B E E R E S E A R C H c O P I E SV.XXI DECEMBER 1977

ECOTYPES OF TRIFOLIUM PRATENSE L. IN rROGRAMMEDCULTIVATION OF TETRAPLOID VARIETIES

Stanisław Góral

IHAR Radzików, Poland

During the eultivation of Trifolium pratense L. in different locationsand under various programmed proeedures, by a proeess of naturalselection a wide variety of forms came into being. OnIy euItivatedforms however, with straight stems, growing flourishingIy, are favouredin cultivation. Uneultivated popuIations, having undergone merely theprocess or natural seleetion in their own locale, differ kom the culti-vated forms in their morphology and physiological functions. Specimensof these trefoils are, as a rule, shorter, and of more or less proeumbenttype. Their thin sterns are filled with stem core and the amount ofleaves in the green mass of sueh forms is visibly smaller when com-pared to that of sowing clover.

The great majority of seientists J a n o s s y 1966, J u l e n 1956,Łączyńska-Hulewicz 1957, Nuesch 1960, Polak 1974examining polyploid red clover maintain that its low fertility is due totoo poor a genetic base of forms obtained from eultivated tetraploids.Attempts are being made therefore, to inerease the genetic mutabilityof polyploids produced in the course of exchanging specimen seeds bet-ween cultivation eentres as well as through the poIyploidization of va-rieties and ecotypes eoming from different parts of the world. Inconjunetion with this, attention was foeused on the uneultivated formsof Trifolium pratense L. which may be a source of genes deterrniningnot only good seed setting but also eold resistanee and hardiness. These

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plant properties can be grafted relatively easily into cultivated forms ofTrifolium pratense L. var. sativum Schreb through cross-Iertilization.These two forms cross-fertilize easily both on the dypIoidic and tetrap-loidic levels; their hybrids showing full fertility.

Uncultivated ecotypes of red clover can be found in Poland in nume-rous natural ecvironments. However the acreage of natural meadows,pastures and waste land is continually decreasing. In the near futureenvironments of this clover will disappear completely, due to the increasein agricultural production and the drainage of land. The destruction ofwild forms of Trifolium pratense L. will lead to the loss of a numberof genes, which in the future may appear indispensable in cultuvatingand utilizing red clover.

MATERIALS AND MERHODS

The material used in the experiment was made up of wild redclover specimens Trifolium pratense L. var. spontaneum Willk. collectedin natural meadows and pastures in the districts of Olsztyn, Warszawa,Białystok, Kraków, Rzeszów, Kielce as well as of cultivated tetraploidsobtained from selected ecotypes.

The number of flowers and inflorescences on the plant and ona given area unit was determined, and the degree of seed setting andamount of seed yield defined. Biometrie measurements of inflorescencewere made and its nectaring was defined by Jabłońsky's method. J a-b ł o ń s k i. 1965. The selffertilization of dyploid and tetraploid formswas examined.

RESULTS

The populations of Trifolium pratense L. var. examined differedconsiderably in the duration of the florescence period and the timeof its occurence. A large number of ecotypes started to bloom as earlyas 50 days after spronting, Their bloom was abundant, usually in thefirst half of the florescence stage, After yielding seed, they died down,no rosette of leaves, characteristic of the clover however, was found.From the point of view of farming production these plants appear tohave no practical value since they are, as a rule short and poorlyleaved. When cut during the budding stage or at the beginning of theflowering period they died down or grew very weakly.

The last to bloom was winter clover, which did not undergo theflorescence stage in the year of sowing. This form constituted only,a small part of the clover population; it could be found most abunalantlyin the materia l collected in Białystok Region (Serwy: 8,2%, Rogale: 5,1%)and in the Mountains (Szczawnica).

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Table jPercentagę of one year and winter plants in populations

one year winter Quantitypopulations grown in District plants plants of plants

(0J0) (OJo) examined------.

Szczawnica Kraków 6,7 105Rytro Kraków 2,0 5,0 102:'3taszów Kielce 5,8 104TIuszcz . ,- Warszawa 11,2 1,0 204-::hrzęsne Warszawa 8,9 124Taroty Olsztyn 3,3 186Wadąg Olsztyn 2,7 2,1 188Rogale Białystok 1,6 5.5 180Serwy Białystok 8,2 183

* winter plants not tlowering in the year of their sowmg.

STRUCTURE OF FLOWERS. NECTARING.

The ilowers of wild clover do not differ substantially in theirmorphological structure from the flowers of the cultivated vanieties.Their colour and size on the other hand, can vary flower to flower.In the whole population of ecotypes a wide spectrum of colours, rangingfrom fine white to dark bluish carmine, can be observed.

The main purpose of the experiment was to determine the size ofthe corolla, which in the red, both dyploid and polyploid clover, has animportant influence on flower pollination by honeybees.

The length of the flower tubes of meadow clover ran in particularvarieties, from 4,3 do 9,1 mm, that of the Gloria from 6,4 to 10,8mm;the average length of Gloria tubes being 8,8 mm. The flowers of colchi-ploids (C2 and C3) obtained from the ecotypes were longer and widerthan those of the primary forms. Those flowers (5,8-11,8 mm) weresimilar in proportions to the flowers of the Gloria but their size wasalways smaller than the tetraploid variety Wielkolistna (6,6-11,9 mm)(table 2).

The width of the flower tube may also play an important role duringpollination by honey-bees. If the tube is wide enough, a bee can intro-duce not only its sucking-Iicking mouth parts into it but also thefront part of its wedge-shaped head, which makes it possible for theinsect to reach a drop of nectar placed deep inside the tube. A thintube, on the other hand, anables a bee to introduce only the thinner partits licking-sucking mouth parts, which means the shortening of its"working length".

Meadow ecotypes of clover varied markedly from cultivated forms

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Flower tube Iengths and nectar height

populatlon

flower tube

nectar height (mm)length (mm) I diameter (mm)

Tłuszcz 2X 7,93 1,62 1,14Wadąg 2X 8,61 1,74 1,18Serwy 2X 8,20 1,68 1,27Gloria 2X 8,82 1,88 1,32

x-2X 8,39 1,73 1,23

Tłuszcz 4X 8,98 1,86 1,56Wadąg 4X 9,12 1,92 1,62Serwy 4X 9,43 2,03 1,60Wielkolistana 4X 9,84 2,24 1,64

x-4X 9,34 2,01 1,60

The least differencerecorded (0,05) 0,32 0,18 0,22

in respect of the diamexter of the flower tube. The tubes of the formerwere about 12,4010 and 25010 thinner than those of the Gloria and theWielkolistna variety respectively.

After polyploidization in the generation C2 the diameter reached,on average 1,97 mm. It was greater, then, by 17,2010 than the width 'ofthe tubes of the primary forms, and by 4,8010 than the diameter ot theGloria (Table 2).

The height of the nectar level in the flowers of the ecotypes wasgenerally less than that of the Gloria, and reached 1,19 mm (in theGloria: 1,32 mm). Polyploidic forms of clover produced more nectar:the height of the nectar level reached 1,59 mm in colichiploid meadowclover and 1,64 mm in the variety Wielkolistna (table 2)

The inflorescence of meadow clover ecotypes do es not differ substan-tially in structure from the inflorescence of cułtivated clover: it is, asa rule, smaller, which is due to the fact that its flower tubes are shorter(table 2). As regards the number of flowers in the inflorescence uniculti-vated forms differ markedly from cultivated ones. The number offlowers per head in the ecotypes ranged from 37 to 154 whereas in thestandard specimen, Gloria, it ran from 63 to 138. Comparing the figuresgiven in the tables 1-3, it can be observed that the number of flower"per head was bigger in populations blooming earlier.

The number of flowers per head in tetraploid populations (C2 and C3)was smaller than that found in the primary forms. In this caseit was difficult to observe a regularity since considerable divergences

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between the different families of the same population were found. Forinstance, some tetraploid families obtained from the population growingin Wadog had a substantial number of flowers per head (127,3) whereasothers of the same origin had 76,22 or 86,3 flowers. A similar variationin this feature was observed in tetraploids obtained from populationsgrowing in Tłuszcz and Serwy. The averagę number of flowers for a11tetraploid fami1ies reached 99,1 and was sma11er than that found inprimary dyploid forms (106,6) and in the variety Wielkolistna (104,2)(table 3).

In the majority of clover forms examined a decreasing number offlowers in the inflorescence in the second half of the flowerlng periodwas observed. All polyploids lowever, behaved a bit differently; it wasobserved that the drop in the number of flowers in later heads wasslower. Presumably this was due to the fact that the primary polyploidforms we~e prior to the actual polyploids. By comparing the numberof flowers per influorescence with the number of flower s on the plants,a negative correlation of these features was obtained (r = -0,31). Plantswith a small number of flowers per head appeared to have more inflo-rescences. This could be easily observed, especially while comparing, thin-stemmed ecotypes, spreading abundantly, with the Wielkolistna varietycharacterized by having relatively fewer stems.

The number of flowers on a plot (definite unit) of clover sown in

Table 3Number of flowers and seeds per head

population Ploidalality Number of seed setting Number offlowers (%) seeds

Tłuszcz 2X 108,2 62,3 67,4Tłuszcz 4 X (C3) 102,9 34,3 35,3Chrzęsne 2X 123,8 72,7 90,0Jaroty 2X 111,1 68,7 76,3Wadąg 2X 120,4 53,1 64,0Wadąg 4 X (C3) 111,1 39,2 43,6Bartoszyce 2X 95,1 66,3 63,1Gierłoż 2X 94,3 59,3 55,9Rogale 2X 100,3 71,9 71,8Serwy 2X 91,0 66,3 60,3Serwy 4 X (C2) 83,2 35,1 29,2Gloria .• 2X 98,8 61,6 61,9Wielkolistna • 4X 104,2 27,0 28,1

The least differencerecorded - (0,05) 14,7 9,1 11,2

"••"- eulttvated varietes

13 - Pszczelnicze Zeszyty Naukowe 19:3

TablE~ .•Coefficient of correlation between .clover features ćcndttionlng seed setting

in ecotypes of meadow clover

features examined I Number of I Number of I Number offlowers pet head heads per plant stems per plantNumber of headsNumber of stemsNumber of heads per 1m2

-0,31+0,07-0,14

+ 0,82·*+ 0,63· + 0,47 *

• - important, given P ~ 0,05•• - important, gtven p = 0,01

drills was largely conditioned by the degree of spreading of a particularpopulation. In this case a positive correlation (r = +0,4*) (table 4) wasobserved.

SEED SETTING THROUGH SELFPOLLINATION ANDOUT-POLLINATION

The averagę percentagę oi plants setting seeds under the insulatorin the population of wild meadow clover was visibly lower than thatin the standard variety "Gloria". Meadow tetraploid s, as a rule, setseeds belter under self-pollination than primary forms (table 5).

The Inbreeding to the level Si and ~ usually caused a decrease inthe number of seeds per head. A comparison of the dropin seed settingunder self-pollination of the dyploid and tetraploid populations, showedthat these latter were affected by inbreeding to a smaller degree: thegeneration ~ set on the average, 5,3 seeds per head, which made olf 53°/0

Table 5Self fertility. of three ecotype generatlona and their tetraploida

Number of seedsPercentagę of plants So per head in

Poliploidi- selfpollinatingPopulation zation plan ts

selffertile I Non Sa St S:zselffertileMeadowecotypes 2X 18,3 81,7 3,4 2,3 1,1Ecotypes of theKolchiploids 4X 43,0 57,0 10,0 7,2 5,3

"Gloria" 2X 31,7 68,3 4,4"Wielkolistna" 4X 55,0 45,0 6,7

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Table aSeed weight perarea unit

Quantity of seed (kg)

Varieties 1967 1968 1970 1971

Olsztyn Olsztyn Skrzesze- Skrzesze-wice wice

Łąkowa 427 2X 3,28 1,74 2,82 1,07Gloria 2X 2,63 1,31Łąkowa 402 4X 1,90 0,80 2,02 0,68Wielkolistna 4X 1,12 0,53Mieszaniec (R-72). 4X 1,62 0,91 1,74 0,63

The least differencerecorded (0,05) 0,23 0,14 0,23 0,28

* hybrid (R-27): meadow variety X "Wielkolistna".

of the seed setting in 80. In dyploids, on the other hand, the averagęfertility of the generation 82 dropped to 32% (table 5).

Among the meadow clover ecotypes examined many forms withgood seed setting ability under free pollination were found. The afore-mentioned feature varied markedly from population to population. Besidethe seminiferous individuals setting seeds in over 80% of flowers formswere found in which the number of seeds per head was not higherthan in that tetraploid variety "Wielkolistna". However seed settingwas better in them than in the cultivated clover.

The polyploidization of meadow clover caused as was the case withother species, a dominution of fertility but in each case the degresof seed setting per 100 flowers was higher in this species than in thestandard variety "Wielkolistna". Meadow colchiploids set, on average,from 34,3 to 39,2% seeds, whereas the control "Wielkolistna" set only27% seeds. The seed yield obtained from o plot of ground (defined unitof ground) was from 25% to 32% higher in the population of wildmeadow clover than in the variety "Gloria" (table 6). Likewise, colchi-ploids of meadow clover yielded about a 50% higher seeds crop thanthe variety "Wielkolistna".

CONCLU8ION8

1. Wild ecotypes of Trifolium pratense L. vaT. spontanum Willk.found in Poland in natural surroundings display a great variation inphysiological and morphological features. Forms blooming earlier andspecies of the procumbent type, which have a negligeable forming valueconstitute a great propartion of clover populations.

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2. The great majority of ecotypes bloom more abundantly thancultivated species. Their flower tubes are shorter, and their nectar moreeasily accessible to pollinators. They yield more seed than the cultivatedvarieties.

3. Wild meadow clover and its off-shoots show a smaller selfferti-lizing capacity than cultivated clover.

4. Tetraploids obtained from meadow clover show gigantism andmutability of other morphological and anatomical features, very muchiike cultivated clover colichiploids, Their flowers, however are smallerin size; they set seeds better than the tetraploid variety "Wielkolistna".

Summary

The paper presented some observations made on ecotypes of Trifo-lium pratense L. var. spontaneum Willk from various regions of Polandand on tetraploid s obtained from them, It was observed that wild clovershows great variation in physiological and morphological features. Itsflowers are smaller in size and its nectar is more easily accessible pol-linator insects. This clover sets seeds more easily both on the dyploidand tetraploid levels, than the cultivated varieties of Trifolium pratenseL. var. sativum Schreb. Its farming value then is high.

LITERATURE

J a b l o ń s ki B. (1965) - Pszczelnicze Zeszyty Naukowe 4, 81-92.J a n o s s y A. (1966) - Agrobotanika 7, 11-19. IJ u l e n G. (1956) - 7-th Intern. Grassl. Congress, New Zealand, 471-478.L ą c z y ń s k a - H u l e w i c z T. (1957) - Roczniki Nauk Rolniczych, 75-A-3 291-

-338.N u e s c h B. (1960) - Landw. Jahrbuch der Schweiz. 4, 301-407.P o l ak J. (1974) - Acta F.R.N. Univ. Comen., Genetica, 5, 149-:-162.

EKOTYPY TRIFOLIUM PRATENSE L.

S. Gór a l, IHAR, Polska

Streszczenie

Badano ekotypy Trifolium pratense L. var spontaneum WiHk. z różnych rejonówPolski oraz wyhodowane z nich tetraploidy. Stwierdzono, że dzikie koniczyny majądużą zmienność cech morfologicznych i fizjologicznych. Kwitną obficiej i lepiejwiążą nasiona niż formy siewne. Ich kwiaty są mniejsze, a nektar łatwiej dostępnydla zapylaczy. Koniczyny te lepiej wiążą nasiona niż formy siewne Trifolium pra-tense L. var sativum Schreb., zarówno na poziomie di- jak i tetraploidalnym. Mająwięc dużą wartość hodowlaną.

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