Kaurene synthetase B activity (conversion of copalyl pyrophosphate to ent-kaurene) is readily detectable in crude cell-free extracts of 3- to 4-day old dark-grown sunflower (Helianthus annuus cv. Mammoth) seedlings, whereas little or no kaurene synthetase AB activity (conversion of geranylgeranyl pyrophosphate to ent-kaurene) can be found in these extracts under comparable assay conditions. A l...

The effect of copperchloride (CuCl2) on the level of chlorophyll (a+b), proline, protein and abscisic acid in sunflower (Helianthus annuus L.) seedlings were investigated Control and copper treated (0.4, 0.5 and 0.6 mM) seedlings were grown for ten days in Hoagland solution. Abscisic acid content was determined in root, shoot and leaf tissues of seedlings by HPLC. Copper stress caused significa...

Sunflower (Helianthus annuus) is annual plants native to Mexico and is valuable from economic, as well as from ornamental point of view. In this paper the edification of the primary and the secondary structure of the vegetative organs were followed during the ontogenesis. The root with primary structure is tetrarch, with four strands each of xylem and phloem that alternate with one another. In ...

The response of RIMI [imazethapyr-tolerant (T)] sunflower (Helianthus annuus L.) hybrid and the local imazethapyr-sensitive hybrid "Zoltan" (S) was investigated under controlled conditions. Hybrids grown in pots were treated post-emergence with imazethapyr at the two pairs of leaves stage. Visual injury evaluation and vegetative parameters were recorded. ALS (acetolactate synthase) enzyme activ...