The Mode of Pollination and Stigma Receptivity in Vitis coignetiae Pulliat

Size: px

Start display at page:

Download "The Mode of Pollination and Stigma Receptivity in Vitis coignetiae Pulliat"

Audra Manning
5 years ago
Views:

1 The Mde f Pllinatin and Stigma Receptivity in Vitis cignetiae Pulliat PAULO H. KIMURA ~*, GORO OKAMOTO 2, and KN HIRANO 3 Vitis cignetiae Pulliat, a diecius grape cultivated fr wine making, exhibits fluctuatins in prductivity frm year t year. Pllinatin mde and stigma receptivity were studied in an attempt t identify the factrs invlved in this phenmenn. Analysis f airbrne pllen using Durham samplers and experiments preventing insects visitatin n clusters shwed that wind cntributed little t crss-pllinatin. There was n crrelatin between airbrne pllen and the distance frm pllenizer. A high level f self-pllinatin was nted, and insects cntributed mre t crss-pllinatin than did wind. The amunt f fertile pllen (pllen frm male vines) n stigmas was little, even fr pen pllinated flwers. Hand-pllinatin carried ut at 0, 2, 4, and 6 days after anthesis shwed that stigmas were mst receptive tw days after flwer pening. Year t year yield variatin in Vitis cignetiae may be due t differences in pllinatin level. KY WORDS diecy, wild grape, yield variatin The mde f pllinatin in grapes has been widely discussed [3,8,11,15,18]. Mst cmmercial cultivars pssess functinally hermaphrditic flwers, and fertilizatin is accmplished mainly by self-pllinatin. The level f natural crss-pllinatin amng hermaphrdite cultivated grapes may be influenced by climatic cnditins during the flwering perid and by the presence f pllinatrs. Amng the diversity f Vitis species arund the wrld, sexual expressin varies and three main flwer types are expressed. Individual vines can prduce perfect hermaphrdite flwers, functinally male flwers r functinally female flwers, and male flwers f sme species can be sex-cnverted [1,6,10,11,13,14,15,21]. Diecism is cmmn in wild species f grapes, including Vitis cignetiae, a native species fund in Japan [12,18]. Female vines f Vitis cignetiae prduce pistillate flwers with reflexed stamens cntaining sterile pllen in their anthers, while male vines prduce staminate flwers with abrted pistils but their anthers cntain fertile pllen. This grape has been cultivated in cmmercial rchards at Hiruzen, Okayama Prefecture fr the last decade, fr juice prductin and wine making. Year t year variatin in yield has been a prblem in Vitis cignetiae vineyards, and results frm ur previus studies indicated that lw level f fertile pllinatin was a factr clsely related t yield variatin [7]. This paper reprts investigatins carried ut t understand pllen transprt mechanisms in a cmmercial vineyard f Vitis cignetiae and their cntributin t yield fluctuatin. Materials and Methds Plant material A vineyard f Vitis cignetiae established in 1984 at Hiruzen, Okayama Prefecture, was 1,2, 3 Faculty f Agriculture, Okayama University, Tsushima-Naka, Okayama 700, Japan. *Crrespnding authr. This research was cnducted with the cllabratin f Hiruzen Wine C.. The authrs thank the winery's Directr Mr. Keiji Ueki fr assistance given t this research. Manuscript submitted fr publicatin 18 Nvember Cpyright 1998 by the American Sciety fr nlgy and Viticulture. All rights reserved. selected fr investigatins. The vines were wn-rted, 2.0 m 2.5 m spaced, hedge-trained, and cane-pruned. Canpies varying in size and in number f shts were supprted n three parallel wires psitined at 50, 100 and 150 cm abve grund level (GL). Vine rws were planted in an east-west rientatin. Distributin f male vines within the vineyard was irregular, and ne male vine was available fr abut 40 female vines. Investigatins were carried ut during the flwering seasns f 1994 and Airbrne pllen Pllen dispersal frm a male plant at full blm was measured using Durham samplers [5,9]. Samplers were placed riented t the nrth, suth, east and west side f a male plant in an islatin range f 18 m frm ther pllenizers. Alng each directin, samplers with traps (micr-slides smeared with Vaseline petrleum jelly) inside were placed at 3, 6, and 9 m frm the male plant, and they were supprted at 100 cm abve grund level (GL). The traps were munted at 0600 hr and changed at tw-hur intervals until 1800 hr. Other traps, in samplers lcated 5 m frm a male plant and supprted at 60, 120, and 180 cm abve the GL, were left unchanged frm 0600 hr t 1800 hr and frm 1800 hr t 0600 hr. Pllen grains stuck n the traps were stained with basic fuchsin and cunted under a light micrscpe. Wind speed and directin were autmatically recrded every 10 minutes, and main directin and average velcity fr 30 minutes were calculated and used as reference. Insect visitatin Blming flwer clusters n male and female plants were bserved fr insect visits during a sunny day. One hundred clusters frm bth sexes were bserved frm 0600 hr t 1800 hr. Insects that landed n the clusters were cunted and captured when pssible. Ttal number and types f insects were recrded each ne-hur interval. Anemphily and entmphily ffectiveness f anemphilic (wind transprted) and entmphilic (insect transprted) pllinatin was cmpared by cntrlling pllinatin in emasculated and nn-emasculated flwers with insect-prf nets r paper bags. Clusters

2- KIMURA et al. 1.0 9m- -2.1 ~ _Distance frm.9.0 male plant e- "~,_ II 3m m ~ _.~ ~ 9m!... 9m ii~i!iiiili~i!i!iiii!ii! t t 1.3 0.9-1.5 3m- - 2.4 3m 3m e 1.7 1.3 3m-- 2.4 5m- - 1.9 9m Distance 1.6 1.

2 2- KIMURA et al m ~ _Distance frm.9.0 male plant e- "~,_ II 3m m ~ _.~ ~ 9m!... 9m ii~i!iiiili~i!i!iiii!ii! t t m m 3m e m m m Distance Grains/cm 2 9m- Distance " 2.5 Grains / cm Day time hurs Fig. 1. Airbrne pllen f staminate (male) plant sampled at 100 cm abve grund level during daytime in a vineyard f Vitis cignetiae. used fr this experiment were cvered with paper bags until full blm, then they were re-cvered with nets, maintained bagged, r cmpletely expsed accrding t the aim f treatments. Thirty pistils cllected randmly frm three clusters per treatment were analyzed with regard t number f pllen grains n their stigmas after allwing a tw-day pllinatin perid. Stigmas were singly excised frm the pistils, placed n micr-slides tgether with a drp f acetcarmine (Nacalai Tesque Inc., Kyt) and lacerated using a needle t disperse pllen. Types and number f pllen grains were bserved under a light micrscpe. Stigmatic receptivity Duratin f stigmatic receptivity f female flwers was determined by the capacity f pllen germinatin n them. Twelve clusters at full blm stage were chsen and nly their newly pened flwers were used. The newly pen flwers were judged by the clr f their anthers and presence f green calyptra which remain ciled n the styles. Clusters were divided in fur grups and maintained bagged until hand-pllinatin. ach grup was pllinated at 0, 2, 4, r 6 days after blm with pllen f Muscat f Alexandria grape. Germinatin f pllen used was mre than 40% n agar medium (20% sucrse + 1% agar, 8 hurs at 25 C). Thirty pistils frm each grup were cllected at randm tw days after pllinatin and fixed in a slutin f 50% ethanl, frmaldehyde, and glacial acetic acid (FAA v/v). Pistils were then examined fr pllen tube grwth by the methd f paraffin sectin. Results and Discussin Airbrne pllen Pllen types were distinguished n basis f their mrphlgy. Pllen grains f Vitis cignetiae were clearly distinguishable frm ther plants by their shape and size [7]. Pllen grains frm male flwers pssessed germinative aperture while Fig. 2. Difference n pllen density in the air as influenced by directin and distance frm staminate (male) plant in a vineyard f Vitis cignetiae at full blm. Airbrne pllen grains were cllected frm 0600 hr t1800 hr at 100 cm abve grund level. thse frm female flwers did nt. Amng the pllen grains analyzed, 17.55% were pllen frm male plants, 33.47% frm female plants, and 48.98% frm ther btanical families. Pllen discharge frm the male plant int the air increased during mrning perid and reached a peak between 1000 hr and 1200 hr and thereafter decreased in the afternn (Fig. 1). The number f pllen grains n the traps was in general small, and traps placed at 1 m, 3 m, and 9 m frm a male plant shwed n crrelatin between distance frm pllen surce and amunt f trapped pllen. The amunt f trapped pllen shwed a slight directinal tendency, being higher n traps placed in the nrth and suth rientatins (Fig. 2). A maximum f 2.5 pllen grains/cm2 were trapped ver a 251 ~ 2.0-,,.,, c t_ m 1.5- i- ra,, t_.q = 0.5- Z 0.0 Nrth.e,g.t II 60 cm 12crn lii i i 180 cm I~ ii~ilili~iiiii~il ~iiiiiii~i!ii ~iiiiii!i~~i~i~i!i!~!i!~i! ~I;II ~?!!i i!i... i! ~, iiiiiiiiiiiiiii iii! i ii!!iiii iiiii ili!i~!i!i!i!'~i;i~i~!i~i ~I~I Suth Fig. 3. Airbrne pllen f staminate (male) plant f Vitis cignetiae sampled at different heights frm the grund level. Pllen traps were placed 5 m apart at the nrth and suth side f a male vine frm 0600 hr t 1800 hr.

POLINATION AND STIGMA RCPTIVITY m 3 m/s 0.6 0.5,, ". 8O 60, All insects Female Flwers = Cleptera Diptera --- Hymenptera " a. 0.4 " e,, m 0.3 ;;--~ ~'~ ;, ',, / ', ', ', /,, -/ ',, / '.

3 POLINATION AND STIGMA RCPTIVITY m 3 m/s ,, ". 8O 60, All insects Female Flwers = Cleptera Diptera --- Hymenptera " a. 0.4 " e,, m 0.3 ;;--~ ~'~ ;, ',, / ', ', ', /,, -/ ',, / '.,i ;/,m > ~_ 40 e~ ~_.~ ~--~, Z 20 f.0 II I i I " I ' I I I " I " I " l ' I ' I ' I ' Day time hurs Fig. 4. Wind speed and wind directin during day time. Pints anexed with arrws indicate average wind speed and main wind directin fr each 30 minutes. 12-hur perid. Cnsidering the small surface area f a stigma, it seems anemphilic pllinatin wuld be insufficient. A crrelatin between the amunt f germinable pllen in the air and vineyard prductivity was reprted [4]. Crrelatin between pllen cncentratin and distance frm pllen surce, hwever, was fund nly fr distances smaller than 1.5 m [4]. The number f pllen cllected als varied with height frm GL, being higher at 60 cm fr the nrth side and higher at 180 cm fr the suth side (Fig. 3). Inefficiency f anemphilic pllinatin in diecius wild Vitis has been attributed t fast sinking f pllen grains released frm anthers [3]. Wind speed varied thrughut day time but remained quite lw. Strngest gusts ccurred during 1030 hr t 1200 hr and 1500 hr t 1530 hr at an average velcity f 0.5 m/s (Fig. 4). Wind directin als varied during the mrning perid but remained cnstant after 1200 hr blwing frm the nrthwest. Wind speed during night perid remained belw 0.4 m/s, blwing mainly frm the nrth (data nt presented). The number f pllen grains cllected during the night perid (1800 hr t 0600 hr) were less than 0.2 grains/cm 2, being insignificant fr any directin r trapping height. fficiency f anemphilic pllinatin might be influenced by density f male flwers and wind speed. Insect visits Bth male and female flwers f Vitis cignetiae were mainly visited by insects belnging t three rders, i.e., Cleptera, Diptera, and Hymenptera (Fig. 5 A and B). Insects f these rders als cmprise the main visitrs f flwers f Vitis vinifera and Vitis riparia [5]. Visits by hney bees were nt bserved, althugh visits by ther types f bees and wasps ccurred n a small scale. Patterns f visits were similar fr bth flwer types; hwever, frequency f visits tended t be higher n male flwers. Amunt f flral resurces such as pllen and nectar are knwn t be imprtant fr insect attractin [2,17]. Peaks f visi- u} > O q),,,._ 40 J~ 2O 0 ~.A,J a l b ' 8 Day Time ~!i! Male Flwers ; Day Time Fig. 5. Frequency f insects visitatin n female flwers (A) and male flwers (B) f Vitis cignetiae. Observatins were dne n a hundred flwer clusters f each sex at full blm stage fr an ne-day perid. tatin ccurred between 0800 hr t 1100 hr and 1300 hr t 1600 hr. Similar patterns f visitatin bserved in Vitis vinifera subsp, silvestris, was reprted [3]. This might indicate a diurnal variatin in insect activity, prbably attributable t feeding habit and changes in inslatin. Further studies n perfrmance f flwer visitrs such as pllen lad capacity and lcmtin ability within a vineyard is necessary t determine thse insects mst beneficial t pllinatin f Vitis cignetiae. Studies n relatinship between pllinatrs and vineyard envirnment may be als necessary as this may aid in adptin f practices that may increase pllinatrs' ppulatins. Cntrlled pllinatin The ttal number f pllen grains n stigmas f nn-emasculated flwers was highest in pen pllinated (cntrl) r bagged clusters

4 4- KIMURA et al. Table 1. Pllinatin levels in Vitis cignetiae after different cluster treatments ~. Pllen type Ttal n. f Stigmas with Treatment pllen grains/ Male flwer Female flwer Other flwers male flwer stigma 2 pllen (%) N. % N. % N. % masculatin 16.9 c 0.4 b 3 (2.4) 15.8 c (93.1) 0.9 b (4.4) masculatin + net cver 7.9 c 0.3 b (3.2) 7.4 c (94.2) 0.2 b (2.6) Net cver 76.9 b 0.4 b (0.5) 74.8 b (98.8) 0.7 b (0.7) Bagging a 0.0 c (0.0) a (100.0) 0.0 c (0.0) Cntrl a 2.4 a (1.1) a (96.6) 5.3 a (2.4) 1Fr each treatment 3 clusters lcated 6 m apart frm a male plant were used. 2Averages fr 30 stigmas cllected randmly. 3Means fllwed by different letters are significantly different, p_< 0.05, Duncan's multiple range test (Table 1). Ttal pllen per stigma averaged ca. 220 grains fr cntrl, while fr nn-emasculated net-cvered clusters this number was three-times smaller. Free access t clusters permits insect mvement n flwers and this may have favred bth crss- and selfpllinatin. All pllen grains n the stigmas f bagged clusters were bviusly frm female flwers. Since their numbers were similar t the cntrl, it wuld appear that the bags have acted like wind blcks, such that, pllen released frm anthers in the upper part f a cluster may have fallen directly n pistils in the lwer part withut being blwn away by wind. In additin, pllen retained within the bag, cnsequently, may have been dusted repeatedly n the stigmas by the mvements caused by wind. Results indicate that under natural cnditin the level f entmphilic pllinatin is higher than anemphilic pllinatin. Stigmas frm emasculated clusters had 4.5- t 10- times less pllen than thse frm nn-emasculated clusters. There was n significant difference in the amunts f ttal pllen r male vine pllen n stigmas between emasculated net-cvered and emasculated uncvered clusters. Befre landing n flwers, insects are firstly attracted by flwer scent; hwever, if there is n pllen, they generally avid the flwers [3]. This suggests that the small number f pllen grains n stigmas Table 2. ffect f pllinatin date n pllen germinatin and tube grwth in Vitis cignetiae pistils pllinated with Muscat f Alexandria pllen. Pllinatin date At blm Blm + 2 days Blm + 4 days Blm + 6 days Avg. number f pllen tubes/pistil 1 Stigma Ovary middle Micrpyle 1.3 b 2 (58) 0.1 b (8) 0.04 b (4) 23.5 a (79) 5.0 a (58) 1.93 a (50) 0.9 b (25) 0.2 b (17) 0.08 b (4) 0.3 b (13) 0.0 b (0) 0.00 b (0) 1Average fr 30 pistils per treatment examined 2 days after pllinatin. 2Means fllwed by different letters are significantly different, p < 0.05, Duncan's multiple range test. 3percentage f pistils shwing pllen tubes. f emasculated clusters was mainly transprted by wind. Fr all treatments, mre than 90% f ttal pllen grains n the stigmas were frm female flwers. Percentages f stigmas shwing at least ne pllen grain frm male vines fr emasculated, emasculated + net cvered, nly net cvered and cntrl clusters were 25%, 25%, 29% and 63%, respectively. Lw percentages f stigmas with small number f male vine pllen grains in emasculated r net cvered clusters resulted in less than ne germinable pllen grain per pistil. Under such cnditins, clusters rarely will set berries. In the cntrl, the number f male vine pllen grains n the stigmas was at least six-times higher than the ther treatments. Pllen frm ther btanical species was als bserved n stigmas, thugh in small numbers. This indicates the flwering perids f ther plants cincide with that f Vitis cignetiae, creating sme cmpetitin fr insects attractin. Such a situatin might reduce the number f insects available as pllinatrs f Vitis cignetiae cntributing t pr yields. Reductin f ther flwering species in the vicinity f the vineyard and a increase in the current number f male vines may induce sme imprvement in natural fertile pllinatin. Insufficiency f male vines, hwever, des nt seem t be the main factr respnsible fr lw fertile pllinatin, since ther vineyards f Vitis cignetiae with higher male/female rati have been presenting similar prblems f pllinatin. Pllenizer psitining can als influence pllinatin, and may need t be cnsidered in the case f Vitis cignetiae [19]. Hand-pllinatin Germinatin f pllen tubes was better when flwers were pllinated tw days after anthesis than fr thse pllinated earlier r later (Table 2). Pllinatin tw days after anthesis gave almst 80% f pistils with pllen tubes penetrating the stigma, and an average number f 23.5 pllen tubes per stigma. Percentages f pistils shwing pllen germinatin in the stigma fr flwers pllinated at zer, fur, and six days after anthesis were 58%, 25%, and 13% with averages f 1.3, 0.9 and 0.3 pllen tubes per stigma, respec-

5 POLINATION AND STIGMA RCPTIVITY- 5 tively. In pistils pllinated tw days after anthesis, average number f pllen tubes reaching the micrpyle was 1.9, while in thse pllinated at ther dates this number varied between zer t The results indicate that stigma receptivity at tw days after anthesis was higher than ther dates chsen fr pllinatin. This seems an useful data fr further studies n practical use f artificial pllinatin in Vitis cignetiae. Cnclusins Bth enthmphilic and anemphilic pllinatin ccurs in Vitis cignetiae, althugh the frmer is mre imprtant. Female vines f Vitis cignetiae has a high level f self-pllinatin and pr crss-pllinatin with pllen frm male flwers. Since pllen f female vines is sterile, self-pllinatin des nt cntribute t fertilizatin. An increase in crss-pllinatin may imprve fertilizatin and, cnsequently, berry set. Pllen tube grwth in this species is mre efficient when pllinatin ccurs tw days after blming than at earlier r later stages. Since insects appear t be the main cntributrs t pllinatin, variatins in insect ppulatin r activity during blming may have an effect n the year t year variatins in yield f Vitis cignetiae. Literature Cited 1. Barrett, H. C. Sex determinatin in a prgeny f a self pllinated staminate clne f Vitis. Prc. Am. Sc. Hrtic. Sci (1966). 2. Bawa K. S., S. H. Bullck, D. R. Perry, R.. Cville, and M. H. Grayum. Reprductive bilgy f trpical lwland rain frest trees. I1. Pllinatin systems. Am. J. Bt (1985). 3. Branties, N. B. M. Pllinatr attractin f Vitis vinifera subsp. silvestris. Vitis (1978). 4. Carrar, L., G. Lmbard, G. Cargnell, and F. M. Cerla. Further bservatins n the factrs related t the lw prductivity f Piclit giall. Vitis (1981). 5. Kearns, C. A., and D. W. Inuye. Techniques fr Pllinatin Bilgists. University Press f Clrad, Niwt, CO (1993). 6. Kevan, P. D., D. C. A. Blades, U. Psluszny, and J. D. Ambrse. Pllen dimrphism and diecy in Vitis aestivalis. Vitis (1988). 7. Kimura, P. H., G. Okamt, and K. Hiran. Flwer types, pllen mrphlgy and germinatin, fertilizatin and berry set in Vitis cignetiae Pulliat. (In press, 1997) 8. Knuth, P. Handbk f Flwer Pllinatin, Vl. 2. pp Clarendn Press, Oxfrd (1908). 9. Maitani, T., and S. Takur. Observatin f airbrne pllen within and abve a rice and a wheat canpy. [In Japanese.] J. Agric. Met (1985). 10. Mre, J. N. Cytkinin-induced sex cnversin in male clnes f Vitis species. J. Am. Sc. Hrtic. Sci (1970). 11. Mullins, M. G., A. Buquet, and L.. Williams. Bilgy f the Grapevine. 239 pp. University Press, Cambridge (1992). 12. Nakagawa, S. Studies n the use f Japanese native Vitis species fr grape prductin. In Japanese. Osaka. Pref. Univ. Fac. Agric. Sci. Rep. (1986). 13. Negi, S. S., and H. P. Olm. Studies n sex cnversin in male Vitis vinifera L. (sylvestris). Vitis (1970). 14. Negi, S. S., and H. P. Olm. Cnversin and determinatin f sex in Vitis vinifera L. (sylvestris). Vitis (1971). 15. Negi, S. S., and H. P. Olm. Inductin f sex cnversin in male Vitis. Vitis (1971). 16. Pratt, C. Reprductive anatmy in cultivated grapes - A review. Am. J. nl. Vitic (1971). 17. Renner S. S., and J. P. Feil. Pllinatrs f trpical diecius angisperms. Am. J. Bt (1993). 18. Sawanbri, H. Yamabudu - Jinkusaibai n kkrmi. In Japanese. Nu-bunkyu Tkusan Series (1986). 19. Sharpies, G. C., F.. Tdd, S.. MacGregr, and R. L. Milne. The imprtance f insects in the pllinatin and fertilizatin f the Cardinal grape. Prc. Am. Sc. Hrtic. Sci (1965). 20. Westwd, M. N., and J. Grim. ffect f pllinizer placement n lng term yield f Anju, Barlett and Bsc pears. Prc. Am. Sc. Hrtic. Sci (1962) 21. Winkler, A. J., J. A. Ck, W. M. Kliewer, and L. A. Lider. General viticulture. Univ. Calif. Press, Berkeley (1962).

Unit 8 ~ Learning Guide

Unit 8 ~ Learning Guide Name: INSTRUCTIONS Cmplete the fllwing ntes and questins as yu wrk thrugh the related lessns. Yu are required t have this package cmpleted BEFORE yu write yur unit test. D yur best