Does transpiration have an essential function in long-distance ion transport in plants?

Abstract. Long-term effects of transpiration on growth and on long-distance ion transport were investigated in maize over a whole growth cycle. Maize plants were grown with nutrients supplied at adequate levels in hydroculture or in soil at 50–60% and at >95% relative humidity. Although the amount of water lost by the plants under these conditions differed by a factor 2 to 3, there was neither a decrease in growth (fresh weight and dry weight) nor in ash content of the 'humid'plants. This was also found when the upper part of the shoot (70–150 cm) was tested separately. It is suggested that transpiration is not essential for long-distance transport of mineral elements in plants. Alternatives are discussed.     

Phosphorylase activity in relation to starch synthesis in developing Hordeum distichum grain

Activity, control and primer requirements of starch phosphorylase in developing barley endosperm were investigated. Phosphorylase was detected in endosperm extracts from 3 days after anthesis. Unprimed activity was predominant between 2 and 10 days after anthesis, when it constituted 70–80% of total activity, but this proportion declined rapidly as the grain developed. The existence of at least 2 isoenzymes was indicated by studies of pH dependence and phosphate inhibition, and was further supported by acrylamide gel electrophoresis and column chromatography using DEAE-cellulose. The two isoenzymes which ere possibly both glyco proteins, appear in barley endosperm soon after anthesis. One appears capable of unprimed activity, and may be associated with the initiation of a-1,2 glucans, which then serve as primers for starch synthetase. This disappears by 13–15 days after anthesis. The other isoenzyme is capable of some unprimed activity but undergoes modification between 15 and 20 days after anthesis, resulting in the loss of unprimed activity. The relevance of the results to initiation of starch synthesis and to starch synthetase in amyloplasts is discussed.     

Indol-3yl-acetic acid in roots of Zea mays

Indol-3yl-acetic acid was identified in extracts of sterile roots of Zeamays seedlings by means of TLC, chromogenic reactions, GLC and GC-MS.     

Phytochrome control of oscillating levels of phenylalanine ammonia lyase in Hordeum vulgare shoots

Five-day-old etiolated barley shoots respond to brief illumination with red light by increasing their level of PAL ca 50% within 5 hr. When assayed s     

Grain or coleoptile tip as the source of IAA in cereal shoots?

Abstract. Current opinion is divided on whether the free IAA in cereal shoots is derived from the coleoptile tip or from the grain. To date these hypotheses have been considered to be mutually exclusive. In this paper the idea is advanced that both sources may function in the supply of IAA in the shoot. Critical review of the literature shows that such an explanation best fits all the available evidence. It is argued that the relative importance of each source may vary between species of the Gramineae, with the supply of IAA in Avena shoots being derived predominantly from the grain, whereas in Zea the coleoptile tip is the more important source.     

The typification of Lolium perenne L. and Loliutn temulentum L. (Poaceae)

LOOS, B. P. & JARVIS, C. E., 1992. The typification of Lolium perenne and Lolium temulentum (Poaceae). The typification of the Linnaean species Lolium perenne and Lolium temulentum has been studied. Lolium perenne is typified by material in LINN, as proposed by Terrell, but it has been necessary to select a lectotype for L. temulentum , and material in the Burser herbarium (UPS) has been chosen for this purpose. The study shows that although Linnaeus used awns as a diagnostic character to distinguish the two species, he was aware of the intraspecific variability in this character.     

Lignin-carbohydrate complexes from Lolium perenne

Lignin-carbohydrate and lignin-hemicellulose complexes were extracted sequentially from four varieties of Lolium perenne which had previously been     

Polyamine oxidase from Zea mays shoots

Polyamine oxidase of maize shoots purified 10-fold had a pH optimum of 6·3 with spermidine as substrate, and K_m of 6 × 10^?4 M. The enzyme was inhibited by the acridine compounds quinacrine, 6,9-diamino-2-ethoxyacridine and acriflavin, but carbonyl reagents, typical thiol inhibitors and copper-binding agents were without effect. Inhibition by quinacrine was reversed by FMN and FAD. Furthermore, about 50 % of the activity of the apoenzyme was restored by the addition of FAD, but not by FMN or riboflavin, indicating that the maize polyamine oxidase is an FAD-dependent flavoprotein.