Land Application of Lake-Dredged Materials for Bahiagrass Establishment in the Subtropical Beef Pasture

Background  The continued need to dredge lakes, rivers, and canals in Florida, both for maintenance and environmental improvement, will produce millions of cubic meters of dredged materials. Productive disposal options of lake-dredged materials (LDM) may provide substantial and intangible benefits that will enhance the environment, community, and society. Objective  The objective of this study was to assess lake-dredged materials from Lake Panasoffkee as soil amendment for early establishment of bahiagrass (BG,Paspalum notatum Flügge) in subtropical beef cattle pasture at Sumter County, Florida. Results and Discussion. This study encompassed two phases: Phase 1 comprised of five small observation plots (0.3 x 0.3 m); Phase 2 consisted of five larger test plots (30.5 x 30.5 m). Each of the plots in Phase 1 and Phase 2 had a different ratio LDM to natural soil (NS): Plot 1 (0% LDM + 100% NS); Plot 2 (25% LDM + 75% NS); Plot 3 (50% LDM + 50% NS); Plot 4 (75% LDM + 25% NS); and Plot 5 (100% LDM + 0% NS). Each plot was seeded with BG and early growth and yield establishment were monitored for 16 weeks. Conclusion  Results disclosed significantly taller (p ≤ 0.001) plants and higher biomass production (p ≤ 0.001) of BG from plots amended with 75% LDM than those of BG planted on plots with 0% LDM. Results suggest that LDM can serve as source of lime and fertilizer to establish BG beef pasture fields. Sediments with high CaCO₃ improved the physical and chemical conditions of subtropical beef pastures. Lake-dredged materials could be removed from the spoil containment areas, trucked to other locations, and incorporated into existing fields for agricultural uses. There is still much to be learned, but it is certain that Lake Panasoffkee sediments should be regarded as a resource, with no observed harmful ecological effects. Recommendation and Outlook  The agricultural or livestock industry could utilize these LDM to produce forages. LDM should be regarded as a beneficial resource, as a part of the ecological system. This study has been continued for several years to explore and assess the long term efficacy of LDM on productivity and quality of BG beyond its early establishment stage. Joint contribution of the USDA-ARS and the Florida Agricultural Experiment Station, Journal Series No, R-09253.     

Stocks and decay dynamics of above- and belowground coarse woody debris in managed Sitka spruce forests in Ireland

Coarse woody debris (CWD) has become recognised as an important component of the carbon (C) pool in forest ecosystems. In Ireland, managed Sitka spruce (Picea sitchensis (Bong) Carr.) forests account for 52.3% of the total forest estate. To determine the stock and decay dynamics of above and belowground CWD, field surveys using fixed area sample plots, were conducted in six even-aged Sitka spruce stands, representing the young, intermediate and mature stages of a typical commercial rotation. The volume, mass, density loss and C:N ratio of all CWD types (logs, stumps, and coarse roots) were determined using a five-decay class (DC) system. The decay rates and half life of CWD was also determined. To estimate CWD coarse root mass; roots associated with stumps classified in different decay classes were excavated. The coarse roots were categorised into small (2-10 mm), medium (10-50 mm) and large (>50 mm) diameter classes.CWD C-mass ranged from 6.98 to 18.62 Mg ha⁻¹ and was highest in an intermediate forest (D35), while the aboveground volume varied from 6.31 to 42.27 m³ ha⁻¹. Coarse roots accounted for 21% to 85% of the total CWD C-pool in the surveyed stands. The total CWD C-mass was poorly correlated with the number of thinning events (R² = 0.29), when data from D35 was excluded. The density loss was significant in logs (45%), stumps (58%), and small- (38%), medium- (50%) and large roots (38%) as decay progress from DC 0 to 4. There was a 46%, 41%, 51%, 72% and 57% decline in C:N ratio of logs, stumps, small-, medium- and large roots, respectively, as decay progressed from DC 0 to 4. The density decay rates were 0.059, 0.048 and 0.036 kg m⁻³ year⁻¹ for logs, stumps and coarse roots, respectively. The size classification of roots did not significantly affect their decay rate. The half life (50% decomposition) of CWD was estimated has 12-, 14- and 19 years for logs, stumps and roots of Sitka spruce. Regression curves showed a strong correlation between the density and C:N ratio (R² = 0.69, 0.74 and 0.93 for logs, stumps and coarse roots, respectively). The long term storage of C and its slow rate of decomposition make CWD a vital structural and functional component of the CWD C-pool and a major controller of forest ecosystem C-retention.     

Relationships between spur- and orchard-level fruit bearing in almond (Prunus dulcis)

Almond is often considered to be a moderately alternate-bearing species but historical yield data typically do not exhibit clear patterns of alternate bearing at the orchard level, while research has indicated that spurs (the main fruit bearing unit in almond trees) rarely produce fruit in two subsequent years. The objective of the present work was to analyze the bearing behavior of almond trees at both the orchard level and the individual spur level over multiple years to explain this apparent paradox. The 10-year yield patterns of three almond cultivars grown at three different sites within California were analyzed for tendencies of alternate bearing at the orchard level. At the individual spur level, data on spur viability, and number of flowers and fruits per spur were collected on 2400 individually tagged spurs that were observed over 6 years to characterize bearing at that level. At the orchard level one cultivar (Nonpareil) did exhibit a tendency for alternate bearing at one site (Kern) but other cultivars and sites did not. The orchard and the individual trees in which the spur population study was conducted showed tendencies for alternate bearing but the spur population did not. Only a relatively small percentage of the total tagged spur population bore fruit in any given year and therefore while individual fruiting spurs exhibited a high level of non-bearing after fruiting the previous year the spurs that did produce fruit in any year generally did not constitute enough of the total spur population to exhibit alternate bearing at the whole population level. Our results suggest that annual bearing fluctuations in almond are probably mainly due to year-to-year variations of parameters affecting fruit set and that high rates of fruit set in a given year may involve a larger-than-normal percentage of a spur population in fruit bearing. This would limit the size of the spur population available for flowering in the subsequent year and could cause alternate year bearing. However, from historical records, this would appear to be the exception rather than a normal circumstance. Therefore, almond should not be considered to be a strictly alternate-bearing species.     

KOI-126: a triply eclipsing hierarchical triple with two low-mass stars

The Kepler spacecraft has been monitoring the light from 150,000 stars in its primary quest to detect transiting exoplanets. Here, we report on the detection of an eclipsing stellar hierarchical triple, identified in the Kepler photometry. KOI-126 [A, (B, C)], is composed of a low-mass binary [masses M(B) = 0.2413 ± 0.0030 solar mass (M(⊙)), M(C) = 0.2127 ± 0.0026 M(⊙); radii R(B) = 0.2543 ± 0.0014 solar radius (R(⊙)), R(C) = 0.2318 ± 0.0013 R(⊙); orbital period P(1) = 1.76713 ± 0.00019 days] on an eccentric orbit about a third star (mass M(A) = 1.347 ± 0.032 M(⊙); radius R(A) = 2.0254 ± 0.0098 R(⊙); period of orbit around the low-mass binary P(2) = 33.9214 ± 0.0013 days; eccentricity of that orbit e(2) = 0.3043 ± 0.0024). The low-mass pair probe the poorly sampled fully convective stellar domain offering a crucial benchmark for theoretical stellar models.     

Diagnostic potential for human malignancies of bacterially produced HTLV-I envelope protein

Two regions of the gene for the human T-cell leukemia virus subgroup I (HTLV-I) envelope were expressed in Escherichia coli by use of the vector pJLA16. One corresponds to the carboxyl terminal region of the major envelope protein p46, and the other corresponds to the transmembrane protein p21E. Reactivity of the expressed protein with human serum was tested by the Western blot procedure. Each of 11 sera tested that had been shown to contain antibodies to HTLV-I or HTLV-II by an enzyme-linked immunosorbent assay recognized the bacterially synthesized envelope proteins. There was no reaction detected when 17 control sera were tested. This system will be useful for large-scale seroepidemiological surveys for HTLV-I and related human retroviruses.     

Independently evolved virulence effectors converge onto hubs in a plant immune system network

Plants generate effective responses to infection by recognizing both conserved and variable pathogen-encoded molecules. Pathogens deploy virulence effector proteins into host cells, where they interact physically with host proteins to modulate defense. We generated an interaction network of plant-pathogen effectors from two pathogens spanning the eukaryote-eubacteria divergence, three classes of Arabidopsis immune system proteins, and ~8000 other Arabidopsis proteins. We noted convergence of effectors onto highly interconnected host proteins and indirect, rather than direct, connections between effectors and plant immune receptors. We demonstrated plant immune system functions for 15 of 17 tested host proteins that interact with effectors from both pathogens. Thus, pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life-cycle strategies.     

The dog genome: survey sequencing and comparative analysis

A survey of the dog genome sequence (6.22 million sequence reads; 1.5x coverage) demonstrates the power of sample sequencing for comparative analysis of mammalian genomes and the generation of species-specific resources. More than 650 million base pairs (>25%) of dog sequence align uniquely to the human genome, including fragments of putative orthologs for 18,473 of 24,567 annotated human genes. Mutation rates, conserved synteny, repeat content, and phylogeny can be compared among human, mouse, and dog. A variety of polymorphic elements are identified that will be valuable for mapping the genetic basis of diseases and traits in the dog.