Ocena niektórych cech morfologicznych zasobów genowych lnu zwyczajnego (Linum usitatissimum L.) zgromadzonych w latach 1955–1971 w Polsce

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2015

, Jan Bocianowski2, Kamila Nowosad3, Marcin Praczyk1 1

Institute of Natural Fibres and Medicinal Plants

2 _{Poznań University of Life Sciences, Department of Mathematical and Statistical Methods}

3

Wroclaw University of Environmental and Life Sciences, Department of Genetics, Plant Breeding and Seed Production

Adres korespondencyjny autora – J. Bocianowski, e-mail: jboc@up.poznan.pl DOI: 10.5604/12338273.1195679

Evaluation of some morphological traits

of flax gene resources (Linum usitatissimum L.)

collected within 1955–1971 in Poland

Ocena niektórych cech morfologicznych zasobów genowych

lnu zwyczajnego (Linum usitatissimum L.)

zgromadzonych w latach 1955–1971 w Polsce

Key words: germplasm resources, flax, Linum usitatissimum, morphological trait descriptors,

valorisation, canonical variable analysis

Summary

The research materials were Polish varieties and ecotypes of flax, which were chosen from four genotype groups studied for several years. The following flax traits were studied: plant natural height, stem length (technical length), panicle length, stem number of branches, stem thickness, slenderness and 1000-seed weight. The following values were evaluated for each tested trait: mean, minimum, maximum, standard deviation and coefficient of variation. The least significant differences (LSDs) were calculated for each trait and for homogenous groups determination. Correlation between the examined traits was determined by correlation coefficients. The results of one-way analysis of variance (ANOVA) indicate a statistically significant effect of groups on the plant natural height, stem length (technical length), panicle length and slenderness of plants. Eleven significant correlations were observed between the tested morphological traits. The correlation between the examined traits was also presented graphically.

Słowa kluczowe: zasoby genowe, len, Linum usitatissimum, deskryptory cech morfologicznych, waloryzacja, analiza zmiennych kanonicznych

Streszczenie

Materiałem badawczym były polskie odmiany i ekotypy lnu, które wybrano z czterech grup genotypów badanych przez kilka lat. Badano następujące cechy lnu: naturalną wysokość rośliny, długość łodygi (długość techniczną), długość wiechy, liczbę rozgałęzień wiechy, grubość łodygi w środku długości technicznej, wysmukłość łodygi i masę 1000 nasion. Dla każdej cechy oszacowano wartości: średnią, minimalną, maksymalną, odchylenie standardowe oraz współczynnik zmienności. Dla każdej cechy estymowano wartości najmniejszych istotnych różnic, na poziomie istotności α = 0,05 i na ich podstawie wyznaczono grupy jednorodne. Współzależność pomiędzy

obserwo-Grażyna Silska …

86

wanymi cechami oszacowano na podstawie odpowiednich współczynników korelacji. Wyniki

jedno-czynnikowej analizy wariancji (ANOVA) wskazują na istotny statystycznie wpływ grup na wysokość

roślin, długość łodyg, długość wiech oraz wartości określające wysmukłość roślin. Pomiędzy

obserwowanymi cechami morfologicznymi zaobserwowano 11 istotnych statystycznie współczyn-ników korelacji. Współzależność pomiędzy obserwowanymi cechami przedstawiono także graficznie.

Introduction

Flax (Linum usitatissimum L.) is one of the important species cultivated as an oil seed crop in some areas of the world. Flax seeds are used for oil production and also in food industries (Mohammadi et al. 2010).

Polish flax breeding began during the twenty-year period between the First and the Second World War. The first Polish cultivar was Wołożyński. This cultivar

was selected by Cz. Dębski from local populations of flax. He worked on this

cultivar since 1925 in Siedliszcze (Wołożyn District, Lithuania). The Institute of

Natural Fibres and Medicinal Plants (former Institute of Natural Fibres) has a long tradition of gathering the genetic resources of flax. The present collection includes 827 genotypes of the Linum L. genus, including 815 accessions of flax (Linum

usitatissimum L.) and 12 wild species of flax (Silska and Praczyk 2013).

The key features for flax are morphological traits. They are determined mainly by genes with additive effect and are greatly modified by environmental factors (Tyson 1989, Popescu et al. 1999). In fibrous forms they comprise mainly straw yield, the content and quality of the fibre, whereas for oil flax – seed yield, fat content and its chemical composition. The straw yield is closely associated with plant height and technical length (Rolski et al. 2001). Seed yield depends on their 1000 seed weight, number of seeds per capsule and the number of plants per square meter. Therefore, the assessment of quantitative traits which directly or indirectly determines the economic value of flax varieties is a very important task. Determination of variability and mutual influence of individual traits is an important step in the selection of initial materials for breeding from the genotypes in the collection.

The aim of this paper was to systematize the knowledge about the oldest flax genotypes gathered in the collection or bred in Poland.

Materials and Methods

The oldest 49 genotypes of Linum usitatissimum L. used in the study were collected from local populations or bred in Poland (Silska et al. 2014). The Kujawa 1-362 is a Polish local cultivar too, but the sample was received from Agritec Ltd. Company in Šumperk, Czech Republic (Donor Institution Code – CZE 122). Genotypes of flax were created in the period 1955–1971 and included to the

Evaluation of some morphological traits of flax gene resources… 87

collection in four time’s periods (groups): (I) 1982–1984, (II) 1983–1984, (III) 1986–1988, (IV) 1985–1987. The breeding material, based on its origin, was classified as breeding lines, varieties and local cultivars (Table 1). All samples were collected by Institute of Natural Fibres. Genotypes of Linum usitatissimum L. are kept alive in long term storage gene bank facilities of the National Centre for Plant Genetic Resources at Plant Breeding and Acclimatization Institute in Radzików (Institution code – POL003). The genotypes from the collection of Polish flax were examined in field trial without repetition but during three years

2011–2013. The plot size was 1.6 m2. Biometrical measurements of plants were

done on 15 plants collected from middle row of plot. Field trial was held in Experimental Station of Institute of Natural Fibers and Medical Plants in Wojciechów (50°53’48’’ N, 18°23’30’’ E).

The following traits were observed: plant natural height [length from root crown to the top of a stem], panicle length [length from the lowest branches of panicle to the top], stem length (technical length) [length from root crown to the

lowest branches of panicle] (Woyke and Muśnicki 2003), stem number of

branches, stem thickness, plant slenderness [ratio of stem length (technical length) to the stem diameter measured in the middle of technical length] (Woyke and Muśnicki 2003) and 1000 seeds weight. Panicle length was determined subtracting the technical length from plant natural height. Stem thickness was measured in the middle of technical length. Morphological trait descriptors applied in the presented work are used in the International Flax Database (Pavelek 1994, 2006).

The following parameters were evaluated for each tested trait: mean, minimum, maximum, standard deviation and coefficient of variation. One-way analysis of variance (ANOVA) was used to verify the null hypothesis of the lack of group effect on variability of the flax traits. The least significant differences (LSDs) were calculated for each trait and homogenous groups were determined on this basis. Relationships between traits were examined on the basis of correlation coefficients. The multivariate analysis of variance (Chatfield and Collins 1986) was applied to test the null hypothesis of the lack of variability between groups. The Mahalanobis distances (Mahalanobis 1936) were calculated for the analyzed

groups as well as the critical Mahalanobis distances D2cr (at the level of

significance α=0.05). The canonical variable analysis (Rencher 1998) was applied

for visual representation of the multi-trait variability of the analyzed groups. Application of the principal component analysis (PCA) made it possible to create a graphic dispersion of 49 accessions on the plane characterized with respect to all treated traits together. All calculations in the statistical analysis were conducted using the GenStat v. 15 statistical package.

Ta bl e 1 The pa ss por t da ta o f f la x ac ce ss ions a cc or di ng to E ur ope an s ee d ca ta log ue (E U RI SC O ): G enus – L inum , S peci es – u sita tis sim um L. , C oun tr y of or igi n – PO L ( code of the c ount ry in w hi ch t he s am pl e w as or ig ina lly c ol le ct ed or br ed) , I ns tit ut ion c ode – P O L003 ( co de of the Ins tit ut ion w he re the acces si on is m ai nt ai ned – P la nt B re ed in g a nd A cc lim atiz atio n I ns tit ute ) D ane pas zp or tow e ob ie kt ów lnu w edł ug EU RI SC O : R odz aj – L in um , G at une k – us itat is si m um L ., K raj poc hodz eni a – PO L (k od kr aj u ze br ani a lub w yho dow ani a) , K od daw cy – P O L00 3 (k od Ins ty tut u, w k tór ym je st ut rz ym yw any o bi ek t – IHA R) No Nr G roup num be r N ume r gr up y C olle ctin g num be r N ume r ko lekcyj ny A cc es si on num be r N r o bi ekt u A cces si on n am e N az w a o bi ek tu C reat io n' s d at e D at a ut w orze ni a D onor Ins tit ut e C ode a K od daw cy OR IGI N b Poc ho dz eni e 1 I 165 50 8 IN F0 00 37 For tu na 196 9 POL 026 3 2 165 50 1 IN F0 00 52 Iz ol da 196 9 POL 026 3 3 165 56 7 IN F0 00 53 K -401 – POL 4 4 165 61 5 IN F0 00 54 K -471 – POL 4 5 165 58 2 IN F0 00 55 K -378 – POL 4 6 165 57 4 IN F0 00 61 K ot ow ieck i – PO L0 26 3 7 165 57 8 IN F0 00 65 LC SD 200 – PO L0 26 3 8 165 55 4 IN F0 00 95 R 2 /1 – POL 4 9 II 165 65 4 IN F0 01 45 G ol ęci ńs ki – PO L0 26 3 10 165 66 5 IN F0 01 55 K uj aw a 1 -362 196 9 C ZE 1 22 3 11 165 90 7 IN F0 01 56 K -291 – POL 4 12 165 66 6 IN F0 01 57 J.J. – PO L0 26 4 13 165 66 7 IN F0 01 58 Lazu r 195 5 So bó tka 3 14 165 67 8 IN F0 01 66 Pu ła w sk i 2 -43 195 8-04 -14 PO L0 57 4 15 165 68 0 INF 001 67 Pu ła w sk i 2 -13 195 8-04 -14 PO L0 57 4 16 165 67 9 IN F0 01 68 Puł aw sk i O dpor ny 195 8-04 -14 PO L0 57 4 17 165 68 1 IN F0 01 69 Pu ła w sk i Ol iw ko wy 195 8-04 -14 PO L0 57 4 18 165 69 6 IN F0 01 84 Sw ad zi m sk i 195 5 PO L0 26 3 19 165 70 4 IN F0 01 92 Zwi sł y – PO L0 26 3 20 III 165 71 7 IN F0 02 05 A ria dna 198 3-10 -07 PO L0 26 3 21 165 72 7 IN F0 02 15 B ry ta (P et 7 9) 198 3-10 -25 PO L0 26 3 22 165 84 5 IN F0 03 28 W az a 197 8-09 -16 PO L0 26 3

23 III 165 90 9 IN F0 03 93 LC SD 210 195 5 PO L0 26 3 24 165 51 1 IN F0 03 94 M ile niu m 196 6 PO L0 26 3 25 165 91 1 IN F0 03 95 Pet 2 3 197 6 PO L0 26 4 26 165 92 0 IN F0 04 02 177 8/ 17 83 POL 4 27 165 91 8 IN F0 04 03 Lip iń sk a I 197 1-03 -24 POL 2 28 165 91 9 IN F0 04 04 Lip iń sk a II 197 1-03 -24 POL 2 29 165 92 1 IN F0 04 05 Li pi ńs ka III 197 1-03 -24 POL 2 30 165 92 2 IN F0 04 06 Lip iń sk a IV 197 1-03 -24 POL 2 31 165 92 3 IN F0 04 07 Lip iń sk a V 197 1-03 -24 POL 2 32 165 92 4 IN F0 04 08 Lip iń sk a V I 197 1-03 -24 POL 2 33 165 92 5 IN F0 04 09 Lip iń sk a V II 197 1-03 -24 POL 2 34 165 92 6 IN F0 04 10 Lip iń sk a IX 197 1-03 -24 POL 2 35 165 92 7 IN F0 04 11 Lip iń sk a X 197 1-03 -24 POL 2 36 165 92 8 IN F0 04 12 Lip iń sk a X II 197 1-03 -24 POL 2 37 165 92 9 IN F0 04 13 Li pi ńs ka X III 197 1-03 -24 POL 2 38 165 93 0 IN F0 04 14 Lip iń sk a X IV 197 1-03 -24 POL 2 39 165 93 1 IN F0 04 15 Lip iń sk a X V 197 1-03 -24 POL 2 40 165 93 2 IN F0 04 16 Lip iń sk a X V I 197 1-03 -24 POL 2 41 165 93 3 IN F0 04 17 Lip iń sk a X V II 197 1-03 -24 POL 2 42 165 93 4 IN F0 04 18 Li pi ńs ka X V III 197 1-03 -24 POL 2 43 165 93 5 IN F0 04 19 Lip iń sk a X IX 197 1-03 -24 POL 2 44 165 93 6 IN F0 04 20 Lip iń sk a X X 197 1-03 -24 POL 2 45 IV 165 88 4 IN F0 03 71 Puł aw sk i R óż ow y 195 8-04 -14 PO L0 57 4 46 165 88 5 IN F0 03 72 Pu ła w sk i 2 -I -II 195 8-04 -14 PO L0 57 4 47 16 58 89 IN F0 03 76 RJ -15 POL 4 48 165 89 0 IN F0 03 77 RJ -16 POL 4 49 165 89 5 IN F0 03 82 Sva po 197 7 PO L0 26 3 a D on or In st itu te C od e: P O L0 26 – In stit ute o f N at ur al F ib re s — In styt ut W łó ki en N at ur al ny ch , C ZE 12 2 – A gr ite c L td . C om pa ny in S um pe rk , C ze ch R ep ub lic , B re ed in g C en te r i n S ob ót ka — H od ow la R oś lin S ob ót ka , PO L0 57 – S ta te S ci en ce In st itu te o f R ur al D ev el op m en t i n P uł aw y — In sty tu t U pr aw y N aw oż en ia i G le bo zn aw stw a w P uł aw ac h b O rig in (t yp e o f t he a cc es si on b as ed o n i ts o rig in ) – P oc ho dz en ie (t yp o bi ek tu w o pa rc iu o p oc ho dz en ie ): 4 – br ee di ng li ne — lin ia h od ow la na , 3 – c ul tiv ar — od m ia na , 2 – lo ca l c ulti va r – o dm ia na lo ka ln a

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Results and Discussion

Results from the experiment described in this paper were partially presented by Silska et al. (2014). The results of the analysis of variance (ANOVA) indicate a statistically significant effect of groups on the plant natural height, stem length (technical length), panicle length and slenderness of the stem (Table 2).

Table 2 Mean squares from one-way analysis of variance for observed traits of flax

Średnie kwadraty z jednoczynnikowej analizy wariancji obserwowanych cech lnu

Source of variation Źródło zmienności d.f. Plant natural height Naturalna wysokość rośliny Stem length Długość łodygi Panicle length Długość wiechy Panicle number of branches Liczba rozgałę-zień wiechy Stem thickness Grubość łodygi Plant slenderness Wysmukłość łodygi 1000 seeds weight Masa 1000 nasion Groups Grupy 3 1198.37 *** 1079.7 *** 33.913 * 0.9897 0.0306 22598 *** 0.784 Residual Błąd 45 68.57 101.8 9.261 0.5768 0.0199 3273 0.302 * P < 0.05; *** P < 0.001

d.f. – number of degrees of freedom — liczba stopni swobody

Mean values, range (minimum and maximum), standard deviation and coefficient of variation for individual traits are presented in Table 3.

Significant differences in plant height between the four groups of flax genotypes were observed (Table 3). By far, the highest average plant height was recorded for group IV, in which the plants were significantly higher than in the other three plant groups. The lack of significant differences in plant height was found between groups I and II. All of the analyzed genotypes of flax were characterized by a low variation of plant height. The coefficient of variation showed the highest values in group IV, with the highest plant height (Table 3).

Evaluation of some morphological traits of flax gene resources… 91

Table 3 Characteristics of studied groups of flax genotypes for studied traits

Charakterystyka badanych genotypów lnu ze względu na obserwowane cechy

Groups

Grupy

Mean

Średnia Minimum Minimum

Maximum Maksimum Standard deviation Odchylenie standardowe Coefficient of variation Współczynnik zmienności [%]

Plant natural height — Naturalna wysokość rośliny

I 64.55 c 57.5 77.3 6.435 9.97

II 68.62 c 63.7 76.7 4.621 6.73

III 80.14 b 67.5 97.2 8.664 10.81

IV 93.46 a 77.1 105.0 13.97 14.95

LSD — NIR0,05 = 8.17

Stem length — Długość łodygi

I 46.23 c 36.9 61.1 7.436 16.08

II 50.63 bc 44.8 61.0 4.878 9.63

III 59.96 b 43.0 83.2 11.501 19.18

IV 75.14 a 57.0 87.0 13.995 18.63

LSD — NIR0,05 = 9.96

Panicle length — Długość wiechy

I 18.32 ab 15.7 22.5 2.392 13.06

II 17.99 b 12.7 22.7 3.303 18.36

III 21.04 a 14.0 27.5 3.236 15.38

IV 18.32 ab 16.3 20.7 2.020 11.03

LSD — NIR0,05 = 3.003

Number of panicle branches — Liczba rozgałęzień wiechy

I 6.450 a 4.4 7.6 0.9885 15.33

II 6.064 a 4.9 7.0 0.7567 12.48

III 6.148 a 4.5 7.8 0.7060 11.48

IV 5.480 a 5.0 6.5 0.5975 10.90

LSD — NIR0,05 = 1.149

Stem thickness — Grubość łodygi

I 1.844 a 1.64 2.12 0.1559 8.45

II 1.886 a 1.55 2.11 0.1733 9.19

III 1.956 a 1.69 2.13 0.1192 6.09

IV 1.936 a 1.77 2.11 0.1460 7.54

LSD — NIR0,05 = 0.139

Plant slenderness — Wysmukłość łodygi

I 253.4 c 205 366 54.57 21.54

II 270.6 bc 220 326 36.31 13.42

III 312.9 b 203 467 65.81 21.03

IV 385.8 a 322 431 48.20 12.49

LSD — NIR0,05 = 56.45

1000 seeds weight — Masa 1000 nasion

I 5.624 a 4.87 6.88 0.9382 16.68

II 4.989 a 4.33 6.57 0.6791 13.61

III 5.045 a 4.65 5.59 0.2489 4.93

IV 5.096 a 4.57 5.89 0.5253 10.31

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The height of plants in each tested group was presented as the stem length (Table 3). The sequence of mean values of the stem length for the analyzed groups was the same as in the case of plant height. The longest stems were characteristic for group IV of the studied genotypes, while the shortest were found in group I. Plants from the genotype group IV had significantly longer stems than plants in other groups. Variability of the total height of plant was insignificant (Table 3).

The highest mean value for panicle length was observed in group III of studied flax genotypes while the lowest for group II (Table 3). Intra-group variability in all four groups was similar and ranged from 11.03 to 18.36%, similarly to the variability of the features discussed previously.

The number of panicle branches in group IV of the tested cultivars was significantly lower than in the remaining groups (Table 3). The varieties in group IV are therefore characterized by high plant height and stem length and a small number of branches that would show the typical shape of fibrous flax forms, which suggests the usefulness of the plants from group IV for breeding new varieties of fibrous flax. The variability of the number of branches in the research stages was low (Table 3). Mean values of stem thickness were on the same statistical level (Table 3).

Very significant differences in mean values were observed for slenderness. The highest average value was found for the group IV, while the variation for this group was the smallest. In contrast, the smallest slenderness was in group I – with the largest variation (Table 3).

There were not statistically significant differences between the groups for 1000 seeds weight. The lowest variability was found for group III, while the largest – for group I (Table 3).

Eleven significant correlation coefficients were observed between tested traits (Table 4, Fig. 1). Seven of them were positive which confirms a significant mutual correlation between the traits.

Very high, positive, significant correlation was observed between plant natural height and stem length (r = 0.956), the technical length and slenderness (r = 0.923) as well as plant natural height and slenderness (r = 0.832). The calculated correlation coefficient was smaller, but also significantly positive for the length and the number of panicle branches, panicle length and stems thickness, number of branches and stem thickness and the number of branches and 1000 seed weight (Table 4). The obtained results have been confirmed by numerous reports about the complex nature of the main traits of flax and the influence of the component trait characteristics on the main traits (e.g. Tyson 1989, Popescu et al. 1999, Sood et al. 2007).

Evaluation of some morphological traits of flax gene resources… 93

Table 4 The Pearson correlation coefficients matrix for the observed traits ofLinum usitatissimum L. Macierz współczynników korelacji prostej Pearsona dla obserwowanych cech Linum usitatissimum L. Trait Cecha PNH [cm] SL [cm] PL [cm] SN ST [mm] S SL [cm] 0.956*** PL [cm] -0.021 -0.228 SN -0.542*** -0.667*** 0.624*** ST [mm] 0.282 0.114 0.622*** 0.458** S 0.832*** 0.923*** -0.408** -0.760*** -0.190 TSW [g] -0.130 -0.165 0.069 0.313* 0.261 -0.238 * P<0.05; ** P<0.01; *** P<0.001

PNH – plant natural height — naturalna wysokość rośliny,

SL – stem length (technical length) — techniczna długość łodygi, PL – panicle length — długość wiechy,

SN – number of panicle branches — liczba rozgałęzień wiechy, ST – stem thickness — grubość łodygi,

S – slenderness — wysmukłość łodygi, TSW – 1000-seed weight — masa 1000 nasion

Fig. 1. Scatterplot matrix for relationships between the seven observed traits of the investigated flax genotypes for four groups (I, II, III and IV) — Macierz wykresów rozrzutu współzależności pomiędzy siedmioma obserwowanymi cechami badanych genotypów lnu dla czterech grup (I, II, III i IV) — objaśnienia jak w tabeli 4

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The multivariate analysis of variance (MANOVA) allowed to discard the tested hypothesis about the lack of multi-trait variability between the groups (P < 0.001). The first two canonical variables account for 91.62% of total variability between the groups. Figure 2 shows variability of the analyzed groups in distribution of the first two canonical variables.

Fig. 2. Distribution of the four groups in the space of the first two canonical variables — Rozkład czterech grup genotypów w przestrzeni dwóch pierwszych zmiennych kanonicznych

The analysis of phenotypic Mahalanobis distances between the groups revealed that the groups I and II were the most similar with respect to all the traits observed jointly, whereas the highest phenotypic distance was found for the groups I and IV (Table 5).

Table 5 Phenotypic distances between four groups, calculated as the Mahalanobis distance based on seven traits — Odległości fenotypowe pomiędzy czterema grupami genotypów, obliczone jako odległości Mahalanobisa na podstawie siedmiu cech

Groups — Grupy I II III IV

I 0

II 1.618 0

III 2.903 2.475 0

IV 4.023* 3.695* 1.871 0

* P < 0.05

The first two principal components account for 99.79% of total variability (Fig. 3). The first principal component was significantly positively correlated with the plant natural height (r = 0.8453), stem length (r = 0.9323) and slenderness

Evaluation of some morphological traits of flax gene resources… 95

(r = 0.9997) and negatively correlated with panicle length (r = -0.3956) and number of stem branches (r = -0.7566). The second principal component was significantly positively correlated with plant natural height (r = 0.5299), stem length (r = 0.3381), panicle length (r = 0.5877) and stem thickness (r = 0.8146).

Fig. 3. Distribution of 49 flax accessions in the space of two first principal components for all observed traits —Rozmieszczenie 49 obiektów lnu w przestrzeni dwóch pierwszych składowych głównych dla wszystkich obserwowanych cech

Multivariate analyses, like the canonical variable analysis and principal component analysis, are very informative tools in presentation of variability of studied genotypes on the basis of observed traits considered simultaneously.

Conclusions

1. The effect of groups on performance of plant natural height, stem length

(technical length), panicle length and slenderness of plants was significant.

2. Eleven significant correlation coefficients were recorded between the tested

morphological traits. Strong positive significant correlations were observed between plant natural height and stem length, the technical length and slenderness as well as plant natural height and slenderness.

3. Canonical variable analysis and principal component analysis were very

informative tools in presentation of variability of groups as well as of the oldest 49 flax genotypes on the basis of observed traits considered simultaneously.

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References

& Hall, London, 247 pp.

Mahalanobis P.C. 1936. On the generalized distance in statistics. Proceedings of the National Institute of Science of India, 12: 49-55.

Mohammadi A.A., Saeidi G., Arzani A. 2010. Genetic analysis of some agronomic traits in flax (Linum usitatissimum L.). Australian Journal of Crop Sciences, 4: 343-352.

Pavelek M. 1994. Descriptors for the evaluation of flax. Workshop summary of the second meeting of the Flax Breeding Research Group of the European Cooperative Network on Flax, 8-9 November 1994, Brno, Czech Pepublic.

Pavelek M. 2006. First meeting of a Working Group on Fibre Crops (Flax and Hemp) International Plant Genetic Resources Institute, Newsletter for Europe, 33.

Popescu F., Marinescu I., Vasile I. 1999. Combining ability and heredity of some important traits in linseed breeding. Rom. Agric. Res., 11: 33-43.

Rencher A.C. 1998. Multivariate statistical inference and applications. John Wiley and Sons, New, 527 pp.

Rólski S., Heller K., Silska G. 2001. The biological progress in breeding of fiber flax in Poland.

Natural Fibres – Włókna Naturalne. Special ed. Proc. conf. Best Plants in the New Millenium,

3-6 June, 2001, Borovets, Bulgaria, 1: 104-109.

Silska G., Kozak J., Rajewicz M., Mańkowska G. 2014. Charakterystyka mofrologiczna genotypów

lnu (Linum usitatissimum L.) pochodzących z Polski. Polish Journal of Agronomy, 17: 38-47.

Silska G., Praczyk M. 2013. Descriptors of characterization and evaluation in International Flax Database. Biuletyn IHAR, 268: 161-171.

Sood S., Kalia N., Bhateria S., Kumar S. 2007. Detection of genetic components of variation for some biometrical traits in Linum usitatissimum L. in sub-mountain Himalayan region. Euphytica, 155: 107-115.

Tyson H. 1989. Genetic control of seed weight in flax (Linum usitatissimum L.) and possible implications. Theor. Appl. Genet., 77: 260-270.

Woyke T., Muśnicki Cz. 2003. Len. W: Szczegółowa uprawa roślin. Red. Jasińska Z., Kotecki A., AR Wrocław: 527-546.