Root architecture and biomass allocation of three range grasses in response to nonuniform supply of nutrients and shoot defoliation

Arredondo, J. T.; Johnson, Douglas A.

doi:10.1046/j.1469-8137.1999.00460.x

Cited by 69 publications

(67 citation statements)

References 35 publications

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“…The present experiment used contrasting, but homogeneous, soil treatments only. It has been reported for some grasses that contrasting but uniform nutrient conditions may not cause differences in the root system, whereas responses do become visible when contrasting conditions are combined into non-uniform treatments (Arredondo and Johnson 1999;Fitter and Stickland 1991). Hence, further studies are needed to test whether the present conclusion that root morphology is conservative across the elevational gradient of a salt marsh is also valid in non-uniform, patchy soil environments.…”

Section: Discussionmentioning

confidence: 45%

Coping with low nutrient availability and inundation: root growth responses of three halophytic grass species from different elevations along a flooding gradient

et al. 2001

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We describe the responses of three halophytic grass species that dominate the low (Spartina anglica), middle (Puccinellia maritima) and high (Elymus pycnanthus) parts of a salt marsh, to soil conditions that are believed to favour contrasting root-growth strategies. Our hypotheses were: (1) individual lateral root length is enhanced by N limitations in the soil but restricted by oxygen limitations, (2) the density of root branching within a species is inversely related to the length of the lateral roots, and (3) species from high elevations (i.e. the driest parts of a marsh) are the most responsive to changing soil conditions. Plant growth responses and soil parameters showed that the contrasting but uniformly applied soil treatments were effective. All three species showed a small but significant shift towards a finer root diameter distribution when N was limiting, partly because of the finer diameters of the laterals (Elymus and Spartina) and partly because of increased length of individual 1st-order laterals (Elymus and Puccinellia). The increased length of the 1st-order laterals of Elymus and Puccinellia grown under low N indicates that the first part of hypothesis 1 may be true. However, lack of effect of flooding and reduced soil conditions lead us to reject the second part of hypothesis 1. Hypothesis 2 was rejected for these three halophytes, as the branch density of 1st- and 2nd-order laterals appears to be controlled by other factors than length of individual laterals. Hypothesis 3 may be true for specific root characteristics (e.g. length of individual 1st-order laterals), but cannot be generalised (e.g. branch density and topological index). In conclusion, the present data on root growth in contrasting but homogeneous soil conditions indicate that morphological responsiveness of the root systems of these halophytic grass species is limited, regardless of their location along the elevational gradient.

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Section: Discussionmentioning

confidence: 45%

Coping with low nutrient availability and inundation: root growth responses of three halophytic grass species from different elevations along a flooding gradient

et al. 2001

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“…For grasses, the finely branched, 'herringbone' architecture enables more efficient mobile nutrient acquisition than 'dichotomous' root systems found in species like Scots pine (Fitter 2002). Grasses also exhibit high values of specific root length (SRL), that can reach 700 m g À1 (Ryser 1996;Arredondo and Johnson 1999;Atkinson 2000;Craine et al 2001;Nicotra et al 2002), while that of tree species hardly reaches 10-15 m g À1 in the case of Scots pine (Curt et al 2005). This is achieved by constructing roots of thin diameter or low tissue density (Fitter et al 1991;Lambers and Poorter 1992;Reich et al 1998).…”

Section: Discussionmentioning

confidence: 97%

The role of below-ground competition during early stages of secondary succession: the case of 3-year-old Scots pine (Pinus sylvestris L.) seedlings in an abandoned grassland

Picon‐Cochard

Coll

Balandier³

2006

Oecologia

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In abandoned or extensively managed grasslands, the mechanisms involved in pioneer tree species success are not fully explained. Resource competition among plants and microclimate modifications have been emphasised as possible mechanisms to explain variation of survivorship and growth. In this study, we evaluated a number of mechanisms that may lead to successful survival and growth of seedlings of a pioneer tree species (Pinus sylvestris) in a grass-dominated grassland. Three-year-old Scots pines were planted in an extensively managed grassland of the French Massif Central and for 2 years were either maintained in bare soil or subjected to aerial and below-ground interactions induced by grass vegetation. Soil temperatures were slightly higher in bare soil than under the grass vegetation, but not to an extent explaining pine growth differences. The tall grass canopy reduced light transmission by 77% at ground level and by 20% in the upper part of Scots pine seedlings. Grass vegetation presence also significantly decreased soil volumetric water content (Hv) and soil nitrate in spring and in summer. In these conditions, the average tree height was reduced by 5% compared to trees grown in bare soil, and plant biomass was reduced by 85%. Scots pine intrinsic water-use efficiency (A/g), measured by leaf gas-exchange, increased when Hv decreased owing to a rapid decline of stomatal conductance (g). This result was also confirmed by delta 13C analyses of needles. A summer 15N labelling of seedlings and grass vegetation confirmed the higher NO3 capture capacity of grass vegetation in comparison with Scots pine seedlings. Our results provide evidence that the seedlings' success was linked to tolerance of below-ground resource depletion (particularly water) induced by grass vegetation based on morphological and physiological plasticity as well as to resource conservation.

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“…Maintenance of lateral root growth also contributed to a stronger feedback loop on shoot growth in signalgrass as the leaf-to-root DM ratio was greater at high P supply (a more optimal level of P supply) while shoot P concentrations remained unchanged. Arredondo and Johnson (1999) suggested that plant growth rate might increase if more C was available for shoot re-growth and if the capacity for soil nutrient acquisition was greater. In fact, maintenance of root growth and extensive root systems have been suggested to underlie edaphic adaptation of brachiariagrass genotypes (Rao et al 1996a;1996b;Miles et al 2004).…”

Section: Discussionmentioning

confidence: 99%

A comparative study on plant growth and root plasticity responses of two Brachiaria forage grasses grown in nutrient solution at low and high phosphorus supply

et al. 2009

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Brachiaria forage grasses are widely used for livestock production in the tropics. Signalgrass (Brachiaria decumbens cv. Basilisk, CIAT 606) is better adapted to low phosphorus (P) soils than ruzigrass (B. ruziziensis cv. Kennedy, CIAT 654), but the physiological basis of differences in low-P adaptation is unknown. We characterized morphological and physiological responses of signalgrass and ruzigrass to low P supply by growing both grasses for 30 days in nutrient solution with two levels of P supply using the hydroxyapatite pouch system. Ruzigrass produced more biomass at both levels of P supply whilst signalgrass appears to be a slowergrowing grass. Both grasses increased biomass allocation to roots and had higher root acid phosphatase and phytase activities at low P supply. At low P supply, ruzigrass showed greater morphological plasticity as its leaf mass density and lateral root fraction increased. For signalgrass, morphological traits that are not responsive to variation in P supply might confer long-term ecological advantages contributing to its superior field persistence: greater shoot tissue mass density (dry matter content) might lower nutrient requirements while maintenance of lateral root growth might be important for nutrient acquisition in patchy soils. Physiological plasticity in nutrient partitioning between root classes was also evident for signalgrass as main roots had higher nutrient concentrations at high P supply. Our results highlight the importance of analyzing morphological and physiological trait profiles and determining the role of phenotypic plasticity to characterize differences in low-P adaptation between Brachiaria genotypes.

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Root architecture and biomass allocation of three range grasses in response to nonuniform supply of nutrients and shoot defoliation

Cited by 69 publications

References 35 publications

Coping with low nutrient availability and inundation: root growth responses of three halophytic grass species from different elevations along a flooding gradient

Coping with low nutrient availability and inundation: root growth responses of three halophytic grass species from different elevations along a flooding gradient

The role of below-ground competition during early stages of secondary succession: the case of 3-year-old Scots pine (Pinus sylvestris L.) seedlings in an abandoned grassland

A comparative study on plant growth and root plasticity responses of two Brachiaria forage grasses grown in nutrient solution at low and high phosphorus supply

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