Abstract

This paper summarises the effects of breeding works upon the development of winter and spring oilseed CMS lines, restorers and composite hybrids bred at Plant Breeding and Acclimatization Experimental Station Malyszyn.

The results, we have obtained hitherto allowed to introduce into the State Official Trial five winter and three spring composite hybrids of oilseed rape. In 1999 the first Polish-French composite hybrid named Margo was introduced on the Polish Variety List.

Introduction

Several traditional varieties of winter oilseed rape were bred at Plant Breeding and Acclimatization Experimental Station Malyszyn. During the 1980’s and 1990’s varieties Mar, Leo, Polo, Marita, Kana and Gara were developed and introduced into production which increased the yield and improved the quality of seeds. However, better yield results may be also obtained by the exploitation of the heterosis effect.

Breeding activities towards the development of hybrids of oilseed rape started at the Experimental Station Malyszyn in 1993. From the beginning the main aim of our works was the creation of CMS ogu lines with good combining ability, good winter resistance and well adapted to specific soil and climatic conditions of Poland. Intensive investigations are performed towards to development of winter and spring restorers with low content of glucosinolates. However, because of the lack of proper restorers winter and spring composite hybrids of oilseed rape have been bred hitherto.

Materials and methods

CMS ogu lines

The source of CMS ogu system was some winter and spring lines from INRA (France). In the beginning our best varieties and lines of double low winter and spring oilseed rape were transferred on CMS ogu system. After several backcrosses, CMS lines of BC₃ and higher generations were used to create the composite hybrids as well as to general combining ability (GCA) and specific combining ability (SCA) estimate. One should be emphasised that cytoplasm of CMS ogu is very stable in various climatic conditions. Plants which possess this cytoplasm are luxuriant and possess many stem branches with numerous pods. Frosty winters in 1996 and 1997 years allowed us to select some CMS lines with very good winterhardiness. The results in table 1 show, that several of CMS lines has good winterhardiness, better than best polish traditional variety Kana. Lines 16,109,126 and 130 have good GCA. CMS lines bred in Malyszyn Station are very promising material to produce hybrids.

Table 1. Winterhardiness of selected CMS lines in comparison to traditional varieties of winter oilseed rape. Results expressed as differences between winterhardiness degree of CMS lines and checks: Marita, Kana, MAH 1592 in 3 places: Santocko, Klodawa and Malyszyn (winterhardiness in grade 1-9, 1-winterkilled, 9-no damages)

* - CMS lines with good GCA

Restorers

Seeds of winter and spring oilseed rape restorers had been received from INRA (France). All forms had high glucosinolates contents. Firstly, we crossed restorer with high glucosinolate content 60 μM/g from INRA with our low glucosinolate CMS lines. After BC₃ backcrosess we made selection of restorers for low glucosinolate content. Every year we analysed about 500 individual restorer plants. Most of them were taken out after simple glucose test. Only the seeds from left plants were analized using HPLC method. In the first stage we selected two genotypes (J3R and J9R) of spring restorers with much lower content of glucosinolates than others one.

Table 2. Selection of spring oilseed rape restorers to low content of glucosinolates in 1996-1998.

Those two forms were used as donor of restorer genes. Comparisons between developed restorers showed that all-promising forms with low glucosinolates had been found only among combinations (J31R and J66R) with above-mentioned genetic donors. We also stated that the selection among high glucosinolates forms for the decrease of glucosinolate contents was not effective with exception of 2 lines. Mean value of glukosinolates content lowered from 74,6 μM/g in 1996 to 27,5 μM/g in 1998 (Tab. 2). After the three selection cycles the J3R restorer has 7,9 μM/g mean content of glucosinolates.

During severe conditions of winters in 1996 and 1997 all winter restorers were winterkilled. Thus, first selection among restores for decreased of content glucosinolates was in 1998. Now, our investigations and breeding works aimed at the development of winter oilseed rape restorers with good quality traits are continued.

Composite hybrids

We share the opinion that composite hybrids will be eliminated, as restorers with proper quality will allow creating full restored hybrids. Nevertheless, it seems that cultivation of hybrids may increase seed and oil yield to the higher level than traditional varieties.

Approximately 300 winter and 200 spring composite hybrids have been investigated at our Station. Composite hybrids were made using the CMS lines and pollinators bred at Station Malyszyn.

Results of our trials show, that our composite hybrids are more productive and more resistant to frost than French composite hybrid Synergy (Tab. 3). The low winterhardiness of Synergy had big influence on yield loses of this hybrid in Poland.

Table 3. Yielding and winterhardiness of selected composite hybrids and check traditional variety Bor in three trials in 1996/97 season (winterhardiness in grade 1-9, 1-winterkilled, 9-no damages)

Results from preliminary trials conducted in 1998 show, that all 128 investigated winter composite hybrids better yielded than traditional variety Bor. Productivity of composite hybrids bred at Station Malyszyn was higher than that of other well-known varieties, in some instances 140% of classical varieties.

The effect of our co-operation with French colleagues working in INRA and SERASEM was the registration in the Polish Variety List of the first spring composite hybrid named Margo.

Moreover, in 1998 five winter composite hybrids were introduced into Official Trial, and in 1999 we introduced also 3 spring composite hybrids.

General combining ability

The second aim of our investigation is the estimation of GCA and SCA of normal oilseed rape lines and CMS lines. In the table 4 of GCA of 55 inbred lines and heterosis effects of F₁ hybrids of spring oilseed rape are presented. The experiment was carried out in 1996. GCA was significant for seed yield, 1000 seed weight, begining of flowering and fat content. However, it has been proved that GCA was not significant for two traits: plant height and protein content in seed.

Results of the studies revealed: 24 hybrids with significant higher yielding than tester cv. Global, 14 hybrids with significant earlier begining of flowering in comparison with Global, 3 hybrids with significant shorter plants than hybrids with significant higher fat content than Global, 3 hybrids with higher protein content in comparison with tester. The best hybrid J21a yielded 36% higher than tester Global. Nevertheless the average effect of heterosis with respect to the yielding was 10% in comparison with the tester Global.

Table 4. Significance of general combining ability, means of spring oilseed rape hybrids and range of studied traits

x - differences significant at p ≤ 0,01

Results of general combining ability of 64 inbred lines and heterosis effects of F₁ hybrids of winter oilseed rape are presented in table 5. The experiment was carried out in 1996/1997 year.

GCA was significant for seed yield, 1000 seed weight, winterhardiness, beginning and end of flowering, fat and protein content. However, it has been proved that GCA was not significant for plant height.

Results of the studies revealed: 9 hybrids with significant higher yielding than tester (check) cv. Lirajet, 19 hybrids with significant better of winterhardiness, than tester 35 hybrids with significant earlier beginning of flowering in comparison with Lirajet, 22 hybrids with significant earlier ending of flowering, 3 hybrids with significant higher weight of 1000 seeds, 2 hybrids with significant shorter plants than tester, 13 hybrids with significant higher fat content than tester Lirajet. The best hybrids yielded about 40% higher than tester Lirajet. Nevertheless the average effect of heterosis with respect to the seed yield was 16% in comparison with the tester Lirajet. Moreover, Spearman coefficient of correlation between winterhardiness and yield was r_s=0.48** (significant at p ≤ 0.01).

Table 5. Significance of general combining ability, mean of winter oilseed rape hybrids and range of studied traits

*, ** - differences respectively significant at p ≤ 0,05 and p≤0,01

The development of full restored hybrids appears not to be very easy, but presented results allow us to expect that this goal will be achieve in the next future.