Search

Most Passiflora species present self-incompatibility and thus depend on cross-pollination for fruit production. Therefore, the objective of this work was to evaluate the floral and reproductive biology of 17 Passiflora species, through pollen viability, stigma receptivity, fruit and seed set formation, as well as the pollen-pistil interaction in three floral development stages (pre-anthesis, anthesis and post-anthesis), seeking to maximize the efficiency of controlled pollinations. Pollen viability was estimated by in vitro pollen germination, fluorochromatic reaction and Alexander’s solution, as well as fruiting and pollen-pistil interaction. The stigma receptivity was determined in alpha-naphthyl acetate. The highest percentages of pollen viability, stigma receptivity, fruit and seed set were observed during floral anthesis for all Passiflora species studied, while the lowest values were observed in pre-anthesis. The species P. rubra L. presented the highest percentages of in vitro pollen germination, viability with FDA, stigma receptivity, pollen/pistil compatibility, and high fruit set in anthesis. In contrast, the lowest values of these traits were observed in P. galbana L. The results obtained can support the selection of genetic material and allow inferences about the best pollen collection moment and the peak stigma receptivity to maximize the chances of pollen germination and consequently increase the efficiency of controlled pollinations for both agronomic and ornamental purposes. [ABSTRACT FROM AUTHOR]

Asynchronous maturation of male and female flowers in date palm trees is frequently occurs, making pollen storage operation necessary to ensure pollination. The aim of this study was to investigate the effect of pollen storage temperatures on pollen viability, fruit set and fruit quality of six date palm male cultivars. Pollen grains of six date palm cultivars namely ‘Bouhlesse’, ‘Deglat Beida’, ‘Deglet Nour’, ‘Ghars’, ‘Halwaya’ and ‘Moch Deglat’ were stored at room temperature (24 ± 2 °C), 4 °C or −20 °C. In vitro pollen germination and pollen tube growth were examined after 0, 1, 3 and 13 months of storage. Influence of pollen storage on fruit set and fruit quality were also analyzed. Storage temperature, storage duration, cultivar and interaction between all variables had highly significant effect on pollen viability and pollen tube length (p < 0.0001). High values of pollen germination (up to 87%) and pollen tube length were recorded in fresh pollen (at 0 months of storage). For all cultivars, pollen stored at room temperature lost the most of their viability between the 2 or 3 months of storage. However, pollen viability was extended over time when pollen was stored under low temperature, with a storage temperature of −20 °C preferable to 4 °C. Fruit and pulp weight decreased slightly but significantly in most cultivars as a result of pollen storage temperature, although fruit set was not affected. The pollen of ‘Deglet Nour’ showed high pollen viability after 1 year of storage at −20 °C (∼89%) and may be used as good cultivar for storage. [ABSTRACT FROM AUTHOR]

Cryopreservation of pollen is an additional way to conserve many species. In particular, it can be used as an alternative strategy to preserve the genetic variation of the genus Ananas. The aim of this study was to cryopreserve pollen from wild pineapple accessions to conserve a gene pool of the genus Ananas , as well as to minimize problems of asynchronous flowering among accessions preserved in a germplasm bank. Accessions of all botanical varieties were used to investigate different protocols for freezing pollen, as well as to determine their viability in vitro/in vivo during the investigation and after freezing in liquid nitrogen. Anthers with pollen of the different accessions were dehydrated and then immersed in liquid nitrogen for periods of 24 h, 60 days and 120 days. After freezing, the viability percentage and pollen tube length were determined. In vivo viability tests were performed through 24 pollinations involving different accessions. The results showed that the cryopreservation of pollen was efficient, attaining in vitro germination rates ranging from 8.24% to 94.25%, with average of 62.67% achieved 120 days after cryopreservation and pollen tube lengths longer than 0.23 mm after this same period. In the in vivo pollinations with cryopreserved grains, the seed formation rate was 70.83% for the different combinations. It was possible to cryopreserve pollen from all the pineapple accessions investigated after dehydration for 6 h on silica gel, with significant in vitro germination percentages and production of viable seeds. [ABSTRACT FROM AUTHOR]

Pollination remains crucial to achieve valuable fruit yield in European pear ( Pyrus communis ) orchards. An innovative approach to improve pollen transfer involves the use of pollen dispensers at the hive entrance. Due to its commercial availability, Nashi ( Pyrus pyrifolia ) pollen is proposed in pollen dispensers fitted in bumblebee hives for European pear tree pollination. Our objectives were (1) to investigate whether Nashi pollen is suitable for pollination of European pear and (2) to assess the efficiency of pollen dispenser in bumblebee hives. To test the compatibility between both species, Nashi pollen were used in hand-pollination of two European pear tree cultivars ‘Conférence’ and ‘Doyenné du Comice’. The impact of Nashi pollen on the bumblebee behaviour was investigated at the hive exit. Nashi pollen was suitable for pollination of ‘Conférence’ and ‘Doyenné du Comice’. ‘Conférence’ fruits resulting from pollination with Nashi were smaller (53 ± 1.5 mm) than those pollinated with ‘Doyenné du Comice’ (60 ± 1.1 mm) while fruit diameter of ‘Doyenné du Comice’ did not vary with the pollen origin (71 ± 1.3 vs. 69 ± 1.2 mm). Pollen deposit at the hive entrance did not modify bumblebee behaviour. All insects leaving the hive were covered with pollen even if their pollen charge decreased by 53% 24 h after pollen deposit. All together our results suggest that Nashi pollen could be used in pollen dispenser for pollination of the European pear cultivars ‘Conférence’ and ‘Doyenné du Comice’ if pollen dispenser is refilled at least once a day. [ABSTRACT FROM AUTHOR]

• Liquid medium without Ca+2 at 32 °C was optimal for onion pollen germination in vitro. • Pollen should be dehydrated before storage at low temperatures (−80 1 1 Add °C after -80 in the second highlight and −20 °C). • The viability of pollen stored at −80 °C was higher than that stored at −20 °C. • Pollen stored at −80 and −20 °C for two years was successfully used to produce seeds. The preservation of viable pollen is essential to overcome the problems related to the asynchronous flowering of the parental lines in onion hybrid breeding programs. The aim of this study was to establish a simple, inexpensive, and easily reproducible protocol for medium-term onion pollen storage. First, the conditions for assessing the in vitro pollen germination were optimized. The liquid medium favored the counting of germination of pollen grains in comparison to the solid medium. The addition of 75 mg/l Ca(NO 3) 2. 4H 2 O to the medium did not improve pollen germination, while that of 150 mg/l Ca(NO 3) 2. 4H 2 O inhibited pollen germination. The highest germination percentage was achieved by incubation at 30–35 °C in the dark. Second, fresh or dehydrated pollen (maintained in a desiccator with silica gel at 25 °C for 18 h) was stored at 4, –20, and –80 °C for two years to study pollen preservation. In addition, the viability and germination capacity of stored pollen were periodically evaluated at 0, 15 and 30 days; 2 and 6 months; and 1 and 2 years. Pollen viability was best retained at low relative humidity and temperatures below zero. Dehydration was essential for pollen preservation at –20 and –80 °C. The results showed that dehydrated pollen stored at –20 °C could be used, with guarantees, for pollination throughout the flowering season. However, the highest viability and in vitro germination percentages after two years of storage (29 and 32%, respectively) were achieved with dehydrated pollen stored at –80 °C. Finally, the capacity of stored pollen to produce seeds was confirmed in crosses with male sterile lines. In this way, dehydrated pollen stored at –80 °C for two years produced an average of 47.9 seeds/100 flowers, representing 43% of the seed in the control crosses. This is the first report in onion research of seed production after pollination with preserved pollen at –80 °C for two years. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: An improved in vitro pollen germination assay was developed to assess the viability of stored Hedychium pollen. The effect of polyethylene glycol (PEG) (10, 15, and 20%, w/v) on pollen germination and tube growth was evaluated for Hedychium longicornutum and two commercial Hedychium cultivars, ‘Orange Brush’ and ‘Filigree’. Overall, the inclusion of PEG 4000 in the medium improved both pollen germination and tube growth for the three different genotypes tested and the results varied depending on genotype. In vitro germination was used to assess the viability of Hedychium pollen stored up to two months. Pollen nucleus status was determined for four Hedychium cultivars, ‘Orange Brush’, ‘Anne Bishop’, ‘Filigree’, and ‘Daniel Weeks’. Pollens of ‘Orange Brush’, ‘Anne Bishop’, and ‘Daniel Weeks’ were found to be binucleate but ‘Filigree’ was shown to possess both binucleate and trinucleate pollens. High pollen:ovule ratio values were obtained in several Hedychium taxa. The results obtained on the nuclear pollen status and pollen:ovule ratios will further our understanding of the pollination biology and help clarify the taxonomy and phylogeny of Hedychium species. [Copyright &y& Elsevier]

Abstract: ‘Success’ or ‘Red Splendor’ plants propagated by shoot tip culture or embryogenesis had higher pollen germination than those propagated by cutting. All clones of ‘Pepride’, ‘Peter Star’ and ‘Nobel Star’ propagated by cutting or by embryogenesis or shoot tip culture did not have viable pollen. ‘Peter Star’ mutants through mutagenesis could recover pollen viability. When both parents were propagated by tissue culture, fruit set increased compared to when one or both parents were propagated by cuttings. Furthermore, the number of the harvested seeds doubled per pollination set, when the tissue culture parents were used instead of cutting-propagation plants. [Copyright &y& Elsevier]

• Adaptability of floral characteristics of N. hybrid to pollinators was investigated. • Breeding system was gauged via P/O ratio, outcrossing index, and field experiments. • N. hybrid stigma receptivity was the highest on the 1st day of floral anthesis. • Pollen viability was the highest before noon on the 2nd day of floral anthesis. • Reproductive biology favored outcrossing and bee pollinators in N. hybrid. Nymphaea hybrid is a precious aquatic plant of the family Nymphaeaceae that has esthetic, economic, medicinal, and ecological values. Owing to its spectrum of color, especially that of the rare blue strain of the genus Nymphaea , it has gained importance in the breeding of water lilies. However, the lack of research on its flowering characteristics and reproductive biology has severely hindered the reproduction and breeding of superior water lily varieties. In this study, the flowering phenology, floral characteristics, and flower-visiting insects of N. hybrid were assessed. The microstructures of stigmata and pollen grains were observed and the stigma receptivity was determined. Pollen viability was measured by an in vitro germination experiment. We also evaluated the breeding system by measuring the pollen/ovule (P/O) ratio, determining the outcrossing index (OCI), and performing field pollination experiments. The N. hybrid population flowered from late May to mid-November, with a flowering period of approximately 160 days. The florescence of a single flower ranged for 3‒5 days from June‒August and for 5‒10 days from September‒November. Inverse herkogamy and protogyny were exhibited by N. hybrid flowers. Stigmata were wet with papillae distributed on their surface, and the pollen grains were oblate with granular ornamentation of different sizes on their surface. The pollen germination rate was highest when they were deposited in a medium containing 5% sucrose, 0.001% boric acid, 1% agar, and 20 mg/L calcium chloride and cultured at 30 °C. Stigma receptivity was the strongest on the 1st day of floral anthesis, and pollen viability was the highest between 9:30 a.m. and 11:30 a.m. on the 2nd day of floral anthesis. The P/O ratio suggests that xenogamy is the main reproductive system. Artificial pollination results indicated that N. hybrid favored outcrossing and required the participation of pollinators, such as Bombus lucorum L. and Xylocopa s.str. valga Gerstaecker, both of which are effective bee pollinators. These results can aid in formulation and implementation of strategies for N. hybrid hybridization programs, and can also improve the controlled pollination efficiency for agronomic and ornamental purposes. [Display omitted] [ABSTRACT FROM AUTHOR]

• We examined the reproductive biology of Physalis angulata , known popularly as "camapu". • The flowers are hermaphrodite and the anthesis occurs between 06:00 -0:800 h (am). • Apis mellifera was identified as main floral visitor of P. angulata. • Acetocarmine and 2,3,5-triphenyltetrazolium chloride exhibited high viability above 80% and there was no in vitro pollen germination. • The pollen/ovule ratio and in vivo pollination, will help better understand the reproductive system of P. angulata. Physalis angulata L., a member of the family Solanaceae, known popularly in Brazil as "camapu", is widely used in folk medicine. Its leaves have various pharmacological activities and fruits can also be used as human food. Considering the species' potential economic importance, further knowledge is necessary of its reproductive biology for germplasm conservation and to obtain new hybrid combinations in breeding programs. Therefore, the objective of this study was to elucidate aspects of the reproductive biology of P. angulata. We investigated the floral morphology, anthesis, nectaries and pollinator-attraction structures, identified floral visitors, and estimated pollen viability by the colorimetric method with acetocarmine and 2,3,5-triphenyltetrazolium chloride (TTC) at different collection times. In addition, we evaluated the reproductive systems by measuring the pollen/ovule ratio (P/O), as well as by observing pollen-pistil interaction and seed germination after pollination. The P. angulata plants presented hermaphrodite flowers, and the floral opening occurred between 06:00 h and 08:00 h. Anthers and pollen were the main attractive structures to pollinating insects, especially Apis mellifera , the floral visitor found in greatest abundance, followed by nectar, which was analyzed by neutral red solution. Regarding pollen viability, in the first three collection hours it was greater than 90 % according to both staining methods evaluated, and no in vitro pollen germination was observed. According to the P/O ratio, P. angulata was classified as facultative autogamous. Controlled pollination under field conditions indicated the species is self-compatible with a mixed reproductive system. With respect to fruit production and seed formation, the plants originating from natural self-pollination had the best results, with a fruiting rate of 86 % and production of 156 seeds per fruit. The results obtained from studies of the reproductive biology can aid in planning of crosses and establishment of Physalis breeding programs, and also increase the efficiency of controlled pollinations for agronomic purposes. [ABSTRACT FROM AUTHOR]