Vicine and convicine are anti-nutritional compounds that accumulate in the cotyledons of faba beans. When humans consume beans with high levels of these compounds, it can cause a condition called favism in individuals harbouring a deficiency in the activity of their glucose-6-phosphate dehydrogenase. When faba beans are used in animal feeds, there can be effects on performance. These concerns have resulted in increasing interest within plant breeding in developing low vicine and convicine faba bean germplasm. In order to facilitate this objective, we developed a rapid and robust screening method for vicine and convicine, capable of distinguishing between faba beans that are either high (wild type) or low in vicine and convicine. In the absence of reliable commercial reference materials, we report an adaptation of a previously published method where a biochemical assay and spectral data were used to confirm the identity of our analytes, vicine and convicine. This method could be readily adopted in other facilities and open the way to the efficient exploitation of diverse germplasm in regions where faba beans play a significant role in human nutrition. We screened a collection of germplasm of interest to a collaborative plant breeding programme developing between the National Institute for Agricultural Botany in the UK and L'Institut Nationale d'Agronomie de Tunisie in Tunisia. We report the results obtained and discuss the prospects for developing molecular markers for the low vicine and convicine trait.

Public concern about NO‐3 levels in potable waters, together with improving techniques for maintaining NH4+ availability in soils, has renewed research interest in the effects of N form on crop growth. The effects of NO‐3 versus NH+4 on growth and morphology of juvenile corn (Zea mays L.) were investigated in two experiments. In Exp. 1, 16‐d‐old, solution‐grown plants produced less shoot fresh weight when grown with NH+4 than with NO‐3 nutrition. Root fresh weights were similar, but elongation of the primary root axis and its longest first order lateral was less with NH+4 nutrition. Under NH+4 nutrition, apparent thickness (grams per meter) of primary roots was 54% greater, and the frequency of first order laterals with second order laterals was 65% greater, than under NO‐3 nutrition. In Exp. 2, plants were grown in the greenhouse until 40 d after emergence in a slightly alkaline 3:1 sand:soil mix. Nitrogen (75 mg N kg−1) was supplied as either Ca(NO3)2 or (NH4)2SO4 plus nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine]. Ammonium‐grown plants produced 2.3 times the dry matter and had higher concentrations of N in both stems (18.5%) and leaves (27.5%) compared to NO‐3‐ grown plants. Tillering was increased by NH+4‐ nutrition. Apparent root thickness was again greater under NH+4 nutrition, but the difference between N regimes was only 15%. Results indicate that under conditions of course‐textured soils and slightly alkaline pH an enhanced NH+4‐ N regime may be advantageous for growth of corn. Differences in pH regimes between the hydroponic and soil‐based experiments may account for the contrasting results.