Effects of Nitrogen Supply on the Root Morphology of Corn and Velvetleaf (original) (raw)
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Nitrogen supply affects root:shoot ratio in corn and velvetleaf (Abutilon theophrasti )
Weed Science, 2005
Competitive outcome between crops and weeds is affected by partitioning of new biomass to above-and belowground plant organs in response to nutrient supply. This study determined the fraction of biomass partitioned to roots vs. shoots in corn and velvetleaf in response to nitrogen (N) supply. Pots measuring 28 cm in diam and 60 cm deep were embedded in the ground and each contained one plant of either corn or velvetleaf. Each plant received one of three N treatments: 0, 1, or 3 g N applied as ammonium nitrate in 2001, and 0, 2, or 6 g N in 2002. Measurements of total above-and belowground biomass were made at 10 sampling dates during each growing season. The root:shoot ratio decreased over time for both corn and velvetleaf as a result of normal plant growth and as N supply increased. Root: shoot ratio was greater for corn than for velvetleaf at comparable stages of development and at all levels of N supply. Both corn and velvetleaf display true plasticity in biomass partitioning patterns in response to N supply. Velvetleaf root:shoot ratio increased by 46 to 82% when N was limiting in 2001 and 2002, respectively, whereas corn root:shoot ratio increased by only 29 to 45%. The greater increase in biomass partitioned to roots by velvetleaf might negatively impact its ability to compete with corn for light when N supply is limited.
Comparative Nitrogen Uptake and Distribution in Corn and Velvetleaf (Abutilon Theophrasti)
Weed Science, 2007
Weeds compete with crops for light, soil water, and nutrients. Nitrogen (N) is the primary limiting soil nutrient. Forecasting the effects of N on growth, development, and interplant competition requires accurate prediction of N uptake and distribution within plants. Field studies were conducted in 1999 and 2000 to determine the effects of variable N addition on monoculture corn and velvetleaf N uptake, the relationship between plant N concentration ([N]) and total biomass, the fraction of N partitioned to leaves, and predicted N uptake and leaf N content. Cumulative N uptake of both species was generally greater in 2000 than in 1999 and tended to increase with increasing N addition. Corn and velvetleaf [N] declined with increasing biomass in both years in a predictable manner. The fraction of N partitioned to corn and velvetleaf leaves varied with thermal time from emergence but was not influenced by year, N addition, or weed density. With the use of the [N]-biomass relationship to forecast N demand, cumulative corn N uptake was accurately predicted for three of four treatments in 1999 but was underpredicted in 2000. Velvetleaf N uptake was accurately predicted in all treatments in both years. Leaf N content (N L , g N m 22 leaf) was predicted by the fraction of N partitioned to leaves, predicted N uptake, and observed leaf area index for each species. Average deviations between predicted and observed corn N L were , 88 and 12% of the observed values in 1999 and 2000, respectively. Velvetleaf N L was less well predicted, with average deviations ranging from 39 to 248% of the observed values. Results of this research indicate that N uptake in corn and velvetleaf was driven primarily by biomass accumulation. Overall, the approaches outlined in this paper provide reasonable predictions of corn and velvetleaf N uptake and distribution in aboveground tissues. Nomenclature: Velvetleaf, Abutilon theophrasti Medic. ABUTH; corn, Zea mays L. 'Pioneer 33A14'.
Intercropping effect on root growth and nitrogen uptake at different nitrogen levels
Journal of Plant Ecology, 2014
Aims Intercropping legumes and non-legumes may affect the root growth of both components in the mixture, and the non-legume is known to be strongly favored by increasing nitrogen (N) supply. the knowledge of how root systems affect the growth of the individual species is useful for understanding the interactions in intercrops as well as for planning cover cropping strategies. the aim of this work was (i) to determine if different levels of N in the topsoil influence root depth (rD) and intensity of barley and vetch as sole crops or as an intercropped mixture and (ii) to test if the choice of a mixture or the N availability in the topsoil will influence the N uptake by deep roots. Methods In this study, we combined rhizotron studies with root extraction and species identification by microscopy with studies of growth, N uptake and 15 N uptake from deeper soil layers, for studying the root interactions of root growth and N foraging for barley (Hordeum vulgare l.) and vetch (Vicia sativa l.), frequently grown in mixtures as cover crops. N was added at 0 (N0), 50 (N1) and 150 (N2) kg N ha −1. the roots discrimination relying on the anatomical and morphological differences observed between dicots and monocots proved to be a reliable method providing valuable data for the analysis. Important Findings the intercrop and the barley attained slightly higher root intensity (rI) and rD than the vetch, with values around 150 crosses m −1 and 1.4 m, respectively, compared to 50 crosses m −1 and 0.9 m for the vetch. at deep soil layers, intercropping showed slightly larger rI values compared to the sole-cropped barley. the barley and the intercropping had larger root length density (rlD) values (200-600 m m −3) than the vetch (25-130) at 0.8-1.2 m depth. the topsoil N supply did not show a clear effect on the rI, rD or rlD; however, increasing topsoil N favored the proliferation of vetch roots in the intercropping at deep soil layers, with the barley:vetch root ratio ranging from 25 at N0 to 5 at N2. the N uptake of the barley was enhanced in the intercropping at the expense of the vetch (from ~100 mg plant −1 to 200). the intercropped barley roots took up more labeled nitrogen (0.6 mg 15 N plant −1) than the sole-cropped barley roots (0.3 mg 15 N plant −1) from deep layers.
Japan Agricultural Research Quarterly
Cereals and legumes that originated from the semi-arid tropics (SAT) are mainly grown in marginal soils with limited water and nutrient resources. Initial root system development is crucial for crop establishment in order to acquire these minimal resources. A comparative study of the root system morphology and of some physiological parameters at initial growth stages was carried out for 3 legumes: pigeonpea, chickpea and groundnut, and 3 cereals: sorghum, pearl millet and maize, the component crops of the semi-arid tropics. Considerable differences were observed for all the root morphological traits among the species. Among the legumes, chickpea produced few thick and lengthy laterals, while pigeonpea produced a high frequency of thinner laterals. However groundnut had a larger root system than the other 2 legumes. Among the cereals, maize formed a large root system followed by sorghum with a high frequency of laterals, while millet displayed a smaller root system with thin roots. The root respiration rate was significantly correlated with the N uptake activity. The legumes showed a higher efficiency of N uptake in terms of respiratory requirement. The transpiration rate showed a significant correlation with total N concentration in shoot, indicating that transpiration may be partly related to nitrogen flow to and accumulation in shoot in case of nitrate nitrogen as a sole nitrogen source. Morphological and physiological characters of the root system using rather simple indices were found to be better criteria for describing functional differences among crop species.
Plant and Soil, 2014
Background and aims Roots have morphological plasticity to adapt to heterogeneous nutrient distribution in soil, but little is known about crop differences in root plasticity. The objective of this study was to evaluate root morphological strategies of four crop species in response to soil zones enriched with different nutrients. Methods Four crop species that are common in intercropping systems [maize (Zea mays L.), wheat (Triticum aestivum L.), faba bean (Vicia faba L.), and chickpea (Cicer arietinum L.)] and have contrasting root morphological traits were grown for 45 days under uniform or localized nitrogen and phosphorus supply. Results For each species tested, the nutrient supply patterns had no effect on shoot biomass and specific root length. However, localized supply of ammonium plus phosphorus induced maize and wheat root proliferation in the nutrient-rich zone. Localized supply of ammonium alone suppressed the whole root growth of chickpea and maize, whereas localized phosphorus plus ammonium reversed (maize and chickpea) the negative effect of ammonium. The localized root proliferation of chickpea in a nutrient-rich zone did not increase the whole root length and root surface area. Faba bean had no significant response to localized nutrient supply. Conclusions The root morphological plasticity is influenced by nutrient-specific and species-specific responses, with the greater plasticity in graminaceous (eg. maize) than leguminous species (eg. faba bean and chickpea).
Corn Root Effects on the Nitrogen-Supplying Capacity of a Conditioned Soil
Agronomy Journal, 2002
that root presence increases decomposition rate of soil organic matter (Billes and Bottner, 1981; Fisher and Gosz, The design of sustainable N management strategies requires a 1986b; Cheng and Coleman, 1990). Others reported no better understanding of the processes influencing the ability of soils to supply N to a growing crop. Although commonly ignored, the change (Cuenca et al., 1983; Harmer and Alexander, release of C by plant roots may have a tremendous impact on soil 1985) or even a reduction in presence of plant roots organic matter turnover under certain soil conditions. The main objec-(Gadgil and Gadgil, 1975; Jenkinson, 1977, Sparling et tive of this study was to determine if living corn (Zea mays L.) roots al., 1982; Fisher and Gosz, 1986a; Staaf, 1988; Faber and would increase the N-supplying capacity of a soil with an enhanced Verhoef, 1991). mineralizable N pool. A rotation of corn-corn-soybean [Glycine max Reports on the influence of roots on N mineralization (L.) Merr.]-wheat (Triticum aestivum L.) in combination with cover have also been contradictory. A stimulatory effect of crops and the application of composted manure were used to increase plant roots on N mineralization has been observed in the mineralizable N pool. The N-supplying capacity of bare soil and some studies (Bartholomew and Clark, 1950; Molina soils planted with corn and wheat was calculated, and changes in N
Acta Physiologiae Plantarum, 2014
Root plasticity, a trait that can respond to different soil environments, may assist plants to scavenge the nutrients in heterogeneous soils. The objective of this paper is to understand the NH 4 ?-responsive root architectural changes in rice for better acquisition of Nitrogen (N). Using a root basket method, we examined the variation in root plasticity among diverse rice genotypes grown under hydroponics with different NH 4 ? concentrations. Significant variation in NH 4 ?-responsive root architectural changes was observed among rice genotypes studied. From the hydroponic study, five contrasting genotypes with distinct rooting patterns (mono and dimorphic) were selected based on the ratio of deeper roots and rooting pattern value. These distinct genotypes were evaluated in the field to identify the role of root architecture on plant performance under different N applications. Our field results revealed that the dimorphic rooting genotypes enhance the grain yield and shoot biomass under N-deficit conditions than monomorphic root genotypes. We conclude that root architectural plasticity and dimorphic rooting pattern would be helpful to enhance the nitrogen-acquisition efficiency under N-deficit conditions in rice. Keywords Dimorphic root system Á NH 4 ? response Á Nitrogen acquisition Á Nitrogen-deficient tolerance Á Root angle Á Ratio of deep rooting Abbreviation CSSL Chromosome segment substitution line DAS Day after sowing DAT Day after transplanting FP Farmer's practice N Nitrogen NAE Nitrogen acquisition efficiency NDT Nitrogen-deficit tolerance NUE Nitrogen-use efficiency NIL Near isogenic line P Phosphorus QTL Quantitative trait loci RDR Ratio of deep rooting RPV Rooting pattern value RSA Root system architecture Communicated by W. Filek.