Physical-chemical characterization and wet milling yield of four maize hybrids

The influence of physical-chemical characteristics of maize grains and lactic acid concentrations on byproduct yields, generated by conventional wet milling, was studied during steeping, for four maize hybrids and two lactic acid concentrations (0.55 and 1.00%). For physical-chemical characterization, grain dimensions (length, thickness, and width) were determined, as well as mass of 100 grains, percentage of floating grains, volumetric mass, and centesimal composition. Statistical differences were found for percentage of floating grains (2.33 to 24.67%), volumetric mass (0.814 to 0.850 kg.L-1), mass of 100 grains (0.033 to 0.037 kg), water content (11.86 to 12.20%), proteins (8.21 to 9.06%), lipids (3.00 to 4.77%), and ashes (1.07 to 1.26%). There were no relationships of wet milling yields with maize appearance and physical-chemical characteristics. The addition of 1.00% lactic acid did not statistically improve byproduct yields; however, it favored separation of the grain components.

Chemical attributes of soil and dry mass accumulation of maize fertilized with cassava wastewater

The aim of this study was to evaluate chemical attributes alterations of a clay-loam textured soil and dry mass accumulation of maize submitted to application of cassava wastewater doses in three assessment periods. The experiment was conducted under greenhouse using a completely randomized experimental design in a factorial 5 × 3, with four replicates. The analyzed factors of research were doses of cassava wastewater (0; 12.6; 25.2; 50.4; 75.6 m3 ha-1) andassessment periods (20, 40 and 52 days after germination). The following parameters were determined: electric conductivity of soil saturation extract, pH in water, content of available P, content of exchangeable K+, Ca2+, Mg2+ and Na+of soil, dry mass of leaves and stem. The application of cassava wastewater on soil enables increase of pH, electric conductivity of saturation extract, contents of available P, contents of exchangeable K+ and Na+ and dry mass of leaves and stem. However, only pH and content of exchangeable K+ of soil, the electric conductivity of saturation extract and dry mass of leaves and stem are influenced by assessment period.

Spatial influence of physical and chemical parameters on management zone definition in apple orchards

ABSTRACT Precision agriculture adoption in Brazilian apple orchards is still incipient. This study aimed at evaluating the spatial variability of certain soil properties as soil density, soil penetration resistance, electrical conductivity, yield, and fruit quality in an apple orchard through digital mapping, as well as assessing the correlation between these factors by means of geostatistics, establishing management zones. Forty representative points were set within 2.5 hectares of apple orchard, wherein soil samples were collected and analyzed, besides measurements of fruit quality (Brix degree, size or diameter, pulp firmness and color) to generate an overall index quality. We concluded that the fruit quality indexes, when isolated, did not show strong spatial dependence, unlike the index of fruit quality (FQI), derived from a combination of these parameters, allowing orchard planning according to management zones based on quality.

Diagnostic value of copper parameters to predict growth of suckling calves grazing native range in Argentina

A study was conducted to evaluate the predictive diagnostic value of different copper (Cu) parameters as indicators of average daily gain (ADG) in growing calves. The effects in calves of cow Cu supplementation in the last one-third gestation period were also evaluated. Five supplementation trials, with a total of 300 calves, were carried out. Two groups of 30 calves were randomly assigned to each trial, one group was parenterally supplemented (SG) and the other was not supplemented (NSG). Trials began when calves were three-month-old and ended at weaning time. At each sampling calves were weighed and blood was taken to determine Cu concentrations in plasma, Whole Blood (WB), Red Cells (RC) and Packed Cell Volume (PCV). Liver samples from six animals of each group were taken both at the beginning and at the end of the trial. In two trials the mothers of the SG received Cu supplementation at the last one- third gestation period. Four of the five trials exhibited low ADG in the NSGs. In these groups, plasma Cu concentration decreased rapidly before low ADG was detected, which occurred with values remaining below 25µg/dl. The decrease of RC Cu concentration was considerably slow. WB showed an intermediate position. PCV in the SGs was higher than in the NSGs in all trials. Cow supplementation was insufficient to generate a liver storage able to last after calves reached the 3 months of age. These data could be useful to predict the risk of low ADG in grazing calves.

Leishmanicidal and cholinesterase inhibiting activities of phenolic compounds of Dimorphandra gardneriana and Platymiscium floribundum, native plants from Caatinga biome

In recent years, the Brazilian Health Ministry and the World Health Organization have supported research into new technologies that may contribute to the surveillance, new treatments, and control of visceral leishmaniasis within the country. In light of this, the aim of this study was to isolate compounds from plants of the Caatinga biome, and to investigate their toxicity against promastigote and amastigote forms of Leishmania infantum chagasi, the main responsible parasite for South American visceral leishmaniasis, and evaluate their ability to inhibit acetylcholinesterase enzyme (AChE). A screen assay using luciferase-expressing promastigote form and an in situ ELISA assay were used to measure the viability of promastigote and amastigote forms, respectively, after exposure to these substances. The MTT colorimetric assay was performed to determine the toxicity of these compounds in murine monocytic RAW 264.7 cell line. All compounds were tested in vitro for their anti-cholinesterase properties. A coumarin, scoparone, was isolated from Platymiscium floribundum stems, and the flavonoids rutin and quercetin were isolated from Dimorphandra gardneriana beans. These compounds were purified using silica gel column chromatography, eluted with organic solvents in mixtures of increasing polarity, and identified by spectral analysis. In the leishmanicidal assays, the compounds showed dose-dependent efficacy against the extracellular promastigote forms, with an EC50 for scoporone of 21.4µg/mL, quercetin and rutin 26 and 30.3µg/mL, respectively. The flavonoids presented comparable results to the positive control drug, amphotericin B, against the amastigote forms with EC50 for quercetin and rutin of 10.6 and 43.3µg/mL, respectively. All compounds inhibited AChE with inhibition zones varying from 0.8 to 0.6, indicating a possible mechanism of action for leishmacicidal activity.

Influence of wheat straw and rhizosphere on seed germination, early seedling growth and bio-chemical attributes of Trianthema portulacastrum

Decomposing wheat (Triticum aestivum) straw and rhizosphere-infested soil were evaluated for their suppressive activity against horse purslane (Trianthema portulacastrum), a noxious summer weed in Pakistan. Two separate pot studies were carried out. Wheat straw was incorporated at 4, 6 and 8 g kg-1 soil five days before the sowing of horse purslane. Pots without straw incorporation were maintained as control. In a second study, soil was taken from 15 and 30 cm depths from a previously cropped wheat field immediately after its harvest and was used as growing medium. Soil from an intentionally uncropped area of the same field was used as control. Suppressive activity was measured in terms of germination dynamics, seedling growth, and biochemical attributes such as chlorophyll contents, total soluble phenolics, soluble protein and antioxidant enzymes. Germination, seedling growth, chlorophyll contents and soluble protein of horse purslane were all negatively influenced. Higher phenolics and enhanced activities of antioxidant enzymes were noticed in response to wheat residues incorporation and its rhizosphere soil. Both studies established that the phytotoxic influence of wheat straw and wheat-infested rhizosphere soil on horse purslane can further be exploited for horse purslane management as a sustainable approach.

Tolerance of sugarcane cultivars to chemical eradication

Knowledge of the minimum rate of glyphosate required to eradicate sugarcane ratoons can reduce the amount of herbicide used. To confirm this hypothesis, this study aimed to investigate the tolerance of different sugarcane cultivars to chemical eradication, at different glyphosate rates. The experiment was conducted in a randomized block design in a split-plot scheme, with four replications. The sugarcane cultivars (IACSP94-2094, IACSP94-2101, IACSP93-3046, IACSP94‑4004, IAC86-2480, and RB72454) were allocated in plots and the glyphosate rates (0, 1,440, 2,160, 2,880, 3,600, and 4,320 g ha-1), in the sub plots. The traits evaluated were signs of poisoning symptoms; total chlorophyll content, plant height, percentage of dead tillers, and dry weight of the plants. At 45 days after application (DAA), the glyphosate rate of 1,440 g a.e. ha-1 eradicated the cultivars IACSP94-2094 and IACSP94-2101, as well as RB72454 with application of 2,160 g a.e. ha‑1. Application of glyphosate 2,880 g a.e. ha-1 eradicated both IACSP93-3046 and IAC86-2480 and glyphosate 3,600 g a.e. ha-1 eradicated IACSP94-4004. The most tolerant cultivar was IACSP94‑4004, eradicated at the rate of 3,600 g. a.e. ha-1. This confirms the hypothesis that knowing the cultivar's tolerance leads, in practice, to a smaller amount of herbicide applied to the environment, which also reduces production costs.

Aqueous tissue extracts of Conyza canadensis inhibit the germination and shoot growth of three native herbs with no autotoxic effects

Conyza canadensis is a widespread weed species forming dense populations in most regions of China. Petri dish bioassays with aqueous extracts of the aboveground parts and roots of C. canadensis at three concentrations (0.05, 0.1, and 0.2 g mL-1) were undertaken to investigate the autotoxic effects of C. canadensis, and the possible effects on three dominant native weed species, Plantago asiatica, Digitaria sanguinalis and Youngia japonica. The results showed that seed germination and the shoot length of three native species were significantly inhibited by aqueous extracts of C. canadensis at almost all concentrations that generally increased with increasing extract concentration. However, the seed germination and shoot length of C. canadensis itself was not significantly affected by the same extracts at all concentrations. These results suggested that the potential allelopathic compounds produced by the tissue of C. canadensis may contribute to its invasive success in invading southern China.

Chemical control of morning glory as a function of water restriction levels

Among the herbicides recommended for the dry season and registered to sugarcane crop, amicarbazone, isoxaflutole and the association diuron + hexazinone + sulfomethuron-methyl can be highlighted. These are pre-emergence herbicides efficient against broad-leaved weeds. Morning glory causes large losses in infested sugarcane fields by bending the stalks and interfering in harvesting. In this study the effectiveness of pre-emergence herbicides for two species of morning glory (Ipomoea hederifolia and Ipomoea grandifolia) was evaluated. Treatments were arranged in completely randomized factorial design (4 x 7). There were four periods of water restriction (0, 30, 60 and 90 days), seven chemical treatments [diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1507.5 + 425 + 36.25 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1658.25 + 467.5 + 39.87 g a.i. ha-1), diuron + hexazinone + sulfometuron­methyl (1809 + 510 + 43.5 g a.i. ha-1), amicarbazone (1190 g a.i. ha-1), amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha-1)] and a control with no application. At 7, 14, 21 and 28 days after the restoration of moisture, control was visually evaluated. After the final evaluation, the dry mass of morning glories was measured. At 90 days of water restriction, diuron + hexazinone + sulfometuron-methyl was more effective to control I. hederifolia than the amicarbazone + isoxaflutole tank mixture. The four diuron + hexazinone + sulfometuron­methyl doses have reduced morning glory dry mass to zero; whereas treatments with amicarbazone have not. The most effective treatment for morning glory control was diuron + hexazinone + sulfometuron-methyl. This result may be due to a possible synergistic interaction.

Sorption and desorption of Suflafenacil in two soils in the state of São Paulo with different physical and chemical attributes

A study was conducted to evaluate the sorption and desorption of 14C herbicide saflufenacil (pyrimidinedione) in two soils in the State of São Paulo, classified as Red Yellow Latosol with clayey texture (LVA-1) and medium texture (LVA-2), using the batch method through isotherms. The soils were air dried and sieved a 2 mm mesh. The radioactivity was determined by liquid scintillation spectrometry in acclimatized room (25 ± 2 °C). Sorption isotherms were conducted for 5 concentrations of saflufenacil (5.0; 2.5; 1.0; 0.5 and 0.05 μg mL-1) and the results were adjusted to the Freundlich equation, thus obtaining the parameters of sorption followed by two extractions with 0.01 M CaCl2 to determine desorption parameters similarly to sorption. The results showed that saflufenacil sorption was low for both soils studied, being greater for the LVA with higher organic matter content. The desorption coefficients were greater than their sorption coefficients, suggesting the occurrence of hysteresis. The sorption and desorption isotherms (classified as type C isotherms), hysteresis and the t-test between the angular coefficient of the respective isotherms showed that both the sorption and desorption occur with equal intensity.

Chemical control of Pileamicrophylla in cattleya seedlings (Cattleyatenebrosa x Cattleyaleopoldy)

Species of the orchidaceae family are grown for marketing flowers and among them the genus Cattleya stands out. However, due to its slow growth, the substrate is subjected to weed infestation. Therefore, this study aims to evaluate the selectivity and efficiency of herbicides in controlling Pilea microphylla in Cattleya orchid seedlings (Cattleya tenebrosa x Cattleya leopoldy). We used a completely randomized design with four replications. The evaluated herbicides were oxyfluorfen (0, 120, 240 and 480 g ha-1), flumioxazin (0, 12.5, 25 and 40 g ha-1), nicosulfuron (0, 20, 40 and 80 g ha-1) mesotrione (0, 96, 144 and 192 g ha-1), clethodim (0, 60, 84 and 108 g ha-1) and metsulfuron-methyl (0, 1.2, 1.8 and 2.4 g ha-1). At post-emergence applying time, the Cattleya plants had three bulb sand were 10 cm tall, while P. microphylla, where 5 cm tall. Nicosulfuron, mesotrione and clethodim herbicides did not control P. microphylla, while oxyfluorfen and flumioxazin showed over 90% efficiency level sin controlling P. microphyllafrom 14 days after application (DAA). As to metsulfuron-methyl, it showed efficiency superior to 90% from the control dose of 1.8 g ha-1 at 28 DAA. All herbicides were selective plants of Cattleya, however, only oxyfluorfen, flumioxazin and metsulfuron-methyl were effective in controlling P. microphylla.

Selectivity of chemical weed control systems in conventional cotton

Cotton is highly susceptible to the interference imposed by weed community, being therefore essential to adopt control measures ensuring the crop yield. Herbicides are the primary method of weed control in large-scale areas of production, and usually more than one herbicide application is necessary due to the extensive crop cycle. This study aimed to evaluate the selectivity of different chemical weed control systems for conventional cotton. The experiment took place in the field in a randomized block design, with twenty nine treatments and four replications in a split plot layout (adjacent double check). Results showed that triple mixtures in pre-emergence increased the chance of observing reductions in the cotton yield. To avoid reductions in crop yield, users should proceed to a maximum mixture of two herbicides in pre-emergence, followed by S-metolachlor over the top, followed by one post-emergence mixture application of pyrithiobac-sodium + trifloxysulfuron-sodium.

Chemical control of different Digitaria insularis populations and management of a glyphosate-resistant population

This study aimed to control different populations of Digitaria insularisby glyphosate herbicide, isolated and mixed, besides the combination of methods (chemical and mechanical) to manage resistant adult plants. Three experiments were conducted, one in pots which were maintained under non-controlled conditions and two under field conditions. In the experiment in pots, twelve populations of D. insularis were sprayed with isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p tefuryl (0.12 kg i.a. ha-1). The treatment of 1.44 kg a.e. ha-1 of glyphosate plus 0.12 kg a.i. ha-1 of quizalofop was sufficient for adequate control (>95%) of all populations. Population 11 (area of grain production in Itumbiara, GO) was considered sensitive to glyphosate. Others populations were moderately sensitive or tolerant to the herbicide. In the field, the plants of D. insularis of one of the experiments were mowed and, in the other, there were not. Eight treatments with herbicides [isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p-tefuryl at 0.12 kg a.i. ha-1), clethodim at 0.108 kg a.i. ha-1) or nicosulfuron at 0.06 kg a.i. ha-1)] were assessed, in combination with or without sequential application of the standard treatment, sprayed 15 days after the first application. The combination of the mechanic control with the application of glyphosate (2.16 and 1.44 kg a.e. ha-1) plus quizalofop-p-tefuryl (0.12 kg a.i. ha-1) or clethodim (0.108 kg a.i. ha-1), associated to the sequential application, was the most effective strategy for the management of adult plants of resistant D. insularis.

CHEMICAL CONTROL OF WHITE CLOVER IN SOYBEAN CROPS

ABSTRACTWhite clover is tolerant to many herbicides, making difficult a chemical control of this species during soybean crop establishments. The objective of this research was to select herbicides applied postemergence to control white clover in soybean and know the effects of this control on soybean yield. Seven herbicides were assessed, applied postemergence, with or without sequential application of glyphosate, and two control treatments (no control and total control of white clover). Glyphosate (with two sequential applications), fomesafen (with a sequential application of glyphosate), chlorimuron-ethyl and lactofen have shown a satisfactory control of white clover (above 80%). The lower control efficiency has resulted in lower production of soybeans.

Sinningia allagophylla(Gesneriaceae): in vitro cultivation of a native plant of the Brazilian cerrado

We used axillary buds as initial explants for hormone interaction studies required for in vitro cultivation of S. allagophylla. Callus production was achieved on gelled Murashige & Skoog medium (MS) supplemented with indole-3-acetic acid (IAA= 0.1 and 0.5 mg.l­1 alone or combined with 6 benzylaminopurine) (BA= 0.01 and 0.1 mg.l-1). A hormone balance between IAA and BA that would encourage shoot bud development was not found. Nodal segments from axenic cultures grown in the presence of cytokinin (0.1 mg.1­1 of BA) without any auxin on MS medium with half-strength macronutrients were used as a standard explant source for subsequent experiments on optimum mineral culture media composition for S. allagophylla in vitro cultivation. We found that explants kept in vitro on gelled Gamborg et al. (B5) mineral composition culture medium showed better shoot and specially root growth than on MS medium. Comparisons of the ammonium and nitrate ratios of MS and B5 media indicate that B5 medium has a substantial reduced ammonium ion when compared to MS medium, as well as a lower total nitrogen level. The growth response pattern obtained in vitro may be evidence of the adaptation of this species to soils of poor mineral composition as found in the Brazilian cerrado, as well as an indication that nitrogen levels play a key role for S. allagophylla growth.