Cover crops and herbicide timing management on soybean yield under no-tillage system

The objective of this work was to evaluate the effect of cover crops and timing of pre-emergence herbicide applications on soybean yield under no-tillage system. The experiment consisted of four cover crops (Panicum maximum, Urochloa ruziziensis, U. brizantha, and pearl millet) and fallow, in addition to four herbicide timings (30, 20, 10, and 0 days before soybean sowing), under no-tillage system (NTS), and of two control treatments under conventional tillage system (CTS). The experimental design was a completely randomized block, in a split-plot arrangement, with three replicates. Soybean under fallow, P. maximum, U. ruziziensis, U. brizantha, and pearl millet in the NTS and soybean under U. brizantha in the CTS did not differ significantly regarding yield. Soybean under fallow in the CTS significantly reduced yield when compared to the other treatments. The amount of straw on soil surface did not significantly affect soybean yield. Chemical management of P. maximum and U. brizantha near the soybean sowing date causes significant damage in soybean yield. However, herbicide timing in fallow, U. ruziziensis, and pearl millet does not affect soybean yield.

Grazing intensities and poultry litter fertilization levels on corn and black oat yield

The objective of this work was to assess the effect of poultry litter fertilization levels on corn and black oat yield using different grazing intensities, poultry litter levels (mixture of manure and bedding material) and a chemical fertilization level. The experimental design was a randomized complete block in a split-plot arrangement with four replicates. Black oat + ryegrass grazing intensities, characterized by different pasture sward management, with animal entrance at 25, 30 and 35-cm heights and exit at 5.0, 10 and 15-cm heights, were established at the main plots. After the grazing period, corn was grown at the subplots with four levels of poultry litter (0, 4,953, 9,907 and 14,860 kg ha-1), aiming to supply 0, 100, 200 and 300 kg ha-1 of nitrogen, and a treatment with chemical fertilizer, according to soil analysis. Grazing intensities had no effect on corn yield. Corn yield was 7,493, 8,458, 9,188, 10,247 and 11,028 kg ha-1, respectively, for the treatments without and with 4,953, 9,907 and 14,860 kg ha-1 of poultry litter, and the treatment with chemical fertilization. Poultry litter levels have a residual effect on the production of black oat grown in succession to corn.

Foraging behavior and ruminal fermentation of dairy cows grazing ryegrass pasture alone or with white clover

The objective of this work was to evaluate the influence of pasture composition and regrowth age on the relationship between feeding behavior and ruminal fermentation in dairy cows grazing perennial ryegrass with or without white clover. The experiment was carried out in a 2x2 factorial arrangement, with two sward types and two ages of regrowth. Swards of perennial ryegrass sown alone (PRG) and of perennial ryegrass mixed with white clover (GC) were evaluated. Twelve late-lactation Holstein cows, fistulated at the rumen, were distributed in a 4x4 latin square experimental design with four 12-day periods. Daily distribution of grazing was similar in the PRG and the GC swards, but the concentration of rumen volatile fatty acids (VFA) was higher and the proportion of propionate was lower on mixed swards during the day. Daily distribution of grazing was similar in pastures of different ages. However, in the oldest swards, rumen fluid pH increased and VFA concentration decreased after evening milking. Time spent grazing does not influence ruminal fermentation, which depends on the changes that occur as different sward layers are grazed.

Piperine as a phytogenic additive in broiler diets

The objective of this work was to determine the effect of piperine as a phytogenic additive in chicken broiler diet. Seven‑day‑old male chicks were randomly allocated in four experimental treatments (n = 24), with four replicates (n = 6). The piperine was added to diets at concentrations of 0, 60, 120, and 180 mg kg‑1 for 35 consecutive days. The following were evaluated: biochemical, hematological and histopathological parameters; performance and carcass yield. Histomorphometric analyses were also carried out. The addition of 120 and 180 mg kg‑1 of piperine did not alter broiler body weight and feed conversion, whereas 60 mg kg‑1 of piperine interfered positively in both parameters from 36 to 42 days of age and significantly increased the absorption surface of the duodenum and the ileum. No macroscopic alteration in organ size and color was observed in the broilers fed diets with the evaluated concentrations of piperine. The supplementation of 120 and 180 mg kg‑1 of piperine is toxic to liver tissue and reduces the absorption surface of the jejune. The diet supplemented with 60 mg kg‑1 of piperine is safe.

Correlation of physical and chemical attributes of soil with sugarcane yield

The objective of this work was to evaluate the correlation between sugarcane yield and some physical and chemical attributes of soil. For this, a 42‑ha test area in Araras, SP, Brazil, was used. Soil properties were determined from samples collected at the beginning of the 2003/2004 harvest season, using a regular 100x100 m grid. Yield assessment was done with a yield monitor (Simprocana). Correlation analyses were performed between sugarcane yield and the following soil properties: pH, pH CaCl2, N, C, cone index, clay content, soil organic matter, P, K, Ca, Mg, H+AL, cation exchange capacity, and base saturation. Correlation coefficients were respectively ‑0.05, ‑0.29, 0.33, 0.41, ‑0.27, 0.22, 0.44, ‑0.24, trace, ‑0.06, 0.01, 0.32, 0.14, and 0.04. Correlations of chemical and physical attributes of soil with sugarcane yield are weak, and, per se, they are not able to explain sugarcane yield variation, which suggests that other variables, besides soil attributes, should be analysed.

Soil fertility and upland rice yield after biochar application in the Cerrado

The objective of this work was to evaluate the effect of biochar made from Eucalyptus on soil fertility, and on the yield and development of upland rice. The experiment was performed during two years in a randomized block design with four replicates, in a sandy loam Dystric Plinthosol. Four doses of NPK 05-25-15, annually distributed in stripes (0, 100, 200 and 300 kg ha-1), and four doses of biochar (0, 8, 16 and 32 Mg ha-1), applied once in the first year - alone or with NPK - were evaluated. In the first year, biochar positively affected soil fertility [total organic carbon (TOC), Ca, P, Al, H+Al, and pH], at 0-10 cm soil depth, and it was the only factor with significant effect on yield. In the second year, the effect of biochar diminished or was overcome by the fertilizer. TOC moved down in the soil profile to the 0-20 cm depth, influencing K availability in this layer. In the second year, there was a significant interaction between biochar and the fertilizer on plant growth and biomass dry matter accumulation.

Fusarium wilt incidence and common bean yield according to the preceding crop and the soil tillage system

The objective of this work was to evaluate the effects of preceding crops and tillage systems on the incidence of Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and common bean (Phaseolus vulgaris) yield. The cultivar BRS Valente was cultivated under center‑pivot irrigation in the winter seasons of 2003, 2004 and 2005, after several preceding crops established in the summer seasons. Preceding crops included the legumes Cajanus cajan (pigeon pea), Stylosanthes guianensis, and Crotalaria spectabilis; the grasses Pennisetum glaucum (millet), Sorghum bicolor (forage sorghum), Panicum maximum, and Urochloa brizantha; and a consortium of maize (Zea mays) and U. brizantha (Santa Fé system). Experiments followed a strip‑plot design, with four replicates. Fusarium wilt incidence was higher in the no‑tillage system. Higher disease incidences corresponded to lower bean yields in 2003 and 2004. Previous summer cropping with U. brizantha, U. brizantha + maize consortium, and millet showed the lowest disease incidence. Therefore, the choice of preceding crops must be taken into account for managing Fusarium wilt on irrigated common bean crops in the Brazilian Cerrado.

Gas exchange rates, plant height, yield components, and productivity of upland rice as affected by plant regulators

The objective of this work was to evaluate gas exchange rates, plant height, yield components, and productivity of upland rice, as affected by type and application time of plant growth regulators. A randomized block design, in a 4x2 factorial arrangement, with four replicates was used. Treatments consisted of three growth regulators (mepiquat chloride, trinexapac-ethyl, and paclobutrazol), besides a control treatment applied at two different phenological stages: early tillering or panicle primordial differentiation. The experiment was performed under sprinkler-irrigated field conditions. Net CO2 assimilation, stomatal conductance, plant transpiration, and water-use efficiency were measured four times in Primavera upland rice cultivar, between booting and milky grain phenophases. Gas exchange rates were neither influenced by growth regulators nor by application time. There was, however, interaction between these factors on the other variables. Application of trinexapac-ethyl at both tillering and differentiation stages reduced plant height and negatively affected yield components and rice productivity. However, paclobutrazol and mepiquat chloride applied at tillering, reduced plant height without affecting rice yield. Mepiquat chloride acted as a growth stimulator when applied at the differentiation stage, and significantly increased plant height, panicle number, and grain yield of upland rice.

Stalk and sucrose yield in response to nitrogen fertilization of sugarcane under reduced tillage

The objective of this work was to evaluate the agroindustrial production of sugarcane (millable stalks and sucrose yield) after successive nitrogen fertilizations of plant cane and ratoons in a reduced tillage system. The experiment was carried out at Jaboticabal, SP, Brazil, on a Rhodic Eutrustox soil, during four consecutive crop cycles (March 2005 to July 2009). Plant cane treatments consisted of N-urea levels (control, 40, 80, and 120 kg ha-1 N + 120 kg ha-1 P2O5 and K2O in furrow application). In the first and second ratoons, the plant cane plots were subdivided in N-ammonium nitrate treatments (control, 50, 100, and 150 kg ha-1 N + 150 kg ha-1 K2O as top dressing over rows). In the third ratoon, N fertilization was leveled to 100 kg ha-1 in all plots, including controls, to detect residual effects of previous fertilizations on the last crop's cycle. Sugarcane ratoon was mechanically harvested. A weighing truck was used to evaluate stalk yield (TCH), and samples were collected in the field for analysis of sugar content (TSH). Increasing N doses and meteorological conditions promote significant responses in TCH and TSH in cane plant and ratoons, in the average and accumulated yield of the consecutive crop cycles.

Rice yield estimation based on weather conditions and on technological level of production systems in Brazil

The objective of this work was to evaluate an estimation system for rice yield in Brazil, based on simple agrometeorological models and on the technological level of production systems. This estimation system incorporates the conceptual basis proposed by Doorenbos & Kassam for potential and attainable yields with empirical adjusts for maximum yield and crop sensitivity to water deficit, considering five categories of rice yield. Rice yield was estimated from 2000/2001 to 2007/2008, and compared to IBGE yield data. Regression analyses between model estimates and data from IBGE surveys resulted in significant coefficients of determination, with less dispersion in the South than in the North and Northeast regions of the country. Index of model efficiency (E1') ranged from 0.01 in the lower yield classes to 0.45 in higher ones, and mean absolute error ranged from 58 to 250 kg ha‑1, respectively.

Simulating maize yield in sub‑tropical conditions of southern Brazil using Glam model

The objective of this work was to evaluate the feasibility of simulating maize yield in a sub‑tropical region of southern Brazil using the general large area model (Glam). A 16‑year time series of daily weather data were used. The model was adjusted and tested as an alternative for simulating maize yield at small and large spatial scales. Simulated and observed grain yields were highly correlated (r above 0.8; p<0.01) at large scales (greater than 100,000 km²), with variable and mostly lower correlations (r from 0.65 to 0.87; p<0.1) at small spatial scales (lower than 10,000 km²). Large area models can contribute to monitoring or forecasting regional patterns of variability in maize production in the region, providing a basis for agricultural decision making, and Glam‑Maize is one of the alternatives.

Yield and nutritional composition of oyster mushroom strains newly introduced in Bangladesh

The objective of this work was to evaluate yield and chemical composition of oyster mushroom strains newly introduced in Bangladesh. Strains of Pleurotus high‑king (strain PHK), P. ostreatus (strain PO2), and P. geesteranus (strains PG1 and PG3) were evaluated as to yield components and proximate composition. Pleurotus ostreatus was used as control. Pleurotus high‑king showed fastest growth of primordia, but moderate flush of effective fruiting bodies. Pleurotus geesteranus (PG1) showed higher economic yield and biological performance, and better chemical composition, especially in terms of protein and mineral contents. Pleurotus geesteranus (PG1) shows better performance than P. ostreatus (PO2), the most commercially cultivated edible species in Bangladesh, and, therefore, it should be recommended for commercial cultivation.

Yield QTL analysis of Oryza sativa x O. glumaepatula introgression lines

The objective of this work was to evaluate the yield performance of two generations (BC2F2 and BC2F9) of introgression lines developed from the interspecific cross between Oryza sativa and O. glumaepatula, and to identify the SSR markers associated to yield. The wild accession RS‑16 (O. glumaepatula) was used as donor parent in the backcross with the high yielding cultivar Cica‑8 (O. sativa). A set of 114 BC2F1 introgression lines was genotyped with 141 polymorphic SSR loci distributed across the whole rice genome. Molecular analysis showed that in average 22% of the O. glumaepatula genome was introgressed into BC2F1 generation. Nine BC2F9 introgression lines had a significantly higher yield than the genitor Cica‑8, thus showing a positive genome interaction among cultivated rice and the wild O. glumaepatula. Seven QTL were identified in the overall BC2F2, with one marker interval (4879‑EST20) of great effect on yield. The alleles with positive effect on yield came from the cultivated parent Cica‑8.

Micromeasurement of total and regional CO2 productions in the one-day-old chick embryo.

A conductometric micromethod combined with image analysis system has been developed allowing to determine the CO2 production within 'two-dimensional' tissues, i.e., flat and thin cell layers or epithelial sheets. The preparation was mounted into an airtight chamber separated in two compartments by a thin silicone membrane permeable to gases. The lower compartment contained the nutritive medium and the preparation. The upper compartment and a conductivity measuring capillary connected in series were perfused with a solution of Ba(OH)2. The CO2 produced by the tissue precipitated as BaCO3 and the resulting decrease of electrical conductivity was linearly related to the total CO2 production. In addition, the pattern of CO2 production was directly observable as the BaCO3 crystals formed upon the silicone membrane over the regions which produced CO2. The spatial distribution of the crystals was quantified by video image processing and the regional CO2 production evaluated with a spatial resolution of 100 microns. This new microtechnique was originally developed to study the CO2 production in the early chick blastoderm which is a disc 1-5 cells thick. At the stage of young neurula the CO2 production was found to be 235 +/- 37 nmol.h-1 (mean +/- SD; n = 10) per blastoderm and large variations of local CO2 production were detected from one region to another (from 0.6 to 6.5 nmol.h-1.mm-2). These results indicate a high metabolic and functional differentiation of cells within the blastoderm. The possible applications and improvements of such a microtechnique are discussed.