Soil compaction is a primary impediment to vegetation regeneration on military land used for M1A1 Abrams tank training. As such, there is a need to identify soil compaction thresholds and develop guidelines with which military range managers can determine appropriate timing and intensity of training exercises using the 63-ton M1A1 tank. A study was initiated at the Camp Minden Louisiana Training Site (CMTS) to develop guidelines which will allow for maximum utilization of the land resource with minimum degradation. The study was designed to evaluate soil moisture content and traffic rates as experimental variables using a replicated 3 x 3 x 3 factorial design with 3 soil moisture ranges (< 20%; 20 to 30%, and > 30% water fraction by volume, wfv) and 3 traffic load rates (3, 6, or 9 passes) on 5 m2 plots. Comparison of pre- and post-trafficked soil bulk density (BD), soil penetration resistance (PR), and soil-moisture retention characteristics (SMR) were used to evaluate the effects of soil moisture and traffic rates on relative compaction. Post-trafficked BD increased in all treatment combinations with root-limiting thresholds of 1.65 g/cm3 exceeded at the 20 cm depth in the Mid (20% to 30%) moisture range plots with as few as 6 passes and in the Hi (>30%) moisture range plots with as few as 3 passes. SMR curve data indicate a reduction in total porosity from 0.44 to 0.38 cm3/cm3 in soil cores from Hi moisture treatment plots with a corresponding shift in pore size distribution toward a predominance of smaller pores across the range of pressures investigated to 12.5 bars. We conclude that training exercises are best when moisture contents for silty and loamy soils are at or below 20% on a volume basis. Furthermore, training exercises should be avoided at moisture contents above 30% to prevent root limiting compaction levels. Soil moisture levels exceeding the recommended thresholds commonly occur between December and April at CMTS annually. Suspending training maneuvers for this period is impractical. Therefore, we recommend range management plans include disking operations to loosen soil in tank trafficked areas when compaction levels exceed 1.65 g/cm3.

Four studies were conducted at the LSU AgCenter Rice Research Station near Crowley, Louisiana to evaluate the effects of simulated herbicide drift on Cocodrie rice. Herbicides were applied at 6.3 and 12.5% of the labeled usage rate of 863 g ae/ha of glyphosate, 70 g ai/ha of imazethapyr, 493 g ai/ha of glufosinate, and 44 g ai/ha of imazamox. Herbicides were applied to rice at the 1-tiller, panicle differentiation (PD), boot, and physiological maturity growth stages. Spray volume varied proportionally to herbicide dosage and was 15 L/ha for the 6.3% rate and 29 L/ha for the 12.5% rate using 234 L/ha as the target spray volume and were applied with a tractor-mounted CO2-pressurized sprayer. Glyphosate reduced plant height and primary and total crop yield, with the greatest reduction in primary crop yield resulting from glyphosate applied at boot. Primary crop rice seed germination was reduced by glyphosate. Glyphosate reduced ratoon crop rice seed weight; however, ratoon crop seed germination was not reduced. Imazethapyr reduced plant height and primary and total crop yield, with the greatest reduction in primary crop yield resulting from imazethapyr applied at boot. Primary crop rice seed weight was reduced by imazethapyr applied at boot. Primary crop rice seed germination was reduced by imazethapyr. Ratoon crop rice seed germination was reduced by imazethapyr applied at PD. Glufosinate reduced rice plant height and, when applied at boot, reduced primary and total crop yield. Primary crop rice seed germination and primary crop seedling vigor were reduced by glufosinate. Imazamox reduced plant height and primary and total crop yield with the greatest reduction in yield observed from rice treated at boot. Primary crop rice seed germination was reduced by imazamox. Primary crop seedling vigor was reduced with imazamox applied at boot. Ratoon crop rice seed weight and germination was not affected by imazamox. Simulated glyphosate, imazethapyr, glufosinate, and imazamox drift applications did not affect rice when applied at maturity. The greatest reduction in primary crop yield was observed when glyphosate, imazethapyr, glufosinate, and imazamox were applied to rice at boot and they all reduced primary crop rice seed germination.

Sequence related amplification polymorphism (SRAP) marker technique was used to assess genetic relationships and diversity among genotypes of Saccharum and allied genera. In the SRAP technique, the primers were arbitrarily designed with an AT- and GC-rich motif to anneal introns and exons, respectively. The level of polymorphism observed proved that the SRAP system was robust and amplified markers across species and genera and established evolutionary history interconnecting members of the Saccharum complex. The resolving power of the SRAP markers coupled with the fact that some of the amplicons could be amplifying gene-rich regions from diverse loci of the genome, was indicative of its potential usefulness for linkage and quantitative trait loci (QTLs) mapping in sugarcane. S. spontaneuam has been the most important source of wild germplasm for sugarcane cultivar development in Louisiana. Genetic diversity and structure of 51 S. spontaneum genotypes in the local collection (USDA, Houma, LA) was assessed using amplified fragment length polymorphism (AFLP) markers. Fifty-one genotypes grouped largely according to their geographical origins namely Central and East zones. The contribution of alleles from the S. spontaneum collection in the modern cultivars was low and about equal. This study also allowed us to realize that S. spontaneum germplasm representing the west zone was not present in the collection. A framework genetic linkage map of LCP 85-384 was constructed using 300 selfed progeny based on 773 single-dose (SD) markers generated by 64 AFLP, 12 TRAP and 19 SSR markers. Out of 773 SD markers, 717 markers were assigned onto 108 co-segregation groups (CGs) with a cumulative map length of 5,384 cM. With the estimated genome size of 12,720 cM, the map covered an estimated 42% of the genome. Of the 108 CGs, 31 CGs were assigned into 12 homo(eo)logous groups (HGs) based on the SSRs and information from the parental maps. Repulsion phase linkages studied suggested the preponderance of disomic segregation between CGs within the homo(eo)logus chromosomes. The framework map established in this study will provide an important background for mapping QTLs associated with sugar related traits and thus, information will be useful for crossing and selection of clones in the breeding program.

Cotton (Gossypium spp.) is the most extensively used natural fiber in the textile industry. Understanding the genetic diversity, population structure and marker trait associations are of great importance in marker assisted selection. Microsatellite, AFLP and TRAP markers were used to construct a linkage map with 94 F2 diploid individuals derived from a cross between G. arboreum x G. herbaceum. A total of 606 polymorphic markers gave rise to 37 linkage groups covering a total of 1109cM with an average distance of 7.92cM between each loci. Discriminant analysis identified three markers each for petal color and seed fuzziness, and four markers for petal spot. For quantitative traits, a total of 19 QTLs were identified and linked with five fiber traits using composite interval mapping. Markers such as qFL4-1, qFS4-2, qELO1-1 and qSI2-1 were found to be significantly linked with fiber length, strength, elongation and seed index respectively. Association mapping principles were applied to upland cotton genotypes in order to examine population structure and marker trait associations. A set of 232 genotypes were genotyped using AFLP markers. The molecular diversity was in the range of 0.48-0.574 with molecular variance found to be 10% among the groups. Bayesian and MCMC based population structure analysis, there existed six subpopulations, in accordance with their geographical origin. The mixed and mixed-multiple regression (MMR) models identified significant markers for lint yield and fiber traits, showing low AICC, BIC and SBC values and high adj. R2. Two way epistatic interaction analyses further confirmed their strong association. In the similar study, a set of 75 upland cotton genotypes were analyzed for seed quality traits such as seed protein, oil and fiber content. Population structure based mixed models showed 32 significant markers, associated with these seed quality traits. MMR models identified several markers, notably E4M3_440, E4M3_200 and E5M7_195 for seed protein, oil and fiber content respectively. Finally, 60 upland genotypes from RBTN program were screened with AFLP markers. The pairwise kinship estimates were ranging between 0.1-0.88 accounting for most of the shared ancestral alleles. The MMR models improved the efficiency of marker selection with 38 markers associated with eight traits.

Nickel (Ni) is one of many trace metals widely distributed in the environment. High concentrations of Ni in soils and aquifers have been observed worldwide, causing several potential human health impacts. Better understanding of Ni transport in soils and aquifers is necessary to assess and remediate insitu environmental contamination. The movement of Ni in soils and aquifers is highly dependent on adsorption-desorption reactions in the solid phase. In this study, kinetic batch, sequential extractions, and miscible displacement experiments were conducted to investigate the effect of several of environmental factors including soil type, reaction time and competing ions, on the fate of Ni in soils. In addition, forward and inverse modeling efforts were made to mathematically predict the reactivity of Ni transport in soils. Based on batch study results, adsorption of Ni was highly nonlinear and strongly kinetic. The comparison of Ni sorption on soil followed the sequences: Windsor < Olivier < Webster, which was related to soil propertities (CEC, clay content, pH and organic matter). Desorption of Ni from all soils were hysteretic in nature which is an indication of lack of equilibrium retention and/or irreversible or slowly reversible processes. A sequential extraction procedure provided evidence that a significant amount of Ni was irreversibly adsorbed on all soils. Moreover, a multi-reaction model (MRM) with equilibrium, kinetic and irreversible sorption successfully described the adsorption kinetics of Ni in Windsor, Olivier and Webster soils and was capable of predicting the desorption of Ni from these soils. Column transport experiments indicated strong Ni retardation followed by slow release or extensive tailing of the breakthrough curves (BTCs). We evaluated several MRM formulations for prediction capability of Ni retention and transport in soils and concluded that nonlinear reversible, along with a consecutive or concurrent irreversible reactions were the dominant mechanisms. The use of batch rate coefficients as model parameters for the predictions of Ni BTCs underestimated the extent of retention and overestimated the extent of Ni mobility for all soils. When utilized in an inverse mode, the MRM model provided good predictions of Ni BTCs and the distribution of Ni with soil depth in soil columns. In natural soil and water environments the competition between Ni and Cadmium (Cd) has the potential of increasing Ni mobility and bioavailability. Our results from batch experiments demonstrated that rates and amounts of Ni adsorption by these soils were significantly reduced by increasing Cd additions. The presence of Cd in soils increased mobility of Ni in columns as well as forced Ni sorption at higher affinity (or specific sorption) sites. The simultaneous presence of Ni and Cd also changed the distribution of Ni and Cd from an accumulation pattern to a leaching pattern in Olivier soil column, which has the potential risk of contamination of ground water.

The bioavailability and fate of Zinc (Zn) in soils is influenced by reactions occurring at the water-mineral interface. Understanding Zn interaction with mineral surfaces is essential to the understanding of Zn fate and toxicity. In this study, adsorption experiments investigated the impact of ligands and pH on the adsorption of Zn to mineral surfaces. X-Ray Absorption Fine Structure Spectroscopy (XAFS) was used to elucidate the adsorption mechanisms of Zn to mineral surfaces as impacted by ligands. Impact of ligands on Zn adsorption was dependent on mineral type and pH of the system. XAFS analysis showed that adsorption mechanisms of Zn were impacted by pH and ligand presence. In the ferrihydrite system, Zn adsorption was enhanced in presence of citrate and phosphate (PO4), reduced in presence desferrioxamine (DFO-B), and reduced in presence of humic acid (HA) at pH>6.0. XAFS analysis showed that Zn formed strong linkages with high affinity edge sites of ferrihydrite in the control and in presence of enhancing ligands (citrate and PO4), whereas formed weaker, low affinity linkages in presence of supressing ligands (DFO-B and HA). From an environmental perspective, Zn was more likely to be desorbed from the ferrihydrite surface in the presence HA and DFO-B. In the kaolinite system, Zn adsorption was reduced in presence of citrate and DFO-B, and increased in presence of HA. Zn formed inner sphere complexes at pH 5.5 in the control and in presence of ligands. At pH 7.5, a Zn-Al layered double hydroxide was formed in the control, that was absent in presence of any ligand, suggesting that ligands suppress the formation of Zn-Al LDH in kaolinite. In the mixed ferrihydrite-gibbsite system, Zn adsorption was enhanced in presence of all ligands, excluding DFO-B. Adsorption mechanisms of Zn to ferrihydrite were unaffected by ligand presence. The impact of organic matter (OM) degradation on heavy metal distribution in sewage sludge was investigated. Cu, Pb and As were bond with the OM fraction of sludge, whereas Zn was bond to Fe/Mn oxide fraction. OM degradation increased mobility and bioavailability of Zn and Cu, whereas it had less impact on Pb and As.

The spatial and temporal variation of soil properties was evaluated on three sites in close proximity to Bayou Wikoff, St. Landry Parish, Louisiana. A total of 1,068 surface (0-5 cm) samples were collected, geo-located, and transported to Louisiana State University for physical and chemical analyses. Physical and chemical properties were spatially and temporally displayed using ArcGIS. Interpolation techniques such as spline, kriging, and inverse distance weighting were evaluated to determine the best fit model for the project. Spline and inverse distance weighting were found to be the least accurate interpolation models. Kriging provided the most accurate model of spatial and temporal data distribution. Clay content (for total suspended solid control), P levels, and organic C % were a primary focus for this study, as potential non-point source pollution threats to water quality in Bayou Wikoff. All three sites were evaluated individually, as each had unique management practices. Pasture Site 1 exhibited larger concentrations of nutrient deposition proportional to increasing organic C % and clay content in areas of lower elevation. These areas were nearest to the bayou and potentially allowed for runoff, reducing water quality. Pasture Site 2 has artificial swale formations that affected the distribution of the evaluated properties. Extensive research at this site exhibited patterns of nutrient distribution that correlated with the swale formations. In the low portion of the swale, clay content, organic C %, and corresponding nutrient concentrations increased. The Pristine Site, used as a control site, showed evidence that the surface soil (0-5cm) was heavily altered from natural deposition as a result of being turned, moved, or replaced. Overall, spatial and temporal assessments revealed that while the three sites have unique distribution patterns of clay and organic C %, the soils are not hazardous for water quality. However, best management programs should focus on swales and low lying areas to determine the affect of spatial variability.

Cotton (Gossypium spp.), the most important textile fiber crop in the United States (US), is cultivated in 17 states across the southern US. and a very important agricultural commodity for several states. The use of hybrids in the US has been limited due to seed cost production. The objective of this study was to investigate a novel method for the production of F2 cotton hybrids using honey bees as pollinators and Roundup Ready® gene as selection trait. This research was conducted during three years (2005-2007) in Louisiana. Crosses between non-transgenic and transgenic varieties were made in 2005 to obtain F1 cottonseeds using honey bees. In 2006, F2 cottonseed was obtained. In 2007, F1, F2, and parents were field tested using a randomized complete block design with 3 replications in two locations. Data analysis was conducted using the SAS PROC MIXED procedure with estimates of means generated using least square means (LS means). Results indicate that all crosses exhibited heterosis in the F1 hybrid populations relative to the best parent. The crosses LA1110023/PHY410R and ARKRM24-12-04/PHY410R exhibited a higher degree of heterosis for yield averaging 33.1% and 20.6%, respectively, across locations. Yield heterosis in the F2 population was of 20.9% and 19.5%, respectively, and statistically different from the best parent. The ARK9506-40-05/PHY410R cross had yield heterosis averaging 15.6% in the F1 population and 13.5% in the F2 population; however, these were not significantly different from the best parent. The lack of significant yield heterosis might be attributed to experimental error and suggests the need for further field testing. Fiber quality descriptors from the six crosses, did not have a significant heterosis in the F2 population relative to the best parent. In summary, the use of herbicide resistant varieties as males and Roundup Ready® gene as selection trait, conventional varieties as females and honey bees as pollinators, has proven to be a viable method for developing F2 hybrid varieties. Further variety testing will be required to determine the best combination of parents. Promotion of this technology among seed companies is required for the development of better and improved cotton varieties as F2 hybrids.

Damaging and often irreversible effects occurring in aquatic ecosystems have recently been linked to the presence of pharmaceuticals in water bodies. Because this crisis has only recently been identified, existing reports on the consequences of this contamination are scarce. In EPA standard acute effluent toxicity tests, Ceriodaphnia dubia, Daphnia pulex, Pimephales promelas, Mysidopsis bahia, and Menidia beryllina were subjected to two of the most widely distributed pharmaceuticals in the U.S., ethinyl estradiol (EE2), a synthetic form of estrogen, and fluoxetine HCl (FLX), the active ingredient in Prozac®, for 96 hours to assess and evaluate toxic responses. After test termination, mortality curves were statistically analyzed to quantify 96 hour median effective concentrations (EC50s), no observable effect concentrations (NOECs), lowest observable effect concentrations (LOECs), and chronic values (Ch.V.s). Derived EC50s for both drugs identified C. dubia as the most sensitive organism. In terms of the Ch.V., C. dubia was the most sensitive organism administered EE2 and M. bahia given FLX. The most resilient species was P. promelas regarding the EC50 after EE2 dosing, D. pulex in respect to the Ch.V. after EE2 dosing, and M. beryllina pertaining to the EC50 and Ch.V after FLX dosing. Existing risk assessments and traditional toxicity tests do not incorporate sublethal effects. Because EE2 and FLX have the potential to alter serotonin, dopamine, and estrogenic hormones, biological activities encompassing these chemicals could be affected such as changes in behavior, growth and development, and fecundity. Observations on exposed organisms indicate that there were sublethal effects. The observed increases in abnormal behaviors of exposed organisms included unresponsiveness, irregular swim patterns, erratic activity, and convulsions with observed decreases in feeding habits and aggression. Ethinyl estradiol appeared to accelerate maturation; elevated concentrations appeared to slightly stimulate maturity while appearing to inhibit molting. The organisms exposed to higher concentrations of EE2 and FLX seemed to lack pigment. Continuous environmental pollution of these unregulated chemicals can cause stress on aquatic ecosystems and result in disturbances of the normal development and life cycles of aquatic organisms. If these sublethal disruptions in biological activity continually disregarded, catastrophic destructions of entire ecosystems could transpire.

Research conducted over two years evaluated EPTC at 2.0, 2.9, 3.9, and 4.9 kg ai/ha incorporated on pre-formed sugarcane beds using a Lilliston® rolling cultivator and a hipper/bedder. Averaged across EPTC rates 30 days after application, bermudagrass was controlled 62% when incorporated with a rolling cultivator compared with 43% for the hipper/bedder. For johnsongrass and purple nutsedge, incorporation implements were equally effective and control with EPTC 30 days after application averaged 49 and 30%, respectively. Averaged across incorporation methods, control of all weeds 30 days after EPTC application was maximized at 3.9 kg/ha, but control was no greater than when applied at 2.0 kg/ha (45% bermudagrass, 57% johnsongrass, and 33% purple nutsedge control). EPTC treatments were followed by glyphosate at 2.24 kg ai/ha and weed control was compared with a glyphosate alone program consisting of two applications of glyphosate at 2.24 kg ai/ha. Where EPTC was applied 60 days earlier and followed by one application of glyphosate, weed control was no greater than when glyphosate was applied twice (bermudagrass ground cover no more than 5% and johnsongrass control at least 88%). In contrast, purple nutsedge was controlled 31 to 40% where EPTC was followed by one application of glyphosate compared with 63% for two applications of glyphosate. An economic analysis of EPTC and glyphosate programs was performed using herbicide costs and variable costs associated with operation of incorporation implements and herbicide application. Cost of EPTC at 2.0 kg/ha plus application and incorporation would be $38.36/ha with the rolling cultivator and $49.33/ha for the hipper/bedder. Where EPTC at 2.0 kg/ha is followed by glyphosate as Roundup Original Max®, total cost would be $18.66/ha more than where generic glyphosate is used. For EPTC at 2.0 kg/ha incorporated with a rolling cultivator and followed by generic glyphosate, total cost would be $15.31/ha more compared with generic glyphosate applied twice. In other research, EPTC applied at 2.9 to 6.8 kg/ha and incorporated at planting did not negatively affect sugarcane shoot population 35 and 186 days after planting compared with standard herbicide treatments. EPTC was ineffective on grass and broadleaf winter weeds.