Cotton (Gossypium hirsutum L.) grown in North Carolina requires intensive management for achieving optimal yields in an early-season environment. Recent increases in production costs require cotton producers to adopt practices that allow yield potential to be reached, while reducing input costs or optimizing the timing of agronomic inputs. Six experiments were conducted in North Carolina from 2006 to 2008 to investigate various production practices that could potentially reduce production costs and to define optimal timings of agronomic inputs. The first experiment investigated precision application of in-furrow insecticides for cotton planted in a hill-dropped configuration. The second experiment investigated application rates and timings of mepiquat chloride (MC) for cotton grown in conditions that promote excessive vegetative growth. The third experiment investigated the effects of MC applied at various rates and timings on the correlation (regression) between two techniques for measuring light interception and canopy coverage: the light quantum sensor method and the overhead digital imagery method. The fourth experiment investigated the effects of MC applied at physiological cutout, in terms of defoliation, regrowth, maturity, and yield. The fifth experiment investigated the effects of preconditioning defoliation treatments for tall cotton portraying dense canopies which improve standard defoliation practices and the timeliness of harvest. The sixth experiment investigated the effects of ethephon rate in defoliant mixtures on harvest date, with regard to defoliation timing and prior MC treatment.

Allelopathy is an ecological phenomenon in which chemicals produced by and released from a plant affect the germination or growth of another plant. A possible exploitation of allelopathy is the use of allelopathic cover crops for weed management. Organic farming systems can utilize allelopathy as an alternative to synthetic herbicides and conventional farming can reduce reliance upon pre-emergence herbicides. Rye (Secale cereale) is a cover crop species known to be allelopathic to many weeds. In addition to allelopathic activity, rye is a successful cover crop because of prolific biomass, high germinability and winter hardiness. The objective of this research was to investigate the potential to develop a rye cultivar with increased allelopathy through a conventional breeding approach. A population of 150 half-sib families of rye was grown in two North Carolina locations. Above ground tissue was utilized to assess rye allelopathic activity. To assess allelopathy in the population, we aimed to develop a greenhouse bioassay which utilized a rye incorporated soil media and redroot pigweed (Amaranthus retroflexus) as the indicator species. It is necessary to identify a screening protocol to quantify variation in allelopathic activity and to identify high performing lines. The greenhouse bioassay was fast, inexpensive and able to screen the large number of genotypes in the rye population. Results of redroot pigweed fresh weight biomass were reproducible and were utilized to estimate genetic parameters for allelopathy in the rye population. Estimates of genetic variation, genotype x environment interaction and narrow sense heritability help plant breeders develop an appropriate breeding program for the trait of interest. The estimates also give an idea of the rapidity at which progress can be made with selection. Genetic variation for rye allelopathy was not significant across locations but was significant within each location. Redroot pigweed fresh weight biomass was normally distributed indicating that allelopathy in rye is a quantitative trait. Heritability estimates were low on a per-plot basis and moderately low on an entry mean basis. A petri dish bioassay was also utilized to estimate genetic parameters for allelopathy in rye. Redroot pigweed germination and root length measures were utilized to quantify allelopathic activity. Genetic variation was not significant across locations for germination or root length. Analysis of variance within each location detected variation among the genotypes grown at the Kinston location but not at the Clayton location. Measures of redroot pigweed germination and root length were normally distributed. Heritability estimates were low on a per-plot basis and on an entry mean basis. This study demonstrates that allelopathy in rye is under genetic control and that it is a quantitative trait. Results suggest that a conventional breeding approach may be used for the development of a highly allelopathic rye cultivar.

Demand for goat meat in the southeastern USA is steadily increasing as a result of preferences exhibited by expanding ethnic communities. Feeding systems can be developed to take advantage of the natural preference of goats for browse. A field study was undertaken in Raleigh, NC to measure the effects of spacing (1.0 or 0.5 m) and coppice height (0.25 or 0.5 m) of a 5-year old stand of black locust (BL; Robinia pseudoacacia L.) on growth characteristics such as herbage mass (HM), canopy height (H) and width, number and size of main branches, above ground woody biomass, and root collar diameter. A second objective was through regression analysis to identify one or more of the previously mentioned characteristics as a rapid method to estimate HM. The third objective was to determine the relationship between growing-degree-days (GDD) and HM, H, herbage quality indicators (N, in vitro true dry matter disappearance, neutral and acid detergent fiber (NDF and ADF), cellulose, and 72% sulfuric acid lignin) and anti-quality indicators (Folin-reactive phenolics, condensed and hydrolyzable tannins) of BL. The final objective was to evaluate the N metabolism of goats fed BL foliage. Results indicated that coppicing BL trees at 0.5 m and planting at the widest spacing (1.0 m) produced the greatest plant growth. Average HM (2,600 kg ha-1) was observed for the highest coppice height (0.5 m). The character most closely related to HM was size of main branches. In 1999, a dry year, there was a significant relationship between GDD and NDF, ADF (r2 =0.90 and 0.80, respectively). In 2000, a wet year, GDD was a poor predictor of NDF and ADF. For 1999 and 2000, GDD was a poor predictor of BL tannin concentrations. From the conclusions of the N metabolism trial, goats consuming BL had lower digestibilities and higher content of N in the feces. Overall, BL contributes well to a silvopastoral system.

The ultimate objective of a tobacco breeder is to use genetics to improve traits contributing to improved crop production efficiency and that affect product quality. Two leaf surface chemistries, cis-abienol and β-methylvaleric acid-containing sucrose esters (BMVSEs), are known to be associated with organoleptic properties of tobacco products and may contribute to resistance against insect pests and fungal pathogens. The black shank disease, caused by Phytophthora nicotianae, causes severe crop losses annually in many tobacco growing regions of the world. Multiple races of this pathogen make it difficult to develop tobacco cultivars with high levels of resistance to all races. In the current study, an investigation was carried out to gain insight into the genetics controlling two leaf surface chemistry traits and black shank resistance using the assistance of microsatellite markers. A cigar tobacco line, âBeinhart 1000,â was chosen as a source of the ability to accumulate the two leaf surface chemistries and as a source of high levels of resistance against multiple races of the black shank pathogen. A doubled haploid population of 118 lines was developed from a cross between Beinhart 1000 and the flue cured cultivar, Hicks, which lacks the ability to produce the two leaf surface chemistries and is highly susceptible to the black shank disease. Field evaluations in disease nurseries were conducted using replicated trials in three environments. A genetic linkage map with 24 linkage groups was constructed by genotyping the mapping population with 190 microsatellite markers. Both genes controlling leaf surface chemistry traits were positioned on linkage group 4 and were separated by a genetic distance of 8.5 centimorgans (cM). Multiple interval mapping (MIM) analysis identified a total of six quantitative trait loci (QTL) (on linkage groups 2, 4, 8, 9, 11, and 14) associated with black shank disease resistance in Beinhart 1000. Two QTLs on linkage groups 4 and 8 were identified as having major effects and explained 20.5% and 23.5% of the phenotypic variation for end percent survival, respectively. The QTL on linkage group 4 was found to be strongly linked with the gene, Abl, controlling cis-abienol accumulation. Growth chamber evaluations of the mapping population with specific races (Race 0 and Race 1) revealed that the two major QTLs on linkage groups 4 and 8 were significantly associated with resistance to both races. The QTL on linkage group 8 was observed to have consistent large effects in both field and growth chamber evaluations. An attempt was also made to draw genetic comparisons between Beinhart 1000 and the currently most widely exploited source of black shank disease resistance, âFlorida 301â. A mapping population of 125 recombinant inbred lines (RILs) developed from the cross between Florida 301 and Hicks was used for this study. Microsatellite markers representing the six genomic regions identified to be associated with resistance in Beinhart 1000 were tested for their association with resistance in Florida 301. Markers on linkage group 8 and 2 were identified to be associated with resistance in Florida 301. Markers on linkage group 4 and other regions of interest were not significantly associated with resistance in Florida 301. Results may be useful for transferring the two leaf surface chemistry traits and black shank resistance into new cultivars using marker assisted breeding.

Bermudagrass (Cynodon spp.) is the primary choice for athletic fields and golf course fairways in the southeastern United States. Its superior heat and drought tolerance as well as excellent recuperative capacity allow it to withstand many of the stresses often associated with recreational turf. There are several new cultivars on the market with little available information regarding their performance. Six cultivars of bermudagrass, ?TifSport?, ?Tifway?, ?GN-1?, ?Quickstand?, ?Navy Blue?, and ?Tifton 10? were established by sprigs on a Candor sand (Sandy, siliceous, thermic, Arenic Paleudult) at the rate of 0.1m3/100m2 on 28 June 2001 at the Sandhills Research Station in Jackson Springs, NC. During year one of the study, data were taken on establishment, rooting, disease incidence, fall color, and spring green-up of each of the six bermudagrasses. Tifton 10 demonstrated the ability to establish faster than all other cultivars based on its ranking on all observation dates followed by Quickstand and GN-1, which had five and four top rankings, respectively. No differences in rooting density were found among the six cultivars. Navy Blue exhibited significantly more dollar spot (Sclerotinia homoeocarpa F.T. Bennett) incidence than all other cultivars, while GN-1 had significanctly higher incidence of Large patch (Rhizoctonia solani). During April 2002, 10.8 cm diameter plugs were taken from the field plots for the low temperature study. Sixty stolons per cultivar were excised from the plugs and placed into a Low Temperature Stress Simulator (LTSS) where they were exposed to four different temperatures of 2oC, 0oC, ?2oC, and -4 oC for a period of 24 hr. No significant differences were found among cultivars in their ability to tolerate low temperatures, but mortality did increase as temperature decreased. After the field plots had achieved one year of growth, data were taken on growth characteristics such as root and rhizome mass, recuperative potential, surface hardness, seedhead production, and overall quality. No significant differences were found in root or rhizome mass among the six cultivars. Quickstand produced a harder surface than all other cultivars on 24 July, while Tifton 10, GN-1, and TifSport were the softest. TifSport consistently produced the highest turf quality of the six cultivars followed by Tifway, GN-1, and Navy Blue. Quickstand and Tifton 10 had the poorest quality over four observation dates, primarily due to their coarse texture and off-green color. Differences among these six bermudagrass cultivars imply that they may not all be suitable for the same situation. Turfgrass managers can match this data to their intended use and more accurately choose which cultivar will perform best under their specific conditions.

Use of recycled water for turfgrass irrigation is increasing in the southeastern U.S. because of population growth and interest in protecting water quality. Turfgrass systems are perceived to be well suited for effluent dispersal due to their proximity to waste treatment facilities, in-ground irrigation systems, and ability to efficiently absorb (i.e. filter) nutrient contaminants when actively growing. However, effluent generation is continuous and bermudagrass growth is seasonal in the southeastern U.S. Clearly, there is a need to more thoroughly understand the capacity of bermudagrass, the turfgrass most often involved with effluent dispersal, for receiving effluent irrigation. This series of experiments was designed with the overall intent of examining the capacity of a bermudagrass turf/soil system for handling effluent applications. Experiments involved 1) characterizing seasonal changes in nitrate assimilation efficiency of the system, 2) determining the effects of prolonged soil saturation on nitrate uptake efficiency, and 3) characterizing internal nitrogen relations during the spring emergence period. While it is difficult to extend the results of these experiments, quantitatively, to situations where effluent is being applied in the field, the evidence does support a few basic observations. Bermudagrass appears to be capable of assimilating large amounts of N when growing, an ability that may well extend into transition months when little vertical shoot growth is occurring. Furthermore, although reduction in quality occurred, shoot growth and nitrate uptake efficiency of bermudagrass and centipedgrass was relatively unaffected by prolonged saturated soil conditions, a condition that may be likely with effluent irrigated sites.

Research evaluated new herbicides to improve weed management in conventional and minimum-tillage production in cotton and peanut, herbicide physiology in cotton, peanut, and selected weeds, and morningglory response to neighboring plants and objects. Diclosulam preemergence plus metolachlor PRE in conventional and strip-tillage peanut production usually controlled common lambsquarters, common ragweed, eclipta, prickly sida, and entireleaf morningglory. Flumioxazin applied preplant at 71 or 105 g ai/ha tank mixed with the isopropylamine salt of glyphosate at 1.12 kg ai/ha, paraquat at 1.05 kg ai/ha, or with the trimethylsulfonium salt of glyphosate at 1.12 kg ai/ha controlled common chickweed, common lambsquarters, common ragweed, Palmer amaranth, and smooth pigweed ¡Ý 96% at 29 to 43 days after treatment. Differential absorption, translocation, and metabolism at various growth stages, as well as the development of a bark layer, are the bases for differential tolerances of cotton at different growth stages to flumioxazin applied as a postemergence-directed spray. Morningglories initial planting distance from structures as well as the structures spectral reflectance influenced the percentage of ivyleaf morningglory that exhibited climbing growth as well as their final weight. Flumioxazin treatments at 1.4 mmol/L did not influence germination compared to non-treated peanut across all temperature regimes. Peanut treated with flumioxazin PRE and receiving irrigation at emergence and at 2 and 4 d after emergence were injured between 40 and 60%, while peanut treated at 8 and 12 d after emergence were injured between 25 and 15%, respectively. Total 14C absorbed by ivyleaf mornigglory was 57% of applied while sicklepod absorbed 46%, at 72 hours after treatment (HAT). Peanut absorbed > 74% of applied 14C 72 HAT. Ivyleaf morningglory contained 41% of the parent herbicide 72 HAT while sicklepod and peanut contained only 24 and 11% parent compound, respectively. Regression slopes indicated slower metabolism by ivyleaf morningglory compared to sicklepod and peanut.

Aflatoxin contamination causes economic loss for the global peanut (Arachis hypogaea L.) industry and raises human and animal health concerns. Peanut genotypes with resistance to aflatoxin accumulation should be an important part of an integrated aflatoxin management program. This study was conducted to identify AFLP markers tightly linked to genetic factors controlling reduced aflatoxin accumulation. A segregating F2 population was generated by crossing high-aflatoxin producing cultivar Gregory with low-aflatoxin producing interspecific tetraploid line GP-NC WS 2, phenotyped for aflatoxin accumulation using an in vitro assay, and screened with AFLP markers previously identified to be associated with reduced aflatoxin accumulation. An F-test was used to determine whether markers were associated with the trait, a genetic linkage map was generated, and interval mapping was used to identify regions of the genome that influence aflatoxin accumulation. Gregory produced significantly more aflatoxin than GP-NC WS 2, and the F2 population exhibited high-parent heterosis. Thirty-five of 38 AFLP markers used to screen the F2 population had segregation distortion favoring the A. hypogaea cultivar. Six markers were significantly associated with reduced aflatoxin accumulation at the 5% significance level. Thirty-three markers were included in a genetic linkage map covering 60 cM and a putative QTL was identified at map position 9 cM. Linked markers could be utilized in a marker-assisted selection program to identify individuals that support low levels of aflatoxin accumulation.

<p>The endoplasmic reticulum (ER) stress response is an important signal transduction pathway that senses ER stress caused by misfolded proteins or increased secretory protein traffic and induces molecular chaperone expression to counter such stress. The response has been well characterized in yeast and mammals where it has been associated with a variety of metabolic pathways, such as phospholipid biosynthesis, translational inhibition, and ER associated degradation. In plants, however, the connections of the ER stress response with metabolic pathways other than those involved in chaperone biosynthesis have not been characterized. This study defines a connection between phospholipid synthesis and the ER stress response in plants. Two model systems were used to characterize this association, the maize mutant floury-2 (fl2), which displays a unique endosperm specific ER stress response mediated by a mutant seed storage protein, and soybean cell cultures treated with the pharmacological agents tunicamycin (Tm) or azetidine-2-carboxylic acid (AZC). These chemicals interfere with normal protein synthesis and processing events, and are well characterized inducers of ER stress responses in animals, plants, and yeast. Investigation of both of these systems revealed a common theme; induction of the ER stress response in plants leads to increased activity and/or expression of various phospholipid biosynthetic enzymes. These increases were correlated with previously described amplifications in expression of the molecular chaperones binding protein (BiP), protein disulfide isomerase (PDI) and calreticulin. Certain aspects of the ER stress response may be unique to plants. A seed-specific result of the ER stress response was the accumulation of triacylglycerols (TG), which specifically increased in the endosperm of the fl2 mutant to more than 3-fold higher than normal endosperm levels by 36 days after pollination (DAP). The maize and soybean systems used in this study provide a starting point for the investigation of other details of the ER stress response in plants and represent important tools for future efforts to define the components of the signaling pathway. <P>

<p>Low commodity prices and environmental concerns have compelled cotton growers to increase production efficiency while decreasing inputs. Research evaluated weed interference, strip-tillage production, transgenic cultivars, and new herbicides to improve weed management in peanut and cotton. The rectangular hyperbola model described the effect of common ragweed density on percent peanut yield loss. With the asymptote constrained to 100% maximum yield loss, the I coefficient (yield loss per unit density as density approaches zero) was 68.3 + 12.2%. Common ragweed height was not affected by weed density or peanut canopy diameter. Weed height exceeded peanut height throughout the growing season, indicating that competition for light occurred between the two species. Common ragweed above-ground dry biomass per plant decreased as weed density increased, but total weed dry biomass per m crop row increased with weed density. Studies evaluated weed management using diclosulam and flumioxazin in strip-tillage and conventional-tillage peanut. Dimethenamid plus diclosulam or flumioxazin preemergence (PRE) controlled common lambsquarters, eclipta, and prickly sida at least 91%. Diclosulam and flumioxazin controlled Ipomoea morningglory species (59 to 91%) and bentazon plus acifluorfen postemergence (POST) provided >90% control. Dimethenamid plus diclosulam or flumioxazin PRE produced equivalent yields and net returns with no significant differences between the two PRE options. The tillage production system did not influence weed control of eight weeds, peanut yields, or net returns. Studies were conducted to evaluate weed management systems in non-transgenic, transgenic bromoxynil-resistant, and transgenic glyphosate-resistant cotton in strip- and conventional-tillage environments. Tillage did not affect the level of weed control provided by the herbicide systems evaluated. Excellent (>90%) control of common lambsquarters, Ipomoea species including entireleaf, ivyleaf, pitted, and tall morningglories; jimsonweed, prickly sida, and velvetleaf was achieved with programs containing bromoxynil, glyphosate, and pyrithiobac early postemergence (EPOST). Glyphosate systems controlled fall panicum, goosegrass, and large crabgrass more consistently than bromoxynil and pyrithiobac systems. Bromoxynil and pyrithiobac EPOST did not control sicklepod unless applied in mixture with MSMA and followed by (fb) a late postemergence-directed (LAYBY) treatment of prometryn plus MSMA. Herbicide systems that included glyphosate EPOST controlled sicklepod with or without a soil-applied herbicide treatment. The highest yielding systems included all the glyphosate systems and bromoxynil systems that included a soil-applied herbicide treatment. Non-transgenic systems that included a soil-applied herbicide treatment yielded less than soil-applied treatment plus glyphosate EPOST system. Net returns from glyphosate systems were generally higher than net returns from bromoxynil or pyrithiobac systems.<P>