Effects of nitrogen and potassium fertilisers on contents of carbohydrates and free amino acids in Italian ryegrass. II. Changes in the composition of the non‐protein nitrogen fraction and the distribution of individual amino acids

Abstract

Italian ryegrass (Lolium multiflorum) S22, grown in a greenhouse in K-deficient soil in pots, was given 40,SO and 160 mg of N/kg of soil (as ammonium nitrate) and 0, 60, 120 and 240 mg of K/kg of soil (as potassium chloride). In grass grown without added K, increasing N fertiliser increased the concentrations of total N, non-protein-N, ammonium-N, nitrate-N, free amino acids, amides and amines. With adequate K fertiliser all these N fractions decreased.The percentage distribution of N in the free amino-acid pool varied with the amount of N and K given. Without K fertiliser, increasing N had no consistent effect on most amino acids and amides, although it decreased the percentages of alanine and ethanolamine. Increasing K had relatively little effect on the percentage distribution in grass given the two smaller amounts of N. However, in the grass given the largest amount of N, it increased the percentage of most amino acids, especially alanine and 4-amino-n-butyric acid, and decreased glutamine and asparagine. p-Alanine was found only in K-deficient plants.The effect of K in relation to N metabolism and the nutritive value of herbage is briefly discussed.

Herbage Yield and Chemical Composition of Switchgrass as Affected by N, S, and K Fertilization1

“…Adams and Sheard (1) have reported a negative relationship between concentrations of K and S in the herbage of orchardgrass. Likewise, other researchers (6,7,9) have reported a negative correlation between K fertilization and total N concentration in herbage tissue. It is possible that fertilization with K may have an inhibitory effect on N and S uptake.…”

“…They and other researchers (2,14) found that deficiencies of S increased the concentration of total N in plant herbage. Several researchers (6,7,9) also have reported a negative relationship between K fertilization and total N concentration in herbage.…”

Free and Total Amino Acid Composition of Edible Parts of Beans, Kale, Spinach, Cauliflower and Potatoes as Influenced by Nitrogen Fertilisation and Phosphorus and Potassium Deficiency

“…Printed in Great Britain studied (Nowakowski and Byers 1972;Rendig 1984). Their importance for all aspects of plant metabolism is generally recognized and metabolic studies of different N-compounds of plants abound (Miflin and Lea 1977).…”

Effect of grazing management on herbage protein concentration, milk production and nitrogen excretion of dairy cows in mid‐lactation

“…In spring, nitrate losses are compounded by both high rainfall and high fertilizer‐N use. Practices that rely on N fertilizers to promote early season pasture production are also likely to increase the solubility by increasing the proportion of non‐protein N in the herbage (Goswami and Willcox, ; Nowakowski and Byers, ). While increasing the proportion of rumen undegradable protein (RUP) can reduce urinary N losses (Castillo et al ., ), recent studies on plant N fractions have shown little effect of pasture management on altering the proportion of RUP (Hoekstra et al ., ; Bryant et al ., ).…”