Jeff W. Stringer

Bio: Jeff W. Stringer is an academic researcher. The author has contributed to research in topics: Nitrogen fixation & Nitrogen deficiency. The author has an hindex of 1, co-authored 1 publications receiving 12 citations.

The effects of combined nitrogen on growth, nodulation, and nitrogen fixation of black locust seedlings

Abstract: Black locust (Robiniapseudoacacia L.) seedlings grown for 50 days in sand culture with 5 mM NH4NO3-supplemented nutrient solution had 74% lower nitrogen-fixation rates (acetylene reduction) than seedlings grown without nitrogen. Nodule activity was not affected by treatment, and differences in nitrogen fixation between treatments reflected decreased nodulation in seedlings grown with NH4NO3. Relative growth rate was approximately 3 times greater in seedlings supplied with NH4NO3, indicating maximum biomass accumulation cannot be supported by nitrogen fixation alone. Growth was positively correlated with the nitrogen-fixation rate in seedlings grown without nitrogen, but this correlation was not found in NH4NO3-treated seedlings. Leaf nitrogen content was less for seedlings grown in the nitrogen-free sand culture and observations suggested that a nitrogen deficiency in these seedlings restricted their growth.

Nodulation and nitrogenase activity in nitrogen-fixing woody plants stimulated by CO2 enrichment of the atmosphere

Abstract: The responses of three species of nitrogen-fixing trees to CO2 enrichment of the atmosphere were investigated under nutrient-poor conditions Seedlings of the legume, Robinia pseudoacacia L and the actinorhizal species, Alnus glutinosa (L) Gaertn and Elaeagnus angustifolia L were grown in an infertile forest soil in controlled-environment chambers with atmospheric CO2 concentrations of 350 μl −1 (ambient) or 700 μl −1 In R pseudoacacia and A glutinosa, total nitrogenase (N2 reduction) activity per plant, assayed by the acetylene reduction method, was significantly higher in elevated CO2, because the plants were larger and had more nodule mass than did plants in ambient CO2 The specific nitrogenase activity of the nodules, however, was not consistently or significantly affected by CO2 enrichment Substantial increases in plant growth occurred with CO2 enrichment despite probable nitrogen and phosphorus deficiencies These results support the premises that nutrient limitations will not preclude growth responses of woody plants to elevated CO2 and that stimulation of symbiotic activity by CO2 enrichment of the atmosphere could increase nutrient availability in infertile habitats

Black locust as a bioenergy feedstock: a review.

Abstract: Short rotation woody bioenergy crops (SRWC) could contribute a substantial portion of the biomass required to meet federal mandates and offset carbon emissions. One SRWC with strong bioenergy potential is black locust (Robinia pseudoacacia L.), planted extensively for wood and energy applications globally, but under-studied in its native US. This member of the Fabaceae family can fix nitrogen, tolerate stress, and sequester carbon while generating biomass yields up to 14 Mg ha-1 yr-1. This article offers a comprehensive state-of-the-art review of production practices, biomass and energy yield estimates, environmental risks and benefits, and economic considerations for this promising feedstock.

Allometry of acetylene reduction and nodule growth of Robinia pseudoacacia families subjected to varied root zone nitrate concentrations

Abstract: The effects of nitrate (NO(3) (-)) on acetylene reduction and growth were examined in nodulated seedlings from three open-pollinated families of black locust (Robinia pseudoacacia L.) grown in sand culture. In the first study, nine-week-old seedlings were supplied with 0.0, 0.5, 1.0, 5.0 or 15.0 mM NO(3) (-), for two weeks during which acetylene reduction and biomass were measured five times. In the second study, eight-week-old seedlings were supplied with 0.0, 1.0 or 5.0 mM NO(3) (-) for 51 days during which acetylene reduction and biomass were measured six times. Results were analyzed with and without adjustments for seedling size. In the first study, 15.0 mM NO(3) (-) significantly decreased total acetylene reduction but lower concentrations did not. In seedlings given 15.0 mM NO(3) (-), both nitrogenase activity and nodule biomass were reduced. Inhibition of nitrogenase activity by NO(3) (-) was reversible. In the second study, both the 1.0 and 5.0 mM NO(3) (-) treatments increased plant growth compared to the control (0.0 mM). At the end of the 51-day treatment period, total acetylene reduction and nodule biomass were greatest in the 1.0 mM NO(3) (-) treatment and least in the 5.0 mM NO(3) (-) treatment. However, when adjusted for seedling size, total acetylene reduction and nodule biomass were similar in the 0.0 and 1.0 mM NO(3) (-) treatments. The greater total acetylene reduction and nodule biomass of seedlings grown with 1.0 mM NO(3) (-) resulted from increased seedling size due to fertilization. After adjustment for plant size, total acetylene reduction, nodule biomass and nitrogenase activity were significantly lower in the 5.0 mM NO(3) (-) treatment compared with the control or 1.0 mM NO(3) (-) treatment. Adjustment for seedling size, by means of allometric principles, appears necessary to interpret treatment effects on total acetylene reduction and its components, nodule biomass and nitrogenase activity correctly.

Nitrate reductase activity, nitrogenase activity and photosynthesis of black alder exposed to chilling temperatures

Abstract: Christoph S. Vogd and Jeffrey O. DawsomVogel, C. S, and Dawson, J, O. 1991, Nitrate reductase activity, nitrogenase activityand photosynthesis of black alder exposed to chilling temperatures, - Physiol, Plant,82: 551-558,Actinorhizal (/^ran/rifl-nodulated) black alder [Alnus glutinosa (L.) Gaertn,] seed-lings fertilized with 0,36 mM nitrate (low nitrate fertilizer treatment) or 7,14 mMnitrate (high nitrate fertilizer treatment) and acclimated in a growth chamber for 2weeks were exposed to 2.5 h of night-time chilling temperatures of —1 to 4°C. Coldtreatment decreased nitrogenase activity (acetylene reduction activity) 33% for lownitrate fertilized plants and 41% for high nitrate fertilized plants. Recovery ofnitrogenase activity occurred within 7 days after chilling treatment. In contrast, invivo nitrate reductase (NR) activities of leaves and fine roots increased immediatelyafter chilling then decreased as nitrogenase activities recovered. Fine roots of alderseedlings exhibited NR activities proportional to the amounts of nitrate in the rootingmedium. In contrast, the NR activities of leaves were independent of substrate andtissue nitrate levels and corresponded to nitrogenase activity in the root nodules. In aseparate experiment, net photosynthesis (PS) of similarly treated black alder seed-lings was measured before and after chilling treatments. Net PS declined in responseto ehiUing by 17% for plants receiving low nitrate fertilizer and 19% for plantsreceiving high nitrate fertilizer. After chilling, stomatal conductance (gj decreasedby 39% and intemal CO'2 concentration (c^) decreased by 5% in plants receiving thehigh nitrate fertilizer, whereas plants receiving the low nitrate fertilizer showed noebange in gs and a 13% increase in q. Results indicate that chilhng stimulates stomatalclosure only at the high nitrate level and that interference with bioehemtcal functionsis probably the major impact of chilling on PS,Key words - Aetinorhizal, Alnus glutinosa, black alder, chilling temperatures, di-nitrogen fixation, Frankia, nitrate reductase, nitrogenase, photosynthesis.C. S. Vogel and J. O. Dawson (corresponding author), Dept of Forestry, Univ. ofIllinois, 1301 West Gregory Dr., Urbana, IL 61801, USA.ing temperatures began to occur and after the leaves ofIntroduction associated woody deciduous broad-leaved trees haveBlack alder \Alnus glutinosa (L.) Gaertn,] is a temper- been shed (Neave et al, 1989),ate deciduous tree that forms symbiotic dinitrogen fix- Leaf N resorption in black alder during the autumning root nodules in association with soil actinotnycetes can be affected by soil fertility and Frankia nodulation,of the genus Frankia. Black alder sheds its leaves much Cote et al. (1989) demonstrated that N-fertili2ed blacklater and resorbs less net leaf N during autumnal se- alder seedlings lacking Nj-fixing nodules showed no netnescence than do most other temperate deciduous trees resorption of leaf N during autumn, while alders de-(C6te and Dawson 1986, Gote et al, 1989, Dawson and pendent on N derived from symbiotic fixation resorbedFunk 1981, Dawson etal, 1980), This delay in autumnal 38% of their leaf N prior to leaf abscission. The declinesenescence apparently allows leaf physiological proc- in leaf N coincided with the temperature-dependentesses to continue longer, since photosynthesis (PS) in decrease in nitrogenase activity. Fertilized plants lack-black alder may cotitinue for up to a month after freez- irtg nodules continued to absorb and utilize availableReceived 5 November, 1990; revised 26 March, 1991