Title: POLLEN AND POLLINATION EXPERIMENTS 8. THE EFFECT OF SUCCESSIVE POLLINATIONS WITH COMPATIBLE AND SELF INCOMPATIBLE POLLEN IN APPLE MALUS AND PEAR PYRUS
Authors: VISSER T; VERHAEGH J J; MARCUCCI M C; UIJTEWAAL B A
Authors affiliation: INSTITUTE FOR HORTICULTURAL PLANT BREEDING, WAGENINGEN, NETHERLANDS.
Published in: Euphytica, volumn 32, pages 57-64, (1983).
Abstract: “In compatible pollen combinations, viable but infertile irradiated pollen Cr appears to compete much more in a mixture (the mentor pollen situation: C + Cr), than when used 1 day in advance (the pioneer pollen situation: Cr/C). Seed set of Cr/C was usually also greatly superior to that of C/Cr and, using self-incompatible pollen S instead of Cr, S/C was nearly always much better than C/S. This is in accordance with the promotion of the second by the 1st (pioneer) pollen. When Cr of S are applied second in C/Cr or C/S, more ovules are rendered ineffective (blocked or aborted) than in the reverse combination when Cr or S act as pioneer pollen. The combinations C/C + S, C + S, C/S tended to produce more selfed seeds in that order. Although mentor or pioneer pollen assist in removing the style barrier for self pollen, embryo abortions appears to be a 2nd obstruction towards seed formation. High spring temperature during pollination may promote the production of selfed seeds in the presence of compatible pollen. The surfeit of self pollen in orchards with a minority of pollinators is not necessarily an unfavorable factor, it may both directly and indirectly contribute to fruit and seed set.”
Anyone know if the Cr infertile pollen germinates but doesn’t successfully fertilize, or doesn’t it germinate at all?
Title: THE PERFORMANCE OF DOUBLE OR MIXED POLLINATIONS WITH COMPATIBLE AND SELF-INCOMPATIBLE OR INCONGRUOUS POLLEN OF PEAR AND APPLE
Authors: VISSER T; MARCUCCI C M
Authors affiliation: INST HORTIC PLANT BREEDING, WAGENINGEN, NETH.
Published in: Euphytica, volumn 35, pages 1011-1016, (1986).
Abstract: " Six pear [Pyrus] and five apple [Malus] trials were carried out to ascertain the outcome of combinations of compatible pollen (C) with self (S) or incongruous pollen (I) as to the pollination index (PI = seeds/pollinated flower). The PI of the mixture C + I (1:5) was consistently depressed as compared to that of the control C. The results of the double pollinations S/C and I/C were affected by the temperature at pollination their PI’s at 15.degree. C, being well above and below the PI of C in the former and latter case respectively. The opposite was true for the C/S combination, the pI of which increased with the pollination temperature; the PI of C/I did not differ much from the PI of C, irrespective of temperature. The conclusion was reached that the interaction previously and presently found between compatible and self-incompatible pollen also exists to a fair extent between compatible and incongruous pollen. However, in pear neither the mentor nor the pioneer pollen technique proved to aid its hybridization with apple, the formation of self seed was not observed either. In apple the production of apple .times. pear hybrids was likewise doubtful, but the double pollinations S/C and C/S formed 4-10% self seed.
Title: THE INTERACTION BETWEEN COMPATIBLE AND SELF-INCOMPATIBLE POLLEN OF APPLE AND PEAR AS INFLUENCED BY THEIR RATIO IN THE POLLEN CLOUD
Authors: VISSER T; MARCUCCI M C
Authors affiliation: INST HORTICULTURAL PLANT BREEDING, P BOX 16, 6700 AA WAGENINGEN, NETH.
Published in: Euphytica, volumn 33, pages 699-704, (1984).
Abstract: " The production of self-seed was investigated in apple [Malus] and pear [Pyrus] with the aid of viable and compatible mentor/pioneer pollen in relation to the proportion of self-incompatible pollen present in the pollen cloud. Treatments consisted of mixtures of compatible and self-incompatible pollen at ratios of 1:1, 1:2 and 1:9, applied once or twice or followed by self-pollination. Selfing only, whether once or twice, produced virtually no fruits or seeds, while mixed pollinations did. Generally, fruit set tended to decrease and the percent self-seed to increase with increasing amounts of self pollen in the pollinations. The pioneer-pollen method (compatible in advance of self pollen) appeared more effective than the mentor pollen method (compatible and self pollen mixed). The use of viable instead of dead mentor/pioneer pollen causes competition for the ovules with the self pollen, but has the advantage that, in addition to some self-seed, other seeds are formed which, e.g., in apple are necessary to keep the fruits on the tree until harvest. Fruit set was moderately reduced at ratios of compatible pollen to self pollen not exceeding 1:9 with pear and 1:5 with apple which constitute maximal ratios in practice as regards pollinator trees; trees of the main cultivar. In fruit orchards and probably in nature with other species, the interaction between compatible and self pollen may result in more self-seed, and so suggests that inbreeding played a greater part in the evolution of self-incompatible species, than the meager results of artificial self-pollination imply".
Title: MENTOR POLLEN EFFECT ON THE IN-VIVO GERMINATION OF SELF INCOMPATIBLE APPLE MALUS POLLEN
Authors: MONTALTI P; FILITI N
Authors affiliation: IST COLTIVAZONI ARBOREE, UNIV DI BOLOGNA, ITALY.
Published in: Scientia Horticulturae (Amsterdam), volumn 23, pages 337-344, (1984).
Abstract: “The influence of mentor pollen on the performance of self pollen in apple styles was investigated. Self-incompatible ‘Starkrimson’ flowers on branches, placed at room temperature or in a growth chamber, were self-pollinated, cross-pollinated with compatible untreated or irradiated (150 krad) ‘Golden Delicious’ pollen, or pollinated with a mixture (2:1 wt/wt) of irradiated (mentor) pollen and self pollen. After 18 h, nearly the same proportion (> 90%) or the self-incompatible pollen germinated on the stigma and penetrated the apical part of the style as compatible pollen. Subsequent growth of the self-pollen tubes was inhibited. After 48 h, < 1% reached the stylar base as compared with 21-24% of the compatible pollen tubes. Irradiation strongly impaired pollen vitality; only 1% of the tubes had reached the base of the style after 48 h. The mixture of the irradiated mentor pollen and self pollen performed better. In this case, 6.4-9.9% of the tubes was observed in the basal part of the style, inferring that tube growth of the self pollen was significantly promoted by the mentor pollen.”
Title: FRUIT-SET AFTER PRETREATMENT WITH FOREIGN COMPARED WITH KILLED COMPATIBLE POLLEN
Author: LANE W D
Authors affiliation: AGRIC CAN, RESEARCH STATION, SUMMERLAND, BC V0H 1Z0, CAN.
Published in: Canadian Journal of Botany, volumn 62, pages 1678-1681, (1984).
Abstract: “A mechanism based on pollen growth-promoting substances was previously proposed to explain the effects of mentor (killed compatible) pollen when it improves fertilty of crosses between nearly incompatible parents. Pioneer pollination (2 pollinations a day apart) stimulates growth of the last applied pollen and increases fruit-set. In the present experiments the effects of foreign-pollen pioneer treatments on fruit-set of apple, sweet cherry and apricot were compared with the control, killed compatible pollen. All treatments were followed 24 h later with viable compatible pollen. The foreign pollen, Balsamorrhiza sagittata, did not inhibit fruit-set. When the foreign pollen was heat killed, fruit-set was at least as high as when untreated B. sagittata was used. Two other foreign pollens, Taraxacum officinale and Juniperus communis, resulted in lower fruit-set than B. sagittata but still more than the control. This effect was consistent with a previously hypothesized relationship for mentor pollen, relating size and degree of stimulation. The 2 nonpollen treatments examined, dried yeast and pectinase solution, slightly inhibited fruit set. Mineral analysis of a composite of pollen and anther tissue indicated that B and Ca were not deficient in the control pollen, and incompatibility mechanisms and heat-labile metabolites also were unlikely causes. No direct evidence ws obtained, but pollen growth promotion by a diffusible growth regulator (such as gibberellin) is suggested as plausible and an area worthy of further study.”
Title: POLLEN AND POLLINATION EXPERIMENTS 9. THE PIONEER POLLEN EFFECT IN APPLE MALUS AND PEAR PYRUS RELATED TO THE INTERVAL BETWEEN POLLINATIONS AND THE TEMPERATURE
Authors: VISSER T; MARCUCCI M C
Authors affiliation: INST HORTICULTURAL PLANT BREEDING, WAGENINGEN, NETHERLANDS.
Published in: Euphytica, volumn 32, pages 703-710, (1983).
Abstract: “Double pollinations of apple and pear may double the seed production, to which the 2nd pollen can contribute 3 times as many seeds as the 1st (pioneer)pollen, when the interval between pollinations is long enough (48 h) at low (.simeq. 10.degree. C) or short enough (7 h) at high (.simeq. 20.degree. C) temperatures. With shorter or longer intervals, the contribution of the 2nd pollen to seed production diminishes. The dominance of the 2nd pollen was attributed to promotion by the 1st one, the 2nd pollen probably being optimally stimulation when the tubes of the 1st have passed about 1/3 of the style. The effectiveness of the pioneer pollen method to overcome incompatibility apparently depends on whether the interval between pollinations can be usefully adjusted to both the environmentally (temperature) and inherently determined rate of pollen tube growth of the species.”
Title: EFFECT OF METHANOL AND GAMMA IRRADIATION ON ENZYMATIC ACTIVITY OF APPLE MALUS-DOMESTICA POLLEN
Authors: CALZONI G L; SPERANZA A
Authors affiliation: Address INSTITUTE BOTANY, UNIV BOLOGNA, VIA IRNERIO 42-40126, BOLOGNA.
Published in: Scientia Horticulturae (Amsterdam), volumn 17, pages 231-240, (1982).
Abstract: " In order to characterize devitalized pollen (which can be used as a “mentor” in mixed pollinations), certain hydrolase activities were spectrophotometrically tested in normal and in methanol or .gamma. irradiation-treated pollen of M. domestica Borkh. ‘Golden Delicious’, and in normal pollen of the cultivar ‘Starkrimson’. Enzymatic activities of methanol-treated pollen were somewhat decreased, except for acid phosphatase which was enhanced over the control. This increase could be due to a higher hydrolysis rate by the alcohol, and/or to enzyme activation after damage of the lytic organelle membranes. Amylase, cellulase, RNase and particularly acid phosphatase activities were stimulated in irradiated pollen. There was probably an enzyme leakage from the lytic compartment following pollen irradiation. Comparable effects were induced by either methanol or irradiation treatment of apple pollen."
Title: POLLEN AND POLLINATION EXPERIMENTS 2. THE INFLUENCE OF THE 1ST POLLINATION ON THE EFFECTIVENESS OF THE 2ND ONE IN APPLE MALUS
Authors: VISSER T; VERHAEGH J J
Authors affiliation: INST HORTICULTURAL PLANT BREEDING IVT ,WAGENINGEN, NETH.
Published in: Euphytica, volumn 29, pages 385-390, (1980).
Abstract: " Pollinating apple cultivars [Cox’s Orange Pippin, Elstar, Golden Delicious, James Grieve, Melrose, and Smoothee] twice with compatible pollen at an interval of 1-2 days produced about twice as many seeds per pollinated flower as a single pollination. With the aid of scab- or mildew resistant marker pollen, it could be shown that the 2nd pollen formed on average twice as many seeds as the first. The 1st pollen appears to pave the way.sbd.partly at its own cost.sbd.for the 2nd and was therefore called pioneer pollen."
I have a feeling John Sheldon would find this thread quite interesting. I believe he has been doing some of his own studies on sucessive pollinations.
Interestingly enough, I actually came across another article today while looking into something entirely different, but I think the article fits well with this thread.
FERTILITY PROBLEMS IN CV.