Studies were conducted to evaluate rice competitiveness with red rice and how to utilize glufosinate- and imazethapyr-resistant rice in water-seeded rice to control red rice. In the interference study, CL 121, Cocodrie, Drew, and Jasmine were seeded to obtain 95, 190, and 290 plants/sq m. Red rice density was 0 or 20 red rice plants/sq m. Jasmine, a tall, vigorous tillering, mid-season cultivar was more competitive with red rice. With the exception of Cocodrie grown red rice free, no benefit existed from increasing the seeding rate above 190 plants/sq m. Another study examined the effect of permanent flood establishment in a glufosinate- and imazethapyr-resistant rice system. Glufosinate controlled hemp sesbania, red rice, barnyardgrass, and Amazon sprangletop at least 95%. Imazethapyr controlled hemp sesbania less than 35%. With one exception, barnyardgrass, red rice, and Amazon sprangletop control was at least 95%. Two postemergence imazethapyr applications controlled Amazon sprangletop 79%. All treatments reduced red rice panicle number to less than 1/sq m, but did not delay red rice panicle emergence with respect to rice panicle emergence. Delaying the permanent flood improved rice yield in an imazethapyr system, but not for glufosinate. Another study examined the effect of 500 g/ha glufosinate applied 14, 28, 42, 56, and 70 days after emergence fb 410 g/ha applied 7 d later on rice and red rice. All treatments controlled red rice 91 to 98%. Rice yield was optimized when applications occurred within 35 or 49 DAE for the red rice infested and red rice free treatments, respectively. The fourth study examined imazethapyr use in a water-seeded system receiving no tillage or tilled in the water prior to seeding. Herbicide treatments were 70 g/ha imazethapyr applied 1, 3, or 5 d fb 70 g/ha applied 12 or 19 d after draining the seeding flood (DADSF), 140 g/ha applied 12 or 19 DADSF, and a nontreated. All treatments controlled red rice 88 to 95% and barnyardgrass 73 to 94%. Rice yields did not reflect barnyardgrass control and were higher when the two imazethapyr applications were farther apart.

Best management practices are used by agricultural producers to control or reduce the transport and generation of contaminants to the water resources of the state, ultimately increasing the quality of surface and ground waters. One such practice is residue management used during sugarcane production. The impact of sugarcane residue may have on the retention and release of two herbicides namely; atrazine and metribuzin was the focus of this study is studied. Adsorption-desorption and transport behavior of herbicides are important processes that influence the amount of herbicide retained by the soil or crop residue and that which is susceptible to runoff or movement within the soil profile. Kinetic batch experiments were used to study the adsorption-desorption behavior of atrazine and metribuzin in sugarcane mulch residue and two surface soils. Atrazine retention was consistently stronger than metribuzin for both sugarcane residue and surface soils. To describe the retention of atrazine and metribuzin by the residue as it ages and across growing seasons, only one value (Kd) was needed for each herbicide, and this value is an order of magnitude greater then those determined for surface soils. Miscible displacement experiments under steady flow conditions were also carried out to examine the mobility of the metribuzin within soils. In addition field studies quantified the decay of sugarcane residue in the field following combine harvest. Amounts of residue cover varied with the growing season and variety. Half-lives of 126 to 171 days were determined for sugarcane residue as it remains in the field. With residue age mass decreases leaving greater percentages of more recalcitrant residue such as lignin. Fiber analysis identified these changes, there were no obvious relationships between herbicide retention distribution coefficients and percentage of lignin on a mass basis.

Sheath blight caused by the fungal pathogen fungus Rhizoctonia solani Kuhn, is an economically important disease of rice in the southern United States. The overall goal of this study was to identify proteins that were affected by sheath blight development by comparing protein expression patterns between the susceptible, wild-type cultivar Labelle and the resistant, mutant line LSBR-5. Protein samples were extracted from inoculated and non-inoculated rice leaf sheaths after 24 hrs and then loaded onto a Bio-Rad 2-DE gel system. Approximately 1,000 protein spots stained with Sypro-Ruby were reproducibly resolved in all gels used in the comparison analysis. The comparison analysis of relative abundances of protein spots between inoculated and non-inoculated samples was carried out with PDQUEST image analysis software. With MS/MS spectra produced by ESI-Q-TOF analysis, 27 out of a total of 36 protein spots were identified through NCBI nr and NCBI EST database searching with Mascot MS/MS Ion Search Engines (Matrix Sciences). Twenty two protein spots were detected in response to inoculation of both susceptible and resistant plants where 21 protein spots were up-regulated and 1 protein spot was down- regulated. Sixteen of the 22 proteins were identified. The presumed functions of the identified proteins were related to antifungal activity, energy metabolism, photosynthesis, protein degradation, and antioxidation. Eight of 16 identified proteins showed higher expression ratios in the inoculated LSBR-5 than in the inoculated Labelle. An additional 14 protein spots were detected in the response of the resistant LSBR-5. Eleven of 14 protein spots were identified with presumed functions relating to antifungal activity, signal transduction, energy metabolism, photosynthesis, molecular chaperone, protein degradation, and antioxidation. This study is the first to monitor protein expression patterns of the rice leaf-sheath responding to challenge by R. solani and to detect response differences between resistant mutant and susceptible parental material. The information and detected proteins in this study will serve as a solid foundation for future studies to elucidate induced defense mechanisms of rice when infected with R. solani.

Approximately 5 % of rice growing area in Louisiana experience poor seedling or stand development attributed to anaerobic decomposition of excess plant residue, which create strongly reducing or toxic soil conditions. This study investigated plant residue and flooding regime effects on soil properties as related to rice growth and seedling development. Field experiments were conducted at several commercial farms in Southwest Louisiana (which have experienced problem with rice stand development) to relate observed restricted rice growth to soil redox chemistry and other chemical and physical properties. Field experiments were also conducted at the Crowley Rice Research Station in which various rates of rice straw amendment were added to replicate field plots to determine effect on rice growth and methane emission. The study also include greenhouse experiments on plant residue effect on soil chemical properties as related to rice seedling development and growth including effect of plant residues sources (rice straw or alligator weed on rice seedling germination). These studies showed source and quantity of plant residue significantly affected rice seedling development and germination rates of various commercial rice varieties. Alternating flooded and drained cycles significantly increased growth and grain yield of rice as compared with continuous flooded treatments containing high level of soil plant residue. High rates of plant residue addition increased methane emission (7,350 kg/ha/season) as compared with treatment receiving no added plant residue (370 kg/ha/season). Alternating flooded and drained cycles as compared with continuously flooded resulted in a 50 % reduction in methane emission and increased grain yield by 30 % in treatment receiving 24 t/ha plant residue added. Alligator weed plant residue source had greater effect on rice seedling development as compared with rice straw. Adoption of alternately flooded and drained water management practice, which improves soil chemical properties, can substantially increase rice growth and yield as well as reduces atmosphere methane emission from Louisiana rice soils.

The effect of tillage and weed control programs on LCP 85-384 sugarcane (Saccharum spp. hybrids) growth and yield and on economics was evaluated over two growing seasons. When row shoulders and middles were not tilled in March soil temperature in the non-cultivated sugarcane drill early in the growing season was equal to that where March tillage was performed. Sugarcane and sugar yield were each equivalent for the full season tillage (off-bar tillage in March plus layby tillage in May) and the no-till program. Weeds were effectively controlled with a March application of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kg ai/ha. For the no-till program with herbicide banded in March compared with full season tillage, net return was increased $32.56/ha. In a subsequent study conducted at five locations sugar yield was increased 8.6% and net return was increased $152.68/ha when sugarcane was not tilled in March. Sugar yield was increased 8.0% and net return was increased $143.88/ha when layby tillage in May was eliminated. Mechanical removal of crop residue remaining on the soil surface three weeks after harvest of LCP 85-384 with a combine harvester was compared with burning. Tillage efficiency in March was not reduced when the residue was mechanically removed from the row top and placed in the row middle. Sugar yield was reduced an average of 7.9% when sugarcane residue was not removed compared with mechanical removal or burning in December. Research was expanded to also include mechanical removal of sugarcane residue in January, February, or March. For each residue removal treatment off-bar tillage in March (with or without) was included. Allowing crop residue to remain on the soil surface until March reduced both early season sugarcane height and shoot population when compared with December residue removal. Sugar yield was equivalent when crop residue was removed in December by burning or mechanically and averaged 8,670 kg/ha. Delaying mechanical removal of residue until February or March decreased sugar yields an average of around 13% compared with December burn or mechanical removal.

Potential outcrossing between Clearfield rice and red rice will have a direct impact on the management and long-term usefulness of imazethapyr technology for rice weed control. The principal objective of this research was to determine the rate and agronomic consequences for outcrossing between Clearfield rice and red rice in south Louisiana. Collection and analysis of red rice samples across two years and 24 commercial locations indicated that red rice infestation after imazethapyr application differed substantially at different Clearfield locations. Straw hull and awnless red rice was the principal biotype observed for both years. Red rice populations possessed extensive variation for agronomic traits such as plant height, panicle length, tillers/plant, seeds/plant, seed set and grain weight. Outcrossing occurred from all Clearfield rice varieties (¡®CL121¡¯, ¡®CL141¡¯ and ¡®CL161¡¯) to red rice. An average outcrossing frequency of 0.163% was observed in red rice samples collected in 2002 with a range of 0.017% to 0.583%. A four-fold increase in outcrossing frequency of 0.679% was found in red rice samples collected in 2003 with two locations exhibiting outcrossing > 1%. Outcrossing frequency did not correlate with any agronomic trait from the red rice samples across two years. Imazethapyr resistance was generally controlled by a single dominant gene, except in some F2 populations where significant deviations from expected resistant/susceptible ratios were detected. Similar results were observed in F2 populations for segregation of pubescent/glabrous leaves. F1 hybrids between Clearfield rice and red rice in general did not show increased fitness in flowering characteristics over Clearfield rice, as most hybrids did not flower or produce seeds in the field. However, increased fitness in F1 hybrids, derived from red rice samples collected in 2002, was detected over Clearfield rice for plant height, tillers/plant, and panicles/plant. Enhanced fitness in F1 hybrids from red rice samples collected in 2003 over Clearfield rice was exhibited for plant height, panicle length, spikelets/panicle, and panicles/plant. Results from this study indicate that outcrossing between Clearfield and red rice will occur rapidly at rates that warrant early-season field scouting and a rotation scheme for Clearfield rice to prolong usefulness of the imazethapyr technology.

Calcareous soils make up some of the most productive agriculture lands in Louisiana. Due to their minimal occurrence little research has been done on these soils. Understanding phosphorus (P) chemistry is necessary for environmentally sound management of these soils. In this study, P speciation was investigated using several chemical fractionation procedures as well as x-ray absorption near-edge spectroscopy (XANES) coupled with principal component analysis (PCA) and least-squares linear combination fitting (LCF) on five calcareous Louisiana soils of different geological origins. Phosphorus sorption isotherm parameters were determined and their relationships with other properties were evaluated. In addition, Zinc (Zn) lability due to the interaction with P and other fertilizer nutrients was characterized and a fertilizer P and Zn response trial for corn on a calcareous Norwood silt loam soil was conducted. The results showed that these calcareous soils were dominated by Ca-P phases. All chemically defined sequential P fractions except HCl-P were significantly correlated with different Fe fractions especially amorphous Fe, indicating that Fe-oxides play an important role in P retention. A significant correlation was found between P speciation by XANES analysis and sequential P fractionation for total Ca-phosphates as well as total Fe-/Al-phosphates (R² ≥ 0.81, P ≤ 0.0383). Further, an inclusion of the NaHCO₃ extraction in chemical fractionation procedures caused a redistribution of Fe-/Al-P while Ca-P was unchanged. The evaluation on P and Zn interaction showed that the presence of PO₄^3- decreased where as NH₄⁺ increased Zn lability, suggesting that Zn and P fertilizer placement should be separated while the simultaneous application of Zn and ammonium-N amendments could improve plant Zn availability. The field experiment exhibited a P fertilizer response when Bray II soil test P was < 220 mg kg^-1 while a Zn fertilizer response was dependent on P levels even when soil test Zn was very low by DTPA. It is concluded that P forms not only control P retention mechanisms for agronomic and environmental availability but also affect management of other nutrients in soils.

Studies were conducted in 2001-2004 evaluating genotype by environment interactions in cotton (Gossypium hirsutum L.). Genotype by Environment interactions were characterized using GGE Biplot for conventional cotton cultivars and their transgenic derivatives. Significant interactions existed for several non-target traits. Transgenic cultivars were taller, had greater height to node ratios, larger seed, and lower lint percentages. Transgenic cultivars containing the Bollgard gene yielded more than their conventional parents and STV4691B was the highest yielding, most stable cultivar. In 2002-2004, GGE Biplot was used to identify two levels (high/low) of discriminating locations for three distinct selection criteria. Crosses were made with parents recommended by a least squares means analysis for each population criteria and F₂ plants were planted in the high and low discriminating locations for each population. Gains by selection (h²) were calculated by regressing the F_2:3 plants on their F₂ parents. Genotypic variance was greater among F_2:3 progeny in discriminating environments compared to non-discriminating environments, regardless of population. Heritability was greater in the population containing fiber traits compared to yield. In 2004, GGE Biplot was compared to other widely-accepted stability analysis tools. Correlation coefficients between GGE biplot (stability evaluation) and the Cultivar Superiority Measure, Shukla's Stability Variance, the Eberhart-Russell regression model, Kang's yield stability statistic, and AMMI were 0.54, 0.91, 0.86, 0.63, and 0.55, respectively. Correlation coefficients between GGE biplot (mean performance + stability evaluation) and the Cultivar Superiority Measure, the Eberhart-Russell regression model, Kang's yield stability statistic, and AMMI were 0.95, 0.60, 0.85, and -0.33, respectively. Based on the results of this study and our experience using GGE Biplot, Model 3 with an entry-focused scaling is the most valuable analysis for breeders engaged in cultivar development. GGE Biplot was used with the 1993-2003 Louisiana Official Variety Trials to identify the most desirable (discriminating and representative) test locations in Louisiana for yield and fiber length. St. Joseph loam was ranked 1st for yield, Winnsboro irrigated was ranked 1st for fiber length, and St. Joseph loam was ranked 1st to simultaneously select for both traits. Winnsboro non-irrigated should not be used to select for yield or fiber length.

Runoff of sediments and nutrients, particularly phosphorus (P) from agricultural fields is considered as one of the main causes of water quality impairment. Very little research has been done on relating suspended solids in runoff to soil test information. This two-part study was aimed at:1) evaluating the relationship between total suspended solids (TSS), P forms in runoff, and soil salinity measurements, particularly electrical conductivity (EC), and 2) establishing the relationships between runoff P forms and the various soil test P measures, across a variety of selected Louisiana calcareous and acid soils. In the first part of the study, five Louisiana soils with clay content of 27 to 44% were selected, treated with different concentrations of salt solution (7.5 to 30 dS m-1), subjected to simulated rainfall, and various runoff parameters were measured. The TSS, total phosphorus (TP), and particulate phosphorus (PP) in runoff were found to decrease with consecutive simulated rainfall event. A highly significant relationship existed between TSS and turbidity of the runoff water (R2 = 0.92, P < 0.001). Each of TSS, turbidity, TP and PP negatively correlated to soil EC (R2 = 0.22-0.29, P < 0.05). A very significant relationship was observed between TP and TSS in runoff (R2 = 0.73, P < 0.001). In the second part of the study, nine soils of varying chemical and physical properties (pH, % clay, CaCO3 etc.) were used. The results revealed that among the measures of soil P examined, only water extractable P and Mehlich III P were reliable indicators of DP losses, explaining about 86% and 57% respectively, of the variability in runoff DP. The study showed that Olsen P (R2 = 0.73, P < 0.01), NH4-oxalate P (R2 = 0.50, P < 0.05), and NaOH P (R2 = 0.50, P < 0.05), reasonably correlated with runoff TP. Among the calcareous soils, Bray II P, NH4-oxalate P and NaOH P each explained about 40% of the variability associated with TP in runoff water. Along with soil test P measures, soil EC relationship with TSS could be useful in predicting P losses in runoff and hence requires further examination.

Field studies evaluated the effect of plant population and seeding configuration on cotton (Gossypium hirsutum L.) growth and yield. Seeding configuration did not influence plant growth and development parameters. Averaged across seeding configurations, plants grown at a density of 152,833 plants ha-1 were taller than plants grown at 50,958 and 33,975 plants ha-1, and produced fewer mainstem nodes than all other populations. A 4- and 5-day (2003) and 13- and 14-day (2004) delay in peak bloom was associated with populations of 50,958 and 33,975 plants ha-1, respectively, when compared to 152,833 plants ha-1. Lint yield was not significantly reduced until plant population was lowered to 33,975 (30.5 cm plant spacing) or 50,958 (three plants per hill, 60 cm hill spacing) plants ha-1. Fiber properties were not influenced by plant population or seeding configuration. In field experiments conducted at two Louisiana locations, the effect of late-season insect simulated defoliation (manual leaf removal) and premature harvest-aid application on cotton yield and fiber quality was evaluated. Results suggest a negative impact on yield and fiber quality should not occur when terminating management strategies for late-season bottom defoliating insects at plant development ≥ NAWF5 (five nodes above the uppermost first position white flower, i.e. cutout) +550 HU (heat units), while harvest-aid application should not be initiated until plant development exceeds NAWF5+750 HU. Data obtained from field studies conducted in both Louisiana and Tennessee, which evaluated the effect of carrier volume and nozzle type on cotton harvest-aid efficacy, determined that harvest-aids should be applied through flat fan or hollow cone nozzles at carrier volumes of at least 93.5 L ha-1. These applications are necessary to maximize efficacy, by increasing canopy penetration by spray droplets, to achieve adequate defoliation for a once over harvest. Defoliation timing experiments in Louisiana identified 40 to 60 percent open bolls as the stage of crop maturity when harvest-aid application will result in maximum lint yields. However, a second harvest may be necessary to realize maximum lint yield. Delaying defoliation until after 75 percent open bolls may have detrimental effects on fiber quality resulting in discounts and reduced gross revenue.