Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: A. Anders x
  • Refine by Access: All Content x
Clear All Modify Search

Seeds of tomato (Lycopersicon esculentum Mill., variety Castle rock) were osmoprimed in polyethylene glycol 6000 (PEG; 20%) or K2HPO4 (200 mM) solution for 8 hours, 3 days or 7 days, while another group of seeds were left in water for the same periods. The GA3/ABA ratio was the most important hormone factor, which promoted germination in seeds soaked in H2O and led to improved germination performance. This ratio showed slight variations between hydroprimed and osmoprimed seeds after 8 hours, but afterwards, from 3 to 7 days, it was gradually increased in the osmoprimed seeds and was substantially elevated in seeds germinating in H2O. Changes in the concentrations of phenolic compounds suggested their possible role in germination silencing in the osmoprimed seeds, but at relatively low concentrations. Protein patterns showed no marked variations in hydroprimed and osmoprimed seeds after 8 hours, but different types were observed, particularly after 7 days. A comparison of the protein banding patterns of seeds after 1 day and 7 days in the osmoconditioning solutions (PEG or K2HPO4), H2O, GA3 or ABA showed certain treatment-specific protein bands, particularly in PEG and ABA solutions. Longitudinal sections of seeds (after 3 days) showed lysis of the micropylar endosperm and radicle protrusion in H2O or GA3, whereas in PEG or K2HPO4 solution the radicle expanded inside the seed and the micropylar endosperm was completely intact. In ABA solution, the whole endosperm was compact and the seed became extensively desiccated.

Restricted access

Amblyopia is a visual disorder caused by an anomalous early visual experience. It has been suggested that suppression of the visual input from the weaker eye might be a primary underlying mechanism of the amblyopic syndrome. However, it is still an unresolved question to what extent neural responses to the visual information coming from the amblyopic eye are suppressed during binocular viewing. To address this question we measured event-related potentials (ERP) to foveal face stimuli in amblyopic patients, both in monocular and binocular viewing conditions. The results revealed no difference in the amplitude and latency of early components of the ERP responses between the binocular and fellow eye stimulation. On the other hand, early ERP components were reduced and delayed in the case of monocular stimulation of the amblyopic eye as compared to the fellow eye stimulation or to binocular viewing. The magnitude of the amblyopic effect measured on the ERP amplitudes was comparable to that found on the fMRI responses in the fusiform face area using the same face stimuli and task conditions. Our findings showing that the amblyopic effects present on the early ERP components in the case of monocular stimulation are not manifested in the ERP responses during binocular viewing suggest that input from the amblyopic eye is completely suppressed already at the earliest stages of visual cortical processing when stimuli are viewed by both eyes.

Restricted access

In this study sap flow dynamics of mature sessile oak trees (Quercus petraea) in a marginal sessile oakturkey oak forest was investigated in 2009. That year spring was dry without significant rain in April and May and the driest month was August. Due to the extreme weather conditions the volumetric soil water content (SWC) of upper 30 cm was low on experimental days in May (0.13–0.14 cm3 cm−3) but it reached the lowest value in August (0.08 cm3 cm−3). Sap flow was measured in a dominant and a co-dominant tree by heat dissipation method from 26 March till 30 October. In the present paper several three-day long periods of the continuous seasonal recordings were chosen to represent the effects of typical weather conditions and different stages of canopy development on sap flow dynamics. The daily maximum sap flow density values of dominant and co-dominant trees were similar (0.30–0.32 cm3 cm−2 min−1) in moist period (July). Rains and transient increase of SWC after proceeding drought resulted in change of diurnal course of sap flow in experimental days of July. In this period dominant trees also showed considerable sap flow (0.19 cm3 cm−2 min−1) during night hours and short sap flow peaks in early morning (6:00 to 8:00 a.m.) indicating the refilling of desiccated tissues. After the progressive drought in August the daily maximum sap flow density decreased to 0.07 cm3 cm-2 min-1 in dominant tree and to 0.12 cm3 cm−2 min−1 in the co-dominant. Both trees exhibited gradual stomatal closure from morning hours.

Restricted access