The sap flow (Jv) and the osmotic pressure‐dependent hydraulic conductance (L0) of detached exuding root systems from paprika pepper plants (cv. Albar) were measured. Plants stressed with NaCl (30 mM) and with six times the macronutrients of the Hoagland nutrient solution (6×HNS) were compared with controls grown in complete Hoagland nutrient solution. Jv of +NaCl and +6×HNS plants decreased markedly, but recovered to values similar to those of controls after removal of the treatments. Hydraulic conductance L0 was always less in NaCl plants than in controls and 6×HNS. A total increase in the ion concentration of the xylem (except Na+ and Cl−) was observed with both treatments. In control and 6×HNS plants, HgCl2 treatment (50 μM) caused a sharp decline in L0 to values similar to those of NaCl‐stressed roots, but were restored by treating with 5 mM dithiothreitol (DTT). However, in NaCl roots only a slight effect of Hg2+ and DTT was observed. In each treatment, there was no difference in the flux of K+ into the xylem after HgCl2 and DTT application. The results suggest that NaCl decreased L0 of the roots by reducing either the activity or abundance of Hg‐sensitive water channels. The putative reduction in water‐channel function of NaCl‐treated plants did not seem to be due to the osmotic effect.

No abstract

This work was conducted to investigate changes in the bioactive nutrient content of hot (pungent) paprika as a function of ripening in four of the most important varieties cultivated in Hungary. For the quantitative determination, recent liquid chromatographic (HPLC) methods were applied. Forty carotenoids were separated, with b-carotene and lutein of interest from the biological point of view. The major component of vitamin E was a-tocopherol. Capsaicin, dihydrocapsaicin and nordihydrocapsaicin were the dominant pungency principles. As for vitamin C components, only ascorbic acid could be detected and determined. The results indicated that all the examined compounds were at low level in the mature green fruits, and the onset of climacteric ripening caused their content to grow. In accord with the advance in ripening, carotenoids were being formed even at the overripening stage, while tocopherols, capsaicinoids and ascorbic acid reached their maximum level at the colour break or red stage and then declined. The highest values with regard to carotenoids were estimated in SZ-178 and F0-3 cultivars. The best retention of ascorbic acid was found in SZ-178, which contained 4.86 mg g À1 dry matter in the dry pods. On the other hand, retention of a-tocopherol during ripening and natural drying was found to depend on variety. The highest value for vitamin E was recorded in SZ-178 followed by K-V 2 , which contained the highest level of a-tocopherol at the red stage of ripening.

No abstract

1989. Isoenzyme pattern of superoxide dismutase in different varieties of citrus plants. -Phvsiol Plant. 76: 563-568. Superoxide dismutases (SOD; EC 1.15.L]) in leaves from different cultivars of citrus plants were characterized using isoelectric focusing in polyacrylamide gels. The plants studied included Citrus limonum R, (cvs Verna, Fino, and Eureka), C. paradisi Mac (cvs Red Blush and Marsh), C. auratitium L. (cv. Comun), C. sinensis L. Osbeck (cvs Navel, Valencia, and Salustiano), and C. reticulata B. (cv. Satsuma).The three molecular forms of SOD were distinguished from each other by their different sensitivity to cyanide and H2O2. In C. limonum leaves, four Cu,Zn-SODs, three Fe-SODs and two Mn-SODs were present. However, in leaves from different varieties of C sinensis, C. paradisi, C. aurantium and C. reticulata the activity and number of Fe-SOD isoenzymes were lower than in lemon leaves, whereas the number of MN-SOD isozymes was increased. Cu,Zn-SODs did not show significant variations in the different species and cultivars. The identification of Fe-SODs in several species of the plant family Rutaeeae extends the small number of higher plants where the presence of these Fe-containing metalloenzymes has been demonstrated. Results obtained may be useful from an evolutionary viewpoint and also in mineral nutrition studies using SOD isozymes as markers of functional metals.