S t e i n b e r g (1935) and L u n d (1953) found that the growth of Aspergillus niger is influenced by copper. O r 1 o v et al. (1968) have further observed that 10.0% solution of copper sulphate increases markedly the yield of citric acid when molasses is employed as substrate. T o m l i n s o n et al (1950) studied the influence of Zn, Fe, Mn and Cu on the production of citric acid and obser...

soil and sludge samples based on it, in addition to the total elemental concentrations (Vercoutere et al., 1995; It is important to evaluate different digestion methods to accurately Quevauviller et al., 1993). In many countries (excluding determine elemental concentrations in soils. Three commonly used digestion procedures, hotplate aqua regia, microwave aqua regia, and the USA), this procedur...

boron (b) toxicity is an important disorder that can limit plant growth in arid and semi-arid environments. it has been proven that use of tolerant rootstocks impede b uptake or transport to the aerial portions of plants. this may alleviate b toxicity in the scion, consequently improves the tolerance to excess b in the root zone. an experiment was conducted to find the effects of b toxicity on ...

Recently in this laboratory (1) soybeans grown on manganese-deficient field plots were analyzed for ascorbic acid and ascorbic acid-oxidizing enzymes. Contrary to some reports in the literature, no consistent relationship was found between manganese deficiency symptoms and ascorbic acid or the enzymes which oxidize it. The present study was performed with solution cultures to provide a more rig...

Three laboratories previously have obtained from Zea mays kernels (milk stage) one or more 6-(substituted)aminopurines capable of greatly promoting cell division in plant tissue cultures.1-3 At least two of the laboratories have worked on a single compound4 which has been identified as 6-(4-hydroxy-3-methylbut-2-enyl)aminopurine.5 The name zeatin has been applied to this particular compound.6 O...

Many obscure points remain to be resolved with respect to the transport of photosynthates from source to sink through sieve tubes. It is very important to be able to collect and analyze the phloem sap if an attempt is to be made to explain the phloem transport system. The insect laser technique (Kawabe et al. 1980) has been shown to be useful method for the study of this problem. The insect las...