Sodium Nutrition of Pasture Plants Ii. Effect of Sodium Chloride on Growth, Chemical Composition and the Reduction of Nitrate Nitrogen

Abstract

The effect of increasing concentrations of sodium chloride in the root zone on growth, chemical composition and nitrate reductase activity of perennial ryegrass and timothy was investigated in a glasshouse pot experiment. For ryegrass, a natrophile, sodium chloride had little effect on growth, whereas for timothy, a natrophobe, growth was severely depressed by comparatively low concentrations of salt. The result also indicate that translocation of sodium into the leaves of timothy took place readily only after the accumulation sites in the roots and lower stems had been saturated with this element. This means that relatively large quantities of sodium chloride were needed to produce concentrations of sodium in the leaves of timothy as high as those normally found in the leaves of ryegrass. Sodium chloride increased the uptake of total and nitrate‐nitrogen but, in contrast, depressed the uptake of potassium by ryegrass and timothy It was therefore concluded that the marked stimulation by sodium chloride of nitrate reductase activity in both species was more the result of the increased uptake of nitrates than a specific effect of this salt on the enzyme. The practical implications of these results are discussed.

Influence of sodium and potassium fertilization on the sodium concentration of timothy

“…It has indeed been observed that the Na concentration of timothy increases when plants age (Jarvis 1982). The same phenomenon, in a weaker form, has been observed with perennial ryegrass, meadow fescue and cocksfoot (Rinne et al 1974, Smith et al 1980.…”

“…Introduction mals, and forage should contain Na 1.8-2g kg 1 of dry matter to supply milking cows with sufficient Na (NJF 1975, Smith and Middleton 1978, Horn 1988. Thus, there is a big difference between the requirement of cattle and the supply of Na from farm-produced fodder in Finland, and it has to be compensated with mineral supplements.…”

“…The equivalent ratio K/(Ca+Mg) has been used as a criterion for forage grass quality; values below 2.2 are desired (Ettala and Kossila 1979). Substitution ofNa for K in plants has been shown to increase their Mg concentration (Nowakowski et al 1974, Smith 1974, Smith et al 1980, Mundy 1983. Sodium application can thus improve the feeding quality of herbage by increasing the concentration of Na and Mg and possibly by lowering the concentration of K. Elevated Na concentration of herbage may also increase the intake of fodder by cows (Horn 1988, Chiy et al 1993, resulting in an increase in liveweight gain and in milk production (Chiy et al 1993).…”

Comparison of Nutrient Solutions for Growth of Plants in Sand Culture

“…The temperature was not allowed to rise above 5 °C during the extraction and determination of chlorophyll. Harvested tissue not used for chlorophyll estimations was dried at 90 ''C, weighed and analysed for major and minor elennents by the procedures summarized by Smith, Middleton and Edmonds (1980). Iron concentrations in solution were: (Fej) those recommended in the original publications (see Table 1); (Fe^) modified so that maize was grown with 10 /tg iron ml"* and ryegrass and white clover with 3/ig iron Electrical conductivity and pH were measured on the solution surrounding the roots just before the final harvest of the plants.…”

Effets de NaCl et de Na2SO4 sur les bilans des échanges ioniques en milieux NO-3/NH+4 et sur les coûts énergétiques de la croissance chez l'orge (Hordeum vulgare L)

“…Elles concernent généralement la première (Strogonov, 1964 ;Helal et Mengel, 1979 ;Smith et al, 1980 ;Lucque et Bingham, 1981 ;Aslam et al, 1984). À faible dose, les sels ont peu d'effet sur l'alimentation nitrique; mais à forte dose, ils inhibent l'absorption et le transport de NO -3 , la réduction étant la fonction la moins touchée (Lucque et Bingham, 1981;Aslam et al, 1984).…”