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Sunflower inbred lines testing on resistance to Sclerotinia sclerotiorum

Sunflower breeding programs in the Republic of Croatia have over 30-year tradition, and they be realized through different scientific projects and programs in frame of the Agricultural Institute Osijek (Mijic et al., 2004 ; Krizmanic et al., 2005). Main goal of this program is creation of new superior hybrid with high grain yield (above 5 t/ha), oil content (above 50%) and high and stabile oil yield. Special attention is given to creation of lines with emphasized tolerance to dominant pathogens. Sunflower breeding on resistance/tolerance to main diseases is the best way to control them and environmentally friendly as well (Fick and Miller, 1997 ; Miller and Fick, 1997 ; Skoric et al., 2002 ; Vrataric and Sudaric, 2004). This field inbred lines testing as well as the later investigation in biotechnological laboratory will contribute to higher efficiency of sunflower breeding program by choosing more tolerant lines to creation of new hybrids. Investigation was conducted during 2005 at the Agricultural Institute Osijek experimental fields on 30 trial members. Twelve cytoplasmatic male sterile (CMS) inbred lines (L-97 A, L-193 A, L-115 A, G/04 A, L-301 A, L- 189/II A, L-101 A, L-13 A, L-205/II A, L-205 A, L-81 A, L-83 A), seven sterile single-crosses (possible mother component for three-way hybrids) (G/03 A x L-104 B, G/03 A x L-14 B, G/03 A x L-282 B, G/03 A x L-272 B, G/03 A x L- 102 B, G/03 A x L-190 B, G/03 A x L-302 B), five male fertile lines (L-14 B, L-272 B, L-16 B, L-302 B, L-190 B), four restorer-fertility lines (PI 12/99 R, O3G R, RFS-89 R, O3 MR) as well as two recently recognized hybrids (Favorit and Apolon), all selected at the Agricultural Institute Osijek, Croatia, were used in this study. Each line was sown in two 5 meter long rows and 3 replications. One row of each line was control and the other served for artificial infection. In each replication 7 plants of each line was artificial inoculated in a button stage (R2 according to Schnieter and Miller, 1981). Sunflower stems were inoculated on 7th July by parts of sclerotia originated from sunflower and collected year 2004 at the location around Osijek. Peaces of sclerotia (around 0.5 cm in diameter) were incorporated into holes on stems made by penetration of wooden sharp pencil. After we put sclerotia into a hole, wound was closed by peace of wet cotton and aluminium foil (Vasic et al., 2004). The infection is evaluated three times after inoculation by measuring length of lesions on stems. First evaluation is done one week after inoculation, second two, and a third and final measurement three weeks after inoculation. Analysis of variance (ANOVA) and LSD test were processed by Statistical Analysis System Version 8.2 (SAS Institute). Data were previously tested for a normal distribution. The smallest lesion was recorded for cytoplasmatic male sterile line L-83 A. Also, L-190 B (male fertile line) and O3 MR (restorer-fertility line) according to measurements belong to group of more tolerant lines in comparison to other 24 trial members including recognized hybrids Apolon and Favorit. These three lines could be possible parental lines for creation of one a new hybrid which will be possibly more tolerant to white mold, at least in comparison with these two recognized hybrids used in trial. This could be further investigated in some new trials. However, it is important to point-out that this hybrid maybe could not have desirable other important agronomic traits such as high and stabile grain and oil yield, 1000 seed weight, plant height, head diameter, etc.

sunflower ; inbred-lines ; resistance ; S. sclerotiorum

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