Showing papers by "Erik J. Veneklaas published in 2003"

Chickpea and white lupin rhizosphere carboxylates vary with soil properties and enhance phosphorus uptake

Abstract: Chickpea and white lupin roots are able to exude large amounts of carboxylates, but the resulting concentrations in the rhizosphere vary widely. We grew chickpea in pots in eleven different Western Australian soils, all with low phosphorus concentrations. While final plant mass varied more than two-fold and phosphorus content almost five-fold, there were only minor changes in root morphological traits that potentially enhance phosphorus uptake (e.g., the proportion of plant mass allocated to roots, or the length of roots per unit root mass). In contrast, the concentration of carboxylates (mainly malonate, citrate and malate, extracted using a 0.2 mM CaCl2 solution) varied ten-fold (averaging 2.3 µmol g −1 dry rhizosphere soil, approximately equivalent to a soil solution concentration of 23 mM). Plant phosphorus uptake was positively correlated with the concentration of carboxylates in the rhizosphere, and it was consistently higher in soils with a smaller capacity to sorb phosphorus. Phosphorus content was not correlated with bicarbonate-extractable phosphorus or any other single soil trait. These results suggest that exuded carboxylates increased the availability of phosphorus to the plant, however, the factors that affected root exudation rates are not known. When grown in the same six soils, three commonly used Western Australian chickpea cultivars had very similar rhizosphere carboxylate concentrations (extracted using a 0.2 mM CaCl2 solution), suggesting that there is little genetic variation for this trait in chickpea. Variation in the concentration of carboxylates in the rhizosphere of white lupin did not parallel that of chickpea across the six soils. However, in both species the proportion of citrate decreased and that of malate increased at lower soil pH. We conclude that patterns of variation in root exudates need to be understood to optimise the use of this trait in enhancing crop phosphorus uptake.

Introduction: Structure and functioning of cluster roots and plant responses to phosphate deficiency

Abstract: Introduction H. Lambers, et al. The biology of cluster roots and the acquisition of P from the rhizosphere. Structure, ecology and physiology of root clusters a review B.B. Lamont. The evolution of physiology and development in the cluster root: teaching an old dog new tricks? K.R. Skene. Organic acid behaviour in soils misconceptions and knowledge gaps D.L. Jones, et al. Origins of root-mediated pH changes in the rhizosphere and their responses to environmental constraints: A review P. Hinsinger, et al. Strategies to isolate transporters that facilitate organic anion efflux from plant roots P.R. Ryan, et al. Phosphate transport in plants F.W. Smith, et al. Development of the adhesive pad on climbing fig (Ficus punila) stems from clusters of adventitious roots E.P. Groot, et al. Pathways of carbon metabolism related to enhanced exudation of organic acids and acid phosphatase. Acclimation of white lupin to phosphorus deficiency involves enhanced expression of genes related to organic acid metabolism C. Uhde-Stone, et al. Phosphorus deficiency-induced modifications in citrate catabolism and in cystolic pH as related to citrate exudation in cluster roots of white lupin A. Kania. Secreted acid phosphatase is expressed in cluster roots of lupin in response to phosphorus deficiency J. Wasaki, et al. Effects of altered citrate synthase and isocitrate dehydrogenase expression on internal citrate concentrations and citrate efflux from tobacco (Nicotiana tabacum L.) roots E. Delhaize, et al. Characterization of NAPD-isocitrate dehydrogenase expression in a carrot mutant cell line with enhanced citrate excretion T. Kihara, et al. The influence of organic acid exudation and cluster roots on P and N acquisition. Do cluster roots of Hakea actities (Proteaceae) acquire complex organic nitrogen? S. Schmidt, et al. Lupinus luteus cv. Wodjil takes up more phosphorus and cadmium than Lupinus angustifolius cv. Kalya R.F. Brennan, M.D.A. Bolland. Chick pea and white lupin rhizosphere carboxylates vary with soil properties and enhance phosphorus uptake E.J. Veneklaas, et al. Role of phosphorus nutrition in development of cluster roots and release of carboxylates in soil-grown Lupinus albus J. Shen, et al. The influence of plant nutrition on plant growth and development of cluster roots. Effects of external phosphorus supply on internal phosphorus concentration and the initiation, growth and exudation of cluster roots in Hahea prostrata R. Br. M.W. Shane, et al. Differences in cluster root formation and carboxylate exudation in Lupinus albus L. under different nutrient deficiencies R. Liang, C. Li. Is Fe deficiency rather than P deficiency the cause of cluster root formation in Casuarina species? E.H. Zaid, et al. The formation, morphology and anatomy of cluster root of Lupinus albus L. as dependent on soil type and phosphorus supply C.S. Peek, et al. Localized supply of phosphorus induces root morphological and architectural changes of rice in split and stratified soil cultures Y. He, et al. Interaction of nitrogen and phosphorus nutrition in determining growth C.C.de Groot, et al. Implications of root architecture, root-soil interactions and mycorrhiza on plant P nutrition. Phosphorus acquisition from soil by white lupin (Lupinus albus L.) and soybean (Glycine max L.) species with contrasting root development M. Watt, J.R. Evans. Plantago lanceolata L. and Rumex acetosella L. differ in their utilisation of soil phosphorus fractions A.-M. Fransson, et al. Chickpea facilitates phosphorus uptake by intercropped wheat from an organic phosphorus source L. Li, et al. Using competitive and facilitative interactions in intercropping systems enhances crop productivity and nutrient-use efficiency F. Zhang, L. Li. Phosphorus uptake by a community of arbuscular mycorrhizal fungi in jarrah forest M.Z. Solaiman, L.K. Abbott. Relationships between cluster root-bearing taxa and laterite across landscapes in southwest Western Australia: an approach using airborne radiometric and digital elevation models W.H. Verboom, J.S. Pate. Volume contents. Author index.

Seasonal patterns in water use and leaf turnover of different plant functional types in a species-rich woodland, south-western Australia

Abstract: Woodlands in south-western Australia are evergreen and transpire throughout the year despite the long, hot and dry summers of the Mediterranean climate. Results from a case study in a species-rich Banksia woodland are used to discuss the ecological and physiological properties that appear to be essential features of this and similar communities. Tree, shrub and perennial herbaceous species with long-lived leaves dominate the community, whereas winter-green herbaceous species with short-lived leaves constitute a minor group. The total leaf area index is therefore reasonably constant in all seasons. Leaf area index is low and canopies are open, causing good coupling between the vegetation and the atmosphere, and making stomatal control an effective regulator of transpiration. Mean maximum (winter) stomatal conductances were high at approximately 300 mmol m−2 s−1. Deep-rootedness allows the dominant species to access soil moisture throughout the unsaturated zone, and down to the capillary fringe of the saturated zone. Shrubs and herbs with shallow roots experience greater drought stress during summer. Rates of community evapotranspiration are limited by leaf area index in the wet season, and further reduced by stomatal closure in the dry season. Deep-rooted plants appear to decrease their stomatal conductance before the development of severe drought stress. Such conservative behaviour, possibly related to plant hydraulic constraints, is a contributing factor to the limited seasonality in community water use.