THE PAT"TERN OF SBED SET WITIIII\ THE CAPITT]LUM OF ST]NT'IOWER AND ITS I]\FLUEi\CE O1\{ GERMII\IATION A]TD SBEDLII\G VIGOUR

T. G. PRASAD, M. N. MERWADE, K. GIRI- RAJ and M. UDAYA KUMAR Sunflower Project, University of Agricultural Sciences, GKVK Carnpus, Bangalore-560065 (India)

INTRODUCTION matured. These capitula were dried for 96 hours in an oven mâintained at 40oC. AII seeds In crop plants, the importance of seed size from each concentric seed whorls were re- for high germination percentage and early moved carefully from periphery to the centre seedling vigour is well established. Seed test of the capitulum and were grouped separately. weight was shown to influence plant growth, Total seed number, nun-rber of filled and un- development and subsequent yield in many filled seeds, weight of filled and unfilled seeds crop plants (Harpar and Obeid, 1967; as well as that of kernels were recorded. Seeds Foxtes and OhIrogge, 71972 and Tre- from each concentric whorls were stored se- h a n ,et al., 1975). Crop raised from large seeds parately in an incubator kept at 25oC for 45 was shown to have more leaf area, biological days. Germination and seedling vigour studies yield and seed yield in sunflover (A s h o k - were made by germinating 20 seeds on filter k u m a r et al., 19:79). More dry matter ac- paper medium in petriplates saturated with cu,mulation was observed in the seedling raised 5 ml of distilled uzater and replicated f,ive ti- from heavier seeds in sunflower (S i v a s u - mes. The observations on germination percen- bramanian and Ramakrishnan, tage, shoot and root lengths of 10 seedlings 1997). were recorded at the end of 7 days of incuba- In a sunflower capitulum, the nurn-ber of fil- tion at 30'C. Vigour index was calculated by led seeds and seed weight showed marked re- multiplying germination percentage with mean duction from peripheral seed whorls to inner shoot length, whorls. Besides, oil content and seed moisture Observations on all the characters under content were also found to vary markedly in study were recorcled for a m,inimum of 30 the seeds which were developed in different earheads. The experiment was repeated twice. positions of the capitulum (Mathes and The data of one such experiment are given in U n g a r o, 1983). By using labelled toCOr, this paper. For graphi,cal representations, the Udaya Kumar et a1., (1976) have shown observations recorded on the seeds from '1st, the differential sink capacity of the seeds at 5th, 10th, 15th, 20th and 24th concentric whorl different zones of the capitulum resulting in were used for husk percentage, kernel weight differential translocation of photosynthates. and whole seed weight, while it was only from In the present study, the pattern of seed set, 1st, 5th, 10th, 1r5th and \1l8th seed whorls for seed number and seed weight in relation to its germination studies, since the subsequent position on the capitulum and its subsequent whorls had contributed verv litt1e sample size. influence on germination and seedling vigour in Morden (Cernianka-66) sunflower variety is reported. RESULTS AND DISCUSSION

The pattern of seed distribution within a MATERIAL AND METHODS capitulum was studied in Morden sunflo\Mer variety. Capitula hawing average diameter The base material for the experiment was range of 14 to 1116 cm had shown mean 28 con- coLlected from Morden sunflower variety grown centric whorls. The total seed number in each under fertile irrigated conditions during mon- concentric whorls found to be constant (5,5 soon season (Ju-ly to October, 1984). About 100 seeds) up to the l1th whorl from periphery of capitula of uniforrn size (14 to ,16 cm in dia- the capitulum. However, total seed number meter) which had flowered on the same day ranged from 54.93 in the 12th whorl to 2.43 in were identified and la,belled. Such capitula the 28 th whorl indicating a marked redu,ction were harvested when the plants were fully in total seed number per whorl from periphery

61 A - U*lteA seed veight (g) B - fitfd seed weight (g)

C - totol seed yeist (

?0

+.. ,1 lD ': G60 i; !. 1,,1

t^ â E c, (u 'n 40 .o g ll-= Whort rumber from perphery of the copifutun îig. 2 Weight of filled, unfiiled and total seeds from different- concentric whorls of the sunflower caPitulum

.A - Hurtr percsfqge B - KerneL werght (g) .C - whot" seed weiqhi {9}

Whorl rrumber from PeriPherY of the coPitutum EA. 1 Percentage of filled seeds in different con- -centric whorls of sunflower capitulum to the centre of capitulum. The range of filled seeds per whorls was from 45.36 to 0.57 seeds over different concentric whorls. The number of filled seeds per whorl had increased mar- ginally up to the 4th seed whorl from the pe- riphery and further decreased gradually from 45.21 seeds in the 5th whorl to 1.36 seeds in 2?th whorl (Table 1). Percentage of filled seeds per whorl also exhibited a similar trend (Fig. 1). The mean weight of seeds in an whorl ran- ged from 2.925 to 0.016 g over different con- centric whorls. Higher seed weight was evi- from the periphery dent'up to the 3rd whorl Fig. 3 Husk percentage, kernel and whole seed there was considerable re- - and subsequently weight of individual seeds from different 'concentric duction in seed weight from 4th whorl to 28th whorls of sunflower capitulum whorl (Fig. 2). The marginal increase in mean specific (sin- central whorls (up to 20th whorl). A higher gle) seed weight per concentric whorl was seen husk content was apparent rnarkedly from 21st up to the 3rd whorl from the periphery. It whorl onwards (Fig. 3). had decreased markedly between each succes- Seeds from the outer whorls of the head sive whorls from 4th whorl to 28th whorl had shown generally higher germination rate (Table 1 and Fig. 3). as well as germination counts. Germination Likewise, specific kernel weight also shown percentage of seeds was 98 per cent in the the similar trend as above. Specific kernel seeds from the outermost whorl of the head, weight of 22nd whorl was found to be nearly but it decreased to 81, 66 and 47 per cent in half of that of first whorl (Fig. 3). the seeds raised from the Bth 14 th and rl8th With respect to husk content, there was gra- concentric whorls respectively. Thus, germina- dual marginal increase from periphery to the tion percentage had alsq decreased markediy in

62 Table 7 (r-rl Vcriations in seed number antl specific (single) seed o A - totqt *edli'g ler;,\i weight in a concentric whorl from periphery to oB-Viçur indcx centre of the capitulum in Morden cultivar oC -6erminoiion Percartaç Scolc, 1cm = i! Uniis Specific Concentric seed whorl number rveight from per nôri nh ôrt7 Unfilled Total whorl s3eds seeds (mg)

1 43.86 11.14 55.00 63.00

2 44.29 10.?1 55.00 63.00 3 45.07 9.93 55.00 63.14 i 45.36 9.6'4 55.00 62.21 J 45.2L 9.75 55.00 60.00

6 43.t4 1 1.86 55.00 56.86 7 43.7r tI.29 55.00 55.21

B 42.71 L2.29 55.00 54.36 I 43.50 11.50 55.00 52.50 10 43.29 11.71 55.00 51.57 rl 42.64 12.36 55.00 49.79 1' 42.79 12.t4 54.93 18.29 'ss.zz 13 42.36 10.86 +o.D I IA 41.50 10.07 5r.57 45.21 ID 36.86 12.57 49.43 43.00 Fig. 4 Germination percentage, seedling length and vigour- index of the seed from different con- 16 34.21 11.93 46.14 4t.07 centric whorls of sunflower capitulum t7 31.43 t2.57 44.00 39.43 1B 25.50 t4.7'9 40.29 37.64 Anthesis of sunflower florets starts from the 19 20.21 15.7'9 36.00 34.t4 outermost whorl of the capitulum and du- ration for complete anthesis of head takes 20 14.79 14 a1 30.50 31.93 about 7 to i1L0 days. Under fertile and irrigated 2l 10.14 13.57 23.71 26.45 conditions, more number of florets in the outer 22 6.50 12.57 19.0? 18.57 zone of the head would develop into bolder 23 4.00 11.14 r a. l{t 13.36 seeds and subsequently, the percentage of fil- 24 2.86 8.64 11.50 i0.64 led seed would a'lso be more. seeds 9.93 An analysis of nature of distr,ibution of 25 2.29 7.64 6.07 within a capitulum had shown that total num- 26 2.29 5.36 /.b D 5.50 ber of seeds per concentric whorl remained 27 1.36 3.64 5.00 1.36 constant up to the 11th whorl from periphery 28 0.57 1.86 2.43 1.50 (55 seeds) which may be ascribed to genetic Total factors, but number of filled seeds in a whorl had differed marginally in the outer region of Mean 38.66 the capitulum. However, total number of flo- LSD 5.525 | 5.7L7 6.045 rets initiated per whorl and also filled seed number had reduced marked'ly from '12th whorl the seeds from the outer most whorl to the to 28th whorl of the capitulum. Total seed inner whorls within the head (Fig. 4). weight, spe'cific seed weight and kernel weight The root and shoot lengths of seedtings at had also decreased drastically from 4th seed the end of 7th day after germination had whorl onwards in the capitulum. Reduction in shown that seedlings from outer most whorls the number of filled seeds, specific seed weight of head had longer roots as well as shoots as and kernel weight in the inner whorls was compared to those from inner whorls. In gene- mainly due to physiological reasons. An im- ral, a marked reduction in total seedling length balance in the distribution of adequate photo- was observed in seedlings raised from first synthates to the seeds situated in the inner whorl to lt8th whorl (Fig. 4). Likewise, vigour whorls might have resulted in lesser number index of the seedlings developed from the seeds of filied seeds as well as considerable reduction of different whorls had alsb exhibited similar in the specific seed weight per whorl. U d a y a trend. Vigour index was reduced by 34.17, 57.76 Kumar et al. (1976) and Prasad et al. and 84.22 per cent in the seedlings raised from (1977) have reported differential translocation seeds collected from 6th. 12th. and l8th whorls of labelled photosynthates to the seeds situated respectively as compared to the f,irst concentric at different position of sunflower head. P r a - whorl in the periphery (Fig. 4). sad and Krishna Sastry (1978) have

63 showh the importance of sink capacity for h,ËrÈnÉr,tôiiS translocation of photosynthates to the head and the role of phytochromes in mobilization of Ashok Kumar 1. N., Girira j K., Prasad T. G. and Vidyashankar T. S., 1979, Influence photosynthates which results in in'creased num- of seed test ueight on gield and, grouth para- ber of f,illed seeds and also specific seed weight. meters in sunflouer, Seed Res., 7, t4l-L44. A drastic reduction in percentage of filled Fox,tes L. A. N. and Ohlrogge A. J., 1972, In- seeds per and larger ratio husk fluence of seed size and population on gield, whorl a of and other characteristics of sogbean (Glgci,ne weight to total seed weight observed in this mar. L. Merill), Ag:on. J., 64, 833-836. study have suggested that seed filling might Ilarpar J. L. and Obeid M., 1967, Influence of have affected to a greater extent in the seeds seed, size and ilepth of sowing on the establish- nxent o.nd grousth of uarieties of fibre and oil developed in the inner whorls of the capitu- seed,s Crop. Sci. 7, 527-532. qua- flar, Ium, thus giving rise to seeds of inferior Mathes L. A. F. and Ungaro M. R. G., 1983, Iity. Influence of seed position on oiL percentage Significant reductions in germinability para- dnil nxoisture content in sunfloruer seed., Bru- gantia, 42, 239-244. meters were .observed in the seeds collected Mathur P. N., Sinha M. C. and Singh R. P., from inner whorls of the head. The germina- 1982, Etfect of seed, size on germination and bility and seedling vigour seem to depend on seed oigour in oat (Auena satioa L.), Seed the amount of storage materials availble per Res. 10, 109-113. seed. The higher germination percentage Muniswami Naidu T. C. and Narâyanan 4., and l99l, Utilization of seed reseroes lor seeilling seedling vigour noticed in the seeds from the grotath of groud,nut. I. Effect of seed size i,n outer whorls might be related to the higher d,rg rnatter depletion. Seed Res., 9, 6-11. rate of availability, metabolism as well as Prasad T. G., Udaya Kumar M., Rama translocation of metabolites from the storage Rao S. and Krishna Sastry K. S., 1977, organs growing Grotothregulator induced, mobilization of t4C- to actively parts of the seedl- metaboli,te into sunflotaer heail, Indian J. Expt. ings (Mathur et ai., 1982; Muniswami Biol.. 15. 1022-1024. Naidu and Narayanan, 19&1). Prasad T. G. and Krishna Sastry K. S., The present study has clearly brought out 1978, Eïfect of triioilobenzoic acid on diflusi.ble the importance of higher test weight (around grou:th substance from, sunflotuer head, Indian J. Expt. Biol., 16, 1209-l2ll. 50 seeds) realising better germina- 9/1,000 in V' 1977, Relationship betlDeen seed size and bility and higher seedling estabishment under seedling uigour in sunflouer, Seed Res., 5, the field conditions. 6-10. Trahan K. 8., Hirachand and Mehta S. K., 1975, Measurement of leaf area in sunflotner., CONCLUSIONS Sci. Cult.. 41. 238-239. Udaya Kumar M., Prasad T. G., Rama Râo S. and Krishna Sastry K. S., 1976, Trans- The pattern of seed set, seed number and location of t/,C-metabolites to the heail i,n sun- seed weight in different 'concentric whorls in flo'wer, Indian J. Expt. Biol., 14, 302-304. a capitulum of sunflower cv. Morden were studied. The total number of seeds in an whorl was 55 up to 11th whorl from periphery in LE MODÈLE DE DISTRIBUTION DES GRAINES the capitulum having diameter range of 14 to SUR LE CAPITULE DE TOURNESOL lti cm. A drastic reduction in total number of ET SON INFLUENCE SUR LA GERMINATION seeds was seen from I2th whorl onwards. ET LA VIGUEUR DES PLANTULES Number of filled seeds, seed weight per whor1, Rësumé specific seed weight and kernel weight a in Le cultivar-population à pollinisation libre Cer- whorl showed significant reduction in the suc- nianka 66 a été utilisé comme matéridl biologique, cessive whorls from 4th peripheral whorl on- cultivé dans un sol fertile, en conditions d'irrigation, wards. pendant la saison moussonique de juillet-octo- bre 1984. Germination percentage, seedling growth, vi- gour index Les groupes de graines provenues de chaque cercle of the seedlings raised from seeds concentrique des capitules ont été étudiés. Le nombre from different concentric whorls were studied. total de graines d'un cercle concentrique a été de 55 Seeds having specific seed weight of more than jusqu'à I'onzième cercle, dénombré de la périphérie 49 mg per seed up to llth whorl from peri- du capitule, ayant des diamètres de 14 à 16 ,cm. À phery had higher germination percentage, more partir du 12-ème cercle, le nombre total de graines seedling growth and also higher vigour index. s'est réduit considérablement. En commençant par le 4-ème cercle de Ia périphérie vers le centre du capitule, une réduction successive du nombre des graines pleines, du poids des semences pleines ACKNOWLEDGEMENT d,un cercle concentrique, de la masse de 1 000 graines et de la masse des noyaux a été enregistrée. Les akènes This work was carried out under the Pro- dont la masse de 1 000 graines était supérieure à ject 49 g, obtenues des 11 premiers cercles concentriques "Super Elite and Elite Sunflower Seed de la périphérie Production", financed the du capitule ont eu une meilleure by Indian Council of germination, une croissance plus rapide des plantules Agricuitural Research, New Delhi. et également un index de vigueur pius éIevé.

64 MooËr,o oË r.e nisinieiidroN pÉ sÉntrll,eS de 55 hasia ei undécimo circulo, contado desde la pe. POR EL CAPITULO DE GIRASOL riferia del capitulo, teniendo los diametros de 14 Y SU INFLUENCIA SoBRE GERMINACIÔN hasta 16 cm. Empezando con el duodecimo circulo, el LA nûmero total Y EL VIGOR DE de semillas se redujo considerablemente. LAS PLANTAS Empezando con el cuatro cfrculo desde la periferia hasta eI centro del capitulo se registrô una reduccidn Res{trnen succesiva de : el nûmero de semillas llenas. la masa de las semillas llenas de un circulo concéntrico, la Se utiliz6 como material biolôgico la variedad-po- masa de 1 000 granos y la masa de los corazoneo. blaciôn con polinizaciôn libre Cerneanka 66, cultivada Las semillas con la masa de 1 000 granos mayor a en un suelo fertil, en condiciones de regadio, en la 49 g, que se obtuvieron de los primeros 11 circulos estaciôn musônica JulieOctobre,.1984. concéntricos de la periferia del capftulo mostraron Se estudiaron los grupos de semillas provinientes una germinaci6n mejor, un crecimento mâs râpido de cada circulo concéntrico de los capitulos. El nri- de las plantas y a Ia vez un index de robustez mâs mero total de semillas de un circulo concéntrico fue elevado.