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Publication Date
1981
Description
Although native grasses establish readily on the cracking black clay soils of northwestern New South Wales, it has proven difficult to establish introduced summer grasses. Young grass seedlings were examined to see if morphological differences exist that may explain their differing capacities for establishment. It has been shown that relative differences in the primary and secondary root growth of vario1-,s species can have important effects on the agronomic characteristics of those species. Low soil moisture conditions near the soil surface will restrict greatly or possibly even prevent the growth of secondary roots of young aeedlings. It is well known that the surface layers of this particular soil type dry very :rapidly following :rain. Seedlings of four native and four introduced grasses were grown under favorable conditions, then destructively sampled 3, 4, and 5 weeks after planting. A number of morphological characteristics were examined, including weight of top growth, weight of root growth, length, and weight of primary and secondary roots. There was considerable variation among the species in respect to both the amount and type of growth. Generalizing, native species tended to have smaller seedlings, lower ratios of weight of top growth to weight of roo, growth, and higher ratios of weight of primary root to weight of secondary root. Given that secondary root growth is likely to be restricted by soil surface drying, it would seem the native grasses overcome this problem by having a better-developed primary root system and a less well-developed secondary root system. Also, they have a lower ratio of top growth to root growth, so that the roots should be better able to supply the plant during periods of moisture stress. Results indicate that the selection of introduced species for use on this soil type should be made on the basis of well-developed primary root systems and a low ratio of top growth to root growth.
Citation
Watt, L A., "Establishment of Grasses on Cracking Clay Soils: Seedling Morphology Characteristics" (1981). IGC Proceedings (1981-2023). 10.
(URL: https://uknowledge.uky.edu/igc/1981/section7/10)
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Archival
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Establishment of Grasses on Cracking Clay Soils: Seedling Morphology Characteristics
Although native grasses establish readily on the cracking black clay soils of northwestern New South Wales, it has proven difficult to establish introduced summer grasses. Young grass seedlings were examined to see if morphological differences exist that may explain their differing capacities for establishment. It has been shown that relative differences in the primary and secondary root growth of vario1-,s species can have important effects on the agronomic characteristics of those species. Low soil moisture conditions near the soil surface will restrict greatly or possibly even prevent the growth of secondary roots of young aeedlings. It is well known that the surface layers of this particular soil type dry very :rapidly following :rain. Seedlings of four native and four introduced grasses were grown under favorable conditions, then destructively sampled 3, 4, and 5 weeks after planting. A number of morphological characteristics were examined, including weight of top growth, weight of root growth, length, and weight of primary and secondary roots. There was considerable variation among the species in respect to both the amount and type of growth. Generalizing, native species tended to have smaller seedlings, lower ratios of weight of top growth to weight of roo, growth, and higher ratios of weight of primary root to weight of secondary root. Given that secondary root growth is likely to be restricted by soil surface drying, it would seem the native grasses overcome this problem by having a better-developed primary root system and a less well-developed secondary root system. Also, they have a lower ratio of top growth to root growth, so that the roots should be better able to supply the plant during periods of moisture stress. Results indicate that the selection of introduced species for use on this soil type should be made on the basis of well-developed primary root systems and a low ratio of top growth to root growth.
