Growth requirements ofCuscuta reflexa

M. K. Bhattacharya

Biologia plantarum 1976, 18:415-420 | DOI: 10.1007/BF02922543

Studies underin vitro conditions withCuscuta stem tips have revealed that the parasite depends on the host for the supply of all essential requirements for its growth. The vestigial photosynthetic apparatus inCuscuta cannot meet its total requirements. Thus for supply of energy it depends primarily on the host. Inorganic nutrients seem to be of secondary importance and perhaps help to some extent in its independent metabolic pool. Carbohydrates, particularly sugars, are presumably tapped by the parasite from the translocating channels of the host and further utilised for its own growth. Besides sugars, which form the carbon and...

Role of abscisic acid in the phenomena of abscission of flower buds and bolls of cotton (Gossypium hirsutum L.) and its reversal with other plant regulators

S. K. Vakma

Biologia plantarum 1976, 18:421-428 | DOI: 10.1007/BF02922545

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...

Influence of mutagenic factors on the epidermis of tomatillo, currant tomato and tomato

S. K. Mahna, D. Singh

Biologia plantarum 1976, 18:429-435 | DOI: 10.1007/BF02922547

Epidermal features of control, 16 treated and 7 mutants ofPhysalis ixocarpa BROT. (tomatillo),Lycopersicon esculentum MILL. (tomato) andL. pimpinellifolium MILL. (currant tomato) are studied. Although the distribution, ontogenesis and mature structure of stomata in control as well as in treated and mutant plants were similar, the mutagens reduced the stomatal abnormalities which were abundant (60%) inP. ixocarpa. Maximum rectification was found after combined treatment of gamma radiation (5.16 C kg^-1 [= 20 kR]) + 1 % dimethyl sulphate. Methyl ethane sulfonate, gamma radiation and gamma radiation + DMS caused an...

The regeneration of the tips of the rhizomorphs ofsphaerostilbe repens

B. Botton, P. R. Ly

Biologia plantarum 1976, 18:436-441 | DOI: 10.1007/BF02922549

The tips of the rhizomorphs ofSphaerostilbe repens transferred on agar medium regenerate some aggregated organs without an intermediate mycelium stage. Each extremity of the drawn rhizomorphs can give rise to eoremia on its air face and to rhizomorphs on the contact with tho culture medium. These heterogeneous environmental factors impose polarized regeneration, easily inverted, upon the rhizomorphs. Nevertheless, a residual and stable polarity remains; it is attributed to the apex which is more capable of bearing new organs than the other extremity. Tho efficiency to regenerate depends on the ago of collulos and on tho size of tho rhizomorph...

Tryptophan synthase activity, tryptophan and serine contents in pea (Pisum sativum L.) plants during their ontogenesis

V. Horák

Biologia plantarum 1976, 18:442-449 | DOI: 10.1007/BF02922551

Considerable changes in tryptophan synthase aotivity occur during the ontogenesis of pea plants (Pisum sativum L.) in their individual parts. Maximal tryptophan synthase activity is connected with the vigorous growth period of the individual organs and of the entire plant. The content of free serine which is present in excess and is one of the substrates in the reaction catalyzed by tryptophan synthase, also changes, as well as the content of free tryptophan, the product of the reaction. The changes in the contents of these amino acids do not correspond to the variation in tryptophan synthase activity and mainly follow the alterations in the...

Absorption, translocation and metabolization of phosphates bycuscuta gronovii willd. Seedlings during their preparasitic stage

A. Fer

Biologia plantarum 1976, 18:450-459 | DOI: 10.1007/BF02922553

During their short preparasitic stage, dodder seedlings are able to absorb phosphates, by means of their rudimentary root. The absorbed phosphorus is translocated into the stem of the young parasite and metabolized.

Absence of biological activity in oxidation products of indoleacetic acid

F. Sabater, J. Cuello, J. Sanchez Bravo, M. Acosta

Biologia plantarum 1976, 18:460-463 | DOI: 10.1007/BF02922555

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.

Phosphorus absorption by intact maize plants from flowing solutions influenced by 2.4-dinitrophenol and viscosity of solution

Radmila Čížková-Macůrková, Z. Laštůvka

Biologia plantarum 1976, 18:464-468 | DOI: 10.1007/BF02922556

The investigation of phosphorus absorption by intact plants during a short period has above all confirmed the validity of the results obtained in the foregoing study of the kinetics of absorption by excised roots. Further, the results show the unquestionably important role of mass flow in transporting ions to plant roots, mainly at lower and medium concentrations, that is, from about 0.1 to 10 mM. Under conditions of growth close to the optimum, the supply by means of mass flow can be sufficient even at lower concentrations of phosphorus, such as 1.47 mM KH₂PO₄, or the absorption of phosphorus by plants can be higher than...

The study of the conditions for the fertilizationin vitro in maize

Z. Sladký, L. Havel

Biologia plantarum 1976, 18:469-472 | DOI: 10.1007/BF02922557

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...

Effect of hydration level in primary bean leaves on the activity of photosystems 1 and 2 in isolated chloroplasts

Jana PospíŠilová, J. Zima, Z. Šesták

Biologia plantarum 1976, 18:473-482 | DOI: 10.1007/BF02922558

Water stress in the leaves was induced by gradual decreasing of substrate moisture in five-day cycles.The hydration level of the leaves was characterized by their water potential (ψ_w), osmotic potential (ψ_s), pressure potential ψ_p and water saturation deficit(ΔW _sat ).The activities of Photosystems 1 and 2 were determined polarographically with Pt/Ag(AgOH) electrode as changes in oxygen concentration in chloroplast suspensions. The shape of light curves of Hill reaction was not influenced by leaf (ψ_w), hence both quantum efficiency and dark phase of this...

Systems Analysis and Simulation in Ecology

Danuše Hodáňová

Biologia plantarum 1976, 18:420 | DOI: 10.1007/BF02922544

BLV Naturführer. Pilze. Alle wichtige Pilze nach Farbfotos bestimmen

Vlasta Čatská

Biologia plantarum 1976, 18:428 | DOI: 10.1007/BF02922546

Environment and the Experimental Control of Plant Growth

Ingrid Tichá

Biologia plantarum 1976, 18:435 | DOI: 10.1007/BF02922548

Epidemiologische Aspekte der Krankheitseresistenz von Kulturpflanzen

J. Brčák

Biologia plantarum 1976, 18:441 | DOI: 10.1007/BF02922550

Ökologie der Pflanzen. 2., verbesserte Autlage. Uni-Tasehenbücher Band 232

Ingrid Tichá

Biologia plantarum 1976, 18:449 | DOI: 10.1007/BF02922552

Pollen

Věra Balatková

Biologia plantarum 1976, 18:459 | DOI: 10.1007/BF02922554