Root:shoot ratios of old and modern, tall and semi-dwarf wheats in a mediterranean environment
- 983 Downloads
A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines for Rht dwarfing genes.
Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased.
The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns.
At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUEgr) increased from old to modern varieties.
The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUEgr of modern compared to old varieties.
Key wordsharvest index old and modern wheats root:shoot ratio Rht genes root dry matter root length water use efficiency
Unable to display preview. Download preview PDF.
- Austin R B, Bingham J, Blackwell R D, Evans L T, Ford M A, Morgan C L and Taylor M 1980 Genetic improvements in winter wheat yields since 1900 and associated physiological changes. J. Agric. Sci., Camb. 94, 675–689.Google Scholar
- Burns I G 1980 Influence of the spatial distribution of nitrate on the uptake of N by plants: A review and a model for rooting depth. J. Soil Sci. 31, 155–173.Google Scholar
- Clarkson D T 1985 Factors affecting mineral nutrient acquisition by plants. Annu. Rev. Plant Physiol. 36, 77–115.Google Scholar
- Cholick F A, Welsh J R and Cole C V 1977 Rooting patterns of semi-dwarf and tall winter wheat cultivars under dryland field conditions. Crop Sci. 17, 637–639.Google Scholar
- Gale M D and Youssefian S 1985 Dwarfing genes in wheat. In Progress in Plant Breeding-1. Ed. G E Russell. pp 1–35. Butterworths, London.Google Scholar
- Gregory P J, McGowan M, Biscoe P V and Hunter B 1978 Water relations of winter wheat. 1. Growth of root system. J. Agric. Sci., Camb. 91, 91–102.Google Scholar
- Hamblin A P and Tennant D 1987 Root length density and water uptake in cereals and grain legumes: How well are they correlated? Aust. J. Agric. Res. 38, 513–527.Google Scholar
- Hamblin A P, Tennant D and Perry M W 1990 The cost of living in stressful environments: Dry matter partitioning with changes in seasonal supply of water and nitrogen to dryland wheat. Plant and Soil. (In press)Google Scholar
- Hurd E A 1974 Phenotype and drought tolerance in wheat. Agric. Meterol. 14, 39–55.Google Scholar
- Jordan W R and Miller R F 1980 Genetic variability in sorghum root systems: implications for drought tolerance. In Adaptation of Plants to Water and High Temperature Stresses. Eds. N C Turner and P J Kramer. pp 383–399. Wiley Interscience. New York, NY.Google Scholar
- Klepper B, Belford R K and Rickman R W 1984 Root and shoot development in winter wheat. Agron. J. 76, 117–122.Google Scholar
- Kirby E J M, Siddique K H M, Perry M W, Kaesehagen D and Stern W R 1989 Variation in spikelet initiation and ear development of old and modern Australian wheat varieties. Field Crops Res. 20, 113–128.Google Scholar
- Loss S P, Kirby E J M, Siddique K H M and Perry M W 1989 Grain growth and development of old and modern Australian wheats. Field Crops Res. 21, 131–146.Google Scholar
- Lupton F G H, Oliver R H, Ellis F B, Barnes B T, Howse K R, Welbank P J and Taylor P J 1974 Root and shoot growth of semi-dwarf and tall winter wheats. Ann. Appl. Biol. 77, 129–144.Google Scholar
- Northcote K H 1979 A factual key for the recognition of Australian soils. Fourth edition, Rellim Technical Publication. Glenside, South Australia.Google Scholar
- O'Toole J C and Bland W L 1987 Genotypic variation in crop plant root systems. Adv. Agron. 41, 91–145.Google Scholar
- Passioura J B 1976 Physiology of grain yield in wheat growing on stored water. Aust. J. Plant Physiol. 3, 559–565.Google Scholar
- Passioura J B 1983 Roots and drought resistance. Agric. Water Manage. 7, 265–280.Google Scholar
- Passioura J B 1986 Resistance to drought and salinity: Avenues for improvement. Aust. J. Plant Physiol. 13: 191–201.Google Scholar
- Perry M W and D'Antuono M F 1989 Yield improvement and associated characteristics of some Australian spring wheats introduced between 1860 and 1982. Aust. J. Agric. Res. 40, 457–472.Google Scholar
- Richards R A and Passioura J B 1981b Seminal root morphology and water use of wheat. II. Genetic variation. Crop Sci. 21, 253–255.Google Scholar
- Schultz J E 1974 Root development of wheat at the flowering stage under different cultural practices. Agric. Rec. 1, 12–17.Google Scholar
- Siddique K H M, Kirby E J M and Perry M W 1989a Ear: stem ratio in old and modern wheat varieties: Relationship with improvement in number of grains per ear and yield. Field Crops Res. 21, 59–78.Google Scholar
- Siddique K H M, Belford R K, Perry M W and Tennant D 1989b Growth, development and light interception of old and modern wheat cultivars in a mediterranean-type environment. Aust. J. Agric. Res. 40, 473–487.Google Scholar
- Siddique K H M, Tennant D, Perry M W and Belford R K 1989c Water use and water-use efficiency of old and modern wheat cultivars in a mediterranean-type environment. Aust. J. Agric. Res. (Submitted.)Google Scholar
- Smucker A J M 1984 Carbon utilization and losses by plant root systems. In Roots, Nutrient and Water Influx, and Plant Growth. pp 27–46. A.S.A. Special Publication No. 49. SSSA-CSSA-ASA Madison, WI.Google Scholar
- Soil Survey Staff 1975 Soil taxonomy, a basic system of soil classification for making and interpreting soil survey. U.S.D.A. Agric. Handb. No. 436, U.S. Govt. Printing Office, Washington, DC.Google Scholar
- Subbiah B V, Katyal J C, Narrasimhan R L and Dakshinamurti C 1968 Preliminary investigations on root distribution of high yielding wheat varieties. Intern. J. Appl. Rad. Isot. 19, 385–390.Google Scholar
- Tennant D 1975 A test of a modified line-intersect method of estimating root length. J. Ecol. 63, 995–1001.Google Scholar