In fallowed sugarcane fields, perennial weeds and sugarcane regrowth must be controlled to maximize productivity of sugarcane in the first production year. Isopropylamine salt of glyphosate applied in April at 1.68 kg ai/ha to 15 cm sugarcane provided 85% control 28 d after treatment (DAT). Control of sugarcane 56 DAT with isopropylamine and potassium salt formulations of glyphosate averaged 83% for 1.12 kg/ha. Bermudagrass control with glyphosate at 1.12 kg/ha was 86% 40 DAT and increased to 98% with a sequential application at 1.12 kg/ha. In comparing various combinations of tillage and glyphosate in summer fallow programs, bermudagrass ground cover was 37% in November for tillage alone compared to no more than 7% ground cover for the tillage/glyphosate and no-tillage/glyphosate programs. Perennial weed control was greater when glyphosate replaced a tillage operation. Purple nutsedge tubers were planted in 26.5 L pots with a surface area of 0.093m² at densities of 0, 1, 2, 4, 8, and 16 tubers/pot along with a single node cutting of 'LCP 85-384' sugarcane to evaluate interference. At 64 days after planting, both purple nutsedge shoot and root (including tubers) dry weight increased as initial tuber density increased. Based on sugarcane shoot dry weight, critical weed density was four nutsedge tubers/pot. Using root dry weight, critical weed density was one nutsedge tuber/pot. The sugarcane variety 'L 97-128' was more competitive with purple nutsedge than LCP 85-384, 'Ho 95-988', and 'HoCP 96-540'. In a shade response study, 30% shade reduced nutsedge shoot dry weight 75% compared with full sunlight. Field studies were conducted to evaluate purple and yellow nutsedge control in sugarcane with herbicides applied postemergence (POST) in September around 5 weeks after planting. Halosulfuron at 53.0 or 70.6 g/ha averaged 80% 4 weeks after treatment (WAT) and 77% 6 WAT. Control with the trifloxysulfuron at 15.7 g ai/ha was no more than 71% 6 WAT. Injury to sugarcane was not observed 6 WAT for either herbicide. In April of the following year, nutsedge control with the halosulfuron treatments averaged 74% compared with 44% for the trifloxysulfuron treatments, but sugarcane shoot population did not differ.

Discriminate Analysis as a procedure was evaluated to select molecular markers associated with complex traits in US rice germplasm. Markers for percent head rice, percent total rice, and grain yield were identified with high levels of correct classification that mapped within or near traditional Quantitative Trait Loci (QTL). Mixed model-regression procedure to identify molecular markers that predict phenotypic variance associated with four agronomic traits was created and validated in two distinct rice inbred populations. Main and epistatic effects were identified by standard hypothesis testing and Bayesian information criteria in a multivariate format. The new procedure increased power and enhanced prediction ability of markers in validation samples from both populations. A new SNP discovery and genotyping protocol referred to as Alternative Ecotilling has identified four previously reported and 14 new SNPs in the alk and waxy genes among 57 accessions based on comparisons with sequencing results. The new procedure has been published in 2006 in the journal Plant Molecular Biology Reporter. Application of haplotype-specific markers in exon 7 of the BAD2 gene for marker-assisted identification and introgression of the aroma gene in U.S. rice was evaluated. Aromatic/non-aromatic phenotypes were consistent with corresponding marker haplotypes for all progeny tested which shows the potential of this procedure for marker assisted breeding of new aromatic varieties. Similarly, an allele-specific PCR assays were developed to distinguish between homozygous and heterozygous imazethapyr-resistant S₆₅₃D and G₆₅₄E SNP alleles of the rice ALS gene. Field collections were successfully screened for the presence of S₆₅₃D SNP, and F₂ progeny lines of natural CL 121 x red rice outcrosses were screened for the presence of the G₆₅₄E SNP. These assays were proven successful and are currently used for detection of outcrossing and seed purity for the LSU AgCenter Rice Breeding Project.

Marsh terracing is an innovative restoration technique being used in shallow, open water marshes in coastal Louisiana. When properly constructed and planted with an applicable plant species, terraces promote sediment deposition and accumulation by reducing wave energy. Although used extensively for marsh creation, little published information is available on techniques for establishing vegetation on marsh terraces. The goal of this research was to determine the optimal planting season and most effective plant growth form of Spartina alterniflora for establishing vegetation on newly constructed marsh terraces. Study objectives were to: 1) compare survival and growth rates of different plant growth forms based on planting season, 2) determine the optimal method of handling/storing seed to maximize germination and survival on terraces, 3) characterize soil composition and terrace elevation as compared to ambient marsh, and 4) monitor water depth and salinity of an adjacent water body to determine any relationship to plant response. This research was conducted on a large-scale terracing project on the Pointe aux Chenes Wildlife Management Area. Vegetative transplants of S. alterniflora were established on the terraces and were quantitatively sampled to examine differences in survival and growth. Treatments included plant growth form: containered plants (trade-gallon) and vegetative plugs; planting season: spring and fall planted; and growth period: 6 and 12 months. There was no significant difference in survival among planting seasons (p=0.0933) or growth forms (p=0.5396). Vegetative plugs and trade-gallons had similar growth rates when comparing aboveground biomass (944.79g/m2 and 1173.39g/m2, respectively) and belowground biomass (1187.82g/m2 and 1262.60g/m2, respectively). In a separate seeding study, there was little germination of S. alterniflora seed on the terraces (less than 1%), though the seed proved to be viable under in controlled germination tests. Although direct seeding is not a viable option on marsh terraces, vegetative transplants of S. alterniflora are effective in establishing vegetation on terraces. This study will add to the knowledge base of coastal restoration technology by evaluating the variability in terrace construction and the hydrologic-soil-plant relationship that is essential to terracing success, thus providing restoration project planners with additional strategies that will better incorporate vegetative establishment into terrace engineering.

Aflatoxin contamination of maize (Zea mays L.) grain caused by Aspergillus flavus is a serious health hazard to animals and humans. Resistance to infection by A. flavus is poorly understood. The objectives of this investigation were to identify potential candidate markers associated with resistance in maize kernels and pollen grains to A. flavus using a mapping population derived from a cross between Mp313E (resistant) and SC212m (susceptible) inbred lines. The parents, F₁, and F₂ plants were planted in the field in 2005. Each F₂ plant was selfed to produce F_2:3 seed. Fresh pollen collected from each F₂ plant was germinated on a growth medium in the presence of A. flavus conidia. Selfed seeds from parents, F₁, and F₂ plants were challenged with A. flavus conidial suspension and incubated using a medium-free method. Percent kernels uninfected (PKU) and number of pollen grains germinated (NPG) were recorded. A linkage map was constructed with JoinMap 3.0 using DNA profiles of all F₂ individuals produced from amplified fragment length polymorphism (AFLP) and target region amplification polymorphism (TRAP) markers. Interval mapping and multiple-QTL model (MQM) mapping analyses were performed using MapQTL 4.0 software. Three marker-QTL associations were observed for log-transformed PKU. Potential markers associated with this trait were also identified via discriminant analysis (DA). The markers identified via DA pointed to the same genomic regions as identified via the QTL mapping strategy. For log-transformed NPG, five marker-QTL associations were detected. One QTL was associated with a TRAP marker. The DA confirmed the existence of three QTL. The QTL detected for NPG were different from the QTL detected for PKU. Resistances of pollen and kernels to A. flavus appeared to be controlled by different genetic systems/mechanisms. Correlation between pollen germination and percent kernel infection was negligible (r = 0.067), suggesting that the two traits can be improved independently.

A phosphorus index is a semi-quantitative to qualitative model for assessing the potential for loss of soil and fertilizer phosphorus (P) to ground and surface water, therefore,eutrophication risk. The concept of a P Index is recent and popular, with most states having developed a P Index that is either a simplification or extension the original 1993 concept. The Louisiana P Index assigns ratings for P loss potential depending on soil properties, topography and land use. These ratings are intended to guide P fertilizer (including animal waste materials) application so as to preserve water quality. This project has examined measured loss of P in runoff and compared it to P loss ratings calculated using the Louisiana P Index. This was done using small runoff plots and simulated rainfall, consistent with work done elsewhere in the country. Since loss of P from soils enriched in P from years of application of animal waste was the impetus for development of the concept, Louisiana sites included in this study were from the poultry-producing region of the state. Results showed poor correlation between P in runoff and P loss ratings, which was somewhat improved by omitting high P, low P loss ratings data for a grazed pasture. Further insight into P loading into runoff was gained by examining runoff and P concentrations as functions of time. Runoff could often be well-described using the Green-Ampt model for infiltration. For the forest soil plots examined, however, considerably higher P often appeared in runoff than expected based on soil P desorption, and the source of this P may have been the forest litter layer. Continued difficulties in predicting P loss to runoff based on more mechanistic approaches support use the simpler P Index. However, a better understanding of the mechanisms by which soil P is made subject to runoff loss should lead to improvements in the P Index and better practices for controlling the loss of P to surface water.

Genetic diversity/similarity (GS) was estimated among nine sugarcane parental genotypes using target region amplification polymorphism (TRAP), amplified fragment length polymorphism (AFLP) markers and coefficient of parentage (f). Its relationship to progeny performance was assessed among five bi-parental crosses involving the nine parents. Phenotypic data for stalk-height, -count, -diameter, cane yield and theoretical recoverable sugars (TRS) were collected from which genetic parameters (family means, genetic variances, average mid parental heterosis, percent heterotic clones and mid parental values) were calculated. For TRS, families with higher means and variances had a greater proportion of heterotic clones. AFLP-GS was found to be a good predictor of genetic parameters for most of the traits and TRAP-GS (and f-GS) could be used as a good predictor for TRS. Framework linkage maps of Saccharum officinarum 'Louisiana Striped' and S. spontaneum 'SES 147B' were constructed using AFLP, sequence related amplified polymorphism (SRAP) and TRAP markers: the S. officinarum map comprised of 146 linked markers spanning 49 linkage groups (LG) and the S. spontaneum map comprised of 121 linked markers spanning 45 LG. Compared to AFLP, SRAP and TRAP markers appear less efficient for linkage mapping in sugarcane, a complex polyploid. The Saccharum interspecific F₁ mapping population was evaluated for Brix(B), pol(P) and sucrose(S) at the early(E) and late(L) plant growing seasons in two years, 2004(04) and 2005(05). Conventional quantitative trait loci (QTL) analysis identified markers associated with these traits. In S. officinarum, 50 QTLs were identified with LOD scores ranging from 2.51 to 7.64, explaining from 15.9% (04LP) to 47.8% (04EB) of phenotypic variation. In S. spontaneum, 26 QTLs were identified with LOD scores ranging from 2.69 to 7.51, explaining from 6.5% (04LP) to 43.5% (04LB) of phenotypic variation. Thirty-four digenic interactions were observed in S. officinarum and four in S. spontaneum. Several SRAP and TRAP markers were found to be associated with traits indicating their potential usefulness in QTL tagging. A non-parametric approach, discriminant analysis (DA), also identified several markers which were either similar or localized to the same genomic regions as identified by QTL analysis validating DA as a viable option to identify marker-trait associations. Markers identified in this study in both parents would serve in marker assisted introgression breeding for sugarcane improvement.

Optimizing flowering in the LSU AgCenterâs Sugarcane ( Sacchrum spp. hybrids) Breeding Program is an important step in the variety development program. The effect of nitrogen and ambient air temperature in pot cultured sugarcane were examined as a means of improving sugarcane flowering. The experiment was conducted on agronomic and reproductive traits of sugarcane at the Sugar Research Station, St. Gabriel, LA, on sugarcane genotypes subjected to artificial photoperiod regimes. The potting media consisted of equal parts of washed sand, Canadian peat moss, and a Commerce silt loam soil (fine-silty, mixed, nonacid, thermic aeric Fluvaquents). Early nitrogen (22.4-22.4-22.4 kg ha-1) in addition to a high nitrogen potting media (>200 mg kg-1) was necessary for adequate vegetative growth and stalk numbers for tasseling. Leaf macronutrient levels were examined at reproductive growth stages as affected by pre-photoperiod nitrogen fertilizers (22.4-22.4-22.4 kg ha-1 and 0-22.4-22.4 kg ha-1). Since tasseling in nitrogen and no-nitrogen treatments were 77% and 25%, respectively, the critical leaf nutrient level for nitrogen at the vegetative stage for sugarcane intended for tasseling should be 12.4 g kg-1. A chlorophyll meter was used to collect chlorophyll readings from the same leaves that were sampled for plant analysis. The initiation stage was the only stage that both leaf nitrogen (r = -0.34) and chlorophyll meter readings (r = 0.80) showed significant associations. A chlorophyll index level (34.53) was developed as a maximum threshold level for sugarcane breeding genotypes at the initiation stage. Average daily maximum temperature for specific time intervals can affect sugarcane tasseling. A reduced regression model (P=0.02) for the overall tasseling regime indicated that the percent tasseling is expected to increase 4.19 percent when the May 30 â June 14 temperatures increase by one degree above 31.9° C, decrease by 4.36 percent when the June 15- June 30 temperatures increase by one degree above 32.1° C, and decrease by 4.69 percent when the August 16 â September 10 temperatures increase by one degree above 33.1° C. These results help to explain the variation in tasseling percentages that have been encountered over the years when above average temperatures were experienced.

Uniola paniculata, commonly known as sea oats, is a C4 perennial grass capable of stabilizing sand dunes. Although this species is extensively used in beach restoration projects, production and availability of sea oats seedlings is seriously constrained due to disappearance of the natural stands. Other limitations are poor seed production, seed dormancy, and low seedling survival. With increasing interest in dune restoration, an efficient micropropagation technique is essential to generate sea oats seedlings in mass scale. In this study an efficient, rapid and reproducible plant regeneration system was successfully established for sea oats through somatic embryogenesis and cotyledonary nodal culture. Six sea oats accessions, collected from Alabama, Florida, Louisiana, Mississippi, North Carolina, and Texas were tried for embryogenic callus induction and plant regeneration using mature seeds. Two accessions, one each from Louisiana and North Carolina, were tested for shoot multiplication using cotyledonary nodes as explants. The frequency of callus induction was studied using modified Murashige and Skoog (MS) medium with a variety of combinations of 2, 4-D and Kinetin. Transferring the callus to a lower concentration of 2, 4-D (9.05 µM) in combination with Kn (2.32 µM) increased the embryogenic callus mass. Callus was regenerated in MS medium supplemented with BAP, NAA and Kn and 83.26 mM maltose. Similarly, for cotyledonary nodal culture MS medium supplemented with different concentration of BAP with 87.64 mM sucrose and MS medium in combination with BAP (4.44 µM), NAA (2.69 µM), Kn (2.32 µM) with 83.26 mM maltose were tested. Presence of Kn and NAA enhanced the process of multiplication but the maximum number of plantlets were regenerated in presence of BAP only. All the plantlets were rooted in MS medium supplemented with NAA (5.38 µM) and Kn (0.46 µM). In Texas and Florida accessions, 8 % and 10 % of the plants were albinos, respectively, but no morphological aberration was observed. RAPD (Random Amplified Polymorphic DNA) analysis using 5 arbitrary oligonucleotide decamers revealed genetic uniformity among the regenerants of each accession of sea oats developed via somatic embryogenesis and cotyledonary nodal culture, suggesting that this protocol can be used for clonal propagation of sea oats on a commercial basis.

In 2005 only did statistical analysis indicate a significant cotton density effect with respect to soybean yield. Means separation analysis indicated a lower soybean yield for only the highest cotton density of 5.25 plants /row m-1 when compared to other cotton densities. In 2004 and 2005, statistical analysis indicated no significant cotton interference interval effect on soybean height nor yield in 2004. A significant linear relationship between cotton interference period and soybean yield was observed in 2005. Based on best fit regression equation, a soybean yield reduction for an interference interval of 8 wk would equate to a minimal yield decrease of only 3.3% when calculated from the intercept value. With respect to cotton height, a linear relationship with soybean density was observed both years in Louisiana but not in North Carolina. Based on results at St. Joseph in 2004, height reductions of 6, 3, 1.2, and 0.6% can be expected following season-long competition with soybean densities of 3.3 plants/row m-1, 1.6 plants/row m-1, 0.7 plants/row m-1, and 0.3 plants/row m-1, respectively. Based on 2005 St. Joseph results, expected height reduction was 0, 10.6, 11.3, and 7% for these respective densities. At North Carolina, there was not a significant height effect was not observed. Based on results at St. Joseph in 2004, seed cotton yield reduction of 30, 15, 6, and 3% can be expected at the respective densities. Based on 2005 Louisiana and North Carolina results, expected yield reduction for these densities were similar at 37, 19, 7, and 4% and 21, 11, 4, and 2% respectively. At St. Joseph in 2004, a significant linear relationship between interference period and cotton height was observed. Soybean interference for 4 and 8 wk would result in an expected cotton height reduction of 3 and 5%, respectively. Based on 2004 results in Louisiana and North Carolina, a seed cotton yield reduction greater than 4% can be expected beginning with 4 wk soybean interference, however, in 2005 in Louisiana a similar yield reduction can be expected beginning at 2 wk.

Surface water quality impairment is often associated with agricultural activities. In this study, the effects of three sugarcane residue management techniques, namely burning (BR), shredding (SR), and retention (RR) of residues on: surface water quality, carbon export, and chemical composition of organic matter in the runoff sediments were characterized. Separate studies were conducted to evaluate predictive relationships for biochemical oxygen demand (BOD) in agricultural effluents, and the effectiveness of bauxite residues (red and brown muds) in reducing soluble nutrient/pollutant release from manure-impacted soils. All the selected water quality parameters were determined using EPA-approved analytical methods. The RR technique exported lower total suspended solids (TSS), total phosphorus (TP), BOD5, and inorganic anion loads compared to the BR and SR techniques during the study period. Rainfall amount correlated with TSS, BOD5, total Kjeldahl nitrogen (TKN), TP, nitrate-N, and nitrite-N exports in each treatment, and runoff turbidity significantly correlated with TSS (R2 = 0.95, P < 0.001).The BR treatment exhibited higher total carbon (TC), total organic carbon (TOC), and particulate organic carbon (POC) export, and these parameters were also positively correlated to runoff turbidity and TSS (R2 = 0.42-0.87, P < 0.001). The pyrolysis-GC/MS analysis of the runoff sediments indicated higher intensity of lignin-derived compounds in the BR treatment than in the RR and SR treatments. Polysaccharide-derived compounds, dominated by levoglucosan, tended to decrease over the growing season in all the treatments, and were lower in the BR treatment. Examination of a wide range of simulated agricultural effluents showed that short-term BOD measurements (BOD2 and BOD5) significantly correlated with TOC, POC, and dissolved organic carbon (DOC) (R2 = 0.62-0.77, P < 0.001), as well as to nitrite-N and total N (R2 = 0.45-0.66, P < 0.001), and improved relationships were obtained with multivariate regression analyses. However, these relationships weaken progressively with increasing incubation times. Application of bauxite residues, especially 2% of the neutralized red muds, significantly (P < 0.05) reduced the soluble P, organic C, heavy metals, and also the BOD of runoff water from manure-impacted soils. Overall, appropriate management practices and amendment techniques could improve water quality in selected agricultural systems.