Bloom evolution and flower quality were studied in 10 almond [Prunus amygdalus Batsch syn. P. dulcis (Mill.) D.A. Webb] selections of the Zaragoza breeding program. The opening of individual flowers followed a normal distribution, with deviations reflecting temperature differences during the bloom period. The first open flowers are of better quality than later ones and may contribute more to fruit set. The relative stigma–anther position reflected the possibility of natural autogamy in three of the 10 selections. Natural autogamy might allow single-cultivar orchards without the need for pollinating insects.
Group-author : R. Socias i Company
Rafael Socias i Company and A.J. Felipe
, pursuing autogamy and fruit quality, aiming at defining the best end use of each cultivar ( Socias i Company et al., 2006 ) and taking into account the preference of the Spanish market for ‘Marcona’ and ‘Desmayo Largueta’. Fig. 1. Average blooming
Brad G. Howlett, Samantha F.J. Read, Maryam Alavi, Brian T. Cutting, Warrick R. Nelson, Robert M. Goodwin, Sarah Cross, Trevor G. Thorp, and David E. Pattemore
within-floret (autogamy) and between-floret (geitonogamy) pollination within racemes, because we caged whole racemes rather than individual florets, but our results show that either autogamy or pollen vectors (e.g., very small insects or air movement
Carlos G. Vaz, Domingos de Oliveira, and Orlando S. Ohashi
Cowpea, Vigna unguiculata (L.) Walp., is a very important legume in the diet of the population of the Amazon. Although it is autogamous, this species has a cross-pollination rate of ≈10%. Over several years, the mean productivity of cowpea has declined. We suggest that this is linked to a decrease in or an absence of pollinating insects in the fields. The objective of this study is to ascertain the pollinator contribution to cowpea production, as well as to determine the pollination type of the `BR3-Tracuateua' cultivar. In an experimental design, four treatments were compared: no pollination, with flowers in cages to prevent insect visits; open-pollination, with flowers exposed to all visiting insects; self-pollination, with flowers pollinated with their own pollen; and cross-pollination, with emasculated flowers being pollinated manually with pollen from another plant. We observed higher fruit set in the presence of pollinators (83%) than in their absence (77%, caged flowers). However, cross-pollination reduced both the number of seeds per pod and fruit set relative to self-pollination. This result suggests that pollinators have a complementary role in the yield of cowpea, by creating a mixed pollination system where self-pollination dominates.
Thomas M. Gradziel and Steven A. Weinbaum
The regulation of anther dehiscence by relative humidity (RH) was assessed for detached anthers and detached whole flowers from a limited selection of apricot (Prunus armeniaca L.), peach [P. persica (L.) Batsch], and almond [P. dulcis (Mill.) D.A. Webb, syn. P. amygdalus Batsch; P. communis (L.) Arcangeli, non Huds.] genotypes, as well as an almond X peach F2 progeny. Dehiscence was evaluated at 33, 64, 87, 93 and 97% RH for detached anthers, and at 33, 64 and 97% RH for whole detached flowers. Anther dehiscence was suppressed with increasing RH for all genotypes. Apricot anthers showed the greatest dehiscence at low RH and measurable dehiscence at high RH even when detached. Anther dehiscence in almond appeared more suppressed than in apricot at all RH levels tested, being completely suppressed by high RH in detached anthers. Peach genotypes exhibited the full range of variability between apricot and almond patterns. Evidence for transgressive segregation of RH-controlled anther dehiscence was observed in the occurrence of cleistogamy in an almond × peach F2 progeny. Rates of anther dehiscence were approximately linear with change in RH in detached anthers but exhibited a more buffered, step-wise response when detached whole flowers were tested. Results are consistent with field observations, and highlight the low but measurable risk of cleistogamy in these species, as well as opportunities to modify the breeding systems and crossing environments to facilitate controlled hybridization, and to reduce pollination vulnerability to adverse environments.
Rafel Socias i Company, Ossama Kodad, José M. Alonso, and Antonio J. Felipe
. z Autogamy Self-compatibility was tested as soon as the original seedlings produced the first flowers by examining the arrival or not of pollen tubes at the ovary after self-pollination (data not shown). Sets after self
Renate Karle and Thomas H. Boyle
The effects of floral morphology and breeding behavior on flower longevity were investigated in Easter cactus [Hatiora ×graeseri (Werderm.) Barthlott)]. Four clones were studied: two diploid (n = 11) clones (`Evita' and `Purple Pride') that were highly self-incompatible (SI), and two cytochimeras (diploid epidermis and tetraploid subepidermis) that were recovered from the diploid cultivars, both of which were self-compatible (SC). The clones exhibited differences in the stage of floral development in which autogamy commenced. Autogamy commenced on the day of anthesis in the two `Evita' clones and occurred ≈5 days after anthesis in the `Purple Pride' cytochimera. In the `Purple Pride' diploid clone, anthers and stigmatic lobes remained spatially separated during the period from anthesis to senescence. Examination of styles collected from senesced, undisturbed flowers showed that few pollen tubes traversed to the base of the styles for the two SI diploid clones, whereas large numbers of pollen tubes were present at the base of the styles for the two SC cytochimeras. Flower longevity for the `Evita' cytochimera was significantly less than for `Evita' diploid, but the diploid and cytochimeral clones of `Purple Pride' exhibited similar flower longevities. Application of 2 mm silver thiosulfate, an inhibitor of ethylene (C2H4) action, did not affect flower longevity of `Evita' cytochimera. Our results show that flower longevity in Easter cactus is influenced by breeding behavior and the stage of floral development at which autogamy commences.
Thomas M. Gradziel and Dale E. Kester
Breeding lines have been developed incorporating introgressed genes from three native almond species Prunus fenzliana, Prunus webbii and Prunus argentea. Selected traits include self-fertility and autogamy, late bloom, smaller tree size, early nut maturity, improved cropping potential, and a well-sealed shell (endocarp) with high kernel/shell crack-out percentages. Fertility barriers, while present were easily overcome though linkage to introgressed genes with undesirable phenotypes remains an important obstacle to commercial use. Current breeding results, however, support a general conclusion that the wide diversity present within the range of species related to the cultivated almond (Prunus dulcis) provides an valuable gene pool for variety improvement.
The seed producing system in viola (Viola ×cornuta) was investigated to improve seed yield and to save labor. In a flower five anthers sequentially dehisced; pollen grains were continuously supplied to the anterior petal, which played a significant role in pollination, throughout the flowering period. Evidence from pollen and ovule number suggests that the species is facultative autogamy. Each flower opened more than 10 days was independent of the success in fertilization and kept seed producing ability during the flower longevity period. Pollen grains also maintained viability during the flower longevity period. Pollinators were indispensable for pollination of viola, but pollination in viola was done by a different mechanism from the typical insect-mediated pollination that sticky pollen grains adhere to the exposed stigmas. Pollen grains, accumulated around the entrance of the stigmatic cavity, entered into the cavity by the movement of pollinators. Although the visitation of pollinators was occasional, solitary bees primarily contributed to the pollination of viola. On the other hand, germination of pollen grains on the stigmatic surface was under 50%. Seed set was much lower than the germination percentage of pollen grains. A viola flower had the ability for additional pollinations and fertilization for some days after the fertilization success in some ovules in the flower. This characteristic suggested that repeated pollination is effective to increase the number of mature seeds in a capsule.
Rafel Socias i Company, Àngel Fernández i Martí, Ossama Kodad, and José M. Alonso
similar fruit sets, which may not always be the case. Third, these fruit sets must reach the level of a commercial crop. From a horticultural point of view, there is a fourth requirement, because these fruit sets must be obtained by autogamy, and that is