Glucosinolate content and amino acid composition of rapeseed (Brassica napus) meal as affected by sulphur and nitrogen nutrition

Abstract

Rapeseed plants have been grown in soil-free culture with varying amounts of nitrogen fertiliser applied as nitrate, and with 50% of the nitrate-N exchanged for ammonium. The experiment was performed at two levels of sulphate fertiliser. Yield, protein content, glucosinolate content and amino acid composition were studied. The glucosinolate content was lower and the protein content was higher at a high level of nitrogen fertiliser. Exchange of 50% of the nitrate-N for ammonium caused no significant change in glucosinolate or protein content. The amount of glucosinolate was higher at the high sulphate level. There were no sulphur-nitrogen interactions. Content of total aspartic acid increased with nitrogen fertilisation, while total content of other amino acids did not change significantly with fertilisation.The effect of a wide variety of applications of sulphate fertiliser on glucosinolate and total amino acid content have been studied in a separate experiment. Although both protein content and methionine content were reduced at a low sulphate level, glucosinolate content was reduced considerably more.Experiments in the field revealed that although a reduction in glucosinolate content of rapeseed may be obtained from using fertilisers low in sulphur on sandy soils this does not seem possible on heavy soils. IntroductionSeed meals of rape (Brassica napus L.) and turnip rape (Brassica campestris L.) contain W 5 % protein in the dry matter with a well balanced amino acid composition.l According to Miller et aZ.1 the limiting amino acids from a nutritional point of view are isoleucine and methionine. Since methionine very often is limiting in proteins of vegetable origin, it is important to obtain as high a content of this amino acid as possible. A factor that is still more limiting for the use of these meals, however, is the content of glucosinolates. These substances can be hydrolysed by the enzymic system myrosinase, yielding sulphate, glucose and isothiocyanates, the last-mentioned compound and its secondary products being toxic to animals, causing for example goitre in non-ruminants.2 Other hydrolysis products, for example nitriles, have also been found.3 Studies of glucosinolate content in seed of rape and turnip rape as affected by variety and environment were made by Josefsson & Appelqvist.4 By fertiliser experiments in plastic boxes (containers), they showed that low applications of sulphate fertiliser resulted in a low content of glucosinolates in the seed, although the protein production approached normal quantities. Fields with light soils where the sulphur fertilisation had been kept on a low level gave samples with a glucosinolate content that was significantly lower than in samples from other fields.4In the studies of Josefsson & Appelqvist, no significant variation in glucosinolate content was found between different levels of nitrogen fertiliser. Trzebny5 found, however, in a study of field-grown material that a high level of nitrogen fertiliser caused a significantly lowered glucosinolate content. ...

Nutritional Significance of Sulphur on Growth, Yield and Quality of Blackgram in Major Contrasting Soil Series of Tamil Nadu, India

“…The synthesis of cysteine as a result of the incorporation of sulphide moiety into O acetylserine appears to be the meeting point between N-and S metabolism. This result was corroborating with the findings of Josefsson (1970) who found that S fertilization had increased the Scontaining amino acids in rapeseed and Jarvan et al, (2008) reported an increase in cysteine and methionine content in wheat grain due to S fertilization.…”

Influence of nitrogen and sulphur on the glucosinolate profile of rapeseed (brassica napus l)

“…In contrast, the study of Josefsson (1970) showed little variation in the relative proportion of both but-3-enyl and 2-hydroxybut-3-enyl among different S and N treatments. Both researchers used a chemical method (steam distillation, followed by titration and spectrometric determination) to quantify the alkenyl glucosinolates, which lacks both accuracy and precision.…”

The Seed Composition of Arabidopsis Mutants for the Group 3 Sulfate Transporters Indicates a Role in Sulfate Translocation within Developing Seeds

“…5 and 7A) involved in the hydrolysis of glucosinolates to nitrile, sulfur, and sulfate (Wittstock and Halkier, 2002;Grubb and Abel, 2006;Kissen and Bones, 2009), which suggests an increased catabolism of these compounds in sultr3;4 developing seeds. Glucosinolates are transported from all parts of the plant into developing seeds, and most of the glucosinolates contained in oilseeds are located in the embryo (Josefsson, 1970;Gijzen et al, 1989). Their catabolism may release sulfate in the seed embryo for assimilatory pathways.…”