Spatial and Temporal Variability of Corn Grain Yield: Site-Specific Relationships of Biotic and Abiotic Factors

Inadequate information on factors affecting crop yield variability has contributed to the slow adoption of site-specific farming (SSF). This study was conducted to determine the effects of biotic and abiotic factors on the spatial and temporal variability of irrigated corn grain yields and to derive information useful for SSF. The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil index (SI)(texture), soil NO₃–N, arthropods, and diseases on corn grain yield were investigated at Halfway, TX on geo-referenced locations. Grain yields were influenced by interrelationships among biotic and abiotic factors. Grain yields were consistently high under high water treatment, at higher elevations, and on soils with high SI (high clay and silt). Soil NO₃–N increased grain yields when water was adequate. Management zones for variable rate fertilizer and water application should, therefore, be based on information on elevation, SI, and soil NO₃–N. The effects of arthropods, diseases, and crop stress (due to drought and N) on corn grain yield were unpredictable. Spider mite (Oligonychus pratensis) and common smut (Ustilago zeae) damage occurred under hot and dry conditions in 1998. Spider mite infestations were high in areas with high soil NO₃–N. Moderate air temperatures and high relative humidity in 1999 favored southwestern corn borer (Diatraea grandiosella) and common rust (Puccinia maydis) incidences. Knowledge of conditions that favor arthropods and diseases outbreak and crop stress can improve the efficiency of scouting and in-season management of SSF. Management of SSF can be improved when effects of biotic and abiotic factors on grain yield are integrated and evaluated as a system.     

Shrimp rearing in biofloc integrated with different mullet stocking densities

This work compared the effects of different densities of Mugil curema integrated in the rearing of Litopenaeus vannamei in a biofloc system on the yield and ecological performance of the system. For that, an experiment lasting 55 days was conducted. Four groups were evaluated as follows: (a) T0: shrimp reared without mullet, (b) T10: shrimp reared with 22 fish per tank, (c) T20: shrimp reared with 43 fish per tank, and (d) T30: shrimp reared with 65 fish per tank, each treatment with four replicates. The sludge:biomass ratio was higher in the T0 treatment, while the T10–T20 treatments were more efficient, producing more biomass and less sludge. The use of water was 17% more efficient in all treatments with mullet. Mullet survival was higher in the T10 and T20 treatments (mean: 84 ± 8%) than in the T30 (61 ± 5%) treatment. The fish final biomass and yield limits of the system were 0.37 kg and 3.7 kg/m³ respectively. Finally, there was no increase in the total nitrogen output of the system up to the T10 density. In conclusion, it is possible to integrate mullet up to 3.7 kg/m³, increasing the yield in 20% and decreasing water use.     

Morphological characterization of the adherence and invasion of Streptococcus agalactiae to the intestinal mucosa of tilapia Oreochromis sp.: An in vitro model

Streptococcosis in tilapia Oreochromis sp. is possibly the most important bacterial disease for fish production worldwide. In Colombia, streptococcosis is caused by Streptococcus agalactiae (GBS), but in other countries, Streptococcus iniae is also involved. Prevention of streptococcosis is required and must be addressed for economic, social, international trade and public health reasons. This research used an in vitro culture of tilapia intestine to detail the intestinal mucosal response once the pathogen contacts the epithelium. We show that S. agalactiae sheds off its capsule to adhere to the epithelium. The bacterium adheres as a single individuum, in groups or in chains and is able to divide on the apical border of enterocytes. GBS adheres at and invades exclusively through the apical portion of the intestinal folds, using the transepithelial route. Once within the cytoplasm of enterocytes, the bacteria continue to divide. On the basolateral side of the epithelium, the microorganisms leave the cells to reach the propria and travel through the microcirculation. No evidence of an immuno‐inflammatory reaction or goblet cell response in the epithelium or the lamina propria was seen during the process of adherence and invasion of the pathogen.     

Dietary ratios of n‐3/n‐6 fatty acids do not affect growth of Nile tilapia at optimal temperatures (28°C) nor at temperatures that simulate the onset of winter (22°C)

Nile tilapia (Oreochromis niloticus) juveniles were fed diets containing 13 g/kg total polyunsaturated fatty acids (PUFAs) at different n‐3/n‐6 dietary ratios (0.2, 0.5, 0.8, 1.3 and 2.9) for 56 days, at 28°C. Subsequently, fish were submitted to a winter‐onset simulation (22°C) for 33 days. PUFA n‐3/n‐6 dietary ratios did not affect fish growth at either temperature. At 28°C, tilapia body fat composition increased with decreasing dietary PUFA n‐3/n‐6. Winter‐onset simulation significantly changed feed intake. The lowest dietary n‐3/n‐6 ratio resulted in the highest feed intake. At both temperatures, body concentrations of α‐linolenic acid, docosahexaenoic acid, eicosatrienoic acid and docosapentaenoic acid decreased as dietary n‐3/n‐6 decreased. Body concentrations of eicosapentaenoic acid (EPA, 20:5 n‐3) increased with decreasing concentrations of dietary EPA. The n‐6 fatty acids with the highest concentrations in tilapia bodies were linoleic acid and arachidonic acid (ARA, 20:4 n‐6). At 28°C, SREBP1 gene expression was upregulated in tilapia fed the lowest n‐3/n‐6 diet compared to tilapia fed the highest n‐3/n‐6 ratio diet. Our results demonstrate that a dietary PUFA of 13 g/kg, regardless of the n‐3/n‐6 ratio, can promote weight gains of 2.65 g/fish per day at 28°C and 2.35 g/fish per day at 22°C.     

Grazing management strategies for Urochloa decumbens (Stapf) R. Webster in a silvopastoral system under rotational stocking

Our objective was to compare herbage accumulation and nutritive value of Urochloa decumbens (Stapf) R. Webster managed under pre-grazing canopy light interception (LI) targets of 90%, 95% and 100% in silvopastoral system (SPS) and 95% in open pasture (OP; U. decumbens under full sunlight) to establish a pre-grazing target for SPS of ~43% shade. The evaluations were made during two rainy seasons and one dry season. The total herbage accumulation in SPS was lower than in OP at all LI targets and seasons. However, the difference in total herbage accumulation between SPS and OP was reduced when SPS was harvested at 95% LI, with reductions of 20% and 28% in both rainy seasons (12,191 × 15,324 kg DM/ha and 11,158 × 15,424 kg DM/ha respectively). Moreover, under 95% LI in SPS, crude protein concentration was 18% and 19% greater than that in OP in both rainy seasons (155 × 131 g/kg DM and 144 × 121 g/kg DM respectively), thus representing the optimal pre-grazing LI target for U. decumbens in SPS. In addition, a canopy height of 20 cm was necessary for 95% LI in OP and a height of 40 cm in SPS. Therefore, U. decumbens should be grazed at 40 cm canopy height, in SPS with ~43% shade to keep 95% LI as the target. However, this target will only be effective if the shade level is maintained, which will reduce height variation over time.     

Pomegranate Juice and Peel Extracts are Able to Inhibit Proliferation,Migration and Colony Formation of Prostate Cancer Cell Lines and Modulate the Akt/mTOR/S6K Signaling Pathway

Plant Foods for Human Nutrition - Pomegranate (Punica granatum) is known to contain polyphenols with many potential health benefits, including anti-tumoral, anti-inflammatory, and anti-microbial...     

The bone degenerative processes in senile fishes from Holocene Brazilian shell mounds

Zooarchaeological collections from shell mounds in Rio de Janeiro (2,470–4,632 cal BP) contain a high prevalence of swollen fish bones belonging to the Atlantic spadefish (Chaetodipterus faber), crevalle jack (Caranx hippos) and fat snook (Centropomus parallelus). Given the lack of knowledge of the bone degenerative process in senile fishes, this study analysed hyperostotic bone in zooarchaeological and modern specimens to obtain high‐resolution morphology and microstructure reconstruction. We used microCT as well as X‐ray diffraction to characterize the crystallographic changes associated with fish senility. Our results showed that trabecular microstructures in hyperostotic bones were consistent with estimated values of the per cent bone volume‐to‐total volume ratio (BV/TV) and were greater than 60% in cortical bone. Hyperostotic bones indicated a high radiograph density, and X‐ray diffractograms showed a decrease in hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] and calcite (CaCO₃) neocrystallization. These crystalline and density changes revealed an advanced stage of fish senile and indicate the vulnerability of ageing fish populations.     

Effect of the Lactiplantibacillus plantarum and Lentilactobacillus buchneri on corn and sorghum silage quality and sheep energy partition under tropical conditions

This study aimed to evaluate the silage quality, ingestive behaviour, and sheep energy partition fed corn and sorghum silages, with or without inoculation with Lactiplantibacillus plantarum and Lentilactobacillus buchneri. Whole plants of one dent corn hybrid (DCS), one flint corn hybrid (FCS), and one forage sorghum hybrid (SS) were ensiled with or without an inoculant containing L. plantarum and L. buchneri (4 × 10⁵ CFU g⁻¹), totalling six treatments (3 × 2 factorial scheme). The treatments were ensiled in metal drums with 200 L capacity. The lactic acid concentrations in the inoculated FCS and DCS were higher by 13.4% and 12.8%, respectively, than those in the non-inoculated plants. In contrast, the lactic acid concentration in the inoculated SS was 23.1% lower than that in the non-inoculated SS. Furthermore, there were differences in pH and acetic acid concentrations only in SS, which were 2.3% and 45.2% higher, respectively, in inoculated silage than in non-inoculated silage. In inoculated DCS and SS, propionic acid concentrations were 1.7 times higher (for both silages), and 1-propanol was 3.7 and 1.8 times higher compared than those in non-inoculated silages. There was a main effect of the inoculant on 1,2-propanediol concentrations, which were 37.5% higher in inoculated silages than in non-inoculated silages. However, ingestive behaviour, heat and methane production, and silage net energy concentrations were not affected by inoculant use. Fermentative modifications caused by inoculation with L. plantarum and L. buchneri in whole plant corn or sorghum silage did not modify sheep energy partition.