ABSTRACT

In a network of field trials conducted in 1994 and 1995 in five locations in France, an ``hybrid line`` composite (Synergy) and some classical lines were compared. The locations included various pedo-climatic conditions. Several parameters as growth (aerial dry matter, nitrogen and sulplur absorption), yield components, yield and seed quality (oil, protein and glucosinolates content) were studied.

The results show that there were no significative difference between the two types of material concerning the studied parameters. The ``hybrid-line'' composite and the classical varieties follow the same general models for growth, yield elaboration and seed quality elaboration.

INTRODUCTION

A new varietal type, the hybrid line composites (CHL) appeared on the french market at the bigining of the 90's. This led CETIOM to question itself about the existence of possible differences between this type of genetic material and the classical lines which were cultivated until them. We aimed in particular at realizing a comparative study on the factors of variation of the quality of the seed which are croped from the hybrid line composites and the classical lines. In order to do this, we used the explicative models of rapeseed still existing (TRIBOI-BLONDEL, 1988 ; MERRIEN and RIBAILLIER, 1988). This study also occasioned an approach of the yield elaboration of these two varietal types.

MATERIAL AND METHODS

Experimental device

This study was done in 1994 and 1995 on a network of field trials which were implanted in a large range of pedoclimatic conditions (table 1). Each year, five trials were implanted. In each of them, the CHL Synergy was compared to a classical line (Eurol in 1994 and Goeland or Bristol in 1995).

The main limiting factors which were identified were as follows :

• 9436 : thick growth of weeds ;

• 9434 : marked and increasing water stress from the flowering to the maturity stage ;

• 9517 et 9534 : marked water stress during the end of the crop.

Observations

At the end of winter, at the bigining of the flowering and at the maturity stage, the weight of aerial dry matter, the total nitrogen content and the total sulfur content were determined. At the maturity stage, the number of pods with at least one seed, the seed yield and the thousand seeds weight were calculated. The number of seeds being set up by square meter was calculated from the yield and the thousand seeds weight. The average number of seeds per pod was calculated from the number of seeds and pods by square meter. The content in oil (expressed in percentage of entire dry seeds), in proteins (expressed in percentage of meal) and in glucosinolates (expressed in micromole by gram of seeds at 9% of humidity) of the seeds were established.

Table 1 : Main characteristics of the trials

Location	Year	Charente- Maritime	Côte d'Or	Hérault	Indre	Meurthe et Moselle
Code	1994	9417	9421	9434	9436	9454
	1995	9517	9521	9534	9536	9554
Type of soil	1994	claye-calcareous	claye	silt-claye	claye-silt	claye-silt-sandy
	1995	claye-silt-sandy	claye-silt	sandy-silt	claye-calcareous	silt-claye
Water soil content	1994	70 mm	80 mm	100 mm	60 mm	180 mm
	1995	70 mm	100 mm	80 mm	70 mm	100 mm
Line	1994	Eurol	Eurol	Eurol	Eurol	Eurol
	1995	Goéland	Goéland	Bristol	Goéland	Goéland
Sowing	1994	930827	930830	930908	930831	930825
	1995	940824	940830	940830	940906	940822

RESULTS

Yield components

The great diversity of pedoclimatic conditions of the network is shown by the large gamme of yield which is obtained : from 1.2 to 4.6 t/ha expressed in dry and clean seeds (figure 1). The highest yields are most frequently obtained in trials without water stress. In 1994, the productivity of Synergy (3.4 t/ha in average) is always superior to the one of the Eurol line (2.5 t/ha in average). The benefit of the yield of Synergy compared to Eurol goes from 13% (9417) to 113% (9421). In 1995, the average yields of the two varietal types were equivalent (3.5 t/ha). The gap varies from +17% (9534) to -22% (9554) compared to Synergy.

Figure 1 : Relation between the seed yield and the number of pods by square meter (a), the number of seeds by square meter (b) (Charente-Maritime : n ; Côte d'Or : H ; Hérault : l ; Indre : s ; Meurthe et Moselle : t ; empty symbols : line ; full symbols : Synergy ; 1994 : 4 ; 1995 : 5)

The yield is relatively well expressed by the number of pods by square meter (figure 1a) and even better by the number of seeds by square meter (figure 1b). It does not appear a relation between the yield and the thousand seeds weight or the average number of seeds by pods (not represented). Synergy and the lines of reference have the same type of behaviour.

Growth

Some positive relations emerge from the seed yield and the weight of the aerial dry matter and the nitrogen uptake in this fraction (figure 2). No clear relation is seem between the sulfur uptake at the moment of the fowering and the yield (not represented). In all the cases, the two varietal types do not seem to have a distinct behaviour.

Then, the levels of growth and of nitrogen absorption explain in part the variability of yield. For instance, in 1995, the plots of Côte d'or and Indre owed their good yield to a high production of aerial dry matter, to a high nitrogen absorption and to good harvest indexes (dry matter and nitrogen). Synergy turns out to be more performable than Goeland in Côte d'Or thanks to a slightly superior growth and to better harvest indexes. In Indre, this phenomenon is comparable, but to the advantage of Goeland.

Figure 2 : Relation between the seed yield and the weight of aerial dry matter (DM) at the stage of maturity (a), the nitrogen uptake (Nupt) at the bigining of the flowering (F1) (b) and at maturity stage (c), the SO3 uptake (SO3upt) at maturity stage (d) (Charente-Maritime : n ; Côte d'Or : H ; Hérault : l ; Indre : s ; Meurthe et Moselle : t ; empty symbols : line ; full symbols : Synergy ; 1994 : 4 ; 1995 : 5)

Quality of seeds

The oil content of the entire seeds and the protein content of the meal are strongly negatively correlated, without any effect of the varietal type being observed (figure 3). Yet, an effect ``year'' clearly appears. In 1995, the contents in oil were lower than in 1994, and the protein contents were higher than the ones which could have been reached in the relation which was established in 1994. The conditions of filling up of the seeds were different. The synthesis of protein was favorised in 1995 in the non-lipidic part of the seeds.

A negative relation exists between the yield and the oil content (figure 3b) and between the thousand seeds weight and the oil content (not represented). A good filling up in the end of the cycle did not lead to an increase of the oil content, contrary to what often observed. The beaviour of Synergy is not noticeable in a particular way compared to the lines.

Figure 3 : Relation between the oil content and the protein content of the meal (a) and between the seed yield in clean and dry seeds and the oil content of the seeds (b) (Charente-Maritime : n ; Côte d'Or : H ; Hérault : l ; Indre : s ; Meurthe et Moselle : t ; empty symbols : line ; full symbols : Synergy ; 1994 : 4 ; 1995 : 5)

A positive relation is observed between the meal proteins content and the nitrogen uptake at the bigining of the flowering (not represented) or at the maturity stage (figure 4) in the aerial parts of the plants. No varietal difference appears. For the same nitrogen uptake at the maturity stage, the protein content was superior in 1995 compared to 1994. This could mean a better translocation of the nitrogen uptake to the benefit of the seeds in 1995.

Figure 4 : Relation between the meal protein content and the nitrogen uptake (Nupt) at the maturity stage in the aerial parts of the plants (Charente-Maritime : n ; Côte d'Or : H ; Hérault : l ; Indre : s ; Meurthe et Moselle : t ; empty symbols : line ; full symbols : Synergy ; 1994 : 4 ; 1995 : 5)

The seed glucosinolates contents were approximatively twice higher in 1995 than in 1994. In 1995, the glucosinolate content was all the higher since the number of seeds being set up was lower and since the thousand seeds weight was high (not represented). Nevertheless, one must point out that this relation is strongly influenced by the position of Synergy in Meurthe et Moselle (trial 9554). This type of relation was not put into light in 1994. These results confirm the previous hypothesises : the most unfavorable situations for low glucosinolates contents are those in which a limitation of the number of seeds by square meter after a stress in flowering goes with an important compensation on the thousand seeds weight. No difference linked to the varietal type is put into light.

A positive relation between the glucosinolates content and the ratio ``quantity of sulfur (S) uptake in the aerial parts at the begining of the flowering on the number of seeds being set up'' is observed too (figure 5). The two studied varietal types seem to follow the same general models.

Figure 5 : Relation between the glucosinolates content and the number of seeds by square meter (a) or the ratio ``quantity of S uptake in the aerial parts at the begining of the flowering by number of seeds by square meter (Supt/nb seeds./m²-) (b) (Charente-Maritime : n ; Côte d'Or : H ; Hérault : l ; Indre : s ; Meurthe et Moselle : t ; empty symbols : line ; full symbols : Synergy ; 1994 : 4 ; 1995 : 5)

CONCLUSION

The trials were set up in varied pedoclimatic situations, having trigger of contrasted general behaviours. In these conditions, the two varietal types have presented comparable characteristics.

The growth of Synergy has been very comparable to the one of the lines. No clear difference could be put into light at the level of the elaboration of the yield.

The determinism of the quality of the cropped seeds seems to be same for the two types of plant material : the contents in oil and in protein vary in the opposite direction, the feeding in nitrogen explains the content in protein well, the ratio ``quantity of sulfur (S) uptake in the aerial parts at the begining of the flowering on the number of seeds by square meter'' is well correlated to the content in glucosinolate.

If the potential of synergy seems superior in a quantitative point of view to the one of the studied lines, it seems to obey to the same general models of functioning than the lines.

References

1. TRIBOI-BLONDEL A.M. (1998) : Azote, croissance, rendement et qualité de la graine chez le colza d'hiver. Cahier technique Colza : Physiologie et élaboration du rendement, ed. CETIOM, 134-139.

2. MERRIEN M., RIBAILLIER D. (1988) : Les glucosinolates chez le colza d'hiver. Bulletin CETIOM, 99, 10-14.