Funaria spores must structure their photosynthetic apparatus before germination. A lack of manganese in the culture media affects neither the final structure of chloroplast nor the chlorophyll synthesis. Fixation of CO₂, reducing power of chloroplasts (DPIP) and RPE photo-induced signal S II are modified by this lack of manganese. The study of Mn/Chl and CO₂ fixed/Mn ratios shows that Mn is a limiting factor for CO₂ fixation and that in the spores depleted of Mn the residual Mn is "structural" Mn.

In only one cultivar out of 1200 investigated cultivars ofPhaseolus vulgaris L. could we find an extreme change in the pattern of reserve proteins on the cathodic side: one of the proteins, called protein I, is completely absent in the cultivar 'Krupnaya sakharnaya' and is replaced on the same site by another protein,i.e. a protein completely different in its immunochemical specificity. The case is of interest from both the phylogenetic and systematic viewpoints and deserves further attention.

The main enzymatic oxidation products of IAA have been tested for biological activity, using as bioassay the straight-growth test ofAvena coleoptile. After being purified by rechromatography, none of these products (including methyleneoxindole) exhibited biological activity within the wide range of concentrations employed; consequently, the results accord with the evidence that IAA is the true hormone of plant growth.

Viable mutations affecting chlorophyll production in black gram (Phaseolus mungo L.) were recovered following treatments with X-rays and ethyl methanesulphonate singly or in combination. Of these theviridis mutant was characterized by viridine green colour of all the leaves and reduced plant size. inchlorotica the emerging leaves were initially yellowish green which gradually changed to dark green at flowering. The terminal 2-3 leaves always remained yellowish green inchlorina-terminalis whereas inchlorina-virescence the emerging leaves were yellowish green that changed to dark green at flowering. Inalbo-virescence the first 3-5 leaves at emergence were white in which small irregular green dots or patches often developed. The subsequent leaves were normal green. The emerging trifoliate leaves ofaureo-virescence were light green which turned to turtle green within a week. It was established thatviridis, chlorotica, chlorina-terminalis, chlorina-virescence, andalbo-virescence mutants were conditioned by a single receissive gene, in each case. Theaureo-virescence character was found to be inherited through the cytoplasm.

When examining plants of white mustard (Sinapis alba L.), a significant relationship between the size of the roots and the yield was found, both in a pot experiment and in a field one. The yield was influenced by the size of the root system during and after flowering time. Especially the number of seeds has increased, and the average weight of seeds showed the same tendencies after the flowering time. The productivity of plants with an above-average yield was increasing more quickly than the size of their root system. From the beginning of the vegetation till the end of flowering these most efficient plants showed the lowest permitivity dispersion and the highest dispersion after the flowering time. The dispersion has increased towards the end of vegetation.

Cytokinin-dependent and cytokinin-autonomous strains of tobacco callus tissue (Nicotiana tabacum L. cv. 'Wisconsin 38') were grown on media containing sucrose, glucose and fructose, respectively. The tissues were kept 14 days in darkness and then transferred for 9 days to continuous light after which time the fresh weight and chlorophyll content were estimated. The highest chlorophyll concentration was recorded at sugar levels which were either suboptimal (sucrose in the case of cytokinin-dependent strain) or supraoptimal (all other sugars for both strains and sucrose for the cytokinin-autonomous strain) for tissue growth. The chlorophyll concentration was increased when the tissue was cultured on media containing glucose or fructose,i.e. sugars whioh did not support the growth as well as sucrose. Chlorophyll synthesis in the cytokinin-autonomous strain is significantly lower than in the cytokinin-dependent strain. This difference was independent of either sugar source or concentration. These results support the observed inverse relationship between tissue growth and plastid development and the limited metabolic activity of plastids in cytokinin-autonomous tissues.

The germination of the pollen from11 individuals of six wildRosa species was studied. The presence of calcium resulted in increased pollen germination, longer pollen tubes, and in a decrease of the requirement of sucrose concentration in cultivation media. Pollen germination in the medium with Ca reached the values of pollen viability estimated by tetrazolium test in all cases except with roses with balanced heterogamy, of the sectionCaninae. The stimulating effect of calcium was generally most pronounced in the pollen from roses of hybrid nature, such asR. jundzillii, R. canina, and especially in the case of the calciphilous speciesR. eglanteria.

A thin layer of homologous antiserum (against the beet yellows virus - BYV) between the leaf surface and a Parafilm membrane totally inhibited the acquisition of BYV by aphidsMyzus persicae (Sulz.), but it did not affect the inoculation of BYV by infective aphids. BYV transmission decreased with aphids picking up the virus from leaves coated with a normal rabbit serum. Aphids sucking on purified BYV suspension through the Parafilm membrane as well as aphids allowed to probe into leaves of healthy plants spread with an infectious purified BYV suspension failed to transmit BYV. No BYV particles could be detected in eluates from stylets and labia cut off from aphids which had probed on BYV infected plants by electron microscopic examination. The acquisition seems to be the most important phase for the aphid transmission of BYV which is apparently carried on the stylet surface.

Flowering ofChenopodium rubrum seedlings fed different sugars at a concentration of 0.6 and 0.4 M, reap, during a single inductive cycle was stimulated or inhibited in dependence on the conditions of germination and initial growth. Plants allowed to germinate at alternating temperatures of 28 °C and 5 °C showed a slower initial growth and their development was stimulated by some sugars as compared to controls induced in the absence of sugars. Plants germinated at alternating temperatures of 32 °C and 5 °C exhibited a rapid initial growth and flowering was inhibited after induction in the presence of sugars. On the other hand, development proceeded more rapidly in control plants induced in the absence of sugars after germination at the higher temperature than after germination at the lower one. The differences between the two variants quoted above could be observed also after induction by two 16 h dark cycles. Glucose and sucrose were most effective in stimulating flowering under appropriate conditions of germination. Fructose was less effective and the action of maltose was very weak. Xylose, ribose and galactose were innocuous, while arabinose, glucoso-6-phosphate and mannitol were toxic to the plants. The sugars inhibited root growth in all cases and led to an increase in starch accumulation in the underground and overground plant organs. At a concentration of 0.6 M they mostly inhibited the length of the cotyledons and, especially, of the first leaf; at a concentration of 0.4 M growth of the overground organs was stimulated. The results are discussed with respect to the possible ohanges in photoperiodic sensitivity brought about by the rate of initial growth.

Algologically pure strain ofOscillatoria sancta (KÜTZING) GOMONT was cultivated in a phototermostat using a modified medium of Chu-Gerloff. The inhibiting effect of Na-humate on the numbers of cells and dry weight of this blue-green alga was investigated in dependence on polyvalent cations (Ca²⁺, Mg²⁺, Fe³⁺) concentration, nature of associated anions, and pH of the nutrient solution. Moreover the absorption of light due to humate colour was taken into consideration. Humate restricted the uptake of polyvalent cations (especially calcium); its unfavourable effect on the growth of the investigated organism decreased at the optimum pH.

The investigations carried out to find the role of abscisic acid in the phenomena of abscission of flower buds and bolls of cotton (Gossypium hirsutum L. cv. 'H-14') have shown abscisic acid content to be low in retained bolls as compared to that in the abscising ones of the same age, suggesting that relatively higher endogenous abscisic acid content to be promotive of abscission. Abscisic acid applied exogenously either to intact flower buds/bolls or boll explants promoted their abscission. Naphthalene acetic acid not only reduced abscission but also could erase completely the promotive effect of abscisic acid on abscission. Gibberellic acid promoted abscission in intact buds and boll explants but applied to intact bolls it reduced their shedding even more than naphthalene acetic acid. Gibberellic acid could also counteract the promotive effect of abscisic acid in the case of intact bolls but enhanced that of boll explants. All the cytokinin-furfurylamino-purine treatments given other than at the abscission zone promoted abscission. Furfurylaminopurine applied in combination with abscisic acid showed some antagonistic effect in the case of intact bolls and boll explants abscission zone treatments. Ascorbic acid applied at a relatively lower dose (0.025 mM) reduced shedding but applied at a higher dose it showed promotion. Ascorbic acid could erase the promotive effect of abscisic acid on abscission to a significant extent.

Uptake of potassium by rice plants at different stages of growth can be described by a biphasic isotherm in the range of 5 × 10^-5 M and is probably mediated bya multiphasic mechanism in the plasmalemma.

The RNA formed in pollen tubes during 4 hours of growthin vitro was resolved by chromatography on methylated albumine on kieselguhr (MAK) into three principal fractions. Acoording to the labelling from uracil-¹⁴C about 11% was eluted with tRNA and 5 S RNA (low molecular weight RNA), 76% just after rRNA (D-RNA) and nearly 14% was recovered from the column by SDS at 35 °C (TB-RNA). In the presence of actinomycin D at concentration of 30 μg ml^-1 the synthesis of the three classes of RNA was inhibited by 71%, 97% and 70% respectively. On sucrose density gradient the radioactive low molecular weight RNA sedimented at 4 S-5 S which suggests that one or both of these RNA species are synthesized in pollen tubes. The D-RNA eluted from the MAK column is polydisperse in size exhibiting a wide range of sedimentation values up to about 35 S with a large peak at 9 S-10 S and two smaller peaks at 14 S-15 S and at about 23 S. The rapid labelling and the polydisperse rather low molecular weight character suggest that the D-RNA is a heterogeneous population of mRNA. The sedimentation profile of TB-RNA was similar to that of D-RNA. The RNA synthesized in the presence of³²PBO3-₄ or uracil-¹⁴C exhibited no radioactivity peaks corresponding to sedimentation peaks of rRNA.

Behaviour of CMV, PVY and BYV was investigated in serological precipitin drop as well as gel diffusion reactions using crude extracts from infected plants and antisera against intact viruses. Gel diffusion reaction of PVY was positively influenced by degradation of viral particles with pyrrolidin while gel tests with CMV and BYV were influenced negatively. Antiserum and antigen titers of CMV, as determined in gel diffusion tests, were 4 to 8 times higher than in drop tests. The titer of PVY antigen, as determined in gel diffusion test, was the same as in drop test. Finally the titer of BYV antigen was 16 times lower in the Ouchterlony tests. On the basis of the ascertained differences in the behaviour of PVY and BYV the pyrrolidin degradation may be recommended for PVY but not for BYV. Diagnosis of PVY or BYV by testing crude extracts from infective sources for the presence of soluble antigen is not successful for the time being.

Peroxidase and polyphenol oxidase activities in malformed mango inflorescences of 'Himsagar' and 'Bombay green' oultivars wore found to be increased considerably following infection byFusarium moniliforme var.subglutinans. Whether such increased activities were due to their synthesis by the pathogen or the host, or both, was not studied although it was found that the pathogen was incapable of producing the enzymesin vitro. The activities of both the enzymes in infected tissues were found to increase considerably during the experimental period. It was found that activities of polyphenol oxidase were inhibited in the presence of sodium diethyldithiocarbamate and phenylthiourea; the former acted as chelating agent of Cu of the enzymes and the latter as a competitive inhibitor. Similarly, peroxidase activity was found to be inhibited by cycloheximide which acted as inhibitor of enzyme protein synthesis. The fact that the 'Himsagar' cultivar showed greater enzyme activity than the 'Bombay green' cultivar possibly suggests its higher resistance to the pathogen.

Treatment with cannabis induces a partial inactivation of the spindle apparatus, and an unequal separation of the chromosomes. There is more or less a tendency to с-mitosis at higher concentrations and to multipolar anaphases at lower concentrations like so many other narcotic substances. The MI value decreases linearly and sharply with the increase of concentrations used,i.e. cannabis had a severe mitodepressive effect. Long treatment for 24 h caused the death of all colls examined.
Cannabis causes a complete dissolution of the matrix substance of the chromosomes and breaks down the chromatin material of the nucleus to minute granules. This phenomenon was observed in all root tips treated with the cannabis. The same picture was observed after letting the roots recover in water.
The application of cannabis may disturb the extrachromosomal mechanism. This disturbance is restricted to the abnormal diffusion of the spindle organizers in many directions instead of two poles.

Suitable conditions for the fertilizationin vitro in maize have been studied. The germinating capacity of pollen in synthetic media was low; it was confirmed that it might be stimulated by supplementing agar with egg yolk. Application of pollen onto styles overhanging from the culture medium of excised ovaries was examined. After 5 days the styles could be cut off the ovaries, for the pollen tubes had already penetrated the embryo sacs. However, better results were obtained when cultivating ovaries along with segments of the maize cob. Solid media were more suitable for the development of kernels. Some of them germinatedin situ and gave rise to normal plants. From nucellar meristems of young kernels a callus could be derived which, on further cultivation, became green and regenerated shoots and roots. The cells of meristems exhibited a varying number of chromosomes.

The course of the transpiration flow rate (Q_w), of transpiration flow acceleration (Q_w/dt) and of the integrated transpiration flow was determined during an average summer day by repeated measurements according to the method of heat balance and the free water capacity of the tree trunk was estimated. The relations between the transpiration flow rate and the temperature and relative humidity of the air and the vapour pressure deficit measured at the same time in their diurnal course, as well as at the single diurnal terms during the whole time at which measurements were carried out were determined by correlation analysis. The problems linked with the effect of various meteorological conditions during different times of the day, of rain showers, solar radiation and soil water content are discussed. The possibilities of explaining the midday depression of transpiration on the basis of repeated measurements of the transpiration flow rate are evaluated.

The effect of 2,4 dinitrophenol and increased viscosity of the absorption solution on the absorption of phosphorus by excised roots of maize plants was investigated. The concentration of the solution was 0.1 mM KH₂PO₄, the activity of³²P was 52 µCi l^-1. The temperature of the absorption solution was 26 °C, pH 5.5, aeration prior to the experiment. There was 11 of solution for every 1 g of roots. Two basic variants were used for comparison: with non-flowing solution and with solution flow (circulation) of 0.162 cm s^-1, respectively. In all cases, 2,4 dinitrophenol reduced the rate of phosphorus absorption by the roots regardless of the mechanism of phosphorus supply to the roots (diffusion, mass flow). If it is proved that 2,4 dinitrophenol inhibits the active uptake of phosphorus, then the uptake of phosphorus by the roots increased under the influence of mass flow will be active,i.e., connected with energy metabolism.
Raising the viscosity of the absorption solution 3.3 times over that of water by means of potato starch substantially reduced the absorption of the phosphorus transported to the absorption zone by diffusion and practically did not affect the rate of absorption, or the amount of anions transported to the absorption area by mass flow.