Dietary fibre, sugar, starch and amino acid content of kale, ryegrass and seed of rape and field beans as influenced by S- and N-fertilization.

In pot experiments, S-deficiency decreased the seed weight of rape from 4.30 to 2.44 g/1000 seeds at highest N-level. N/S ratios varied from 5.8 to 45.0 and from 3.7 to 21.6 in ryegrass and kale. S-deficiency tended to decrease the fat(oil) content. In kale and ryegrass, it was increased by N-applications, but decreased in rape. S-deficiency had very little effect on starch and sugar content, whereas N-deficiency in kale greatly increased starch (eightfold) and sugar content. Soluble (SDF) and insoluble dietary fibre (IDF) content was hardly affected by S-deficiency. In kale and ryegrass N-deficiency decreased SDF-content, but increased IDF-content. Cystine and methionine concentrations (g/16 g N) were affected by S-deficiency, most strongly at high N-levels, where decreases in kale, ryegrass, rape and field beans amounted to respectively 18, 39, 40 and 17% for cystine and 27, 59, 24 and 6% for methionine. Also, lysine, threonine and tryptophan were decreased. S-deficiency increased aspartic acid (asparagine) content of ryegrass (fourfold) and of arginine in rape and kale. In N-balance trials with rats, S-deficiency reduced the biological value (BV) of the protein of kale from 65 to 40 and of field bean seed from 70 to 61. Corresponding decreases in digestible energy (DE) were from 56 to 48 and from 82 to 78, respectively.