The Effect of Supplementary Pollination on Nut Set of Macadamia (Proteaceae)

Transcription

1 nnls of otny 78: , 1996 The Effet of Supplementry Pollintion on Nut Set of Mdmi (Proteee) H. M. WLLCE*, V. VITHNGE nd E. M. EXLEY* * Deprtment of Entomology, Uni ersity of Queenslnd, St. Lui, 472, nd C. S. I. R. O. Di ision of Hortiulture, Cunninghm Lortories, Crmody Rd, St. Lui, 467, ustrli Reeived: 25 ugust 1995 epted: 1 July 1996 The effets of supplementry pollintion on initil nd finl nut set nd nut weight of the Mdmi ultivrs, Hwii griulturl Experiment Sttion 246 nd Hidden Vlley 4, were ssessed over 3 yers t n orhrd in estern ustrli. The finl nut sets of remes gged to exlude inset pollintors were low in ll 3 yers of the study for oth ultivrs. This demonstrted the importne of exposure to inset visitors to inrese nut set of these ultivrs. However, the improved initil nut set y supplementry ross pollintion of 246 in ll 3 yers of the study showed tht inset pollintion is ineffiient ompred to hnd pollintion. Furthermore, supplementry ross pollintion of 246 inresed finl nut set y 57 97% in 1989 nd inresed nut weight y 15 % nd kernel weight y 2 % in Cross pollintion of 4 did not result in ny onsistent pttern of initil nut set nd did not improve finl nut set, ut inresed nut weight y 11 6% nd kernel weight y 18 4%, with higher perentge kernel reovery in In ddition, supplementry self pollintion of 4 inresed nut sets in oth 1989 nd 199. Yield nd qulity of oth ultivrs my enefit from inresing pollen trnsfer in the orhrd nnls of otny Compny Key words: Mdmi integrifoli Miden nd ethe, Mdmi tetrphyll L.. S. Johnson, mdmi, Proteee, ross pollintion, self pollintion, pis mellifer, Trigon, nut set. INTRODUCTION Mdmi, memer of the fmily Proteee, is ultivted for its edile nuts. There re t lest seven speies of Mdmi in ustrli (Gross nd Hylnd, 1993), ut only two speies, Mdmi integrifoli Miden nd ethe nd M. tetrphyll L.. S. Johnson, nd their hyrids, re grown ommerilly. These speies re indigenous to the sutropil rinforests of the est ost of ustrli. Mdmi, like mny tropil trees, is mss flowering, nd produes mny more flowers thn fruits. Flowers re orne in pendulous remes onsisting of 1 3 flowers. Mdmi flowers re protndrous (Sedgley, lesing nd Vithnge, 1985) nd prtilly self inomptile (Sedgley, 1983), nd the initil nut set of mny ommeril ultivrs is redued when self pollintion is ompred with ross pollintion (Urt, 1954; Ito nd Hmilton, 198; Sedgley et l., 199). However, more thn 9% of the nuts tht set t 3 weeks post nthesis (initil nut set) sise y 8 weeks post nthesis (Ski nd Ngo, 1985). Ovries tht sise hve een found to e fertilized nd norml in development (Sedgley, 1981) nd it is not ler whether inreses due to ross pollintion t initil nut set produe inresed finl nut set. Reently, Truemn nd Turnull (1994) hve demonstrted tht rtifiil ross pollintion my in some irumstnes inrese finl set, weight nd kernel reovery of ommeril Mdmi ultivr. Current ddress: Deprtment of Environmentl Mngement nd Eology, L Troe University, lury Wodong Cmpus, Prkers Rd, Wodong, 3689, ustrli $25. Severl studies in Hwii hve limed tht pollintion y the honeyee, pis mellifer L., ws responsile for inreses in yield. Shigeur, Lee nd Silv (197) found n inrese in yield when honeyees were pled in n orhrd. Shigeur (1967, 1968), Ito, Hunter nd Hmilton (197) nd Ito nd Hmilton (198) inferred tht trnsfer of ross pollen y honeyees ws responsile for higher yield nd etter nut qulity oserved in mixed lok plnting ompred with pure lok plnting. Tretments were onfounded in these studies nd reported inreses in yield my hve een due to yer or site effets. In ustrli, the mjor pollintors in ommeril Mdmi plnttions re from two gener of soil ees: the introdued honeyee, pis mellifer, nd ntive ees of the genus Trigon (Vithnge nd Ironside, 1986). The ehviour of these speies of ees influenes their effetiveness s pollintors. Pollen olletors of oth gener mke onsistent ontt with the stigm of Mdmi (Herd, 1994) sine pollen is presented on the swollen tip of the style djent to the stigm. Netr-olleting honeyees only osionlly mke ontt with the stigm nd netrolleting Trigon never mke ontt with the stigm. Sine ontt with the stigm is neessry for effetive pollintion, the type of florl resoure gthered will e importnt in determining the effetiveness of pollintion. This study ws undertken to ssess the effet of ross nd self pollintion on initil nut set nd finl nut set, to ompre pollintion y ees with rtifiil pollintion nd ssess the effiieny of inset pollintors, nd to exmine the reltionship etween initil nut set nd finl nut set of Mdmi nnls of otny Compny Downloded from y guest on 1 Jnury 218

2 766 Wlle et l. Pollintion of Mdmi MTERILS ND METHODS Study site ll experiments were rried out t Hidden Vlley plnttions, eerwh, (26 5 S E), etween ug nd My Trees of two ultivrs of Mdmi were used: Hwii griulturl Experiment Sttion 246 (246), pproximtely 25 yers old, nd Hidden Vlley 4 (4), pproximtely 1 yers old. Pollen from two other ultivrs, Hidden Vlley 16 (16) nd Own Choie, ws used to ross pollinte when neessry. Cultivr 246 ws in pure lok with losed nopy etween trees, nd 4 ws in smll lok surrounded y other ultivrs, with n open nopy. Experimentl design In 1989 nd 199, eight trees of eh ultivr were seleted, nd on eh tree, four rnhes of similr dimeter with pproximtely 3 4 remes were seleted. Every reme on rnh ws tgged. In order to exmine the ontriution of erly flowering to nut prodution, two experiments were onduted on 246 in 1989, one during the sprse flowering in lte ug. nd the other during the hevy flowering in mid-sep. Four lrge rnhes were treted for the ug. flowering nd four smller rnhes, oupying pproximtely one third of the nopy re of the lrger rnhes, were treted for the Septemer flowering. One tree ws exluded from the experiment in Septemer due to synhrony in flowering. rnhes were rndomly ssigned to one of four tretments with eh tree reeiving ll tretments. ll remes on the rnh reeived the sme tretment. In 1991, 5 remes were seleted per tree on eh of four trees nd 25 remes per tree were rndomly ssigned to one of five tretments. The tretments were: (1) gging of flowers to prevent inset pollintion; (2) remes open to pollintors (ontrol); (3) remes open to pollintors, with dditionl hnd pollintion with pollen from nother ultivr (supplementry ross); (4) remes open to pollintors, with dditionl hnd pollintion with pollen from different trees of the sme ultivr (supplementry self); (5) remes gged to exlude pollintors nd hnd pollinted with pollen from different trees of the sme ultivr (gged nd selfed). gs were repled fter eh pollintion. This tretment ws performed in 1991 only. Remes were gged y enlosing in 5 mm 1 mm mesh gs or glssine pper gs from the stge of style looping (pprox. 2 d pre-nthesis) until ll sepls hd withered (pprox. 1 d post-nthesis). Remes tht reeived hnd pollintion were treted fter the method of Ito nd Hmilton (1969), with glss test tue 25 mm internl dimeter nd 3 mm long. Pollen ws pplied to the inner surfe of the test tue y ruing it ginst freshly opened reme. The remes to e pollinted were pled in the test tue nd the tue ws rotted, llowing pollen to mke ontt with the stigm. Two remes were treted using this method efore the test tue ws rinsed in 1% ethnol. This method hs een shown to e effetive in primrily ltering the type of pollen rther thn the numer of pollen grins on the stigm (Truemn nd Turnull, 1994). Hnd pollinted remes were treted s ove every 2 d from nthesis until ll sepls hd fllen. Cultivr 246 ws ross pollinted with 4 in the min flowering in ll three yers, nd with Own Choie in the erly flowering in ug Cultivr 4 ws pollinted with 16 in 1989 nd 199 nd, due to synhrony in flowering, 246 in Initil nut set (INS) ounts for eh reme were onduted 21 d fter the lst pollintion of the reme in 1989, nd 14 d nd 21 d fter the lst pollintion of the reme in 199 nd 1991 for ll remes exept those tht were gged in 199. Florl sission nd ovry swelling of gged remes hd not ourred t 14 d in 199 nd ounts were onduted t 21 d. Finl nut set (FNS) ounts were onduted in mid-jn., pproximtely 4 months fter flowering. Nuts from ll tretments were gged in Mr. 1992, nd llowed to develop until mturity. Mture nuts were olleted from the gs in June nd llowed to dry. Nut in shell (NIS) nd kernel were weighed individully nd individul kernel reovery, qulity ftor used y the industry, ws lulted y dividing kernel weight y NIS weight. Pollintor isits Inset visits were monitored on 4 nd 246 for 1 min eh hour etween 6 h nd 17 h for 4 d during the flowering seson in 1989 (sped over 11 d of the flowering seson), etween 9 h nd 17 h for 11 d in 199 (sped over 44 d) nd etween 8 h nd 17 h for 5 d in 1991 (sped over 18 d). Two study res were exmined eh dy when flowering ws intense, nd one ws exmined etween 3 ug. 199 nd 21 Sep. 199 when flowering ws sprse. Eh study re onsisted of setion of nopy pprox. 1 m on trees of 246, or 4, or oth when flowering of the two ultivrs overlpped. Study res were m ove the ground. Eh study re ontined pprox. ten remes whih hd rehed nthesis. Study res were seleted to ensure tht florl stge, undne nd density of flowers were omprle. In eh study re, the numer of visitors, speies of visitor nd type of resoure gthered were reorded for the 1 min period eh hour. Two Trigon ronri Smith hives were pled in the orhrd in 199 nd one in 1991, within 5 m of the study sites. No honeyee hives were pled in the orhrd in ny yer. Sttistil nlysis The pproprite log or squre root trnsformtion ws performed on the INS dt for the ontrol, supplementry self nd supplementry ross pollintion tretments in order to hieve norml distriution, nd nlysed using n nlysis of vrine proedure of GENSTT with trees regrded s loks. The ssumptions of nlysis of vrine were heked y exmining plots of residuls ginst fitted vlues. Differenes etween mens were ssessed using Tukey s HSD test. Initil nut sets of the gged remes nd the gged nd selfed remes, with the exeption of 4 dt in 1989 nd Downloded from y guest on 1 Jnury 218

3 Wlle et l. Pollintion of Mdmi , were not normlly distriuted nd were exluded from the nlysis of vrine. Dt for 4 in 1989 required n unlned NOV nd were nlysed using the GLM proedure of SS nd tested ginst the type-three sum of squres. ll FNS dt were nlysed s ontingeny tles tested ginst the χ sttisti sine they displyed Poisson distriutions. Very low FNSs were oserved for the gged nd gged nd selfed remes nd these were exluded from the nlysis in ll ses exept 246 erly flowering in 1989 nd min flowering in 199, in whih ses the distriution ws similr to the other tretments. Differenes etween mens were ssessed ginst the χ sttisti, using the Dunn-Sid ks orretion. NIS weights, kernel weights nd individul kernel reoveries were nlysed with n nlysis of vrine nd the differenes etween mens ssessed using Tukey s HSD test. Initil nut set per reme (21 d) g RESULTS Culti r 246 initil nut set There were onsistent differenes in INS of 246 due to pollintion tretment for ll three yers of the study, Initil nut set per reme (21 d) Finl nut set per reme g g Pollintion tretment FIG. 1. Initil () nd finl () nut sets of treted remes of 246 opening in ugust 1989 (prior to min flowering). Numer of remes reeiving supplementry ross pollintion (ross) 47, supplementry self pollintion (self) 59, ontrol remes 6, gged (g) 37. Tretment mens with different letters were signifintly different (P 5). Finl nut set per reme.2.1 g Pollintion tretment FIG. 2. Initil () nd finl () nut sets of treted remes of 246, Numer of remes reeiving supplementry ross pollintion (ross) 247, supplementry self pollintion (self) 282, ontrol remes 282, gged (g) 118. Tretment mens with different letters were signifintly different (P 5). lthough these differenes vried in mgnitude. In ll ses oserved, remes tht reeived supplementry ross pollintion set signifintly more nuts (P 1) thn those reeiving ny other tretment (Figs 1, 2, 3, nd 4, ). Supplementry self pollinted remes did not set signifintly more nuts thn remes tht were open pollinted only (ontrol), with the exeption of 199 (Fig. 3). In ll yers the gged remes set very few nuts, with most remes hving n INS of zero (Figs 1 4). In ddition, gged nd selfed remes set very few nuts, nd sets of these tretments were not signifintly different in 1991 (Fig. 4, ). Culti r 246 finl nut set In 1989 FNS ws ffeted signifintly y pollintion tretment (P 1) in the ugust flowering (Fig. 1). Supplementry ross pollintion of remes inresed finl nut set y 97% in the erly flowering seson ompred to ontrols, with no signifint differenes etween ontrols nd other tretments (Fig. 1). The ugust flowering produed few nuts, ontriuting only 17 9% of the remes nd 17 9% of the finl nuts for 246 in 1989, even though Downloded from y guest on 1 Jnury 218

4 768 Wlle et l. Pollintion of Mdmi Initil nut set per reme (14 d) Initil nut set per reme (21 d) Initil nut set per reme (14 d) Initil nut set per reme (21 d) g + S g + S g g Finl nut set per reme C g Finl nut set per reme C g + S g Pollintion tretment g Pollintion tretment FIG. 3. Initil (, ) nd finl (C) nut sets of treted remes of 246, 199. Tretments s in Fig. 1. Numer of remes reeiving supplementry ross pollintion (ross) 276, supplementry self pollintion (self) 276, ontrol remes 273, gged (g) 251. Tretment mens with different letters were signifintly different (P 5). rnhes oupied pproximtely three times s muh re of nopy s those used in the Septemer flowering. In the Septemer flowering, remes tht reeived supplementry ross pollintion set 57% more nuts thn the ontrol (signifint t P 5). Remes tht reeived supplementry self pollintion lso set more nuts thn the ontrol (P 5), nd there ws no signifint differene in nut set etween supplementry ross nd supplementry self tretments. gged remes set fewer nuts thn those of ny other tretment with fewer thn 1 nuts per reme (Fig. FIG. 4. Initil (, ) nd finl (C) nut sets of the pollintion tretments for 246, Tretments s in Fig. 1; g s, remes gged nd selfed. Numer of remes reeiving eh tretment 1. Tretment mens with different letters were signifintly different (P 5). 2). However in 199 there ws no signifint differene due to ny tretment, nd ll remes, inluding the gged, set very few nuts (Fig. 3C). In 1991 no signifint differenes were oserved etween the ontrol, supplementry self or supplementry ross pollinted remes ut these set mny more nuts thn those tht were gged or gged nd selfed (Fig. 4C). Pollintion tretment ffeted NIS weight (P 1), kernel weight (P 1) nd individul kernel reovery (P 5). Supplementry ross pollintion inresed NIS weight nd kernel weight ompred with supplementry self pollintion nd open pollintion lone (ontrol), whih were not signifintly different (Tle 1). In ddition, supplementry ross pollintion inresed individul kernel reovery in omprison to supplementry Downloded from y guest on 1 Jnury 218

5 Wlle et l. Pollintion of Mdmi 769 TLE 1. Men nut in shell weight, kernel weight nd kernel reo ery of 246, Tretment mens with different supersript letters (in the sme row) were signifintly different t P 5 Tretment Control Supplementry self Supplementry ross Men nut in shell weight (g) Men kernel weight (g) Men kernel reovery (%) No. nuts hrvested Initil nut set per reme (21 d) Initil nut set per reme (14 d) Finl nut set per reme g g Pollintion tretment FIG. 5. Initil () nd finl () nut sets of treted remes of 4, Numer of remes reeiving supplementry ross pollintion (ross) 172, supplementry self pollintion (self) 156, ontrol remes 154, gged (g) 2. Tretment mens with different letters were signifintly different (P 5). self pollintion (Tle 1). Remes of 246 tht were ross pollinted produed nuts tht weighed on verge 15 % more, with 2 % more kernel, thn those resulting from open pollintion. Culti r 4 initil nut set Initil nut set per reme (21 d) Finl nut set per reme C g d In ontrst to 246, the ptterns of initil nut sets in 4 vried from yer to yer. In 1989 the numer of nuts set t 21 d y the ontrol remes ws not signifintly different from supplementry ross pollinted remes while remes of these two tretments set signifintly (P 5) more nuts thn supplementry self pollinted nd gged remes, whih were not signifintly different (Fig. 5). However, g Pollintion tretment FIG. 6. Initil (,) nd finl (C) nut sets of treted remes of 4, 199. Numer of remes reeiving supplementry ross pollintion (ross) 258, supplementry self pollintion (self) 251, ontrol remes 261, gged (g) 237. Tretment mens with different letters were signifintly different (P 5). Downloded from y guest on 1 Jnury 218

6 77 Wlle et l. Pollintion of Mdmi Initil nut set per reme (14 d) Initil nut set per reme (21 d) Finl nut set per reme C g + S g + S g + S g g g Pollintion tretment FIG. 7. Initil (, ) nd finl (C) nut sets of the pollintion tretments for 4, Tretments s in Fig. 1; g s, remes gged nd selfed. Numer of remes reeiving eh tretment 1. Tretment mens with different letters were signifintly different (P 5). remes tht reeived supplementry ross nd self pollintion in 199 set signifintly more nuts thn the ontrol remes, with ross pollinted remes setting signifintly more thn self pollinted remes (Fig. 6, ). The gged remes in oth yers set fewer nuts thn remes of ll other tretments. The pttern ws different gin in 1991 t 14 d, with the highest sets in the gged, nd gged nd selfed remes, nd the lowest in the ontrol remes (Fig. 7). However, t 21 d there ws no signifint differene etween ny tretments (Fig. 7). Culti r 4 finl nut set In 1989 nd 199, in ontrst to 246, supplementry ross pollinted remes did not set signifintly more nuts thn the ontrol. However, remes tht reeived supplementry self pollintion set signifintly more nuts thn the ross pollinted remes (P 5 in 1989, P 1 in 199) nd the ontrol in 199 (P 1) (Figs 5 nd 6C). In 1991, there ws no signifint differene etween the ontrol, supplementry ross pollinted nd supplementry self pollinted remes (Fig. 7C). However, there ws signifint differene in NIS weight (P 5), kernel weight (P 1) nd individul kernel reovery (P 1). Supplementry ross pollintion of 4 remes produed nuts tht weighed 11 6% more thn remes tht were open pollinted only, with 18 4% hevier kernels, nd higher individul kernel reovery (P 5, Tle 2). There ws no signifint differene etween supplementry ross nd self pollintion (Tle 2), or etween supplementry self pollintion nd ontrols. Pollintor isits Honeyees nd Trigon sp. were frequent visitors to Mdmi remes t this site (Tle 3). Pollen olleting, espeilly y Trigon sp., ws often oserved. Pollen ws sre resoure fter 1 h nd Trigon sp. were frequently oserved roing pollen, i.e. removing pollen from unopened or prtilly opened flowers y hewing through the tip of the perinth tue (see lso Herd, 1994). Other inset visitors inluded Metriorrhynus rhipidius Mley (Coleopter; Lyide), Monolept ustrlis Joy (Coleopter; Chrysomelide), flies of the fmily Syrphide nd nts. These visitors were oserved infrequently (Tle TLE 2. Men nut in shell weight, kernel weight nd kernel reo ery of 4, Tretment mens with different supersript letters (in the sme row) were signifintly different t P 5 Tretment Control Supplementry self Supplementry ross Men nut in shell weight (g) Men kernel weight (g) Men kernel reovery (%) No. nuts hrvested Downloded from y guest on 1 Jnury 218

7 TLE 3. Numers of isitors per 1 min per m of Mdmi remes for eh yer of study (n totl numer of 1 min oser tion periods in eh yer). Men nd stndrd error pro ided Wlle et l. Pollintion of Mdmi 771 Yer of study Type of visitor 1989 (n 88) 199 (n 136) 1991 (n 45) Honeyees netr pollen oth totl Trigon sp. netr pollen oth totl Other Totl ) nd will not e disussed further. In 1989 the most numerous visitors were honeyees, with Trigon sp. oserved infrequently (Tle 3). In 199 Trigon sp. ws the dominnt speies, nd similr numers of oth speies were oserved in 1991 (Tle 3). DISCUSSION The effet of supplementry pollintion on nut set nd qulity Inreses in INS due to ross pollintion hve een reported for mny ultivrs of Mdmi (Urt, 1954; Ito nd Hmilton, 1969; Ito et l., 197; Ito, Eyre nd Crl, 1983; Sedgley et l., 199). However, none of these studies exmined whether ross pollintion inresed nut retention t the lter stges of development. In ll 3 yers of our study, supplementry ross pollintion inresed INS of 246 nd, in one of 3 yers, of 4. Furthermore, supplementry ross pollintion inresed FNS in two ses out of four for 246 (Figs 1 nd 2). Cross pollintion sustntilly inresed nut weight nd kernel weight of oth ultivrs, nd individul kernel reovery of 4. This demonstrtes tht ross pollintion my use more nuts of Mdmi to e retined until mturity nd inrese other qulity ftors suh s nut size. Similr inreses in nut set nd weight hve een reported y Truemn nd Turnull (1994) for 66 when pollinted with 246 or 333 pollen. These results onfirm tht differenes in nut set nd nut qulity (i.e. kernel hrteristis) oserved etween pure nd mixed loks (Ito et l., 197; Ito nd Hmilton, 198) my e due to higher levels of ross pollintion in mixed loks. In mny other hortiulturl rops, inluding pen [Cry illinoensis (Wngenh.) C. Koh], vodo (Perse merin Mill.), hestnut (Cstne sti Mill.), pisthio (Pisti er L.), dte (Phoenix dtylifer L.), nd lyhee (Lithi hinensis Sonn.), seeds nd mture fruits produed y ross pollintion re hevier thn those produed y self pollintion (Mrqurd, 1988; Sedgley nd Griffin, 1989; Degni et l., 199; Denney, 1992; Stern et l., 1993). Supplementry self pollintion utilized the sme pollintion tehnique s ross pollintion, the only differene eing the type of pollen used. However, supplementry self pollintion of remes hd no effet on INS ompred to the ontrol remes in five out of six ses of 246 (Figs 1, 2, 3 nd 4, ), nd for 4 in This onfirms tht, in these ses, ny inreses in INS oserved in the ross pollinted remes n e ttriuted to pollen soure (self or ross) rther thn pollintion tehnique or numer of pollen grins on the stigm. surprising result of this study is tht supplementry self pollintion n inrese FNS. Supplementry self pollintion inresed FNS ompred to ontrols in one of three ses for 4, nd equlled the inrese due to ross pollintion in one of four ses for 246. For 4, when nuts were hrvested in 1991, NIS weights, kernel weights, nd kernel reoveries were similr to nuts produed y ross pollintion. Some nuts were produed y gged remes of oth ultivrs eh yer, lthough oth INS nd FNS ws low. More nuts my e produed y suh remes when there is less ompetition for resoures from ross pollinted nuts; for exmple, isolted trees nd pure loks sometimes produe high nut set. The pollintion effiieny of flower isitors Exposure to flower visitors ws importnt for dequte nut sets of oth Mdmi ultivrs exmined in this study. Exlusion of flower visitors (gged tretment) resulted in the lowest INS in ll ses, exept 4 in 1991, nd lower FNS thn ny other tretment in five ses out of seven (Figs 2, 4C, 5, 6C nd 7C). This supports the lim of Shigeur et l. (197) tht pling of ees in n orhrd my inrese yield. However, supplementry pollintion inresed INS nd sometimes inresed FNS, NIS weight, kernel weight nd kernel reovery in oth ultivrs exmined in this study. The results suggest tht nturl levels of pollintion, due to the tivities of flower visitors, were suoptiml. If whole trees respond to pollintion in the sme wy s remes then improved pollintion my inrese ommeril yields of Mdmi. Severl ftors my use indequte nturl pollintion, inluding: (1) low pollintor popultions nd or pollintor tivity in the orhrd, resulting in insuffiient visits y pollintors to remes; (2) insuffiient supply of ross pollen in the orhrd; (3) ee ehviour resulting in trnsfer of self pollen ut not ross pollen. High numers of flower visitors were oserved for ll yers in omprison to other studies (Vithnge nd Ironside, 1986; Herd, 1993; Herd nd Exley, 1994), exept Trigon sp. in 1989 (Tle 3). Vithnge nd Ironside (1986) exmined ee visittion rtes in three orhrds in the re (26 S) nd Herd nd Exley (1994) exmined ee visittion rte in this orhrd nd mny other orhrds in the re. lmost ll visits oserved in the urrent study were y either honeyees or Trigon sp., whih re the mjor pollintors of Mdmi (Vithnge nd Ironside, 1986). Trigon sp. nd, less frequently, honeyees were oserved in the urrent study olleting pollen, inditing tht ee Downloded from y guest on 1 Jnury 218

8 772 Wlle et l. Pollintion of Mdmi ehviour llowed stigm ontt nd therefore pollintion (Herd, 1994). In ft, pollintor tivity ws so intense tht pollen ws sre fter 1 h nd mny Trigon engged in roing ehviour. It is surprising tht supplementry pollintion improved yield in n orhrd with suh intense pollintor tivity. Either Mdmi requires more pollintors thn oserved here for effiient pollintion or some other ftor limits pollintion in this orhrd. Mny other orhrds hve lower pollintor popultions (Herd nd Exley, 1994) nd in these orhrds inresing pollintor popultions my improve yield. Insuffiient supply of ross pollen ould ount for the indequy of nturl pollintion. Cultivr 246 ws plnted in pure loks, nd experimentl trees were 5 1 m from the nerest ross pollen soure. Trees of 4 were up to 5 m from the nerest ross pollen soure, lthough some trees were next to trees of other ultivrs. These trees my hve reeived more ross pollen thn 246, nd onsequently finl nut sets of 4 were not inresed y supplementry ross pollintion. vilility of omptile pollen ould e inresed y improved interplnting of ultivrs, rther thn plnting pure loks of single ultivr, nd plnting ultivrs with synhronous flowering. ee ehviour my lso limit the trnsfer of ross pollen. In pple (Mlus domesti orkh.) orhrds, honeyees tended to remin onstnt to flowers of one ultivr for s long s it ws ttrtive, nd estlished smll forging rnge (Free, 1966). In ddition, in orhrds of dwrf pples, honeyees usully rnged over only out 3 m of one row in one forging trip where rows mde ontinuous hedge (Free nd Spener-ooth, 1964). Jkson nd Clrke (1991) found tht gene flow in lmond [Prunus dulis (Mill) D.. We] ws restrited to neighouring hlves of rossomptile trees nd suggested tht honeyees visited only one ultivr nd flew long rows. Most of the ultivted Mdmi genotypes n now e identified using isozyme systems (Vithnge nd Winks, 1992). This my e useful tool to determine if seeds result from ross or self pollintion, nd to exmine the pttern of gene flow in the orhrd. The reltionship etween initil nd finl nut set Initil nut set hs een used previously s n inditor of ross omptiility nd s preditor of yield (Sedgley et l., 199). However, urrent results show it to e unrelile for either of these purposes. Results will depend on when nut ounts re tken. Other uthors hve used 7 1 d (Ito nd Hmilton, 1969), 1 d fter the lst pollintion (Ito et l., 197, 1983), 15 2 d post-nthesis (Urt, 1954) or 21 d post-pollintion (Sedgley et l., 199; Herd, 1993). In this experiment, in some ses differenes etween tretments were deteted t 14 d ut no differenes were deteted t 21 d. In some ses INS my e ffeted y sesonl influenes. In 1989 nd 199 the sme pollen soure nd experimentl design produed very different initil nut sets for 4. Inreses in INS due to pollintion did not lwys result in inreses in FNS. fter INS, the nut retention on given rnh my depend on the ville rohydrte, nd my represent mternl djustment of rop lod, serving to minimize the mount of resoures lost y sission (Truemn nd Turnull, 1994). The urrent study demonstrtes inreses in FNS due to pollintion under norml orhrd onditions where resoures re limiting. Inresing resoure vilility to remes, for exmple, y girdling, removing ompeting flowers or pplying fertilizer my result in lrger nd more onsistent inreses in FNS due to pollintion. This study, nd tht of Truemn nd Turnull (1994), olletively report pollintion effets on FNS on four ultivrs. Mny other ultivrs re used ommerilly nd different ultivrs my hve different omining ilities, nd this will ffet FNS. The omining ility of some ultivrs hs een exmined using INS (Sedgley et l., 199), ut there is need to investigte omining ility using FNS nd nut qulity. Overll, these results demonstrte tht improving the nturl levels of pollintion n inrese yields of Mdmi. This hs implitions for orhrd design nd mngement. Pollintion ould e improved in severl wys. Firstly, pollintor popultions ould e inresed y pling hives of oth pis mellifer nd Trigon ronri in the orhrd, nd lso y reful plnning of insetiide sprying regimes to void times of pek pollintor tivity (Vithnge nd Ironside, 1986; Vithnge nd Dougls, 1987). Seondly, the vilility of ross pollen ould e inresed y improved interplnting of ultivrs (Sedgley et l., 199). Thirdly, ross pollen trnsfer in the orhrd ould e improved y mnipulting the ehviour of insets, for exmple y inresing the numer of honeyees olleting pollen or using dispensers to pply pollen to ees leving hive (Jy, 1986). In this study, supplementry pollintion resulted in yield inreses in Mdmi orhrd tht experiened high ee visittion rtes. Mny orhrds experiene very low visittion rtes (Herd nd Exley, 1994). Suh orhrds my enefit drmtilly from improved orhrd design nd the introdution of ees. CKNOWLEDGEMENTS We thnk Cmeron MConhie for suggestions, Henry, lison nd Dvid ell of Hidden Vlley Plnttions, eerwh, for ess to trees nd ommodtion, nd Jon Hendrikz for sttistil dvie. This projet ws funded y the ustrlin Speil Rurl Reserh Fund. LITERTURE CITED Degni C, Goldring, dto I, El-stri R Pollen prent effet on outrossing rte, yield nd fruit hrteristis of Fuerte vodo. HortSiene 25: Denney JO Xeni inludes metxeni. HortSiene 27: Free J The forging res of honeyees in n orhrd of stndrd pple trees. Journl of pplied Eology 3: Free J, Spener-ooth Y The forging ehviour of honeyees in n orhrd of dwrf pple trees. Journl of Hortiulturl Siene 39: Gross CL, Hylnd PM Two new speies of Mdmi (Proteee) from north Queenslnd. ustrlin Systemti otny 6: Herd T Pollintor requirements nd flowering ptterns of Mdmi integrifoli. ustrlin Journl of otny 41: Downloded from y guest on 1 Jnury 218

9 Wlle et l. Pollintion of Mdmi 773 Herd T ehviour nd pollintor effiieny of stingless ees nd honey ees on mdmi flowers. Journl of piulturl Reserh 33: Herd T, Exley EM Diversity, undne nd distriution of inset visitors to mdmi flowers. En ironmentl Entomology 23: Ito PJ, Eyre JM, Crl S Preliminry study on pollintion of five mdmi ultivrs. In: Stephenson R, Gllgher EC, eds. Proeedings of the First ustrlin Mdmi Reserh Workshop, Session 4 Pper No. 2. ustrlin Mdmi Soiety Limited, risne. Ito PJ, Hmilton R Initil nut set from ross- nd selfpollintion of six mdmi ultivrs. Hwii Mdmi Produers ssoition nnul Proeedings 9: Ito PJ, Hmilton R Qulity nd yield of Keuhou mdmi nuts from mixed nd pure lok plntings. HortSiene 15: 37. Ito PJ, Hunter JE, Hmilton R Effet of ross-pollintion on initil nd finl nut set nd yields of mdmi ultivrs. Hwii Mdmi Produers ssoition nnul Proeedings 1: Jkson JF, Clrke GR Gene flow in n lmond orhrd. Theoretil nd pplied Genetis 82: Jy SC Sptil mngement of honey ees on rops. nnul Re iew of Entomology 31: Mrqurd R Outrossing rtes in pen nd the potentil for inresed yields. Journl of the merin Soiety for Hortiulturl Siene 113: Ski WS, Ngo M Fruit growth nd sission in Mdmi integrifoli. Physiologi Plntrum 64: Sedgley M Erly development of the Mdmi ovry. ustrlin Journl of otny 29: Sedgley M Pollen tue growth in mdmi. Sienti Hortiulture 18: Sedgley M, ell FDH, ell D, Winks CW, Pttison SJ, Hnok TW Self- nd ross-omptiility of mdmi ultivrs. Journl of Hortiulturl Siene 65: Sedgley M, lesing M, Vithnge HIMV developmentl study of the struture nd pollen reeptivity of the mdmi pistil in reltion to protndry nd self inomptiility. otnil Gzette 146: Sedgley M, Griffin R Sexul reprodution of tree rops. London: demi Press. Shigeur GT Vrietl nut yield nd suggestion of pollintion requirement in mdmi. Hwii Mdmi Produers ssoition nnul Proeedings 7: Shigeur GT Mdmi nut yield s influened y vrieties nd honey ee pollintion- progress note. Clifornin Mdmi Soiety Yerook 14: Shigeur GT, Lee J, Silv J The role of honeyees in mdmi nut (Mdmi integrifoli Miden nd ethe) prodution in Hwii. Journl of the merin Soiety for Hortiulturl Siene 95: Stern R, Gzit S, El-tsri R, Degni C Pollen prent effet on outrossing rte, yield, nd fruit hrteristis of Floridin nd Muritius lyhee. Journl of the merin Soiety for Hortiulturl Siene 118: Truemn SJ, Turnull CGN Effets of ross pollintion nd flower removl on fruit set in mdmi. nnls of otny 73: Truemn SJ, Turnull CGN Fruit set, sission nd dry mtter umultion on girdled rnhes of mdmi. nnls of otny 74: Urt U Pollintion requirements of mdmi. Hwii griulturl Experiment Sttion Tehnil ulletin No. 22. Vithnge HIMV, Ironside D The inset pollintors of mdmi nd their reltive importne. Journl of the ustrlin Institute of griulturl Siene 52: Vithnge V, Dougls TJ Honeyee pollintion of mdmi: florl rewrds nd their effet on pollen flow. Journl of piulturl Reserh 26: Vithnge V, Winks CW Isozymes s geneti mrkers for Mdmi. Sienti Hortiulture 49: Downloded from y guest on 1 Jnury 218