The effects of 6-benzylaminopurine (BAP, 5.10^-5M) treatment of pumpkin cotyledons and their starvation after excision upon polysome/monosome ratio and translational capacity of polysomes in cell-free system were studied. It has been found that starvation causes a progressive polysome degradation. Polysome translation in a wheat germ cell-free proteinsynthesizing system reveals that the translation capacity of polysome preparations decreases with the time after cotyledon excision much more sharply than polysome/monosome ratio. This indicates the starvation damage in elongation steps of protein synthesis. The decrease of postribosomal supernatants activity in the system of poly(U)-directed polyphenylalanine synthesis confirms this conclusion.
BAP treatment brings about a very rapid monosome mobilization into polysomes and activation of cell-free translation of ribosome preparations which is however closely parallel to the polysome percentage in them. That means that during this initial period of BAP action only protein synthesis initiation is under BAP control. The experiments with aurintricarboxylic acid (ATA) support this idea.

Proteolytic activities were studied in cotyledons of germinated and mature dry seed and axis of mature dry seed ofVigna unguiculata (L.) Walp. cv. Seridó using the following substrates: hemoglobin (pH 3.5), casein (pH 6.0), LPA (pH 7.0), and BAPA (pH 7.6). During the germination period (six days) examined, the total activities of LPA-ase and BAPA-ase decreased progressively in cotyledons corresponding to protein depletion. Consequently, the specific activities of the above proteases remain practically constant. In the case of caseinase and hemoglobinase, total activities increased in the cotyledons up to the third day of germination. Thereafter there was a decrease in these activities (total) but an increase in specific activities. Higher values than in the cotyledons for all the activities were obtained with the axis of mature dry seed. A 25 to 50 % ammonium sulfate fraction of a buffered extract from mature dry seed was used as source of enzyme for all the substrates used. Sephadex G-100 chromatography of the 25 to 50 % (NH⁴)²SO⁴ fraction gave two main peaks which correspond to relative molecular mass of 100 000 and 60 000 and contained all the activities.

Field trials on the effect of chlorocholinechloride (CCC) on rye plants of the cultivar Danae and of a selected population "WRS" proved that rye principally shows as reaction analogous to wheat. The CCC-induced decrease of stalk length is due to the reduction of elongation growth of the 4th internode. This shortening effect is mainly the result of decreased cell extension and, in the middle internode, additionally of inhibited cell division in longitudinal direction. The shape of internodes is changed under the influence of CCC. Walls of parenchyma cells of CCC-treated plants are thinner and those of sclerenchyma cells are thicker compared with cell walls of control plants.

The changing pattern, of WSD and concomitant protein changes were scanned in twoZea mays cultivars, with differential sensitivity to water stress. Increasing protein values were recorded in resistant cv. Ageti-76 with decreasing osmotic potentials of substrate (on 3rd day of stress), although the values in susceptible cv. Vijay remained almost on a par with the controls. In another experiment both the cultivars revealed initial increase of protein on 2nd day at osmotic potentials of - 2 and -4 × 10⁶ Pa, however, values declined up to day 7 of stress. WSD showed an increasing trend in both the experiments, although slightly higher values of WSD were registered in cv. Ageti-76 in comparison with cv. Vijay. The significance of protein changes in reference to drought is discussed.

The leaves of two tropical grasses (Panicum maximum Jacq. andPaspalum notatum Flügge) recovered from water deficit within 1 to 3 h after surface wetting. No substantial differences were found in absorption activity of abaxial and adaxial leaf epidermes between apical and basal parts of a leaf blade, or between leaves of different age.

InAnacystis nidulans uptake and efflux kinetics of fluoresceine were studied. It could be concluded that the distribution of fluoresceine depends on the pH_c of the cells. The comparison of different fluoresceine accumulation levels and flux equilibria allows conclusions regarding changes of the pH_c.

Chlorosis induced with a supraoptimum dose of phosphorus in nutrient solution (69 mg P l^-1) was reverted by spraying of leaves of chlorotio maize plants (Zea mays L.) with FeEDTA. Biomass formation, chlorophyll and iron content were decreased in the above-ground parts of plants grown under chlorosis-inducing conditions. Spraying always decreased content of inorganic phosphorus (P_i/Fe ratio was significantly changed), increased chlorophyll content in old plants and stimulated dry mass formation at supraoptimum phosphorus doses. FeEDTA application improved phosphate utilization (portion of phosphate in organic bonds was increased). This may be the basis of chlorosis-reverting effect of FeEDTA.

The results of different photoperiodic treatments preventing flowering and representing the control vegetative treatments in the studies of floral induction and differentiation were studied inChenopodium rubrum seedlings. A fully vegetative growth pattern of the meristem was maintained only in continuous light or after a photoperiodic treatment which consisted in a 15 min light break of the 8 h dark periods which themselves are a threshold for flowering inChenopodium. Light breaks applied to 10 h and longer dark periods did not prevent the changes resembling the early events of transition to flowering. Disappearance of zonal pattern, stimulation of apical growth, precocious initiation of leaf primordia and weakening of apical dominance have been observed. Flower formation did not follow.

The rooting response to exogenous auxin of cuttings in a juvenile phase of growth from plants ofCastanea sativa Mill. was determined and simultaneously the rooting potential of the water extracts was evaluated in presence of IAA by a bean rooting test. The level of the extractable rooting promoters was high in the cuttings which exhibited the highest percentage of rooting. An inhibition of the effect of IAA on rooting was detected in the cuttings which showed the lowest rooting response, the histogram differing not much from that of the adult plant. The results indicate that in chestnut the juvenile condition, easy rooting, is associated with high levels of endogenous rooting promoters.

Nitrate depletion from the media by intact corn seedlings grown under solution culture was measured over a period of time. Two methods were assessed to differentiate corn genotypes for nitrate uptake ability: (1) Nitrate uptake per day per plant basis. (2) Nitrate uptake per day per gram root dry matter basis. The former method was found to be superior as it gave significant and positive correlations with dry matter, nitrate, and reduced nitrogen accumulation in stem, leaf and roots. Nitrate uptake was found to vary with plant age. Root mass and efficiency of roots appear to contribute to the total nitrate uptake ability of the genotype. Corn genotypes studied exhibited marked differences in nitrate uptake ability.

Using polyacryl amide gel electrophoresis isoenzyme patterns were studied of α- and β-glucosidase, α- and β-galactosidase, α-fucosidase, β-glucosaminidase, β-glucuronidase, α-man-nosidase and β-xylosidase in whole root tips, in particular growth zones and in the cortex and central cylinder of broad bean and maize. Though considerable differences even in number and position of isoenzymes were found in particular cases in both objects, no general conclusion could be reached. The mentioned differences are not obligatory and have been observed both between zones of division and elongation and between zones of elongation and maturation. This fact is hard to understand on the basis of proteosynthetic processes involved in proliferative and postproliferative cell growth.

Alfalfa (Medicago sativa; L.) plants susceptible (S) and resistant (R) to the bacterial wilt were fedvia roots with a nutrient solution labelled with⁸⁶Rb⁺, at different times after inoculating them withCorynebacterium insidiosum (McCull.) H. L. Jens. The infection did not influence⁸⁶Rb⁺ uptake per plant in the course of a 14-day-period following inoculation, however it did affect its distribution differentially in the S- and the R-plants.⁸⁶Rb⁺ uptake was significantly decreased due to the infection in the S-plants on the day 49 after the inoculation (a 4-h-exposure to⁸⁶Rb⁺), with the iona also being more slowly translocated to the shoots in diseased S-plants than in diseased R-plants. Likely factors causing these effects and their relationship to alfalfa resistance to the bacterial wilt are discussed.

Fertilizer induced improvement of growth and yield of wheat (Triticum aestivum L. cv. Kalyan Sona), under salinity stress, was associated with an increase in the concentrations of nitrogen, phosphorus and potassium and a decrease in the level of chloride in the tissue. The concentration of chloride in grains was also reduced under high fertility as compared to low fertility condition. Results reveal that under both normal and saline conditions, nutritional improvement leads to higher chlorophyll concentration and increased efficiency of enzymes like nitrate reductase, ATPase, alkaline pyrophosphatase and amylase in the leaves. This imparts importance to fertilizer application under saline conditions.

Barium chloride at 0.1 mM concentration inhibited elongation of mungbean (Phaseolus aureus) roots more strongly than elongation of hypocotyls. Root growth was completely inhibited at 80 mM and there was no germination at 100 mM. Respiration rates which were directly proportional to seedling vigour declined at varying degrees at the growth-inhibitory concentrations of BaCl₂. Barium retarded senescence in isolated leaf discs ofCephalandra indica by maintaining the chlorophyll level in darkness. The carotenes were similarly protected from degradation by Ba in darkness whereas xanthophylls were retained both in darkness and light. Ba also protected anthocyanin pigments in the staminode discs ofCanna indica flowers and reduced to a variable extent the leakage of betacyanin pigment fromBeta vulgaris root discs caused by various membrane active chemicals. Applied either alone or in combination with IAA, Ba inhibited cell enlargement in wheat (Triticum aestivum) coleoptile sections. Barium-induced inhibition of lettuce (Lactuca sativa) hypocotyl elongation was largely overcome by GA₃.

The effect of high concentrations of the simplest polyphenols on extension growth of maize (Zea mays L.) shoot ooleoptile segments, lettuce (Lactuca sativa L.) roots, and on radish (Raphanus sativus L.) seed germination, was studied. Quinone formation in the process of plant incubation in polyphenol solutions was proved. The data obtained are presumably explained by the important part that is played by the quinoid products of phenol oxidation in the ability ofo- andp-biatomic phenols to inhibit growth.