Shikimic acid accumulation in field-grown corn (Zea mays) following simulated glyphosate drift

Field studies were conducted in 2001 through 2003 to determine if shikimic acid accumulation could be used to accurately predict yield reductions in field corn exposed to sublethal rates of glyphosate. Glyphosate (0-0.32 kg ae/ha) was applied to corn at the V6 to V8 growth stage. Corn whorls were randomly collected up to 14 days after application (DAA), and shikimic acid accumulation in the whorls was determined using HPLC-UV. Maximum shikimic acid accumulation occurred 3-7 DAA in corn receiving 0.16 and 0.32 kg/ha. Shikimic acid accumulation 3, 5, and 7 DAA did correlate (r = 0.80-0.86) to yield losses from a sublethal application of glyphosate. Shikimic acid accumulation 3, 5, and 7 DAA was better correlated to visual injury at 14 DAA than to yield reductions. Visual injury ratings 14 DAA were a slightly better indicator of potential yield losses (r = 0.93) than shikimic acid accumulation in field-grown corn whorls (r = 0.8-0.86).     

Detection of bovine leukemia virus by in situ polymerase chain reaction in tissues from a heifer diagnosed with sporadic thymic lymphosarcoma.

An 18-month-old bovine heifer was presented for clinical evaluation after a sudden onset of ventral edema. Clinical and pathological evaluations were consistent with thymic lymphosarcoma, a sporadic form of lymphosarcoma in cattle, which is not generally considered to be associated with bovine leukemia virus (BLV). This heifer was seropositive for BLV at 6 and 18 months of age. Tissues obtained at necropsy were evaluated using in situ polymerase chain reaction. The BLV proviral DNA was detected in lymphocytes of the thymus as well as in epithelial cells of the liver and kidney. This report presents evidence that thymic lymphosarcomas can be associated with BLV infection and that BLV may have a broader cellular tropism than was supposed previously.     

EFFECT OF PLANTING DATE,NITROGEN RATE,AND HYBRID ON SUNFLOWER

Sunflower is a potential crop for the southeastern United States for production of cooking oil or biodiesel. In 2007, we evaluated the effect of planting date (PD, 20 April, 20 May, and 20 June), nitrogen (N) application rate (0, 67, 134, and 202 kg ha^?1), and hybrid (‘DKF3875’, ‘DKF2990’, ‘DKF3510’, and ‘DKF3901’) on sunflower productivity and oil profile in four Mississippi locations, Newton, Starkville, and two sites in Verona. There was a trend of increased oleic acid concentration with earlier planting dates, especially in hybrids with lower oleic acid concentration. Earlier planting dates of ‘DKF3901’ and ‘DKF2990’ (the hybrid with the lowest oleic acid) actually had 200 to 300 g kg^?1 higher concentration of oleic acid when grown in Mississippi vs. the original seed of the same hybrids used for planting and produced at a more northern latitude. This and a recent study in Mississippi suggest that modern hybrids could provide ample yields even when the N fertilization is relatively low.     

Bovine leukemia virus infection in a juvenile alpaca with multicentric lymphoma

A 13-month-old alpaca (Vicugna pacos) was presented for mandibular masses and weight loss. Histopathology of biopsy tissue was consistent with lymphoma. The alpaca was euthanized and necropsy revealed lymphoma masses in multiple organs. Immunohistochemistry for T- and B-cell typing was inconclusive. Serology and in-situ polymerase chain reaction hybridization were positive for bovine leukemia virus.     

Oil productivity and composition of sunflower as a function of hybrid and planting date

Sunflower (Helianthus annuus L.) is a potential cash crop for the southeastern United States for production of cooking oil or biodiesel. Two years (2006 and 2007) of experiments were conducted at each of five locations in Mississippi to evaluate the effect of planting date (April 20, May 20, and June 20), and hybrid (DKF3875, DKF2990, DKF3510, DKF3901, PR63M80, PR62A91, PR63A21, PR63M91, and PR64H41) on seed yield, oil content, and oil composition of sunflower. Seed oil concentration varied from 25 to 47%. The oleic acid concentration in the oil was greater than 85% for DKF3510 and PR64H41, above 65% for PR63M80 and PR63M91, and intermediate for the other hybrids. Total saturated fatty acids (TSFA) concentration in the oil (the sum of palmitic, stearic, arachidic, behenic, and lignoceric acids) ranged from 6.3 to 13.0%, with DKF3510, PR63M91, and PR64H41 having lower concentration of TSFA than the other hybrids. Mean seed yields ranged from 997 to 2096 kg ha⁻¹ depending on location. Mean oil yields at the five locations ranged from 380 to 687 kg ha⁻¹, and calculated biodiesel production ranged from 304 to 550 kg ha⁻¹. Seed and oil yields in this study suggest sunflower in Mississippi should be planted by the last week of May. Later planting (20 June) may significantly decrease both seed and oil yields in the non-irrigated system in Mississippi and in other areas of the southeastern United States with similar environmental conditions.     

Nitrogen applications modify seed and oil yields and fatty acid composition of winter mustard

Winter mustard (Brassica juncea L.) is not a common crop in the Southeastern United States. With increased interest in biodiesel production, there has been corresponding interest in mustard in this region. The objective of this study was to evaluate the effect of N fertilization (0, 50, 100, 150 kg N ha⁻¹) on productivity, oil content, and oil composition of winter mustard ‘Pacific Gold’ grown at three locations in Mississippi (Stoneville, and two locations at Verona, namely Verona silt loam (Verona-SL) and Verona clay (Verona-C)). Nitrogen did not affect oil content (percent oil). Seed and oil yields (kg ha⁻¹) increased with N application relative to the unfertilized control. At the Verona-C location, the concentration of oleic acid was higher in the 50 kg N ha⁻¹ treatment. At Stoneville, linolenic acid concentration was higher in the 150 kg N ha⁻¹ and lower in the 100 kg/N ha⁻¹ treatment, while it was not different in the other treatments. Overall, the yield of the fatty acids (FA) palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, eicosanoic, behenic, erucic, lignoceric, and nervonic acid increased with higher N rates (100 or 150 kg N/h). The highest yield of FA in the two Verona locations were achieved in the 100 kg N ha⁻¹, while greatest yield of FA at Stoneville was achieved in the highest N rate (150 kg N ha⁻¹). Means of mustard oil yields in our study in the higher fertility treatment ranged from 737 to 1094 kg ha⁻¹. This study demonstrated winter mustard production in Mississippi and possibly other areas in the Southeastern United States can be successful and could provide seed and oil yields comparable to yields from other production areas.     

Rice (Oryza sativa) response to drift rates of glyphosate

Greenhouse and field studies were conducted to investigate response of two rice varieties, Priscilla and Cocodrie, to sub-lethal rates of glyphosate in terms of injury, shikimate accumulation and yield. In the greenhouse, more shikimate accumulated in Cocodrie than Priscilla at comparable glyphosate rates applied to plants at the three-leaf stage. In field studies, glyphosate was applied to both varieties when they were 74-cm tall and in the internode separation growth stage. Visual injury, plant height, and leaf-tissue samples for shikimate analysis were collected at 3, 7, 14, 21 and 28 days after treatment (DAT). Rice yield was also determined. Noticeable visual injury and height reduction to both varieties was observed as early as 7 and 3 DAT in Cocodrie and Priscilla, respectively. Shikimate levels in leaves began to increase in both varieties by 3 DAT in a dose-dependent manner and reached a peak between 7 and 14 DAT. Elevated shikimate levels were still detectable by 28 DAT. Similar levels of shikimate accumulated in both varieties at comparable glyphosate rates. However, glyphosate treatment at comparable rates reduced rice yields more in Cocodrie than in Priscilla. The highest rate of glyphosate reduced yield in Cocodrie by 92% whereas there was only a 60% yield reduction in Priscilla. Shikimate levels in glyphosate-treated rice were strongly correlated to yield reductions across both varieties and appeared to be a better predictor of yield reduction than was visual injury. Visual injury coupled with measured shikimate levels can be used collaboratively to identify glyphosate exposure and estimate subsequent rice yield reductions.