Although mine reclamation sites are important targets for ecological restoration, they are generally difficult to regenerate successfully. We evaluated the importance of nursery nutrient loading as a new approach to enhance forest restoration on abandoned mine lands. Northern red oak (Quercus rubra) and White oak (Q. alba) seedlings were nitrogen (N) loaded for 18 weeks at a bareroot nursery in southern Indiana, United States. Fertility treatments followed conventional or modified exponential functions to synchronize N supply with plant demand. Subsequently, nursery-grown seedlings were outplanted the following year onto a mine reclamation site in southwestern Indiana to evaluate effects of nursery N loading on first-year field performance. Nursery N loading promoted total plant dry mass production 25-129% in Red oak and 50-184% in White oak compared to unfertilized plants. Nitrogen loading increased N content 88-145% and potassium (K) content 16-71% for Red oak and N content 124-250% and K content 16-93% for White oak relative to controls. When outplanted, N loading resulted in high seedling survival (>84%) and increased total plant dry mass production 14-30% for Red oak and 23-52% for White oak. Nitrogen loading increased plant N uptake 14-102% in Red oak and 32-105% in White oak under field conditions. Exponential N loading demonstrates potential as a viable technique to improve seedling outplanting performance and reclamation success in Indiana and elsewhere.

2006) Modified exponential nitrogen loading to promote morphological quality and nutrient storage of bareroot-cultured Quercus rubra and Quercus alba seedlings, Abstract Exponential nutrient loading has been used to improve nursery fertilizer uptake efficiency of conifer seedlings, but the technique has received little attention in the culture of temperate deciduous hardwoods. This study examined responses of northern red oak (Quercus rubra L.) and white oak (Q. alba L.) seedlings to modified exponential nitrogen loading during bareroot nursery culture using a broad range of nutrient supply from 0 to 3.35 g nitrogen (N) per plant per season for 18 weeks in Indiana, USA. Seedling growth and nutritional parameters followed a curvilinear pattern that ranged from deficiency to toxicity with increased fertilization consistent with trends depicted in the proposed model for nutrient loading. Fertilization increased plant dry mass by 113 Á260% for red oak and 49 Á144% for white oak. Severe nutrient deficiency occurred under indigenous soil fertility, and limited phosphorus and potassium uptake were found to inhibit seedling growth at higher N supply. The sufficiency and optimum rates were determined to be 0.84 and 1.68 g N per seedling per season, respectively, under the current cultural conditions. Fertilization at 1.68 g N per plant increased N content by 40% in red oak and 35% in white oak. This approach may be used to help refine nursery fertilization practices in hardwood culture to produce high-quality seedlings for field planting.

This study assessed the effect of oral pinitol supplementation on oral and intravenous glucose tolerances and on skeletal muscle insulin receptor content and phosphorylation in older people. Fifteen people (6 men, 9 women; age 66 +/- 8 y; BMI 27.9 +/- 3.3 kg/m(2); hemoglobin A1c 5.39 +/- 0.46%, mean +/- SD) completed a 7-wk protocol. Subjects were randomly assigned to groups that during wk 2-7 consumed twice daily either a non-nutritive beverage (Placebo group, n = 8) or the same beverage with 1000 mg pinitol dissolved into it (Pinitol group, n = 7, total dose = 2000 mg pinitol/d). Testing was done at wk 1 and wk 7. In the Pinitol group with supplementation, 24-h urinary pinitol excretion increased 17-fold. The fasting concentrations of glucose, insulin, and C-peptide, and the 180-min area under the curve for these compounds, in response to oral (75 g) and intravenous (300 mg/kg) glucose tolerance challenges, were unchanged from wk 1 to wk 7 and were not influenced by pinitol. Also, pinitol did not affect indices of hepatic and whole-body insulin sensitivity from the oral glucose tolerance test and indices of insulin sensitivity, acute insulin response to glucose, and glucose effectiveness from the intravenous glucose tolerance test, estimated using minimal modeling. Pinitol did not differentially affect total insulin receptor content and insulin receptor phosphotyrosine 1158 and insulin receptor phosphotyrosine 1162/1163 activation in vastus lateralis samples taken during an oral-glucose-induced hyperglycemic and hyperinsulinemic state. These data suggest that pinitol supplementation does not influence whole-body insulin-mediated glucose metabolism and muscle insulin receptor content and phosphorylation in nondiabetic, older people.

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