Leaf consumption and duration of instars of the cassava defoliator Erinnyis ello (L., 1758) (Lepidoptera, Sphingidae)

The objectives of this research were to evaluate leaf consumption and the developmental time of the larvae of Erynnyis ello (L., 1758) (Lepidoptera, Sphingidae) reared on cassava, in order to obtain information for the integrated management of this pest. The larvae were reared on excised cassava leaves in Petri dishes and later in gerbox, and kept in chambers at 24 ± 2 ºC and 75 ± 10% RH. The total leaf area consumed by the larva to complete its development was 589.67 cm2; each of the five instars consumed, respectively: 1.89 cm2; 5.74 cm2; 17.48 cm2; 76.66 cm2; and 487.90 cm2. The consumption by the first three instars was insignificant, and did not reach 5% altogether; the 4th represented 13%; the 5th presented a consumption significantly higher, about 82.7%. The total time for the larval development was 22.61 days, and the duration for each of the five larval instar was, respectively: 4.35; 3.19; 3.32; 4.52; and 4.94 days. The pre-pupal period lasted 2.29 days. Since the highest consumption is by the 5th instar larva, the control should be applied before this age to avoid heavier damages to the cassava crop.

Variability in leaf rust susceptibility among peach cultivars

The aim of this work was to estimate the susceptibility of thirty-six peach cultivars to leaf rust caused by Tranzschelia discolor f. sp. persica. The incidence and severity of the disease as well as defoliation in peach trees of an experimental orchard of Parana Federal University of Technology, Campus Dois Vizinhos were evaluated on the growing seasons 2004/2005 and 2005/2006. Immunity to this disease was not observed in the studied cultivars. There was difference in leaf rust intensity depending on the growing season conditions. Cultivars 'Pilcha', 'Sinuelo', 'Chirua', 'Sulina', 'Eldorado' and 'Pampeano' showed tolerance to leaf rust, whereas cultivars 'Vila Nova', 'Fla 1372', 'Coral 2', 'Chimarrita', 'Della Nona', 'BR-1 ' and 'Guaiaca' showed high susceptibility.

Influence of leaf retention on cutting propagation of Lavandula dentata L.

Vegetative propagation of lavender offers several advantages over sexual propagation, among them crop homogeneity and yield of higher quality essential oil. However, Lavandula species have been propagated mostly by seeds and are said to be recalcitrant to rooting when propagated by cuttings. During cutting propagation, one of the important variables that influence the rooting capacity of cuttings is the leaf retention. The objective of this work was to evaluate the influence of leaf retention on rooting of L. dentata cuttings. Apical cuttings of L. dentata of 10 cm in length, keeping approximately 1/3, 1/2 or 2/3 of their leaves were planted in commercial substrate Plantmax HT® under intermittent mist. After two months, averages of root number, length of the longest root, root fresh and dry weights, and the survival percentage were evaluated. Root length and fresh weight were statistically greater with 2/3 of leaf retention and when fewer leaves were kept on the cuttings, lower means of root dry weight was observed. Under the conditions applied in this study, greater leaf retention was better for rooting of L. dentata cuttings.

Initial performance of pineapple and utilization of rock phosphate applied in combination with organic compounds to leaf axils

Rock phosphates have low solubility in water, but good solubility in acid. The use of organic compounds together with these phosphorus sources applied to the basal leaf axils of pineapple can increase the solubility of this phosfate source and increase the P availability to the crop. A greenhouse experiment was conducted using Araxá rock phosphate (10 g) in combination or not with solutions containing increasing concentrations of humic acids (0 to 40 mmol L-1 of carbon), with or without citric acid (0.005 mmol L-1), applied to basal leaf axils of pineapple cv. Pérola. Growth and nutritional characteristics of aerial plant parts were assessed. Growth rates of aerial parts and N, P, K, Ca and Mg contents increased curvilinearly with increasing concentration of carbon in the form of humic acids. Maximum values were found for the concentration of 9.3 mmol L-1 of carbon combined with 0.005 mmol L-1 of citric acid and natural phosphate.

The effect of leaf area reduction on corn plants during the reproduction phase

Reduction in leaf area in corn plants during reproduction changes physiological metabolism and consequently the accumulation of dry matter in grains. The aim of this work was to study changes in agronomic characteristics caused by defoliation in corn during the reproduction phase. The experiment was carried out in Uberlândia, Minas Gerais state, in the agricultural year 2007/2008. The experiment was arranged in a randomized block design, consisting of seven treatments: control without defoliation, removal of two apical leaves, removal of four apical leaves, removal of all leaves above spike, removal of four intermediate leaves, removal of all leaves below spike, and removal of all plant leaves, with five repetitions. The genotype used for the evaluations was hybrid NB 7376. Defoliation was carried out when plants were at the growth stage R2. The variables assessed were: yield, density of spikes and corncobs, root resistance and stem integrity. When all leaves above the spike were removed, grain yield was reduced by 20%. Corncob density, stem integrity and root resistance to uprooting were also affected. Spike density was only affected when all plant leaves were removed. The leaf area remaining physiologically active above the spike was found to be most efficient in terms of grain yield.

Broccoli yield in response to top-dressing fertilization with green manure and biofertilizer

The objective of this work was to evaluate the productive performance of broccoli under different top-dressing organic fertilizations. The experiment was conducted under protected cultivation, in a completely randomized design with four replications, with two plants per experimental unit. Broccoli seedlings were produced in a commercial substrate in styrofoam trays. The seedlings were transplanted to plastic pots containing 10.0 L of substrate made up of subsoil and organic compost at the ratio of 3:1 (v/v), respectively, which is equivalent to about 20.0 t ha-1 of organic compost at planting. After seedling establishment, the top-dressing fertilization treatments were applied: gliricidia biomass associated or not with liquid biofertilizer of cattle manure to the soil and bokashi. Two control treatments were established: one with mineral fertilization recommended for the crop and the other without top-dressing fertilization. The broccoli production was evaluated (commercial standard). Plants that received mineral fertilizer were more productive, however, they were not significantly different (p>0.05), by Dunnet test, from the plants fertilized with 2.5 t ha-1 gliricidiabiomass (dry mass) associated with liquid biofertilizer (2.0 L m-2) applied to soil. Top-dressing fertilizations with only gliricidia, at 2.5 and 5.0 t ha-1 of biomass (dry mass), resulted in no significant increase in production of broccoli inflorescence. The use of bokashi in addition to gliricidia biomass and liquid biofertilizer reduced the efficiency of the fertilization compared with plants that received only gliricidia and liquid biofertilizer.

Influence of nitrogen fertilization and green manure on the economic feasibility of no-tilled wheat in the Cerrado

The search for higher profitability in wheat crop with cost reduction technologies that may promote sustainability is an important matter in Brazilian agriculture. This study evaluated the profitability of no-tilled wheat, reducing nitrogen topdressing doses with the cultivation of green manure before the wheat crop. The experiment was carried out in Selvíria (MS), Brazil, in 2009/10. The experiment was arranged in a randomized block design with 36 treatments in splitplots and four replicates. The plots were formed by six types of green manure: Cajanus cajan L. BRS Mandarin, Crotalaria juncea L., Pennisetum americanum L. BRS 1501, fallow area and mixed cropping of Pennisetum americanum L. + Cajanus cajan L. and Pennisetum americanum L. + crotalaria which provided straw for no-tilled wheat in the winter, following the rice crop in the summer. The subplots were formed by six levels of topdressing nitrogen (0, 25, 50, 75, 100 and 125 kg N ha-1) using urea as a nitrogen source. The wheat grown after green manure in the previous winter crop, with no nitrogen topdressing and a rate of 25 kg ha-1 N, had more frequently production costs above the gross income. Wheat production cost after the mixed cropping Pennisetum americanum L. + Cajanus cajan L. and Pennisetum americanum L. + Crotalaria juncea L. from the previous winter crop, combined with nitrogen rates of 50 and 75 kg N ha-1, provided better profitability compared with the other green manures evaluated.

Nitrogen fertilization of coffee: organic compost and Crotalaria juncea L.

Information concerning the response of coffee to organic fertilizers is scarce. This study evaluates the effect of different doses of compost and Crotalaria juncea L. on growth, production and nitrogen nutrition of coffee trees. The treatments consisted of compost at rates of 25, 50, 75 and 100% of the recommended fertilization, with or without the aerial part of C. juncea. C. juncea was grown with NH4-N (2% 15N) and applied to coffee. The use of C. juncea increased growth in height and diameter of the coffee canopy. In the first year, the percentage of N derived from C. juncea reached 8.5% at seven months and 4.1% at fifteen months after fertilization. In the second year, the percentage of N derived from C. juncea reached 17.9% N at the early harvest, five months after fertilization. Increased rates of compost increased pH , P , K , Ca , Mg , sum of bases , effective CEC, base saturation and organic matter and reduced potential acidity. 15N allowed the identification of the N contribution from C. juncea with percentage of leaf N derived from Crotalaria juncea from 9.2 to 17.9%.

Leaf area and epicuticular wax content of Sida spp

Morpho-physiological characteristics and chemical composition are directly related to superior competitive ability of crops. This study intended to make a comparative analysis of dry matter production, leaf area and amount of epicuticular wax of three species of Sida spp: S. urens L., S. rhombifolia L. and S. spinosa L. Plants were collected at three growth stages: V1: stage described as up to 10 fully expanded leaves; V2: between 11 leaves and flowering; and R: after flowering. At stages V2 and R, the highest number of leaves was recorded for S. rhombifolia, followed by S. spinosa at V2 and S. urens at R. These results were relatively proportional to leaf area for all species. S. spinosa at the vegetative stage produced the highest values of specific leaf area (SLA), with no significant differences between species at the stage R. The amount of wax per unit of leaf area between species at the same developmental stage was significantly different only at the reproductive stage, where S. spinosa produced 23.18 and 6.23 fold more wax than S. urens and S. rhombifolia respectively. Between the growth stages of each species, there was decrease in the amount of wax with plant age and increase in leaf area (AFE), number of leaves and dry matter. The leaves of the Sida species exhibit different characteristics and this information can be used to optimize the use of herbicides in the control of these weeds.

Phytomass production and nutrient accumulation by green manure species

Green manuring is recognized as a viable alternative to improve nutrient cycling in soils. The aim of this study was to evaluate the phytomass production and nutrient accumulation in shoots of the summer green manures jack bean [Canavalia ensiformis (L.) DC.], dwarf pigeon pea (Cajanus cajanvar var. Flavus DC.), dwarf mucuna [Mucuna deeringiana (Bort) Merr] and sunn hemp (Crotalaria juncea L.), under nitrogen fertilization and/or inoculation with N-fixing bacteria. A split plot design was arranged with the four Fabaceae species as main plots and nitrogen fertilization (with and without) and inoculation with diazotrophic bacteria (with and without) as the subplots, in a 2² factorial. The experiment was arranged as a randomized complete block design with four replications. In the conditions of this trial, the sunn hemp had the highest production of shoot phytomass (12.4 Mg ha-1) and nutrient accumulation, while the dwarf mucuna had the lowest production of shoot phytomass (3.9 Mg ha-1) and nutrient accumulation. The results showed no effect of nitrogen fertilization or inoculation with N-fixing bacteria on the production of shoot phytomass and nutrient accumulation, except for inoculation without nitrogen fertilization, resulting in greater P accumulation (p <0.05) in the sunn hemp and greater Zn and Mn accumulation in the dwarf mucuna. These findings indicate that N fertilization or inoculation with N2-fixing bacteria for Fabaceae are low efficiency practices in the edaphoclimatic conditions of this study.

In vitro growth and leaf anatomy of Cattleya walkeriana (Gardner, 1839) grown in natural ventilation system

Natural ventilation system facilitates gaseous exchanges in in vitro plants promoting changes in the leaf tissue, which can be evaluated through the leaf anatomy, and it allows a cultivation closer to the photoautrophic micropropagation. The objective of this work was to evaluate the effects on in vitro growth and on the leaf anatomy of Cattleya walkeriana grown in natural and conventional ventilation system with different concentrations of sucrose (0; 15; 30 and 45 L-1) combined with different cultivation systems (conventional micropropagation and natural ventilation system). The culture medium was composed of MS salts, solidified with 7 g L-1 of agar and pH adjusted to 5.8. Forty milliliters of culture medium were distributed in 250 mL flasks, autoclaved at 120 ºC for 20 minutes. The greater plant growth, as well as the greater thickness of the mesophyll was observed with the use of 20 g L-1 sucrose in natural ventilation system. Plants grown in natural ventilation system showed a thicker leaf mesophyll, which is directly related to photoautotrophic crops. The natural ventilation system induced more elliptical stomata and probably more functional formats.

Juvenile tree growth correlates with photosynthesis and leaf phosphorus content in central Amazonia

Light and soil water availability may limit carbon uptake of trees in tropical rainforests. The objective of this work was to determine how photosynthetic traits of juvenile trees respond to variations in rainfall seasonality, leaf nutrient content, and opening of the forest canopy. The correlation between leaf nutrient content and annual growth rate of saplings was also assessed. In a terra firme rainforest of the central Amazon, leaf nutrient content and gas exchange parameters were measured in five sapling tree species in the dry and rainy season of 2008. Sapling growth was measured in 2008 and 2009. Rainfall seasonality led to variations in soil water content, but it did not affect leaf gas exchange parameters. Subtle changes in the canopy opening affected CO2 saturated photosynthesis (A pot, p = 0.04). Although A pot was affected by leaf nutrient content (as follows: P > Mg > Ca > N > K), the relative growth rate of saplings correlated solely with leaf P content (r = 0.52, p = 0.003). At present, reduction in soil water content during the dry season does not seem to be strong enough to cause any effect on photosynthesis of saplings in central Amazonia. This study shows that leaf P content is positively correlated with sapling growth in the central Amazon. Therefore, the positive effect of atmospheric CO2 fertilization on long-term tree growth will depend on the ability of trees to absorb additional amount of P

Weed suppression by green manure in an agroecological system

ABSTRACT Green manure promotes efficient suppression of weeds, but green manure species can exhibit distinct behaviors, depending on the environmental conditions. This study aimed to evaluate the potential of soil mulching and weed suppression by spring/summer green manure species grown in the spring/summer season, at different growth stages and after management (cut), for 90 days during the cassava crop cycle. The study was carried out in the 2010/2011 season, in a system managed under agroecological principles. The treatments consisted of different green manure species and arrangements: Crotalaria juncea, Cajanus cajan, Canavalia brasiliensis, Canavalia ensiformis, Pennisetum americanum, Crotalaria juncea and Pennisetum americanum intercropped; Mucuna aterrima, Sorghum bicolor, a mixture of all the green manures in study and a control plot under fallow. The experiment was arranged in a randomized block design with four replications. The evaluations of the soil cover either by the green manures or weeds were performed at 45, 90 and 105 days after the emergence of the green manures. The cassava crop was planted under reduced tillage system at 11 days after the cut of the green manures. The percentage of soil covered by weeds and the dry matter produced were evaluated at 30, 60 and 90 days after planting. The results showed that the green manures had a suppressive effect on weeds during their life cycle, as well as during the first months after its management (cut), composing the mulch.

Diagnostic leaf to evaluate the nutritional status of Jatropha

ABSTRACT The analytical determination of nutrient levels in recently mature leaves in order to diagnose nutritional status is based on the fact that leaves are metabolically active and more sensitive to variation in nutrients of the soil. In most of cases, there is a direct well known between foliar content and the development and yield of the plant. However, for a more accurate interpretation, it is essential to establish the index leaf. There are few published studies about Jatropha with contrasting results. In order to establish the index leaf, in adult plants, the macronutrient levels were evaluated in samples collected in experimental plots, in which doses of nitrogen and phosphorus were applied, in two parts of the floral branches (in the top and in the middle thirds); and in three positions of leaves of the floral branch (between the 1st and 3rd, 6th and 8th, and 13th and 15th leaves below the inflorescence). The location of the leaf on the plant significantly affects nutrient contents. Nitrogen, phosphorus, potassium and sulfur tend to have higher concentration in young tissues. Calcium and magnesium showed higher levels in the basal leaves of floral branches. Samples collected in the top third of plants (between the 6th and 15th leaves of the floral branch) are more sensitive to variations of nitrogen and phosphorus fertilization. Therefore, we indicate the 6th to 15th leaves of the top third plants as index leaves estimate nutritional status of Jatropha.

GREEN SUPPLY CHAIN: PROTAGONISTA OU COADJUVANTE NO BRASIL?

Questões ambientais passaram a ser introduzidas com maior frequência nos negócios empresariais. Quanto à cadeia de suprimentos, Green Supply Chain Management (GSCM) surge como novo enfoque à responsabilidade das empresas com o meio ambiente. Este artigo objetiva analisar a difusão do conceito e das práticas de GSCM no cenário brasileiro. Para tanto, foram realizadas entrevistas com especialistas do tema cadeia de suprimentos na área de Administração no Brasil. Os resultados indicam que as razões para o lento desenvolvimento do conceito podem relacionar-se com características do mercado nacional, foco empresarial em aspectos internos, falta de legislação rígida e baixa pressão dos consumidores. Especialistas percebem, entretanto, boas perspectivas para o futuro das discussões da temática no País, em virtude da Política Nacional dos Resíduos Sólidos, de pressões do mercado internacional e da busca por certificação ambiental. Este estudo procurou fomentar novas discussões sobre GSCM no Brasil.