Contribution from Stolons and Roots to Estimates of the Total Amount of N2Fixed by White Clover (Trifolium repensL.)

Jørgensen, Finn Vanman; Ledgard, S. F.

doi:10.1006/anbo.1997.0501

Cited by 53 publications

(24 citation statements)

References 25 publications

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“…An extended root growth, e.g. resulting from a reduced soil fertility and nutrient shortage, thus indicates a common physiological stress condition (Marschner, 1995;Jørgensen and Ledgard, 1997). From this, we conclude that relative root growth of MtSucS1-reduced lines geared toward maximized soil contact to further improve nutrient acquisition under N-limiting conditions.…”

Section: Mtsucs1-reduced Lines Suffer From N Starvation Under Nodulatmentioning

confidence: 79%

Antisense Repression of the Medicago truncatula Nodule-Enhanced Sucrose Synthase Leads to a Handicapped Nitrogen Fixation Mirrored by Specific Alterations in the Symbiotic Transcriptome and Metabolome

et al. 2007

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We analyzed the role of the sucrose (Suc) synthase MtSucS1 during nodulation of the model legume Medicago truncatula, integrating data for the developmental, transcriptional, and metabolic processes affected downstream of an impaired Suc cleavage in root nodules. To reduce carbohydrate supply to nodule tissues, transgenic plants expressing a p35S-driven MtSucS1-antisense fusion were constructed. These plants displayed an up to 90% reduction of MtSucS1 proteins in roots and nodules. Phenotypic studies of two independent MtSucS1-reduced lines demonstrated that only under conditions depending on nodulation, these plants appeared to be impaired in above-ground growth. Specifically plant height, shoot weight, leaf development, flowering, as well as seed maturation were reduced, and the efficiency of photosynthesis was affected. Concomitantly, a significantly enhanced root to shoot ratio with a marked increase in root tip numbers was observed. Root nodule formation was found retarded and the impaired nodulation was accompanied by a less efficient nitrogen (N) acquisition. The decreased total N content of MtSucS1-antisense lines and an enhanced carbon to N ratio in roots, nodules, and shoots correlated with the extent of MtSucS1 knockdown. On the level of transcription, effects of an MtSucS1 reduction were evident for genes representing important nodes of the nodule carbon and N metabolism, while metabolite profiling revealed significantly lower levels of amino acids and their derivatives particularly in strongly MtSucS1-reduced nodules. Our results support the model that nodule-enhanced Suc synthase 1 of the model legume M. truncatula is required for the establishment and maintenance of an efficient N-fixing symbiosis.

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Section: Mtsucs1-reduced Lines Suffer From N Starvation Under Nodulatmentioning

confidence: 79%

Antisense Repression of the Medicago truncatula Nodule-Enhanced Sucrose Synthase Leads to a Handicapped Nitrogen Fixation Mirrored by Specific Alterations in the Symbiotic Transcriptome and Metabolome

et al. 2007

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“…Specifically, total vetch aboveground plant N·m −2 was calculated by multiplying the average vetch density (planted at a seeding rate of 7 kg·PLS·ha −1 ) by the aboveground, per plant vetch N and divided by 50% (assuming half is bioavailable, [34,35]). To calculate the seeding rate required for vetch to supply 67 kg·N·ha −1 to the companion crop, target N level was divided by bioavailable vetch N, thus developing a ratio to multiply the current seeding rate that would give the suggested seeding rates of common and hairy vetch (Equation (3)).…”

Section: Nitrogen Fixation Of Legume Intercropsmentioning

confidence: 99%

N2 Fixation of Common and Hairy Vetches when Intercropped into Switchgrass

et al. 2017

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Interest in sustainable alternatives to synthetic nitrogen (N) for switchgrass (Panicum virgatum L.) forage and bioenergy production, such as biological N 2 fixation (BNF) via legume-intercropping, continues to increase. The objectives were to: (i) test physical and chemical scarification techniques (10 total) for common vetch (Vicia sativa L.); (ii) assess whether switchgrass yield is increased by BNF under optimum seed dormancy suppression methods; and (iii) determine BNF rates of common and hairy vetch (Vicia villosa L.) via the N-difference method. Results indicate that chemical scarification (sulfuric acid) and mechanical pretreatment (0.7 kg of pressure for one minute) improve common vetch germination by 60% and 50%, respectively, relative to controls. Under optimum scarification methods, BNF was 59.3 and 43.3 kg·N·ha −1 when seeded at 7 kg pure live seed ha −1 for common and hairy vetch, respectively. However, at this seeding rate, switchgrass yields were not affected by BNF (p > 0.05). Based on BNF rates and plant density estimates, seeding rates of 8 and 10 kg pure live seed (PLS) ha −1 for common and hairy vetch, respectively, would be required to obtain plant densities sufficient for BNF at the current recommended rate of 67 kg·N·ha −1 for switchgrass biomass production in the Southeastern U.S.

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“…Grass and clover herbage samples were collected monthly from the quadrats for 4 months after application of the isotope, and then the isotope application was repeated. The difference in 14 N/ 15 N isotope ratio between the clovers and grasses was determined by mass spectrometry and used to calculate the proportion of clover herbage N (P N ) derived from fixation (Jorgensen & Ledgard 1997). P N was combined with monthly clover DM yields to estimate N 2 fixation, corrected for clover N below cutting height as described in Jorgensen & Ledgard (1997).…”

Section: Nitrogen Fixationmentioning

confidence: 99%

Growth and milksolids production in pastures of older and more recent ryegrass and white clover cultivars under dairy grazing

Crush

Woodward²,

Eerens

et al. 2006

New Zealand Journal of Agricultural Research

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Dairy milksolids (MS) production rates were measured in pastures consisting of different age-classes of perennial ryegrass and white clover cultivars. There were four pasture treatments consisting of factorial combinations of ryegrasses representative of those available to farmers in the 1980s and 1998, and clovers available in the 1960s and 1998. The pasture treatments were grown in self-contained, replicated 4 ha farmlets and rotationally grazed at a stocking rate of three Friesian cows per hectare. The 1998 ryegrass and clover cultivars were more competitive than the older cultivar types, and tended to form a higher proportion of the sward at the end of the trial. This did not translate into significant cultivar age group effects on short-term pasture growth rates or annual pasture dry matter (DM) yields which averaged 17.2 ± 0.9 t DM/ha over years 2-4 of the trial. The 1980s ryegrasses had faster growth rates in spring than the 1998 ryegrasses. Consequently, more silage was made on average on farmlets sown with the 1980s ryegrasses (230 kg silage DM/cow per yr), than with the 1998 ryegrasses (150 kg silage DM/cow per yr), although the yield increase was statistically significant only in the 2001-02 year. Herbage chemical profiles and feeding quality were similar in all treatments. Nitrogen fixed per unit clover grown did not vary with clover types. There was a very strong linear correlation between annual clover yields and annual N fixation. Annual N fixation totals varied substantially from the mean value of 157 kg N/ha, as clover annual DM yields changed. Total annual milksolids (MS) production ranged from 811 kgMS/haperyrto 1250kgMS/ha per yr, with no consistent pasture treatment effects. There was no significant effect of ryegrass type on milk production per cow or milksolids production per hectare in any year. Clover type had an effect on production only in 2001/02, with higher milk production per cow and total milksolids production per hectare on the 1998 clover treatments, due to the higher clover content of pastures in this treatment. We suggest that annual pasture production from these well-managed ryegrass-white clover pastures is very close to the practical limit achievable in this region. Any major increases in herbage yield will require novel plant germplasm.

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Contribution from Stolons and Roots to Estimates of the Total Amount of N2Fixed by White Clover (Trifolium repensL.)

Cited by 53 publications

References 25 publications

Antisense Repression of the Medicago truncatula Nodule-Enhanced Sucrose Synthase Leads to a Handicapped Nitrogen Fixation Mirrored by Specific Alterations in the Symbiotic Transcriptome and Metabolome

Antisense Repression of the Medicago truncatula Nodule-Enhanced Sucrose Synthase Leads to a Handicapped Nitrogen Fixation Mirrored by Specific Alterations in the Symbiotic Transcriptome and Metabolome

N2 Fixation of Common and Hairy Vetches when Intercropped into Switchgrass

Growth and milksolids production in pastures of older and more recent ryegrass and white clover cultivars under dairy grazing

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