A study was conducted at the LSU AgCenter H. Rouse Caffey Rice Research Station (RRS) to evaluate benzobicyclon herbicide application timing on water-seeded rice. Benzobicyclon was applied at seven different timings, at 246 g ai ha-1 in a water-seeded rice production system. Benzobicyclon controlled ducksalad above 90% when applied into the pinpoint flood. Barnyardgrass control was greater than 90% from applications made on pegging rice and immediately following pinpoint flood establishment. At 49 days after treatment (DAT), yellow nutsedge control exceeded 90% following benzobicyclon treatment with a pegging rice or pinpoint flood timing. Ducksalad control was greater than 90% following application into the pinpoint flood. A study was conducted at the RRS and LSU AgCenter Northeast Research Station (NERS) to evaluate nine different rates of benzobicyclon on weeds common to Louisiana rice production. Benzobicyclon was applied at 0, 31, 62, 123, 185, 246, 493, 739, 986, and 1232 g ha-1. Barnyardgrass, yellow nutsedge, and false pimpernel did not exceed 50% control, regardless of benzobicyclon rate. At 42 DAT, benzobicyclon applied at 185 and 246 h ha-1 controlled purple ammannia and Indian toothcup, respectively, and this control was similar to control observed with 986 to 1232 g ha-1 of benzobicyclon. At the conclusion of the study, no differences in fresh weight biomass occurred for barnyardgrass, yellow nutsedge, purple ammannia, or false pimpernel. Benzobicyclon applied at 246 g ha-1 reduced ducksalad and Indian toothcup biomass 87 and 77%, respectively. A glasshouse study was conducted at the LSU campus in Baton Rouge to evaluate five rates of benzobicyclon applied into a 5- or 10-cm flood. Benzobicyclon applied at 246 g ha-1, in either flood depth, reduced yellow nutsedge tuber development and growth. Tuber production is the primary means of yellow nutsedge reproduction in the southern US, and use of this herbicide could impact future nutsedge populations. A field study was conducted to evaluate benzobicyclon in mixture with imazethapyr or imazamox in imidazolinone-resistant rice. The addition of benzobicyclon increased activity on hemp sesbania over imazethapyr or imazamox; however, hemp sesbania control did not exceed 30% when treated with any herbicide mixture.

Leaf scald, caused by Xanthomonas albilineans, is a major sugarcane disease worldwide. The disease is managed primarily with resistant cultivars obtained through classical breeding; however, the erratic symptom expression hinders the reliability and reproducibility of the selection process. The development of molecular markers associated with incompatible/compatible reaction can overcome this limitation. Suppression subtractive hybridization (SSH) and quantitative trait locus (QTL) mapping were the strategies used to find leaf scald resistance-associated genes and molecular markers in sugarcane. SSH results showed that genes involved in signal perception and transduction, and DNA binding, were highly expressed in the resistant clone LCP 85-384 compared to the susceptible clone HoCP 89-846. Also, a higher proportion of overexpressed genes were located in the chloroplast in the resistant clone. Early accumulation and maintenance of high mRNA concentration was hypothesized as the determining factor for leaf scald resistance. A linkage map was constructed using 89 F1 progeny of a cross between the cultivars LCP 85-384 (resistant) and L 99-226 (susceptible) using simple sequence repeat (SSR), leaf scald responsive genes-derived SSR and single nucleotide polymorphic (SNP) markers. Single marker analysis showed that the markers c3-579 (LOD = 3.7189; phenotypic variance explained (PVE = 17.56%), 1x71593 (LOD = 3.0453; PVE = 14.65%) and c1-586b (LOD = 3.013; PVE = 14.48%) were associated with leaf scald resistance. Interval mapping identified 15 QTLs associated with disease resistance that explained 2.5 to 18.6% of the phenotypic variance. Comparative genomic analysis with Sorghum bicolor identified genes previously associated with resistance or tolerance to biotic and abiotic stresses within and flanking the QTLs. The present study resulted in a strong platform for future functional validation of the genes to ascertain their role in leaf scald resistance and marker validation in larger and diverse populations toward development of allele-specific markers for their use in breeding resistant sugarcane varieties.

Fertilizer nutrient losses through leachate and runoff from excessive irrigation in nursery container production and turfgrass management can be high and have negative environmental impacts. The objective of this research was to examine the influence of fertilizer source and irrigation regimen on nutrient losses during nursery container production and turfgrass management. During the container production of coleus (Plectranthus scutellarioides (L.) Codd) 'Solar Sunrise', four fertilizer treatments: an unfertilized control; a controlled-release (CRF); a water-soluble (WSF); and a combination of 10% WSF and 90% CRF, were incorporated into a pine bark substrate at 0.30 kg N and P·m-3 in 3.7-L containers and irrigated at 1.9 cm·day-1 or 3.8 cm·day-1 under greenhouse conditions for 56 days. Plant quality was measured every 14 days and total biomass was measured every 28 days. Leachate was collected weekly and analyzed for N (NO3- and NH4+) and P (dissolved total P, DTP). Plant growth was similar across CRF, combination (WSF and CRF), and WSF treatments and irrigation regimens. Fertilizer source did affect nutrient leaching losses. Coleus fertilized with WSF resulted in higher total N (NO3--N + NH4+-N) and DTP losses compared to coleus fertilized with CRF or combination fertilizer regardless of irrigation regimen. Decreasing irrigation regimen for WSF treatment resulted in a reduction of total N losses, but did not reduce total DTP losses. Three fertilizer treatments: an unfertilized control; a controlled-release (CRF); and a water-soluble fertilizer (WSF), were applied at 97.6 kg N and P· ha-1 to bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) 'Tifway established in runoff trays. Plant growth was measured every 14 days. Rainfall simulation events were held every 4 weeks for 12 weeks during which water samples were collected following 30 minutes of simulated rainfall output at 0.12 cm·min-1 and analyzed for N (NO3- + NH4+) and DTP. There were no differences in bermudagrass plant growth between WSF and CRF treatments. WSF treatment resulted in highest total N and DTP losses. Nutrient leaching can be reduced without sacrificing plant growth during coleus container production and bermudagrass management through the application of CRF.

High yield and superior grain quality are utmost importance in a rice breeding program. The first objective of this research was to identify allele-specific DNA markers for endosperm chalk by analysis of SNP databases and selective genotyping (Experiment I) with subsequent marker evaluation among lines with diverse genetic backgrounds (Experiment II). Experiment I revealed 47 markers associated with chalk in at least one of three environments. Nineteen of these markers were considered stable while 14 were novel. Experiment II conducted in Louisiana and Arkansas in 2016 showed among 89 diverse lines, four common SNP markers for chalk on chromosomes 1, 2, and 12, three SNPs on chromosomes 2 and 6 for the SB5 subgroup, three SNPs on chromosomes 1, 9, and 10 for tropical japonica inbred lines, and five SNPs on chromosomes 1 and 3 for tropical japonica by indica RILs. Significant markers identified in this study may be used in genomic selection scheme to develop Louisiana varieties with low endosperm chalk. The second objective of the research was to identify and develop KASP-SNP markers as alternatives to SNP in male sterile 2009S using haplotype and linkage disequilibrium analyses. No SNP in this study completely distinguished male fertile from male sterile plants. However, two SNPs at the top of on chromosome 2 that differentiated two major haplotypes in adapted Louisiana japonica and indica germplasm may be used for indirect selection of male sterile lines. The third objective was to investigate association of wide compatibility gene S5n with yield and other agronomic characters. For lines with similar genetic background, S5nS5j hybrids produced significantly greater spikelet fertility and yield per plant than S5iS5j hybrids. Three genotypes (S5nS5n, S5iS5i and S5jS5j) were observed in U.S. and Louisiana hybrid parents. Long grain varieties carried S5nS5n while medium-grains exhibited S5jS5j. Male sterile and restorer lines showed mixtures of the three genotypes. Genotypes of testcrosses with low and high spikelet fertility confirmed the association of S5n with normal spikelet fertility in indica/japonica hybrids. S5nSi genotypes showed comparable spikelet fertility and yield to S5nS5n testcrosses. This study emphasized the need to breed and develop S5n male sterile and restorer lines to overcome potential indica-japonica hybrid sterility.

In recent decades, landscape design theory has been affected by an increase in pro-environmental values. Currently, concepts of ‘sustainability’ and ‘ecosystem services’ exert a strong influence. These concepts involve sustaining current human behaviors within the constraints of ecological limits and maintaining or enhancing the goods and services that humans receive from ecosystems, respectively. In this way, they are most characteristic of anthropocentric environmental worldviews with high degrees of concern for the instrumental values of ecosystems, which are indicative of shallow ecology. Previous researchers have advanced theoretical characterizations of the environmental values of landscape architects in terms of environmental ethics. However, as of yet, no statistics-based model has been developed for this purpose. In order to advance such a model, and in the effort to further characterize the environmental values of landscape architects, two studies were performed. Both utilized data collected with the New Ecological Paradigm (revised-NEP) survey. In the first study, a Shallow v. Deep Worldview model was used to characterize revised-NEP survey responses of landscape architecture students and alumni practitioners from Utah State University (USU) in terms of shallow or deep ecology. The results indicate that the groups exhibited essentially anthropocentric environmental values, which were characteristic of shallow ecology worldviews. In the second study, the revised-NEP survey was used to assess the environmental worldviews of general education and landscape architecture students at USU. The results indicate that the landscape architecture students exhibited greater pro-environmental worldviews, which were correlated to differences in political orientation between the groups. Overall, the results of the two studies support the notions that the study or practice of landscape architecture is correlated to greater pro-environmental values than are common for general higher education students, and that, in general, current landscape architecture students and practitioners exhibit environmental values that are characteristic of ecologically-concerned, yet essentially anthropocentric, shallow ecology worldviews.

Studies evaluated impact of dicamba, 2,4-D, and glyphosate at reduced rates to sweetpotato at root formation (RF) and development (RD) growth stages. For DGA salt of dicamba at RF, glyphosate plus dicamba at 1/10x reduced storage root number 42%, canner grade yield 33%, and total yield 36%. With choline salt of 2,4-D at RF, storage root number compared to the non-treated (6.5) was reduced with glyphosate alone at 1/100x (5.1), 2,4-D alone at 1/250x (5.1), and glyphosate plus 2,4-D applied at 1/10 (4.2) and 1/1000x (5). Canner yield was reduced 32% with glyphosate alone 1/10x, 26 and 27% with 2,4-D alone at 1/10 and 1/500x, and 40% with glyphosate plus 2,4-D at 1/10x. Total yield was reduced 40% with glyphosate plus 2,4-D at 1/10x. For BAPMA salt of dicamba at RF, storage root number was reduced 34 and 23% with dicamba alone at 1/10 and 1/100x and 23% with glyphosate plus dicamba at 1/10x. Total yield was reduced with glyphosate alone at 1/750x, dicamba alone at 1/500x, and glyphosate plus dicamba at 1/10 and 1/250x. With DGA salt of dicamba at RD, U.S. no. 1 yield was reduced 70 and 91% with dicamba alone and plus glyphosate at 1/10x. Total yield was reduced 46 and 64% with dicamba alone and glyphosate plus dicamba at 1/10x. For choline salt of 2,4-D at RD, U.S. no. 1 yield was reduced 67 and 54% with 2,4-D alone at 1/10 and 1/100x, and 87 and 62% with 2,4-D plus glyphosate at similar rates. Compared to the non-treated, canner yield was reduced only with glyphosate plus 2,4-D at 1/10x. Total yield was reduced 60 and 85% with 2,4-D alone and glyphosate plus 2,4-D at 1/10x. With BAPMA salt of dicamba at RD, U.S. no. 1 yield was reduced with glyphosate at 1/10x (31%), dicamba at 1/10 (68%) and 1/500x (37%), and the 1/10 (83%), 1/250 (34%), and 1/1000x (30%) rate of glyphosate plus dicamba. Compared to the non-treated, total yield was reduced with glyphosate alone at 1/100x, dicamba alone at 1/10 and 1/750x, and the combination herbicide at 1/10, 1/100, 1/250, and 1/500x.

Wheat stripe rust, caused by Puccinia striiformis, is a common disease that was found primarily in the Pacific Northwest prior to 1990, with occasional minor outbreaks in the eastern wheat regions. A physiological adaptation to higher temperatures that occurred around 1990 led to stripe rust becoming a major disease problem in the Gulf Coast. Race (pathotype) changes have occurred several times since 2000, resulting in cultivars with previously effective resistance genes becoming susceptible. The cultivar LA 841, developed by the LSU AgCenter, has remained resistant to all races of stripe rust in the area for over 15 years. It contains the gene cluster Lr37/Yr17/Sr38 with Yr17, conferring broad-spectrum stripe rust resistance until recent years, when new races of stripe rust became virulent on Yr17. LA841 has remained resistant after Yr17 has lost its effectiveness, which indicates that LA 841 contains alternate/additional stripe rust resistance genes. Our objective was to determine the genetics of the resistance in LA 841. A mapping population consisting of 192 F2 progeny derived from a cross between the resistant line LA 841 and susceptible line NC06BGTAG12, was genotyped with 216 polymorphic SSR and AFLP markers. The F2:3 progeny was phenotyped for their reaction to stripe rust in replicated trials at three locations: Winnsboro, Louisiana; Plains, Georgia; and Fayetteville, Arkansas. Three QTL were identified - two on the short arm of chromosome 2A and one on chromosome 3B which together explained 43.2% of the total variation for stripe rust resistance. The QTL on chromosome 3B was flanked by SSR markers Barc164 and Barc1044. One QTL on the 2A chromosome was flanked by SSR markers gwm 636 and gwm 359 while the other QTL on the same chromosome was flanked by gwm 359 and AFLP marker gcg 800-2. Yr17, located on the short arm of chromosome 2A, is most likely the QTL closest to marker gwm 636, which is linked to the gene. This QTL explained 8.6% of the variation but has a LOD value of 11.2, which is the highest of the three. The QTL with the largest effect was found in the short arm of chromosome 2A, which accounted for 22% of the variation and had an LOD value of 9.8. The QTL on chromosome 3B explained 13% of the variation and has a LOD value of 2.7, just over the threshold of 2.5. Identification of new QTL linked to resistance genes is important in breeding programs for disease resistance due to the constant adaptation of pathogens which overcome previously effective resistance genes.

Atrazine, one of the most widely used herbicides in the United States, is commonly applied to southern lawn grasses to reduce weed encroachment. According to the EPA, atrazine is also one of the most frequently identified herbicidal compounds in surface and ground waters. Given the increased management intensity of home lawns in Louisiana, coupled with urban sprawl and high rainfall has led to a higher potential for movement of atrazine into surface waters during runoff events. Experiments were conducted at the LSU AgCenter Burden Botanic Gardens on centipedegrass (Eremochloa ophiuroides) at a 5% slope to evaluate the effect of atrazine formulation and post application management on atrazine movement. Atrazine was applied as a granular or liquid and either incorporated with 1.25 cm of irrigation or not incorporated. Four days post-atrazine application, treatment combinations were subjected to rainfall simulation at 5.5 cm hr-1 for 30 min of surface runoff. All herbicides exhibited the highest loss at 4 DAT followed by declines in losses with subsequent surface runoff events. In both experimental runs, granular atrazine resulted in lower total atrazine runoff losses compared to liquid applied atrazine. However, in the second experimental run irrigation reduced liquid applied atrazine 36% from unincorporated liquid applied atrazine. When simazine was compared to atrazine following the same application parameters, simazine resulted in >90% total reduction in herbicide losses compared to atrazine. Based on this research atrazine losses from surface runoff can be mediated through application of granular applications, irrigation when liquid atrazine is applied, or selection of simazine for area prone to frequent surface runoff.

Rice yield is adversely affected by various abiotic and biotic stresses. Jasmonic acid (JA) signaling has been implicated in stress response of plants. The nuclear localized basic helix loop helix (bHLH) Myc2 transcription factor is known to be a master regulator of genes involved in the response of the JA-mediated signaling pathway during stress and plant development. Myc2 is also induced by wounding and mechanical damage, and is associated with resistance against herbivore insects. In order to understand the mode of action of Myc2 in stress response of rice, overexpresser (OE) and knock-down (KD) mutants for OsMyc2 were generated in rice. After 7 d of withholding water, OsMyc2 OE plants showed better stress tolerance with respect to their growth and development, and physiological traits such as relative water content, membrane stability, chlorophyll fluorescence, etc. in comparison with the wild type (WT) and KD plants. Similar results were obtained for response to salinity stress (150 mM NaCl in hydroponics) where OE seedlings showed less chlorosis and better shoot and root growth as compared to the WT and KD lines. Furthermore, non-choice feeding assay of the transgenic rice plants with a specialist herbivore Spodoptera frugiperda showed that the life cycle of the insect was affected when the larvae were fed with tissues of the OsMyc2 OE lines. Bioassay with blast fungus, Magnaporthe oryzae, did not show obvious difference with the number of lesions, but the size of lesions was smaller in OE lines relative to that in WT and KD lines. OsMyc2, in addition to its overexpression under various stresses, modulated the expression of genes in JA signaling and associated networks. These results suggested that the OsMyc2 transcription factor is involved in multiple stress responses and can be manipulated to enhance stress tolerance in rice.

A survey was conducted to document the silicon (Si) content of soils from 27 (selected) agrarian parishes of Louisiana using different extraction procedures. For 0.01 M calcium chloride (CaCl©ü) extraction procedure, all surveyed soils (n=212) fell below 56 mg Si kg⁻©ö. For five of the procedures, about 50% of surveyed soils in Louisiana had Si level below the critical Si level that thus far established in other regions. Calcium silicate slag and wollastonite were compared through chemical extractions after laboratory incubation with six different soil types, and then an assessment of quantity of monosilicic acid (H©þSiO©þ) sorbed and the quantity in solution was made. It was concluded that the addition of large quantities of slag or any Si rich fertilizer with high rate of dissolution will lead to the greater polymerization of the H©þSiO©þ. A greenhouse study was also conducted with six soil series of Louisiana with distinct physico-chemical properties, to evaluate different soil test methods and estimate the critical soil Si level for rice. At harvest, dry matter yield and Si uptake by straw and panicles, and soil Si levels using seven different extractants were evaluated. The soil Si extracted by 0.5 M acetic acid (24 hours rest, 2 hours shaking) and 0.01 M CaCl©ü showed maximum linear positive correlation (r ©÷ > 0.45) with shoot biomass yield, and Si uptake. The soil Si critical level determined using quadratic regression model (P < 0.03) for Sharkey clay soil was 110 mg kg⁻©ö but for Crowley silt loam and Commerce silt loam were 37 and 43 mg kg⁻©ö. It is very likely that certain regions in Louisiana would benefit from Si fertilization in rice and sugarcane production. Also, there is a need to establish the soil or site specific extraction procedure because it is unlikely that there is a single universal extraction procedure for all soils.