Breeding of hybrid varieties of winter oilseed rape based on the MSL-system

 

Martin Frauen and Werner Paulmann

 

Norddeutsche Pflanzenzucht (NPZ) Hans-Georg Lembke KG, Hohenlieth, D-24363 Holtsee, Germany; NPZ_Lembke@t-online.de

 

ABSTRACT

The MSL-system (Male Sterility Lembke) is based on a spontanous mutant selected in the NPZ nursery 1982. With MSL it is possible to produce fully restored rapeseed hybrids without any penalty in yield and quality. First winter oilseed rape hybrid varieties were registered in 1995 and are now covering about 250.000 hectares commercial rapeseed production in Europe. Also spring oilseed rape hybrids were developed based on the MSL-system. Besides yield also agronomic characters like plant length, disease resistance, straw stiffness and oil content have been improved.

 

KEYWORDS

Brassica napus, hybrid breeding, male sterility system, seed production

 

INTRODUCTION

Considerable heterosis for seed yield in F1 hybrids of oilseed rape (Brassica napus L.) has been reported by various authors at the beginning of hybrid breeding in rapeseed (Schuster, 1969; Röbbelen, 1985; Grant and Beversdorf, 1985; Lefort-Buson, 1987; Brandle and McVetty, 1989; Paulmann and Frauen, 1991). These results encouraged for the development of pollination control systems, i.e. male sterility, self incompatibility or gametocide application. First oilseed rape hybrid varieties are worldwide on the market using male sterility or self incompatibility. In winter oilseed rape the first hybrid varieties that were registered in Europe are hybrid-line-associations using the INRA ogura system and fully restored hybrids using the MSL system.

 

DEVELOPMENT OF HYBRID VARIETIES

The MSL-system

The MSL-system (Male Sterility Lembke) is a private system owned by NPZ/Lembke. All known conventional rapeseed cultivars and lines are restorer lines for this male sterility system. Therefore it is very easy to create experimental hybrids and test the combining ability of unlimited numbers of pollinators. The resulting hybrids are fully restored and there are no negative effects on quality and agronomic characters in the final hybrid variety due to the male sterility system.

 

Performance of hybrids

The first breeding lines were converted into the male sterility system by repeated backcrossing. The parental lines of the first hybrid varieties originate from breeding programmes of open pollinated cultivars with known combining ability. The yield increase of these first hybrids is between 5% and 15% compared to the best checks. Using parental lines with better agronomic characters resulted in hybrid varieties of the second generation which are in official trials. Additional to the yield other important traits are improved (Table 1).

 

 

 

 

Table 1:

New hybrid combinations in winter oilseed rape with higher yield and better agronomic characters compared to the check varieties EXPRESS, WOTAN and LIRAJET

 

 

relative seed yield 1998

 

plant

straw

winter

variety

loc 1

loc 2

loc 3

mean

%oil

length

stiffness

hardiness

 

 

 

 

 

 

 

 

 

EXPRESS

99

98

100

99

44,6

161

8,6

7,2

WOTAN

102

102

92

99

43,6

176

6,6

7,2

LIRAJET

100

100

108

103

44,1

175

6,3

7,3

 

 

 

 

 

 

 

 

 

Lin 96685

136

123

119

126

44,9

174

8,4

8,2

Lin 96691

137

124

117

126

45,5

175

8,2

7,5

LSD 0,05: 10% (for yield)

 

Use of marker techniques

Molecular markers i.e. RFLP and SSR are used in the hybrid breding programme to estimate genetic distances of selected breeding lines. Parental lines with a genetic distance lower than a fixed minimum are not worthwhile to be tested in the field. This reduces the work of yield trials. A second application of molecular markers in the hybrid breeding programme is the marker assisted backcrossing of selected lines into the MSL-system. This can reduce the backcrossing steps from five to three backcross generations.

 

Creating distinct gene pools

The narrow genetic basis of oilseed rape is a limiting factor of increasing hybrid performance on the long run. By introducing resynthesized genotypes and using reciprocal recurrent selection procedures the genetic basis has to be extended step by step.

 

Seed production of hybrid varieties

Today the multiplication of rapeseed hybrid varieties is carried out in alternating strips where the pollinator is discarded after pollination. Our experience show that good pollination conditions are neccessary for a sufficient yield on the motherline. The relation of mother and pollinator should be 3:1 and 3 to 5 bee hives per hectare are useful.

 

The seed production in alternating strips is the only possibility to get high hybridity levels. Nevertheless it is also possible, but not yet accepted in Europe, to produce hybrid seed after mixing motherline and pollinator. The advantage of mixed production is a reduction of production costs. Our results of two years with different mechanical mixtures of a hybrid and its pollinator show that even 25% of pollinator in the hybrid did not reduce the seed yield significantly (Table 2).

 

Table 2:

Relative seed yields of pure hybrid variety PRONTO and different mixtures with pollinator

 

Mixture

Pronto/pollinator

loc 1

 1997

loc 2

1997

loc 3

1997

loc 4

1997

loc 5

1997

loc 1

1996

loc 2

1996

loc 3

1996

loc 4

1996

loc 5

1996

loct 6

1996

mean

100/0

100

100

100

100

100

100

100

100

100

100

100

100

95/5

103

99

97

101

95

98

101

97

93

99

95

98

90/10

100

100

99

101

100

102

98

92

99

94

96

99

85/15

96

92

97

100

98

103

102

100

102

97

96

98

80/20

100

95

103

102

104

98

101

95

97

91

99

99

75/25

99

92

95

99

101

101

99

94

94

105

93

98

LSD 0,05: 2%

 

Market situation

The acreage of hybrid varieties based on the MSL-system has increased in Europe from 30.000 hectares in 1997 to around 250.000 hectares in 1999 (Table 3). Several winter oilseed rape hybrid varieties are listed and marketed in Europe. Springtype hybrids are just starting in the market in North America (Table 4).

 

Table 3: Acreage of MSL-Hybrids 1999 in Europe

 

Germany

92.000 hectares

8% market share

United Kingdom

60.000 hectares

15% market share

France

53.000 hectares

4% market share

Denmark

7.500 hectares

 

Switzerland

7.500 hectares

 

Austria

5.000 hectares

 

Sweden

4.500 hectares

 

other: CZ, NL, IRL

6.000 hectares

 

 

Table 4: MSL hybrid varieties listed and/or marketed in Europe and North America

 

 

Variety

listed/marketed in

Winter oilseedrape

JOKER

D

 

PRONTO

D, UK, F, A, CZ

 

PANTHER

D, UK, CH

 

ARTUS

UK, DK, D, S, A

 

KASIMIR

S, PL, LV

 

BUFFALO

PL

 

 

 

Spring oilseedrape

ORAKEL

DK

 

CL 2070

USA

 

220

CAN

 

HyPer Star 100

CAN

 

PF 7528/95

CAN

 

CONCLUSION

The development of oilseed rape hybrids is highly competitive worldwide. A prerequisit of successful hybrid breeding work is germplasm, the knowledge of combining ability and a functional pollination control system. The MSL-system is one part to develop successful hybrid varieties.

 

REFERENCES

Brandle, J.E. and McVetty, P.B.E. (1989): Heterosis and combining ability in hybrids derived from

oilseed rape cultivars and inbred lines. Crop Science, 29: 1191-1195.

Grant, I. and Beversdorf, W.D. (1985): Heterosis and combining ability estimates in spring-planted

oilseed rape (Brassica napus L.). Canadian Journal of Genetics and Cytology, 27: 472-478.

Lefort-Buson, M., Guillot-Lemoine, B. and Dattee Y. (1987): Heterosis and genetic distance in

rapeseed : crosses between European and Asiatic selfed lines. Genome, 29: 413-418

Paulmann, W. and Frauen, M. (1991): Einsatz von biotechnologischen Verfahren in der praktischen

Rapszüchtung. Bericht der Arbeitstagung Saatzuchtleiter, Gumpenstein, 173-182

Röbbelen, G. (1985): Züchtung von Hybridraps. Bericht der Arbeitstagung Saatzuchtleiter,

Gumpenstein, 173-185

Schuster, W. (1969): Vergleich von zwei Zuchtverfahren in der Erhaltungszüchtung von Winterraps.

Zeitschrift für Pflanzenzüchtung 62: 47-62