Seeds are a
source of organic (carbon, C) and mineral (nitrogen, N and phosphorus, P)
nutrients for the growing seedling. There is much information on
seed mass and N and P contents, and the relationship between these and seedling
mass. Within the world’s temperate regions, these collectively show that N and
P concentrations remain constant or rise with increase in seed mass and that
seeds are larger and more nutrient-enriched in poorer soils. Seed N and P were
more important than seed C in accounting for seedling mass in 85% of studies we
assessed. In nutrient- and water-limited environments that are not
light-limited, large seeds routinely provision the seedling with N and P that
enhance C-fixation and thus general growth in the first wet season.
This system is so efficient that growth response to soil nutrients may be
negligible in first-year seedlings arising from seeds >15 mg mass, N
content >5 mg and P content >1.6 mg. The elongating
taproot system absorbs nutrients and maintains water uptake as soil water
retreats, enhancing the chances of survival in the first dry season. We outline
an interpretative scenario for the special role of large seeds (>15 mg) in nutrient-
and water-limited environments that recognizes the critical role of N and P for
photosynthesis in ensuring sufficient C-supply to the rapidly descending roots
for effective drought-avoidance by the young plant.
W. J. Ashcroft and D. R. Murray, “The Dual Functions of the Cotyledons of Acacia iteaphylla F. Muell. (Mimosoideae),” Australian Journal of Botany, Vol. 27, No. 4, 1979, pp. 343-352. doi:10.1071/BT9790343
B. B. Lamont and P. K Groom, “Green Cotyledons of Two Hakea Species Control Seedling Mass and Morphology by Supplying Mineral Nutrients Rather than Organic Compounds,” New Phytologist, Vol. 153, No. 1, 2002, pp. 101-110.
M. Fenner, “Relationships between Seed Weight, Ash Content and Seedling Growth in Twenty-Four Species of Compositae,” New Phytologist, Vol. 95, No. 4, 1983, pp. 697-706. doi:10.1111/j.1469-8137.1983.tb03533.x
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D. R. Mulligan and J. W. Patrick, “Carbon and Phosphorus Assimilation and Deployment in Eucalyptus piluaris Smith Seedlings with Special Reference to the Role of the Cotyledons,” Australian Journal of Botany, Vol. 33, No. 5, 1985, pp. 485-496. doi:10.1071/BT9850485
P. Milberg and B. B. Lamont, “Seed/Cotyledon Size and Nutrient Content Play a Major Role in Early Performance of Species on Nutrient-Poor Soils,” New Phytologist, Vol. 137, No. 4, 1997, pp. 665-672.
K. J. Esler, R. M. Cowling, E. T. F. Witkowski and P. J. Mustart, “Reproductive Traits and Accumulation of Nitrogen and Phosphorus during the Development of Fruits of Protea compacta R. Br. (calcifuge) and Protea obtusifolia Buek. ex Meisn. (calcicole),” New Phytologist, Vol. 112, No. 1, 1989, pp. 109-115.
W. G. Lee and M. Fenner, “Mineral Nutrient Allocation in Seeds and Shoots of Twelve Chionochloa Species in Relation to Soil Fertility,” Journal of Ecology, Vol. 77, No. 3, 1989, pp. 704-716. doi:10.2307/2260980
P. Milberg, M. A. Pérez-Fernández and B. B. Lamont, “Seedling Growth Response to Added Nutrients Depends on Seed Size in Three Woody Genera,” Journal of Ecology, Vol. 86, No. 4, 1998, pp. 624-632.
W. D. Stock, J. S. Pate and J. Delfs, “Influence of Seed Size and Quality on Seedling Development under Low Nutrient Conditions in Five Australian and South African Members of the Proteaceae,” Journal of Ecology, Vol. 78, No. 4, 1990, pp. 1005-1020. doi:10.2307/2260949
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J. R. Withers, “Studies on the Status of Unburnt Eucalyptus Woodland at Ocean Grove, Victoria. II. The Differential Seedling Establishment of Eucalyptus ovata Labill. and Casuarina littoralis Salisb.,” Australian Journal of Botany, Vol. 26, No. 4, 1978, pp. 465-483.
P. J. Hocking, “The Mineral Nutrition of Developing Fruits of Kennedia prostrata R. Br. ex Ait., a Perennial Australian Legume,” Australian Journal of Botany, Vol. 28, No. 6, 1980, pp. 633-644. doi:10.1071/BT9800633
P. J. Hocking, “The Nutrition of Fruits of Two Proteaceous Shrubs, Grevillea wilsonii and Hakea undulata, from South-Western Australia,” Australian Journal of Botany, Vol. 30, No. 2, 1982, pp. 219-230.
J. Kuo, P. J. Hocking and J. S. Pate, “Nutrient Reserves in Seeds of Selected Proteaceous Species from South-Western Australia,” Australian Journal of Botany, Vol. 30, No. 2, 1982, pp. 231-249. doi:10.1071/BT9820231
R. H. Groves, P. J. Hocking and A. McMahon, “Distribution of Biomass, Nitrogen, Phosphorus and Other Nutrients in Banksia marginata and B. ornata Shoots of Different Ages after Fire,” Australian Journal of Botany, Vol. 34, No. 6, 1986, pp. 709-725. doi:10.1071/BT9860709
P. J. Hocking, “Mineral Nutrient Composition of Leaves and Fruit of Selected Species of Grevillea from South- Western Australia, with Special Reference to Grevillea leucopteris Meissn.,” Australian Journal of Botany, Vol. 34, No. 2, 1986, pp. 155-164. doi:10.1071/BT9860155
R. H. Groves and K. Keraitis, “Survival and Growth of Seedlings of Three Sclerophyll Species at High Levels of Phosphorus and Nitrogen,” Australian Journal of Botany, Vol. 24, No. 6, 1976, pp. 681-690.
E. T. F. Witkowski, “Nutrient Limitation of Inflorescence and Seed Production in Leucospermum parile (Proteaceae) in the Cape Fynbos,” Journal of Applied Ecology, Vol. 27, No. 1, 1990, pp. 148-158. doi:10.2307/2403574
E. T. F. Witkowski and B. B. Lamont, “Disproportionate Allocation of Mineral Nutrients and Carbon between Vegetative and Reproductive Structures in Banksia hookeriana,” Oecologia, Vol. 105, No. 1, 1996, pp. 38-42.
M. L. Henery and M. Westoby, “Seed Mass and Seed Nutrient Content as Predictors of Seed Output Variation between Species,” Oikos, Vol. 92, No. 3, 2001, pp. 479-490.
M. D. Denton, E. J. Veneklaas, F. M. Freimoser and H. Lambers, “Banksia Species (Proteaceae) from Severely Phosphorus-Impoverished Soils Exhibit Extreme Efficiency in the Use and Re-Mobilisation of Phosphorus,” Plant, Cell and Environment, Vol. 30, No. 12, 2007, pp. 1557-1565. doi:10.1111/j.1365-3040.2007.01733.x
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D. T. Mitchell and N. Allsopp, “Changes in the Phosphorus Composition of Seeds of Hakea sericea (Proteaceae) during Germination under Low Phosphorus Conditions,” New Phytologist, Vol. 96, No. 2, 1984, pp. 239-247. doi:10.1111/j.1469-8137.1984.tb03560.x
D. M. Richardson, B. W. van Wilgen and D. T. Mitchell, “Aspects of the Reproductive Ecology of Four Australian Hakea Species (Proteaceae) in South Africa,” Oecologia, Vol. 71, No. 3, 1987, pp. 345-354.
N. J. Hannon, “The Status of Nitrogen in the Hawkesbury Sandstone Soils and Their Plant Communities in the Sydney District. I. The Significance and Level of Nitrogen,” Proceedings of the Linnaean Society of New South Wales, 1956, pp. 119-143.
M. B. Richards and B. B. Lamont, “Post-Fire Mortality and Water Relations of Three Congeneric Shrub Species Under Extreme Water Stress—A Trade-Off with Fecundity?” Oecologia, Vol. 107, No. 1, 1996, pp. 53-60.
R. L. Specht, P. W. Rundel, W. E. Westman, P. C. Catling, J. D. Majer and P. Greenslade, “Mediterranean-Type Ecosystems. A Data Source Book,” Kluwer Academic Publishers, Dordrecht, 1988.
R. M. Cowling, J. Ojeda, B. B. Lamont, P. W. Rundel, and R. Lechmere-Oertel, “Rainfall Reliability, a Neglected Factor in Explaining Convergence and Divergence of Plant Traits in Fire-Prone Mediterranean-Climate Ecosystems,” Global Ecology and Biogeography, Vol. 14, No. 6, 2005, pp. 509-519.
P. K. Groom and B. B. Lamont, “Reproductive Ecology of Non-Sprouting and Re-Sprouting Hakea Species (Proteaceae) in Southwestern Australia,” In: S. D. Hopper, M. Harvey, J. Chappill and A. S. George, Eds., Gondwanan Heritage: Evolution and Conservation of the Western Australian Biota, Surrey Beatty & Sons, Chipping Norton, 2006, pp. 239-248.
M. E. Hanley, P. K. Cordier, O. May and C. K. Kelly, “Seed Size and Seedling Growth: Differential Response of Australian and British Fabaceae to Nutrient Limitation,” New Phytologist, Vol. 174, No. 2, 2007, pp. 381-388. doi:10.1111/j.1469-8137.2007.02003.x
M. R. Leishman and M. Westoby, “The Role of Seed Size in Seedling Establishment in Dry Soil Conditions: Experimental Evidence from Semi-Arid Species,” Journal of Ecology, Vol. 82, No. 2, 1994, pp. 249-258.
N. J. Enright and B. B. Lamont, “Survival, Growth and Water Relations of Banksia Seedlings in a Sand Mine Rehabilitation Site and Adjacent Scrub-Heath Sites,” Journal of Applied Ecology, Vol. 29, No. 3, 1992, pp. 663-671. doi:10.2307/2404474
W. Schütz, P. Milberg and B. B. Lamont, “Germination Requirements and Seedling Responses to Water Availability and Soil Type in Four Eucalyptus Species,” Acta Oecologica, Vol. 23, No. 1, 2002, pp. 23-30.
B. B. Lamont, P. K. Groom, M. B. Richards and E. T. F. Witkowski, “Recovery of Banksia and Hakea Communities after Fire—The Role of Species Identity and Functional Attributes,” Diversity and Distribution, Vol. 5, No. 1-2, 1999, pp. 15-26.
P. K. Groom, B. B. Lamont and I. W. Wright, “Lottery (Stochastic) and Non-Lottery (Biological) Processes Explain Recruitment Patterns Among Eight Congeneric Shrub Species in Southwestern Australia,” Journal of Mediterranean Ecology, Vol. 2, No. 1, 2001, pp. 1-14.
H. Saneoka, K. Fujita and S. Ogata, “Effect of Phosphorus on Drought Tolerance in Chloris gayana Kunth and Coix lacryma L,” Soil Science and Plant Nutrition, Vol. 36, No. 2, 1990, pp. 267-274.
R. B. Benard and C. A. Toft, “Effect of Seed Size on Seedling Performance in a Long-Lived Desert Perennial Shrub (Ericameria nauseosa: Asteraceae),” International Journal of Plant Science, Vol. 168, No. 7, 2007, pp. 1027-1033. doi:10.1086/518942
C. E. Evans and J. R. Etherington, “The Effect of Soil Water Potential on Seedling Growth of Some British Plants,” New Phytologist, Vol. 118, No. 4, 1991, pp. 571-579. doi:10.1111/j.1469-8137.1991.tb00998.x
D. P. Rokich, K. A. Meney, K. W, Dixon and K. Sivasithamparam, “The Impact of Soil Disturbance on Root Development in Woodland Communities in Western Australia,” Australian Journal of Botany, Vol. 49, No. 2, 2001, pp. 169-183. doi:10.1071/BT00015
F. M. Padilla and F. I. Pugnaire, “Rooting Depth and Soil Moisture Control Mediterranean Woody Seedling Survival during Drought,” Functional Ecology, Vol. 21, No. 3, 2007, pp. 489-495.
B. B. Lamont, “Mineral Nutrient Relations in Mediterranean Regions of California, Chile and South Africa,” In: M. T. Arroya, P. H. Zedler and M. D. Fox, Eds., Ecology and Biogeography of Mediterranean Ecosystems in Chile, California and Australia, Springer Verlag, New York, 1995, pp. 211-235. doi:10.1007/978-1-4612-2490-7_9