The effect of phosphorus and nitrogen deficiency on growth of seedlings of spring barley in dependence on irradiance: Growth analysis

Seedlings of spring barley,Hordeum vulgare L. cv. Mirena, were grown in a controlled environment chamber at high (HI: 122 Wm^?2) and low (LI: 28 Wm^?2) irradiance in the complete Richter’s nutrient solution (R) or in solution lacking either phosphorus (R -P) or nitrogen (R -N). The experiment was terminated 15 days after sowing when plants (R-N) at HI ceased to grow. At that time the dry mass of one plant was 449.8 mg, 145.7 mg and 116.8mg at HI and 203.4 mg, 110.1 mg and 91.0 at LI for R, (R-P) and (R-N), respectively. Deficiency of P and especially N reduced the size of loaf area more under HI than under LI conditions. Specific dry mass of leaves was the highest in R-N plants. The values of relative growth rate and assimilation rate are presented. Interaction of the effects of deficiency of mineral nutrients and irradiance during cultivation should be analyzed in further experiments for determination of optimum conditions for utilization of mineral nutrients.     

Estimation of mass transport parameters in a column packed with BioSep beads

An approach to estimate the parameters needed to describe the performance of a column packed with BioSepTM beads is presented. These parameters, which characterize the transport of materials through the column, have been estimated from experimental residence time distribution (RTD) data using both porous and non-porous beads. A laboratory-scale column was used to obtain the experimental data using several ionic species. © Rapid Science Ltd. 1998     

The function of proteases during the light-dependent transformation of etioplasts to chloroplasts in barley (Hordeum vulgare L.)

The role of proteolysis during the light-induced rapid decrease of the NADPH: protochlorophyllide oxidoreductase in barley was studied. A proteolytic activity with a pH optimum of 4.5 was present in a plastid preparation of etiolated barley seedlings. No other proteolytic activity could be detected. The temperature optimum for the proteolysis was 50°C, and the highest specific activity was measured with hemoglobin as the substrate. In contrast to previous proposals, no evidence for the specific involvement of this protease was found during the light-induced transformation of etioplasts to chloroplasts.