasing for most institutions over the plants development, except for the leaves that showed a decrease in the levels at 160 DAP. The fruits showed greater carbohydrates accumulation in relation to the other evaluated organs.

Nitrogen immobilization by Congo grass roots impairs cotton initial growth

In crop-livestock integration systems the presence of both grass roots in the soil and straw on the surface can temporarily immobilize nitrogen. This study examined the persistence of grass residues in the system as well as their effects on cotton response to N when grown after Congo grass (Brachiaria ruziziensis, Syn. Urochloa ruziziensis). Congo grass was grown in pots with soil. Next, cotton was grown in the same pots without residues, with whole plant residues (Congo grass roots and shoots) or root residues (grass roots) and fertilized with N as ammonium nitrate. Congo grass and cotton roots were separated using stable carbon isotope fractioning. Congo grass roots showed higher C/N ratio than shoots, losing 14% of its mass after 45 days and increasing soil N immobilization. The lower N availability resulted in N deficient and shorter cotton plants with lower dry matter yields. Nevertheless, the application of 80 to 120 mg kg-1 of N compensated the immobilization by the soil microorganisms, allowing cotton to show normal growth. When Congo grass is present in the cropping system, the effects of the decaying roots on soil N dynamics and availability are more important than those of the straw left on the soil surface.

Glyphosate effects on sugarcane metabolism and growth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Growth and flowering of five mango cultivar under subtropics conditions of Brazil

The evaluation of the new cultivars adaptation and yield potential of Mangifera indica L. provides tools to assist and improve the mango production in different climates conditions. This study aimed to evaluate the phenological and reproductive development of five mango cultivars (Bourbon, Haden, Palmer, Parwin and Tommy Atkins), on climate conditions in dry land and four production cycles (from 08/2007 to 01/2011), at São Manuel, São Paulo state, Brazil. The variables were total plant height, trunk height, stem diameter and the first insertion diameter, fruits physical characteristics, yield and harvest period, flowering seasonality and morphological characterization of the inflorescences. It was found that the four-year-old plants of Haden cv. reach 4.0 m high and 0.20 m of trunk diameter. Bourbon cultivar had the highest flowering period, from April to October. Tommy Atkins cv. had productivities of 14779.07 kg∙ha−1 in the fourth cycle and the productivity of Bourbon, Haden and Palmer cultivars was alternated.

Biological control of root rot caused by Pythium aphanidermatum and growth promotion in hydroponic cucumber with microorganisms from mangrove

The prospection of biological control agents in similar environments to the microbe application improves the chances of microorganisms establishment added to the environment. The low survival of these beneficial microorganisms added to hydroponic environment is a problem for the growth promotion and root rot biological control success in hydroponic crops. Because of the environmental similarity between hydroponic systems and mangrove ecosystems, the aim of this work was to evaluate the ability of mangrove microbes to control root rot caused by Pythium aphanidermatum and to improve plant growth in hydroponic cucumbers. Among the 28 strains evaluated for disease control in small-hydroponic system using cucumber seedlings, Gordonia rubripertincta SO-3B-2 alone or in combination with Pseudomonas stutzeri (MB-P3A- 49, MB-P3-C68 and SO-3L-3), and Bacillus cereus AVIC-3-6 increased the seedlings survival and were subsequently evaluated in hydroponic cucumbers in a greenhouse. Bacillus cereus AVIC-3-6 protected the plants from stunting caused by the pathogen and Gordonia rubripertincta SO-3B-2 and Pseudomonas stutzeri MB-P3A-49 increased the plant growth. We concluded that microorganisms from mangroves are useful as biocontrol agents and for improving plant growth in hydroponic crops.

Soil fertility, nutrition and early growth of physic nut as affected by nitrogen fertilization

The initial growth and mineral nutrition of the physic nut (Jatropha curcas L.) as a function of nitrogen (N) fertilization was investigated. The transplanting of seedlings was carried out in plastic pots filled with 50 dm3 of a Rhodic Hapludox, under a plastic greenhouse. In addition to a control treatment, the dosages of 0, 40, 80, 120, and 160 mg dm−3 N were tested. The results demonstrated that N fertilization for the cultivation of physic nut could be added as top dressing from 60 days after planting with a dosage of 65 mg dm−3. A SPAD index of 46 can be used as a nutritional reference to its initial development. Furthermore, the results suggested that the order of nutrient accumulation by the physic nut plants is as follows: potassium (K) > N > magnesium (Mg) > calcium (Ca) > phosphorus (P) > sulfur (S) > iron (Fe) > manganese (Mn) > boron (B) > zinc (Zn) > copper (Cu).

Coffee growth, pest and yield responses to free-air CO2 enrichment

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efficiency of nitrogen sources and rates on growth and dry matter yield of tifton 85

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Eucalyptus growth promotion by endophytic Bacillus spp

Clonal eucalyptus plantings have increased in recent years; however, some clones with high production characteristics have vegetative propagation problems because of weak root and aerial development. Endophytic microorganisms live inside healthy plants without causing any damage to their hosts and can be beneficial, acting as plant growth promoters. We isolated endophytic bacteria from eucalyptus plants and evaluated their potential in plant growth promotion of clonal plantlets of Eucalyptus urophylla x E. grandis, known as the hybrid, E. urograndis. Eighteen isolates of E. urograndis, clone 4622, were tested for plant growth promotion using the same clone. These isolates were also evaluated for indole acetic acid production and their potential for nitrogen fixation and phosphate solubilization. The isolates were identified by partial sequencing of 16S rRNA. Bacillus subtilis was the most prevalent species. Several Bacillus species, including B. licheniformis and B. subtilis, were found for the first time as endophytes of eucalyptus. Bacillus sp strain EUCB 10 significantly increased the growth of the root and aerial parts of eucalyptus plantlets under greenhouse conditions, during the summer and winter seasons.

Glyphosate has low toxicity to citrus plants growing in the field

Gravena, R., Filho, R. V., Alves, P. L. C. A., Mazzafera, P. and Gravena, A. R. 2012. Glyphosate has low toxicity to citrus plants growing in the field. Can. J. Plant Sci. 92: 119-127. There has been controversy over whether glyphosate used for weed management in citrus fields causes significant toxicity to citrus plants. Glyphosate may be toxic to non-target plants exposed to accidental application or drift. This work evaluated glyphosate toxicity in plants of Valencia citrus (Citrus sinensis. L. Osbeck) grafted onto 'Rangpur lime' (Citrus limonia L. Osbeck) and citrumelo 'Swingle' (Poncirus trifoliata (L.) Raf x Citrus paradisi Mad) by trunk- or foliar-directed herbicide applications under field conditions. In the first experiment, glyphosate was sprayed at rates of 0, 90, 180, 260, 540, 1080 and 2160 g a.e. ha(-1) directly on the trunk to a height of 5 cm above the grafting region. In the second experiment, glyphosate was sprayed on the plant canopies at rates of 0, 0.036, 0.36, 3.6, 36, 360 and 720 g a.e. ha(-1). There was no visual damage caused by glyphosate applied directly to the trunk, but the plants were affected by glyphosate sprayed directly on the canopies at rates over 360 g a.e. ha(-1). The main symptom was observed in the new shoots formed after the application, indicating an effect on meristems. Little or no effect was observed in mature leaves. Eight days after application the levels of shikimate, total free amino acids and total phenolic compounds were unaffected. All plants affected by glyphosate recovered between 6 and 12 mo after the treatments. Therefore, despite some transient symptoms Valencia citrus grafted onto 'Rangpur lime' and citrumelo 'Swingle' were tolerant to glyphosate.

A biophysical model of Sugarcane growth

Scientists predict that global agricultural lands will expand over the next few decades due to increasing demands for food production and an exponential increase in crop-based biofuel production. These changes in land use will greatly impact biogeochemical and biogeophysical cycles across the globe. It is therefore important to develop models that can accurately simulate the interactions between the atmosphere and important crops. In this study, we develop and validate a new process-based sugarcane model (included as a module within the Agro-IBIS dynamic agro-ecosystem model) which can be applied at multiple spatial scales. At site level, the model systematically under/overestimated the daily sensible/latent heat flux (by -10.5% and 14.8%, H and E, respectively) when compared against the micrometeorological observations from southeast Brazil. The model underestimated ET (relative bias between -10.1% and 12.5%) when compared against an agro-meteorological field experiment from northeast Australia. At the regional level, the model accurately simulated average yield for the four largest mesoregions (clusters of municipalities) in the state of Sao Paulo, Brazil, over a period of 16 years, with a yield relative bias of -0.68% to 1.08%. Finally, the simulated annual average sugarcane yield over 31 years for the state of Louisiana (US) had a low relative bias (-2.67%), but exhibited a lower interannual variability than the observed yields.

Sugarcane Growth Promotion by the Endophytic Bacterium Pantoea agglomerans 33.1

The promotion of sugarcane growth by the endophytic Pantoea agglomerans strain 33.1 was studied under gnotobiotic and greenhouse conditions. The green fluorescent protein (GFP)-tagged strain P. agglomerans 33.1: pNKGFP was monitored in vitro in sugarcane plants by microscopy, reisolation, and quantitative PCR (qPCR). Using qPCR and reisolation 4 and 15 days after inoculation, we observed that GFP-tagged strains reached similar density levels both in the rhizosphere and inside the roots and aerial plant tissues. Microscopic analysis was performed at 5, 10, and 18 days after inoculation. Under greenhouse conditions, P. agglomerans 33.1-inoculated sugarcane plants presented more dry mass 30 days after inoculation. Cross-colonization was confirmed by reisolation of the GFP-tagged strain. These data demonstrate that 33.1:pNKGFP is a superior colonizer of sugarcane due to its ability to colonize a number of different plant parts. The growth promotion observed in colonized plants may be related to the ability of P. agglomerans 33.1 to synthesize indoleacetic acid and solubilize phosphate. Additionally, this strain may trigger chitinase and cellulase production by plant roots, suggesting the induction of a plant defense system. However, levels of indigenous bacterial colonization did not vary between inoculated and noninoculated sugarcane plants under greenhouse conditions, suggesting that the presence of P. agglomerans 33.1 has no effect on these communities. In this study, different techniques were used to monitor 33.1:pNKGFP during sugarcane cross-colonization, and our results suggested that this plant growth promoter could be used with other crops. The interaction between sugarcane and P. agglomerans 33.1 has important benefits that promote the plant's growth and fitness.