Variable-rate seeding in soybean according to soil attributes related to grain yield

Precision Agriculture - Defining the ideal soybean stand is essential for obtaining maximum grain yield. As a hypothesis of the work, it was questioned whether it is possible to vary seeding...     

Resistance to blackleg and tuber soft rot in sexual and somatic interspecific hybrids with different genetic background

Diploid interspecific hybrids from crosses betweenSolanum tuberosum haploids andS. canasense, S. multidissectum, andS. tarijense, along with tetraploid and hexaploid somatic hybrids S.tuberosum (+)S. commersonii, were screened for resistance to blackleg and tuber soft rot byErwinia carotovora subsp.atroseptica andE. carotovora subsp.carotovora. Among the diploid hybrids, those involving clone mlt la of S.multidissectum and tar 2b ofS. tarijense yielded the highest number of genotypes resistant to both blackleg and tuber soft rot. By contrast, all the hybrids involving clone tar 1lb ofS. tarijense were susceptible to both bacterial diseases. As far as resistance of somatic hybrids is concerned, the most interesting genotype was the tetraploid one which showed resistance to both blackleg and tuber soft rot Significant correlations were found betweenE. carotovora subsp.atroseptica andE. carotovora subsp.carotovora both in resistance to blackleg and in resistance to tuber soft rot, suggesting that resistance to the two subspecies is controlled by the same gene/s or that the relevant genes are linked. On the other hand, correlations between blackleg and tuber soft rot were never significant, indicating that different mechanisms may control resistance in tuber and stems. Alternatively, the resistance could be controlled by the same gene/s under a different spatial/temporal expression pattern. Twelve diploid sexual hybrids and one tetraploid somatic hybrid were selected for resistance to blackleg and/or tuber soft rot and for tuber characteristics.     

Chemical and spectroscopic investigation of porewater and aqueous extracts of corresponding peat samples throughout a bog core (Jura Mountains, Switzerland)

Background, aim, and scope  

Fluorescence and UV-visible spectroscopies are simple but useful methods to characterize organic matter in the aqueous phase according to its aromatic nature and humification degree. Although there are several studies about porewater and water-extractable organic matter (WEOM) from peat, at present, no comparative investigations are available in the literature. Thus, the aim of the present study was to identify and compare chemical and spectroscopic features of porewaters and corresponding WEOM samples along a 105-cm undisturbed peat profile.     

Dairy Production and Reproduction by Crosses of Holstein,Jersey or Brown Swiss Sires with Holstein-Friesian/Gir Dams

The performance was compared of cows sired by Holstein, Jersey or Brown Swiss bulls out of Holstein-Friesian×Gir dams of 1/2 to 3/4 Holstein-Friesian content. The animals were kept in a single herd under the same management. The data were analysed by least-squares techniques under a model that included the fixed effects of breed of sire, Bos taurus fraction of the dam, parity, year and season of calving, and a random cow effect. Based on 480 observations, the milk yields per lactation for the Holstein, Jersey and Brown Swiss sired groups were 2821±163, 2320±61 and 2418±119 kg, respectively. The corresponding means for fat yield per lactation were 96.9±6.6, 86.8±2.5 and 92.8±4.8 kg; for protein yield per lactation were 85.3±5.1, 71.3±1.9 and 76.3±3.7 kg; for lactation length, 339±18, 283±7 and 313±14 days for fat percentage, 3.37±0.10, 3.73±0.04 and 3.77±0.07%; and for protein percentage, 3.02±0.05, 3.10±0.02 and 3.16±0.04%. The respective calving intervals were 487±24, 408±11 and 461±245 days. The yields of milk and protein per day of calving interval were similar in the Jersey and Holstein sired groups, while the former had higher yields of fat, implying that production economics might favour the smaller Jersey crosses in production systems in which the males were not reared. Crossing with Brown Swiss did not improve performance over the Holstein sired crosses.     

Novel use of nanostructured alumina as an insecticide

BACKGROUND: The worldwide need to produce an inexpensive and abundant food supply for a growing population is a great challenge that is further complicated by concerns about risks to environmental stability and human health triggered by the use of pesticides. The result is the ongoing development of alternative pest control strategies, and new, lower‐risk insecticidal molecules. Among the recent technological advances in agricultural science, nanotechnology shows considerable promise, although its development for use in crop protection is in its initial stages. RESULTS: This study reports for the first time the insecticidal effect of nanostructured alumina. Two species were used as model organisms, Sitophilus oryzae L. and Rhyzopertha dominica (F.), which are major insect pests in stored food supplies throughout the world. Both species experienced significant mortality after 3 days of continuous exposure to treated wheat. Nine days after treatment, the median lethal doses (LD₅₀) observed ranged from 127 to 235 mg kg^?1. CONCLUSION: Comparison of these results with recommended rates for commercial insecticidal dusts suggests that inorganic nanostructured alumina may provide a cheap and reliable alternative for control of insect pests. This study expands the frontiers for nanoparticle‐based technologies in pest management. Further research is needed to identify its mode of action and its non‐target toxicity, and to determine the potential of other nanostructured materials as pest control options for insects. Copyright © 2010 Society of Chemical Industry     

Efficacy of Amblyseius largoensis (Muma) as a biocontrol agent of the red palm mite Raoiella indica (Acari: Tenuipalpidae)

Phytoparasitica - The red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), is a severe pest of coconut (Cocos nucifera L.), banana (Musa sp.), and some ornamental palms. The predatory mite...     

Investigating landscape phase transitions in Mediterranean rangelands by recurrence analysis

Context

Socio-ecological landscapes typically characterized by non-linear dynamics in space and time are difficult to be analyzed using standard quantitative methods, due to multiple processes interacting on different spatial and temporal scales. This poses a challenge to the identification of appropriate approaches for analyzing time series that can evaluate system properties of landscape dynamics in the face of disturbances, such as uncontrolled fires.

Objective

The purpose is the application of non-linear methods such as recurrence quantification analysis (RQA) to landscape ecology. The examples concern the time series of burnt and unburnt Mediterranean rangelands, to highlight potential and limits of RQA.

Methods

We used RQA together with joint recurrence analysis (JRA) to compare the evolutionary behavior of different land uses.

Results

Time series of forests and grasslands in rangelands present both periodic and chaotic components with a rather similar behavior after the fire and clear transitions from less to more regular/predictable dynamics/succession. Results highlight the impacts of fire, the recovery capacity of land covers to pre-burnt levels, and the decay of synchronization towards the previous regime associated with vegetation secondary succession consistent with early successional species.

Conclusions

RQA and JRA with their set of indices (recurrence rate: RR, laminarity: LAM, determinism: DET, and divergence: DIV) can represent new sensitive measures that may monitor the adaptive capacity and the resilience of landscapes. However, future applications are needed to standardize the analysis by strengthening the accuracy of this approach in describing the ongoing transformations of natural and man-managed landscapes.

     

Phenotype of hepatic infiltrates and hepatic lymph nodes of lambs primarily and challenge infected with Fasciola hepatica, with and without triclabendazole treatment

The phenotype of the hepatic inflammatory infiltrate and hepatic lymph nodes (HLN) was analysed in lambs primarily and challenge infected with Fasciola hepatica. Group 1 was primarily and challenge infected with two doses of 200 metacercariae (mc) each and was non-treated. Trickle infection was administered to five groups: group 2 was challenge infected and non-treated; group 3 was primarily infected and non-treated; group 4 was primarily infected and treated with triclabendazole (TCBZ) at 12 weeks postinfection (wpi); group 5 was treated at 4 wpi and challenge infected and group 6 was treated at 12 wpi and challenge infected. An uninfected group was used as the control. The distribution of T cell subpopulations (CD3, CD4 and CD8), and B cells (CD79alpha, IgM, IgG) was analysed. The hepatic inflammatory infiltrate was represented mainly by CD3 and CD4 T cells, and B cells (CD79alpha, IgG). These infiltrates were more severe (P < 0.05) in primarily (group 3) or challenge (groups 2, 5 and 6) trickle infected lambs than in the group single challenge infected (group 1). Cellular changes in HLN consisted in an increase of CD4 over CD8 T cells and an increase of B cells and IgG+ plasma cells, and they were more severe in primarily and challenge trickle infected groups than in the group infected with two larger doses of mc, although significant differences were not found with respect to all challenge trickle infected groups. The strong local cellular and humoral immune responses did not protect against subsequent infections, neither in non-treated lambs (group 2) nor in lambs treated with TCBZ at 4 wpi (group 5) or 12 wpi (group 6).     

Influence of seminal plasma during different stages of bovine sperm cryopreservation

This study aimed to evaluate the effect of seminal plasma on bovine sperm cryopreservation and to assess the integrity of plasma and acrosomal membranes, mitochondrial potential, remodelling of F-actin cytoskeleton and sperm chromatin fragmentation during the cooling, equilibrium and freezing/thawing stages. Six ejaculates collected from seven Nelore bulls (n = 42) were used in this study. Each ejaculate was divided into two aliquots (with seminal plasma = SP group; without seminal plasma = NSP group) and packed to a final concentration of 50 × 10⁶ sperm per straw. Statistical analyses were performed using SAS software (version 9.3), and p ≤ .05 was considered significant. A time effect was observed for all sperm characteristics (p < .05), except for chromatin fragmentation (p > .05). The presence of seminal plasma better preserved the acrosomal integrity (SP = 75.2% and NSP = 71.7%; p < .05) and also provided lower F-actin remodelling during cryopreservation process (SP = 29.9% and NSP = 32.4%; p < .05). Regarding to the cryopreservation stages, it was observed that cooling step induced higher remodelling of F-actin than the equilibrium and freezing/thawing stages (56.3%, 32.2% and 23.9%, respectively; p < .05). The equilibrium step had minor influence on overall sperm characteristics while the freezing/thawing stage was responsible for the highest percentage of damage in plasma membrane (−65.2%), acrosomal membrane (−34.0%) and mitochondrial potential (−48.1%). On the other hand, none of the cryopreservation stages affected chromatin integrity. It was concluded that the presence of seminal plasma provides increased acrosomal integrity and reduced remodelling of F-actin cytoskeleton. Higher F-actin remodelling is observed after the cooling step while the freezing/thawing step is most damaging to sperm membranes and mitochondrial potential during bovine sperm cryopreservation.