999 resultados para plant nursery
Resumo:
The purpose of this study was to evaluate the efficiency of integrated managements on white mold control on common bean. Initially, in vitro testing was made to assess the antagonism of 11 Trichoderma isolates against Sclerotinia sclerotiorum and to investigate fungicides (fluazinam and procymidone) inhibitory effects on those fungi. In two field experiments the following combinations were tested: irrigation frequencies (seven or 14 days), plant densities (six or 12 plants per meter), and three disease controls (untreated control, fungicide or Trichoderma spp.). In a third experiment plant densities were replaced by grass mulching treatments (with or without mulching). Fluazinam was applied at 45 and 55 days after emergence (DAE). The antagonists T. harzianum (experiments 1 and 3) and T. stromatica (experiment 2) were applied through sprinkler irrigation at 10 and 25 DAE, respectively. Most of the Trichoderma spp. were effective against the pathogen in vitro. Fluazinam was more toxic than procymidone to both the pathogen and the antagonist. Fungicide applications increased yield between 32 % and 41 %. In field one application of Trichoderma spp. did not reduce disease intensity and did not increase yield. The reduction from 12 to six plants per meter did not decrease yield, and disease severity diminished in one of the two experiments. It is concluded that of the strategies for white mold control just reduction of plant density and applications of fungicide were efficient.
Resumo:
Aqueous extracts of the leaves of Ocimum gratissimum at 10, 25, 40 and 50% (w/v) concentrations induced the production of phytoalexins in soybean cotyledons and sorghum mesocotyls. The aqueous extracts also induced systemic resistance in cucumber to Colletotrichum lagenarium, reflected by reduction in disease incidence and an increase in chitinase production. Modes of action and the existence of possible elicitors of defense response in O. gratissimum leaf extracts are discussed.
Resumo:
Eucalypt plantation has high economical importance in Brazil; however, it has been attacked by various pathogens under different environmental stress conditions. Disease resistance and survival under unfavorable environmental conditions have revealed that the eucalypt has developed highly efficient defense systems. Here we show the results of the Eucalyptus ESTs Genome Project (FORESTs). Using the expressed sequence tags (ESTs) obtained by the Project, contigs of similar sequences from each cDNA library induced and not induced by stress agents were formed, and cDNA sequences similar to other already known molecules, such as plant-signaling molecules, phytoalexins, lignin biosynthesis pathways, PR-proteins and putative genes corresponding to enzymes involved in the detoxification of reactive oxygen species, were identified. We also present general considerations about the mechanisms of Eucalyptus defense against biotic and abiotic stresses. These data are of extreme importance for future eucalypt breeding programs aimed at developing plants with enhanced resistance against pathogens and environmental stresses.
Resumo:
Previous studies have demonstrated that volatile organic compounds (VOCs), produced by the yeast Saccharomyces cerevisiae, were able to inhibit the development of phytopathogenic fungi. In this context, the nematicidal potential of the synthetic mixture of VOCs, constituted of alcohols and esters, was evaluated for the control of the root-knot nematode Meloidogyne javanica, which causes losses to crops of high economic value. The fumigation of substrate containing second-stage juveniles with VOCs exhibited nematicidal effect higher than 30% for the lowest concentration tested (33.3 µL g-1 substrate), whereas at 66.6 and 133.3 µL g-1 substrate, the nematode mortality was 100%. The present results stimulate other studies on VOCs for nematode management.
Resumo:
The pathogenicity of Pratylenchus brachyurusto rubber (Hevea brasiliensis) rootstocks was studied in two experiments: 1) opencross seedlings of 'Tjir 1' x 'Tjir 16' were inoculated with zero, 7,700 or 23,100 nematodes per plant; 2) illegitimate seedlings of 'GT 1', 'RRIM 527' and 'RRIM 600' were inoculated with zero or 12,800 nematodes per plant. After 195 (1st experiment) or 105 days after inoculation (2nd experiment), P. brachyurusdid not affect the relative growth percentage in terms of plant height in both experiments but significantly diminished the stem diameter percentage and increased the stomatal resistance of 'GT 1' , 'RRIM 527' and 'RRIM 600'.
Resumo:
There are reasons of necessity in bio-fuel use and bio-energy fast development. It includes the material about bio-energy technologies, applications and methods. There are basic thermodynamics and economic theories. The economic calculation presents the comparison between two combinations. There are boiler plant below 20 MW in combination with ablative pyrolysis plant for bio-oil production and CHP plant below 100 MW in combination with the RTP pyrolysis bio-oil production technology. It provides a material about wood chips and bio-oil characteristics and explains it nature, presents the situation around the bio-fuel market or bio-fuel trade. There is a description of pyrolysis technologies such as ablative and RTP. The liquid product of the pyrolysis processes is bio-oil. The bio-oil could be different even of the same production process, because of the raw material nature and characteristics. The calculation shows advantages and weaknesses of combinations and obtained a proof of suppositions. The next thing, proven by this work is the fact that to get more efficiency from energy project it is good possibility to built plants in combinations.
Resumo:
Cordia curassavica (Jacq.) Roem. & Schult. (Boraginaceae), also referred to as Cordia verbenacea DC, has been traditionally used for medicinal purposes. This study was driven to verify the behavior of the species in similar conditions to its natural environment, such as high light intensity and sandbank soil, and in conditions of low light intensity and fertilized substratum (dystroferric red nitosoil plus earthworm humus). The growth of the plant, the income of leaf crude extracts and, in the alcoholic extract, the number of substances found in thin layer cromatography and the toxicity of the substratum was observed. The results indicated that the growth of the root biomass, stem and leaves in discharge or lower light intensity was similar, but smaller in sandbank soil than in fertilized soil. The relative income of extracts in ether of petroleum and alcohol was larger in high light intensity and fertilized substratum. The light intensity and the substratum type didn't affect the number of substances detected in the alcoholic extract or the toxicity of this extract. Stains corresponding to the rosmarinic acid were only evidenced in some samples of the alcoholic extract, not allowing the verification of the effect of the treatments about its production.
Resumo:
Different climate models, modeling methods and carbon emission scenarios were used in this paper to evaluate the effects of future climate changes on geographical distribution of species of economic and cultural importance across the Cerrado biome. As the results of several studies have shown, there are still many uncertainties associated with these projections, although bioclimatic models are still widely used and effective method to evaluate the consequences for biodiversity of these climate changes. In this article, it was found that 90% of these uncertainties are related to methods of modeling, although, regardless of the uncertainties, the results revealed that the studied species will reduce about 78% of their geographic distribution in Cerrado. For an effective work on the conservation of these species, many studies still need to be carried out, although it is already possible to observe that climate change will have a strong influence on the pattern of distribution of these species.
Resumo:
Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m) were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.
Resumo:
Immediately after planting, tree seedlings face adverse environmental and biotic stresses that must be overcome to ensure survival and to yield a desirable growth. Hardening practices in the nursery may help improve seedling stress resistance through reduction of aboveground plant tissues and increased root volume and biomass. We conducted an assay to quantify changes in the morphogenesis following application of ethephon on seedlings of Pachystroma longifolium (Ness) I. M. Johnst.during hardening. The results showed no effect of the ethephon treatments on the number of leaves but a reduction of up to 50% in seedling height increment, and an increase in stem diameter increment of up to 44% with the 600 mg L-1 ethephon treatment, which consequently altered seedling Dickson Quality Index. Our results indicate that ethephon may help to promote desired morphological changes that occur during seedling hardening in nurseries.
Resumo:
A pruned stand of eucalypt clone underwent five thinning treatments with the removal of different proportion of the planted trees, at different ages: a) 0% - unthinned, b) 35% at 55 months, c) 35% at 81 months, d) 70% at 81 months, removing sprouts in the thinned plant stumps and, e) 70% at 81 months, without coppice sprouts removal. By the age of 141 months, the Weibull distribution showed higher number of trees in the smallest diameter classes for the unthinned treatment. The 70% thinning, with thinned coppice sprouts removal, presented higher number of individuals in the largest diameter classes. Height and yield were the smallest with the removal of 70% of the trees at 81 months, maintaining coppice sprouts. The afterthinning periodic annual increment was greater by thinning 35% of the trees at 55 months resulting in greater number of trees in the largest diameter classes as compared to the other treatments. Yield was higher for the unthinned treatment. The results of this study indicated that thinning 70% of the trees at the age of 81 months, with coppice sprout removal, could be recommended to obtain trees of larger diameter for multiproduct.
Resumo:
The benefit promoted by ectomycorrhizal depends on the interaction between symbionts and phosphorus (P) contents. Phosphorus effect on ectomycorrhizal formation and the effectiveness of these in promoting plant growth for fungal pre-selection were assessed under in vitro conditions. For P effect evaluation, Eucalyptus urophylla seedlings inoculated with four Pisolithus sp. isolates and others non-inoculated were grown on substrate containing 0.87, 1.16 and 1.72 mg P per plant. For evaluation of effectiveness and fungal pre-selection, other 30 isolates of Pisolithus sp., Pisolithus microcarpus ITA06 isolate, Amanita muscaria AM16 isolate, Scleroderma areolatum SC129 isolate were studied. D26 isolate promoted the highest plant heights for the three P doses, D51 at the lower dose and D72 at the intermediate dose. P doses did not influenced shoot fresh weight and fungal colonization. In the pre-selection of fungi, 14 isolates of Pisolithus sp., P. microcarpus ITA06 isolate and S. areolatum SC129isolate increased plant height and fresh weight. D82 isolate of Pisolithus sp. had effect singly on plant height while D17 and D58 on fresh weight. Of these, only D15, D17, D58 and ITA06 had typical ectomycorrhizae. The cultivation in vitro has shown adequate for pre-selection of ectomycorrhizal fungi. Colonization and benefits depend on species and isolate. D15, D17 and D58 of Pisolithus sp. and P. microcarpus isolate ITA06 are the most promising for nursery studies.
Resumo:
ABSTRACTSchizolobium parahyba pv. amazonicum (Huber ex Ducke) Barneby (paricá) occurs naturally in the Amazon and is significant commercial importance due to its rapid growth and excellent performance on cropping systems. The aim of this paper was to evaluate a microbial inoculants such as arbuscular mycorrhiza fungi (AMF) and Rhizobium sp. that promote plant growth. The inocula was 10 g of root colonized and spores of Glomus clarum and/or 1 mL of cell suspension (107 CFU/mL) of Rhizobium sp. and/or 100 g of chemical fertilizer NPK 20-05-20 per planting hole. The experimental design was complete randomized blocks with five replications and eight treatments (n = 800). Plant height, stem diameter and plant survival were measured. The results were tested for normality and homogeneity of variances and analyzed by ANOVA and Tukey test (p < 0.05). Rhizobium sp and AM fungi showed no effect on plant growth. Environmental factors probably influenced the effectiveness of symbiosis of both microorganisms and plant growth. The chemical fertilizer increased S. parahyba growth. During the first 120 days plants suffered with drought and frost, and at 180 days plants inoculated with microorganism plus chemical fertilizer showed higher survival when compared with control. The results showed that the microbial inoculants used showed an important role on plant survival after high stress conditions, but not in plant growth. Also was concluded that the planting time should be between November to December to avoid the presence of young plants during winter time that is dry and cold.