Ammonium Uptake by Wheat Varieties Differing in Al Tolerance¹

Abstract

Previous studies have indicated that wheat (Triticum aestivum L.) cultivars absorbed nutrients more efficiently and induced a higher pH in the root zone than Al sensitive cultivars. In many of these studies, plants were screened on acid soils fertilized with NH4NO3 or in nutrient solutions containing up to 15% NH+4‐N. The research reported in this paper was conducted to determine the impact of NH+4‐N nutrition on the response of wheat varieties to Al and to define the relationship between plant‐induced pH changes in nutrient solutions and the utilization of NH+4‐N. ‘Atlas’ and ‘Redcoat’ wheat were grown in nutrient solutions that contained variable ratios of NO‐3‐N and NH+4‐N (100/0, 90/10, 80/20, and 70/30) with or without Al. In the absence of NH+4‐N and Al, both Atlas 66 (Al‐tolerant) and Redcoat (Al‐sensitive) wheats increased the pH of the nutrient solution at equal rates. With NH+4‐N (10 to 30% of the total N), Atlas 66 achieved a higher equilibrium pH than Redcoat. The Al treatments with NH+4‐N inhibited the uptake of NO‐3‐N, reduced the rate of pH increase and injured Redcoat more than Atlas. Aluminum injury was intensified by increasing the concentration of NH+4‐N in the solution. It was concluded that NH+4‐N uptake by Redcoat, with the coincident pH decrease and interference with NO‐3‐N metabolism, was a major determinent of sensitivity to Al.

Differential Aluminum Tolerance of High-Yielding, Early-Maturing Canadian Wheat Cultivars and Germplasm

“…Differences in leaf weight were also most Katepwa outperformed PTl4l at 300 and 400 pM, although leaf weights in the two cultivars were equally reduced at 700 and 1000 pM (Fig. 2) (1985, 1986, and 1987) (Foy et al 1974 In a number of species, Al tolerance has been associated with differences in ammonium and nitrate uptake (Fleming 1983;Taylor and Foy 1985c;Keltjens 1987;Keltjens and van Ulden 1987), high nitrate reductase activiq/ (Foy and Fleming 1982), and high protein content of grain (Mesdag et al 1970 …”

Task 3.4--IMPACTS of Cofiring Biomass With Fossil Fuels

“…In fact, the top growth was significantly increased by ammonia treatments and exceeded yields of other cultivars. Root yields, however, did not show a similar relationship (68).…”

Diferenças entre linhagens de milho cultivadas em solução nutritiva quanto à absorção e utilização de nitrogenio

“…Já é sabido que fontes de N influenciam a direção que o pH toma (BERNARDO et alii, 1982;CLARK, 1982;CLARK & BROWN, 1974;FLE-MING, 1983); ele aumenta para cerca de 7,0 ou 8,0 em soluções contendo apenas NO3 como fonte de N, e diminui para cerca de 4,0 em soluções contendo algum NH4. Entretanto, o pH aumentará se a proporção de NH 4 em relação ao NO" 3 for muito baixa (BERNARDO et alii, 1982;CLARK, 1982;FLEMING, 1983), ou quando o NHJ desaparece da solução, deixando apenas NO3 (BERNARDO et alii, 1982). Essas" variações ocorrem em vista da habilidade que as plantas têm de absorver íons da solução e liberar H + e OH" ou HCO3, num sistema de troca em resposta ao crescimento e metabolismo (HIAT & LEGGETT, 1974).…”