In 1985-1989 in conditions of temperate warm and dry climatic zone (Nitra, Slovakia) there was observed the productive ability and quality of 3 groups of winter catch crops: early (hybrid of winter turnip rape Perko PVH, winter rape cv. Silesia); medium-early (rye, vetch-rye mixture); late (wheat, vetch-wheat mixture). It was confirmed that it is reasonable to grow early and medium-early winter catch crops. Brassicaceae catch crops in 3 from 4 years were suitable for harvest by mowing already in the 1st decade of April. The rye and vetch-rye mixture followed. Wheat catch crops did not provide enough green feed till the 1st mowing of perennial fodder crops. Medium-early winter catch crops were the most productive. Brassicaceae catch crops had a lower content of fibre and higher concentration of all macroelements in comparison with the catch crops of the cereal type. The harvest index 2 for nitrogen was within the interval of 105-241.3, for phosphorus 17.9-43.3 and potassium 76.1-500.6.

Flowers of the organ number (meristic) mutant clavatal-1 of Arabidopsis thaliana (Brassicaceae) were studied to examine timing and patterns of floral organogenesis as compared to the wild type. All clavatal-1 flowers examined had four- instead of two-loculed gynoecia; half showed increased numbers of stamens; and 10% formed increased numbers of sepals. An inflorescence plastochron index was used to establish the timing of developmental events during flower organogenesis. clavatal-1 flowers initiate faster but grow more slowly than in the wild type. The stages of sepal and stamen initiation were prolonged compared to those of the wild type. Although gynoecial initiation was not prolonged, the preceding stage was and it was characterized by a proliferation of meristematic cells above the initiating stamens. The clavatal-1 flower apex did not become wider than that of the wild type until after the establishment of the gynoecium. We propose that clavatal-1 is a heterochronic mutant, where flower organ number increases are due partly to prolongation of organ initiation stages.

Few studies have examined the potential for pathogens with complex life cycles to cause selection on their required alternate ( = intermediate) hosts. Here the effects of two fungal pathogens on an herbaceous mustard, Arabis holboellii were examined. One pathogen species uses A. holboellii as a primary host, the other uses it as an alternate host. This plant-pathogen system is especially interesting because the host, A. holboellii, is apomictic; thus individuals reproduce exact copies of themselves. Despite this mode of reproduction, A. holboellii populations are surprisingly genetically diverse. Could frequency dependent selection by pathogens be maintaining clonal diversity? This study assesses the potential for selection by pathogens. In a controlled greenhouse experiment it was showed that there is heritable variation in A. holboellii's resistance to the rust, Puccinia monoica, and that host fitness is severely reduced by P. monoica infection in both the greenhouse and under natural conditions. Field observations indicate that host clones are also differentially susceptible to the short-cycled rust, P. thlaspeos, and that host fitness is reduced by infection to this pathogen as well. Although the preconditions for pathogen-mediated selection are present, frequency-dependent selection by pathogens is unlikely to be important in structuring populations of Arabis holboellii because multiple host genotypes are susceptible to the same inoculum and the pathogen has a long generation time

Unilateral pollen-pistil incompatibility within the Brassicaceae has been re-examined in a series of interspecific and intergeneric crosses using 13 self-compatible (SC, Sc) species and 12 self-incompatible (SI) species from ten tribes. SC x SC crosses were usually compatible, SI x SC crosses showed unilateral incompatibility, while SI x SI crosses were often incompatible or unilaterally incompatible. Unilateral incompatibility (UI) is shown to be overcome by bud pollination or treating stigmas with cycloheximide -features in common with self-incompatibility. Treating stigmas with pronase prevents pollen tubes from penetrating the stigma in normally compatible intra-and interspecific pollinations. The results presented show that the presence of an incompatibility system is important in predicting the outcome of interspecific and intergenerie crosses and, combined with the physiological similarities between UI and SI, would suggest an involvement of the S-locus in UI.

Unilateral pollen-pistil incompatibility within the Brassicaceae has been re-examined in a series of interspecific and intergeneric crosses using 13 self-compatible (SC, Sc) species and 12 self-incompatible (SI) species from ten tribes. SC X SC crosses were usually compatible, ST X SC crosses showed unilateral incompatibility, while SI X SI crosses were often incompatible or unilaterally incompatible. Unilateral incompatibility (UI) is shown to be overcome by bud pollination or treating stigmas with cycloheximide-features in common with self-incompatibility. Treating stigmas with pronase prevents pollen tubes from penetrating the stigma in normally compatible intra- and interspecific pollinations. The results presented show that the presence of an incompatibility system is important in predicting the outcome of interspecific and intergeneric crosses and, combined with the physiological similarities between UI and SI, would suggest an involvement of the S-locus in UI.

The extent of natural variation among wild type Arabidopsis thaliana L. Heynh for response to environmental stimuli that affect flowering is poorly documented. The effects of photoperiod and vernalization on the number of rosette leaves at the time of anthesis was measured for 32 Arabidopsis ecotypes. All ecotypes were vernalized 24 days at 4 C under continuous illumination. Vernalized and nonvernalized plants were transplanted into 8- (short-day) and 20-hour (long-day) photoperiods in controlled environment growth chambers. Two ecotypes failed to flower after 110 days. Mean leaf number was less for all ecotypes under long day compared to short day. Sixteen ecotypes responded to vernalization; eight had reduced leaf number regardless of photoperiod, and eight had reduced leaf number only under short day. Two ecotypes required vernalization to flower in this study. For three ecotypes, vernalization and short day resulted in a reduction in leaf number whereas vernalization and long day resulted in increased leaf number. Documentation of the effects and interactions of photoperiod and vernalization across many ecotypes provides a broader range of described natural variation for genetic and physiologic study.

The repellent effect of enriched neem oil, Azadirachta indica A. Juss, was tested on adults of Schistocerca gregaria Forskal. For this purpose enriched neem oil was applied at the rate of 10 l/ha to one of the two plants of Schouwia thebaica WEBB (Brassicaceae). After the application, 120 adults were released into the cage. The second plant, in the same cage, remained untreated. S. gregaria consumed 100 % of the leaves of the untreated S. thebaica. 244 hours after the application and after that untreated plant was consumed, the adults start feeding on the treated plant. In a second repellent trial, 120 adults were transfered into a cage where only a treated plant of S. thebaica was present without an alternative of untreated plant. 98 locusts that means more than 80 % of the initial population size died within 10 days. On the 11th day the rest of adults start feeding on the treated plant.