The occurrence of Fusarium spp. and associated mycotoxins in asparagus spears was evaluated in Poland in 2002 and 2003 and in Germany in 2002. Spears of two cultivars, Eposs and Gijnlim, were collected from two locations in Poland, Swidwowiec and Poznan, on sandy and sandy loam soil, respectively. Fusarium oxysporum and F. proliferatum were detected at an average incidence of 38.3% and 15.8% in the spear sections sampled, respectively. In stands of 11 (tested) cultivars of asparagus sampled in Germany on sandy soil, the same species dominated, however, they were less frequent than in Poland (26.6% and 5.6% of the spears infected with F. oxysporum and F. proliferatum, respectively). Chemical analyses revealed that fumonisin B 1 (FB 1 ) and moniliformin (MON) were present in some of the spears sampled in Poland. FB 1 was not found and MON was not assessed in spears sampled in Germany in 2002, but F. proliferatum was able to form the toxin in vitro in the range from 101.4 up to 205.8 lg/kg maize kernel substrate. Asparagus samples in Poland contained FB 1 at up to 5.6 lg/kg spear fresh weight. The highest MON concentration (1350 lg/kg) was detected in cultivar Eposs in Marcelin, Poland, in 2002. MON and FB 1 were found in spears infected by both F. oxysporum and F. proliferatum, however, only the latter fungus was able to synthesize both toxins.www.blackwell-synergy.com
Effect of Temperature on the Yield and Quality of Broccoli Heads
The effect of temperature on the yield and quality of broccoli heads was determined. The study involved three cultivars: Cruiser, Skiff and Fiesta. The seedlings were planted on five different dates in 1995 and 1996, nine in 1997 and eight in 1998. The length of time from planting to the first harvest for all the 27 cultivation periods was divided into three equal parts determining in this way three phases of growth. The time of harvest was defined as the fourth phase. Temperatures on a scale from 0°C to 40°C were divided into five-degree ranges. Then, for the four growth phases, correlations were determined between the number of hours at a temperature in the five-degree ranges and the total yield, the percentage of loose heads and the percentages of heads with uneven surface or non-uniform buds.
The length of time at a temperature in the range of 15-25°C during the first growth phase after planting and the phase preceding harvest had the greatest influence on total yield. Longer times at temperatures above 20°C contributed to smaller yields. The longer was the length of time at a temperature ranging from 20 to 25°C during the phase preceding harvest and at a temperature ranging from 5 to 15°C during harvest, the lower the percentage of heads with uneven surface was observed. Longer periods with temperatures above 20°C at harvest time contributed to the loosening of heads.
The research was aimed to elaborate a method for selection of male plants (XY, YY) and female ones (XX) as well as for identification of supermale genotypes (YY) among male phenotypes. The population obtained by self-pollination of andromonoecious plants was analysed. In order to identify the bands differentiating the male from the female genotypes, Bulk Segregant Analysis (BSA) was carried out. Primers identified by BSA analysis were used for RAPD amplification on the template of the male and female individuals. Among the products obtained by the use of primer OPB-20, some bands were linked with sex. A band of about 700 bp was found in all female plants, and in 4 phenotypically male specimens. In the male plants, the band showed a much lower intensity, compared with the female specimens. It seems that this fragment can be linked to the X chromosome in the investigated specimens. In the female specimens with XX karyotype, template duplication occurs and hence the band intensity is twice as high as in the XY karyotype. Three male plants did not include the OPB-20-700 fragment so they could potentially have the supermale (YY) karyotype. If the obtained marker proved its usefulness for identification of supermale plants, it could become a valuable tool facilitating breeding work.
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