Nutrient distribution in root zones. III. Further studies of the effects of phosphorus distribution on corn and wheat

Abstract

A technique incorporating several improvements over previous approaches was used to measure responses of plants to several patterns of phosphorus (P) distribution throughout the root zone. Nutrient solutions were moved in and out of three discrete root zones separated by Permagum barriers. Movement was accomplished by an automatic elevating platform which periodically raised solution reservoirs from a resting position to a height sufficient for flushing each compartment with nutrient solution.Root weight increases were observed in those regions where P was present in the root zone. The lower the zone of P supply, the more diminished was the response. These findings were interpreted in terms of sugar translocation and immobilization within the roots. The P and potassium contents of the roots were unaffected by P distribution patterns but calcium and magnesium contents were markedly increased in older tissues where P was present in the ambient solution. These data supported the concept that internally translocated P and externally absorbed P have apparently differing effects at a given root site because the former does not reach the site in the same quantity as the latter. P uptake data suggested that ions absorbed at one point on a root may depress the absorption at a lower point. No significant treatment effects on shoot growth or cation and N contents of shoots were observed. The P content of the shoots, however, was in proportion to the amount of root surface in contact with ambient P.

The responses of plants to non‐uniform supplies of nutrients

“…First, species and treatments were selected from the Appendix for which measurements of all the variates were available. These were the experiments on Glycine max (Borkert & Barber, 1983), Hordeum vulgare (Drew, 1975;Drew & Saker, 1975, 1978, Lactuca sativa (Burns, 1991), Oryza sativa (Gile & Carrero, 1917), Plantago lanceolata, P. major and P. media (de Jager & Posno, 1979) and Zea mays (Gile & Carrero, 1917;McClure, 1972;Stryker et al, 1974;Anghmoni & Barber, 1980;de Jager 1982de Jager , 1984. Data for the responses of some species to different nutrients were treated separately.…”

Calcium‐enhanced phosphorus toxicity in calcifuge and soil‐indifferent Proteaceae along the Jurien Bay chronosequence

“…Phosphorus (P) toxicity has been studied in a range of plant species, including crops and P‐sensitive species from severely P‐impoverished habitats (Asher & Loneragan, ; Bhatti & Loneragan, ; Robson et al ., ; Grundon, ; McClure, ; Groves & Keraitis, ; Nichols & Beardsell, ; Loneragan et al ., ; Shane et al ., ; Hawkins et al ., ; de Campos et al ., ). Typical P‐toxicity symptoms include leaf chlorosis/necrosis, reduced biomass, and early leaf senescence (Grundon, ; Groves & Keraitis, ; Nichols & Beardsell, ; Webb & Loneragan, ; Shane et al ., ,b; Parks et al ., ; Hawkins et al ., ).…”

“…Other nutrients influence the severity of P toxicity (Robson et al, 1970;Grundon, 1972;McClure, 1972;Nichols & Beardsell, 1981). Potassium (K) and nitrogen (N) generally alleviate the severity of P toxicity, whilst calcium (Ca) increases it (Caenhanced P toxicity).…”

“…Potassium (K) and nitrogen (N) generally alleviate the severity of P toxicity, whilst calcium (Ca) increases it (Caenhanced P toxicity). Grundon (1972) proposed that Ca may act alone in reducing growth in P-sensitive species, whilst Nichols & Beardsell (1981) speculated that Ca stimulates P uptake in Grevillea cv 'Poorinda Firebird' (Proteaceae), increasing the severity of P toxicity, as shown for annual legumes, corn, and wheat (Robson et al, 1970;McClure, 1972). Alternatively, Caenhanced P toxicity may be related to the cell-specific allocation of Ca and P, which must be regulated to avoid deleterious precipitation of Ca phosphates (McLaughlin & Wimmer, 1999;White & Broadley, 2003;Conn & Gilliham, 2010).…”

Crops & Soils Volume 42, Issue 6, 2009

“…Earn 1 CEU in Nutrient Management them (McClure, 1972;Passioura and Wetselaar, 1972;Strong and Soper, 1973;Anghinoni and Barber, 1980a;Borkert and Barber, 1985). Such effects have not been observed for K. Additionally, plants benefit from having an ammonium form of N applied in combination with P in these bands.…”