During the last several years the new interest to flax appeared in Europe and the flax area in Portugal increased. Such situation demands great efforts of breeders to choose the best commercial varieties for Portuguese conditions and, possibly, to breed a new ones.
In 1997 35 accessions were repatriated from All-Russia Institute of Plant Industry, named after N.I. Vavilov (VIR). The main aim of the evaluation was to choose the best initial material for further breeding on the basis of native germplasm, adapted to special conditions of the country environment. Trials were made also to answer the question: at what time of the year flax must be sown in southern areas? The comparison of two variants of sowing time showed, that the results of spring sowing was not so good as that of winter one. The height to inflorescence and total plant height in spring sowing was at an average 10 cm less, then those in winter sowing. That was the reason of comparatively low yield of the straw in the first variant. The grain yield was also not so good as in winter sowing trial although, the seeds size (the weight of 1000 seeds) was practically the same and branching of inflorescence with the number of balls did not differ significantly. Additionally, as spring of 1999 was hot and dry, the trial of spring sowing had no success. It should be mentioned that all accessions of “spring” and “winter” type lived through the Portuguese winter perfectly. They could only be distinguished by the shape of the plants during the coldest time of the year.
The evaluation of Portuguese germplasm revealed perspective initial material for breeding in bough directions: for oil and fibre production. Marta (k-6487) has a sufficient seeds production and very big seeds. 3 accessions (k-6083, k-6084, k-6085) showed good plants height and straw yield and could be used in breeding for fibre. 2 accessions (k-6085, k-6145) have stable characters in spite of environmental changes. All the accessions, revealed by agronomic characters were included in breeding program.
During the last several years the new interest to flax appeared in Europe hence to the economical policy in the European Community. Thus the flax area increased in many European countries, including Portugal. Flax crop has a very long history in Iberian Peninsula and also in Portugal. It's utilization comes from Prehistoric Age, evidenced through vestiges left in caverns and other archaeological discoveries . Seeds not carbonized, dated at Neolithic period, collected in 1945 by the Priest Eugène Jalhay, in Castro of Vila Nova de S. Pedro, are the oldest discoveries related to the flax crop in Portugal [2-4].
More recent are the discoveries in stations of Bronze Age [5,6]. One of them, an axe clothed by flax tissue, which was found in a locality named Ourique, confirms also the existence of a weaving industry . The flax crop had a great expansion in the Middle Ages, as attested by numerous and several types of documents and references , and only in the middle of the XIX century suffers a reverse with the introduction of cotton fiber. However, its decline had already begun to be forewords, not having this crop benefited with the development given to the industrialization in the XVII century by the Count of Ericeira, and in the XVIII century by the Marquis of Pombal .
But for many years interest to flax decreased in the country and many farmers stopped growing this crop. On the other hand, foreign commercial varieties in the last decades replaced the land races of many agricultural plants, including flax. Thus a big part of the local genetic material was lost. With such situation there was a great necessity for Portugal to restore and improve the genetic resources collection to open the possibility of further flax breeding.
As we said above, the fiber obtained from this plant has been replaced by others natural and synthetic fibers. On the other hand, in some regions of Portugal, still today, the production of this raw material prima assumes great importance to the workmanship, such as table-clothes and high quality flax clothes, which have high market-rate .
The main aim of the current evaluation was to choose the best initial material for further breeding on the basis of native germplasm, adapted to special conditions of the country environment. Traditionally flax breeding goes in two main directions: 1. to choose tall plants with one stem and small inflorescence on the top of the stem – for fiber extraction; 2. to choose short branched plant with big inflorescence – for seed production. So, we had to choose initial material for both breeding directions. Trials were made also to answer the agronomic question: at what time of the year flax must be sown?
Materials and methods
In 1997 some part of flax collection from All-Russia Institute of Plant Industry, named after N.I.Vavilov (VIR) was brought to Portugal. This material included 35 accessions of Portuguese origin. Some of them were collected by Vavilov during his expedition to Portugal in 1922, others were brought later from Portugal by another VIR expedition, and the third part was introduced to Russian collection from France.
All accessions were sown on the plots of 1 m2 in the beginning of December of 1997, in the middle of February of 1998, in the end of November of 1998 and in March of 1999. The fist and the second trials were sown in one repetition, hence the lack of the seeds. The third and the forth variants were sown in two repetitions.
The stages of vegetative period, straw and seed yield, and the weight of 1000 seeds were measured for the whole plot. 20 plants in 1998 and 10 plants in 1999 from each plot were chosen to measure the height to inflorescence, the total plant height, inflorescence brunching, the number of balls and branching of the plant.
Results and discussion
In different climatic conditions flax could be sown both as spring and winter crop, although the species does not have a true winter type. Semi-winter type of flax, originating from coasts of Black and Caspian Seas were deeply evaluated in Russia . That type of plants differed from the others by having many stems, prostrated on the soil. When sown in autumn in soft climate of low latitudes, plants stop their development for the period of cold and short day light. With the beginning of spring they continue to grow. Besides, flax can stand the temperature of –5 C. So called “winter” varieties can grow perfectly, being sown in spring, because for turning the development to flowering, they don’t need to be frozen.
In our trials all accessions lived through the Portuguese winter perfectly. During winter two main types of plants could be distinguished. "Spring" type of plants had one, rarely two or three stems. The majority of "winter" type accessions had several stems, prostrated on the soil. With the increase of temperature those prostrated stems go up, and at the stage of bud formation they are not already lying on the ground. In spring sowing trial those “winter” accessions also have several stems. At fist they lie on the soil, but go up very fast. May be this ability of prostrating on the soil, gives them a possibility to stand even more cold winter. It is very interesting, that in spring trial many accessions had statistically sufficient increase of plants brunching (Tabl.1). Being sown in autumn of 1998, many accessions decreased brunching even relatively to that ones of 1997. To discover the reason of this phenomenon special trials are needed.
The spring of 1998 was cold and wet and the crop had a sufficient yield. But spring of 1999 oppositely was hot and dry and this trial had no success. The comparison of two variants of sowing time in the first year of evaluation showed that results of spring sowing was not so good as that of winter one. The height to inflorescence and total plants height in spring sowing was at an average 10 cm less, then those in winter sowing (Tabl.1). That was the reason of comparatively low yield of the straw in the first variant. The grain yield was also not so good as in winter sowing trial although, seeds size (the weight of 1000 seeds) was practically the same (tabl.2). Branching of inflorescence and the number of balls did not differ a lot in winter and spring sowing trials (tabl.3). The comparison of two seasons of flax growing in the south of Portugal, showed that the best is the winter sowing variant. In spring sowing without irrigation there is a very big risk of losing the crop.
Season of 1997-98 was more favorable for flax both in winter and spring, and it gave a possibility to compare the influence of growing conditions on different accessions. As it was discussed already, the lack of water in spring sufficiently reduced the height of all genotypes. Some accessions decreased there height even for 20 sm. But K-6085 (N 44215) and K-6145 (N 10077 Flord) had much more stable phenotypes of plants height, thus having stable yield of seeds and straw. Next year was not so good for flax, even sown in autumn. In tables one can see, that all agronomic characters deteriorated in 1998-99. Two accessions, described above, again showed sufficient stability of evaluated traits, except seeds yield and some variation of vegetative period. So, they could be used as an initial breeding material for stable varieties, adopted to Portuguese conditions.
Among evaluated accessions, both types (fibre and oil) could be found. Maximum height was displayed by K-6083 (N 44211), K-6084 (N 44212) and K-6085 (N 44215). The best of them was K-6084, having better straw yield and stable early maturation. As an initial material for linseed breeding, K-6487 (Marta) could be recommended. This accession has largest seeds (weight of 1000 seeds is approximately 9 gr.) and seeds yield.