P. C. Dekock

Mössbauer studies of plant materials. I. duckweed, stocks, soybean and pea

Abstract Specimens of duckweed, stock (single‐ and double‐flowered), soyabean and pea were isotopically enriched in 57Fe by growing in nutrient solutions which contained iron, primarily as the 57Fe isotope. Whole duckweed and the separated roots, stems and leaves from the other plants were studied by Mossbauer spectroscopy at 77K. Samples of duckweed and pea were also dried in air and studied at room temperature. All specimens showed the presence of iron in the ferric form and, in addition, the pea leaves indicated the presence of some ferrous iron.

Blossom‐end rot of tomato as influenced by truss size

Abstract Thinning of tomatoes to one or two fruits per truss increased the size of the fruits initially but subsequent trusses because severely affected by blossom‐end rot. This is thought to be due to an excessive supply of growth promoting hormones from the loots to the developing fruits.

The effect of copper and nitrogen on the amino acid composition of oat straw

SummaryThe effect of fertilization with nitrogen and copper on the amino acid composition of oat straw has been studied.The plants (Avena sativa cv Yielder) were grown in peat with a very low copper content and supplied with two levels of nitrogen (NH4 or NO3) and three levels of copper sulphate.The higher level of nitrogen stimulated growth only when copper was added, whereas, without copper, it had an adverse effect on growth and prevented grain formation altogether. The higher level of nitrogen increased the nitrogen content of the straw at all levels of copper, but particularly in plants receiving no copper.Total amino acids in the straw hydrolysate of copper sufficient oats accounted for about 50% of the total N and was about 20% higher in copper-deficient tissues. The addition of copper caused a decrease in the amounts of all amino acids. The relative proportions of most of the amino acids to glycine remained fairly constant. Threonine, serine, alanine, iso-leucine, histidine and arginine showed small significant differences with copper treatment, whereas valine, tyrosine, phenylalanine, proline, lysine and cysteic acid (derived from cysteine and cystine) showed no differences. The proportion of aspartic acid relative to glycine in the straw hydrolysate was greatly increased in copper deficient plants supplied with the higher level of nitrogen, particularly as ammonium. The proportion of glutamic acid was also increased by the higher level of nitrogen, but showed no effect of added copper. Most of the difference in aspartic acid could be accounted for as free asparagine. The possible reasons for higher proportions of asparagine are discussed in relation to the metabolism of the oat plant.

A relationship between free amino acid and nickel contents in leaves and seeds ofAlyssum bertolonii

SummaryData are given on the aqueous acetone—soluble (free) amino acid composition and total nickel contents of leaves of wild and cultivatedAlyssum bertolonii and of seeds produced by the former. Leaves of the wild plants show a direct relationship between their total free amino acid N and Ni contents. These are highest in February, show a decrease in June and increase again by October. It is inferred that variations in the Ni uptake and free amino acid contents are functions of seasonal factors. Leaves of cultivated plants showed the lowest Ni content but the highest free amino acid content illustrating the influence of environmental factors.