Increasing soil acidity (from pH 6.5 to pH 2.0) decreased chlorophyll (Chl)a andb contents, dry matter accumulation by plants and the transpiration coefficient. Chl stability to heat significantly increased with increased soil acidity. The Chla/b ratio was increased significantly at pH 5 and 4 and decreased at pH 3 and 2. SprayingSorghum shoots with kinetin solutions counteracted the above adverse effects on Chl content and dry matter accumulation. Kinetin-treated plants showed a lower transpiration coefficient than the untreated plants.

Responses of a salt tolerant and a normal population of an oilseed crop,Eruca sativa Mill. were assessed after four weeks growth in sand culture salinized with 0 (control), 100, 200, or 300 mol m^-3 NaCl. The salt tolerant plants produced significantly greater dry biomass than the normal population. The populations did not differ significantly in leaf osmotic potential, relative water content and leaf soluble proteins. However, the tolerant population accumulated significantly greater amounts of soluble sugars, proline and free amino acids in the leaves compared with the non-tolerant population. It is established that leaf soluble sugars, proline, and free amino acids are important components of salt tolerance inEruca sativa.

Plant regeneration through somatic embryogenesis was obtained in chickpea (Cicer arietinum L.) using immature cotyledons and immature embryonal axes as explants. 2,4-dichlorophenoxyacetic acid (2,4-D), 4-amino-3.5-6-trichloropicolinic acid (picloram) and 3.6-dichloro-0-anisc, acid (dicamba) in concentrations 1, 2, 5, 10 mg dm^-3 were found better than naphthaleneacetic acid (NAA) (10-20 mg dm^-3) for the induction of globular and heart-shaped somatic embryos. The embryos developed upto the dicotyledonary stage on medium supplemented with saccharose, mannitol and silver nitrate (AgNO₃) and developed further into plantlets on medium containing gibberellic acid (GA₃) and abscisic acid (ABA). The frequency of somatic embryogenesis was dependent on the genotype and auxins used.

10-d-old wheat seedlings were grown hydroponically in presence and absence of 100 mM NaCl for 7 d. Salt stress decreased growth of shoots and roots of both cultivars; fresh mass of sensitive cultivar being more affected. NaCl increased membrane permeability to urea, methylurea and ethylurea and decreased membrane partiality in root cortex cells of sensitive cultivar. Neither parameter changed by NaCl in resistant cultivar. NaCl treatment decreased water permeability and osmotic potential in both cultivars; sensitive cultivar was more affected. The results extends our previous data that cell membrane properties are different in salt sensitive and resistant genotypes and so cell permeability could be a potential trait indicating salt tolerance.

The lengths of roots and shoots, fresh and dry matter yield, and the contents of insoluble saccharides and free amino acids were reduced with the rise in NaCl concentration. However, under combination of NaCl with Ca²⁺ ions, these parameters generally raised. Contents of soluble saccharides, proline and quaternary ammonium compounds increased with increasing NaCl concentration, but under addition of CaCl₂ or CaSO₄, contents of these compounds were decreased. Low concentrations of NaCl stimulated soluble proteins, production, but higher concentrations decreased the content of soluble proteins. Addition of Ca²⁺ in the media did not improve the soluble protein production. Insoluble proteins content was increased with the rise of salinity level, but these effects were more pronounced with NaCl and CaCl₂ or CaSO₄ than with NaCl only.

The effect of salinity on vacuolar pH was studied in carrot (Daucus carota L.) cells grown in liquid suspension culture either in the absence or presence of 150 mM NaCl. Both vacuolar and cytoplasmic pH were determined by several independent techniques. These techniques were NMR spectrometry, distribution of radioactive probes and spectrophotometric measurement of the absorbance changes of a naturally occurring vacuolar pH indicator. There was no difference in the cytoplasmic pH between cells grown in the presence or the absence of NaCl, but the vacuolar pH of cells grown in the presence of NaCl was higher by 0.38 to 1.05 pH units (depending on the technique that was used) than the vacuolar pH of cells grown in the absence of NaCl.

Ten major host-encoded pathogenesis-associated proteins have been found in extracts of intercellular sap of cucumber cotyledons infected with tobacco necrosis virus. By native and two-dimensional SDS-polyacrylamide gel electrophoresis, five major acidic virus-elicited proteins have been identified and classified on the basis of their molecular mass in three groups: group 1 included one protein of 14 kD; group 2, one protein of 28 kD and group 3, three proteins of 37-40 kD. Another five viruselicited proteins were basis, and were again classified in three groups: group 1, included two proteins of 15-16 kD; group 2, two proteins of 22-23 kD; group 3, one protein of 40 kD.

Several factors influencing reliability of the quantitative fluorimetric β-glucuronidase (GUS) assay in transgenic plant tissue have been investigated. We obtained linear dependence of fluorescence on both the duration of hydrolysis and the extract concentration. The stability of the enzyme in the homogenate was fairly high, the same as the stability of the substrate solution and of the final reaction product. The modification of the extraction/incubation buffer was proposed, resulting in several times higher activity in comparison with original procedure.

Transport of ions in young maize plants was affected by the temperature gradient (gradT). This influence was dependent on the age of plants and the solute concentrations in compartments at the two sides of plants. When gradT was increased, current, volume and heat flows rose during 20 min and then declined. On the other hand, the diffusive flow only declined. The character of the flow changes was given by the changes in permeability and reflection coefficients. In young plants under low solute concentration on both sides of plants, the permeability of the plant tissues shifted from positive to negative values. Under higher solute concentrations on both sides of the plants such phenomenon was not observed. At high gradT the reflection coefficients of the plant tissues were low, but they rose during levelling the temperature in the two compartments.

Vanadium bioaccumulation calculated as the ratio of its content in plant biomass to that in the substrate (Vbi-index) was studied in pea. Vbi was on average 11.275, 11.770 and 13.153 in the roots, and 0.809, 0.467 and 0.749 in the shoots of the cultivars Opal, Laser and Ramir, respectively. This indicates cultivar differences in vanadium uptake, and low translocation rates from roots to shoots. Vanadium (3 to 30 mg 1^-1) decreased shoot and root fresh and dry masses of the three cultivars. Seedlings of the cv. Opal were the most susceptible to higher concentrations of vanadium (20 to 30 mg 1^-1), whereas seedlings of cv. Laser were the most resistant.

NaCl salinity affected growth, the contents of chlorophyll, carotenoids, saccharides and some minerals (Na, K, Ca, Mg, P) in wheat (Triticum vulgaris L.) plants. Irrigation of soil with CaCl₂ or KCl greatly ameliorated the adverse effects of NaCl salinity. This counteraction was associated with an increase in contents of saccharides, proteins and Ca, Mg and P which might explain their role in osmotic adjustment.

Thidiazuron incorporated into MS medium stimulated rosettes formation only in some treatments. This effect was more pronounced in cultures ofMorus alba thanPrunus sp. Mulberry cultures responded to the optimal concentration of thidiazuron (0.2 mg I^-1) not only with shoot formation but also, with growth of large leaves and poor development of callus tissue. In cultures of both investigated genera the shoot elongation was inhibited. Shoots of mulberry cultures growing on proliferation medium supplemented with thidiazuron formed roots, in many cases.

Investigation was made on a use of microcrystal cellulose as a new and inexpensive gelling agent instead of agar. Microcrystal cellulose in concentration 20 % forms a suitable structure of nutrient medium for in vitro cultivation. The higher humidity in the culture container with microcrystal cellulose causes partial vitrification of Nicotiana tabacum L. plants, cv. Zlatna arda. It is proved by reduced chlorophyll content, changes in protein synthesis and strongly reduced isoenzyme spectrum of peroxidase.

l-alkyl-l-ethylpiperidinium bromides inhibited light induced Mg²⁺-adenosin-triphosphatase activity of isolated thylakoids in both Phaseolus vulgaris L. and Zea mays L. The short chain detergents (C₅ to C₇) were less effective in maize than in bean.

The effects of decreasing Ca²⁺ concentrations (Na/Ca ratios were 24, 49, 99 and 199) of the saline growth medium (NaCl concentration 200 mM) on three grass speciesCenchrus pennisetiformis Hochst. & Steud,Leptochloa fusca L. Kunth. andPcmicum turgidum Forssk. were assessed after 7 weeks growth in sand culture.L. fusca produced the highest dry biomass of all the species at varying Na/Ca ratios. Number of tillers per plant and number of green leaves per tiller were reduced significantly only inC. pennisetiformis. Leaf water potential ofC. pennisetiformis decreased at all external Na/Ca ratios, whereas inL. fusca it decreased only at an Na/Ca ratio of 99. Leaf osmotic potential ofL. fusca consistently decreased at all Na/Ca ratios, whereas that of the other two species remained unchanged. The shoot and root total sugars of all species remained unaffected at all decreasing Ca²⁺ concentrations. InP. turgidum chlorophyllb and total chlorophyll decreased consistently at all Na/Ca ratios, but inL. fusca they decreased only at the highest Na/Ca ratios. The leaf soluble proteins of all the species remained unaffected at all Na/Ca ratios. The leaf free amino acids decreased significantly inL. fusca with the increase in Na/Ca ratios. The leaf proline content was only decreased inL. fusca at the highest Na/Ca ratio. The significant correlations between the growth of the three grass species and other variables determined in this study were not found.

The full length cDNA clone of leghemoglobin I gene fromLupinus luteus was placed under dual promoter into the plant expression vector pCB1399 and the resulting vector (pCB1415) was transfered into theAgrobacterium strain LBA4404 (pAL4404). The binary system LBA4404 (pAL4404, pCB1415) was then used for transformation ofNicotiana plumbaginifolia andLotus corniculatus. In both species kanamycin-resistant plants have been selected and regenerated. The synthesis of LbI protein in transformed plants has not been shown.

The effects of different nitrogen salts on nitrate reductase activity and protein contents were investigated in three Yugoslav cultivars of wheat. The nitrate salts appeared to be a better form of nitrogen than ammonium in respect of the increase of the nitrate reductase activity and root total protein contents, whereas the treatment with ammonium salt resulted in a comparably higher shoot total protein contents. KNO₃ was the best in respect of the level of nitrate reductase activity. Different concentrations of nitrate and ammonium ions in nutrient solution, showed very similar effects on investigated parameters. NS Rana 2 cultivar had the highest values of nitrate reductase activity and protein contents.

The efficiency ofAgrobacterium-based transformation technique in oilseed rape and cauliflower was influenced by cultivar specificity, donor plant age and explant type. Marked differences in demands for plant hormone contents in the regeneration medium were recorded already among different types of nontransformed explants. The highest regeneration capacity was recorded with stem and leaf segments isolated from one-month-old aseptically grown plants. The regeneration was markedly species-dependent. Regeneration of transformed plants from stem segments and thin layers isolated from field-grown oilseed rape plants (at the most 2% of regenerating explants) and from oilseed rape hypocotyls (0.8% of regenerating explants) and cauliflower (1.2% of explant regenerated transformed shoots) was achieved after disarmedAgrobacterium treatment. Hypersensitive reaction of explants could be prevented by using prolongedin vitro precultivation and delayed application of the selective agent.

Relative competition among various plant parts for N during water stress,i.e. nitrogen distribution index (NDI) was determined in relation to specific nitrogenase activity (SNA) and nodule and soil nitrogen in both indeterminate (H-77-216) and determinate (ICPL-151) types of pigeonpea (Cajanus cajan L.) under greenhouse conditions. Two levels of water stress,i.e. moderate (soil Ψ_w) -0.77 MPa) and severe (soilΨ_w -1.34 MPa) were created by witholding the irrigation at vegetative (40 DAS) and flowering (70 DAS) stages. At vegetative stage under moderate stress the highest NDI was in nodules of cv. H-77-216 and in leaf of cv. ICPL-151. Under severe stress both the cultivars showed negative values of NDI, with maximum loss of N from root and nodules. Cultivar ICPL-151 behaved differently at flowering and vegetative stages. Very high loss of N from different plant parts was seen at flowering under severe stress. All the plant parts showed gain in N during rehydration. Loss and gain in N at both the stages under stress and rehydration respectively, correlated with available N in soil. Specific nitrogenase activity (SNA) and nodule N were maximum at moderate stress and related with NDI values of leaf and nodules.

Changes in the levels of free indol-3-ylacetic acid (IAA) and free cytokinins were determined in the course of dormancy and sprouting period in potato tubers(Solanum tuberosum L., cv. Nevskii) stored at 4 °C. The same analyses were performed in potato tubers after Ethrel application, which prolongs dormancy. No significant changes were found in free IAA level during dormancy followed by a rapid decrease during sprouting. After Ethrel application a significant lower IAA level was found 3 weeks after application, but further on no changes in free IAA level between treated and non-treated tubers were detected. Cytokinin level was relatively low and constant till sprouting and increases then by about 55 %, mainly due to an increase in the level of zeatin riboside and isopentenyladenosine. Ethrel application decreased cytokinin level during dormancy slightly, but postpones the increase coupled with sprouting by about 1 month. Thus, IAA does not seem to have a significant effect on tuber dormancy, while cytokinins are probably necessary for sprouting initiation.

The angiosperm root parasiteCynomorium coccineum and the halophytic hostsLimonium delicatulum andArthrocnemum glaucum were invesrigated under natural conditions in a Mediterranean salt marsh in March 1992. The diurnal transpiration rate of the parasite was low and parallel to the climatic factors. The non-infected plants showed higher transpiration rates than the parasite and its hosts. Compared to the non-infected plants, it is apparent that the perennial herbL. delicatulum is more sensitive to infection since its reduction in the fresh and dry mass was higher than that found inA. glaucum.