The importance of male red mason bee (Osmia rufa L.) and male bufftailed bumblebee (Bombus terrestris L.) pollination in blackcurrant (Ribes nigrum L.)

Summary

Male wild bees visit flowers to feed and, despite their lack of specialised organs for carrying pollen, simultaneously pollinate them. We analysed the pollinating efficiency of the males of two bee species for blackcurrant (Ribes nigrum L.): red mason bee (Osmia rufa L.) and bufftailed bumblebee (Bombus terrestris terrestris L.). Both bee species are commercial pollinators and many males are produced during their rearing. Gauze sleeves were used to isolate the inflorescences and to keep the males inside (one per sleeve). In each experimental group, there were six shoots with four neighbouring inflorescences (n = 24). The sleeves were also used to prevent other bees from reaching the flowers, and to allow self-pollination. Non-isolated flowers were pollinated by free-range bees. The effect of male bee pollination was similar to that of free-range bee pollination. The percentages of flowers that developed into fruit were as follows: male bufftailed bumblebee pollination, 79.5%; free-range bee pollination, 71.1%; male red mason bee pollination, 65.1%; and self-pollination, 46.4%; while the mean numbers of fruit per raceme were 5.0, 4.4, 3.6, and 2.4, respectively. The number of non-pollinated flowers per raceme (ranging from 1.3 – 2.8) exhibited an inverse relationship to these numbers of fruit. Our observations showed that male wild bees can pollinate blackcurrant flowers successfully, and could potentially be useful in other crops.     

Pollination requirements of eight cultivars of black currant (Ribes nigrum L.)

Summary

Fruit set and yield of the following cultivars of black currant (Ribes nigrum L.): `Ben Alder', `Ben Lomond', `Ben Nevis', `Ben Tirran', `Ceres', `Ojebyn', `Titania' and `Triton' were investigated in 1994±1996. Percentage fruit set, size of berries and yield of all investigated cultivars were higher when much foraging activity of pollinating insects was observed. The bushes on open-pollinated plots set more fruit (50-200%), had bigger fruits (10±20%) and gave higher yields (60±300%) than plants isolated from insects. All eight cultivars, including `Titania', had lower fruit set when pollinated with their own pollen under nets than when subjected to free pollination in open plots.     

Studies on the Nutrition of Tulips and Narcissi

Summary

We explored the effects of pollination method (hand cross-, hand self-, automatic self-, and open-pollination) and pollen source on fruit set and growth in four red-skinned pitaya (Hylocereus spp.) cultivars [‘Vietnam White’ (‘VNWhite’), ‘Chaozhou 5’, ‘Orejona’, and ‘F11’] in Taiwan.‘VN-White’ has white flesh, while the other three cultivars have red flesh. There were no significant differences in pollen viability or germination rate among the four cultivars, irrespective of whether the pollen was collected at night (approx. 20.30 h) or on the following morning (approx. 08.30 h).The results also indicated that ‘VN White’ was fully self-compatible and exhibited a high fruit set percentage (80 - 96%) following all pollination treatments. This cultivar produced the largest fruit from both hand self- and openpollination, compared to the three other cultivars tested. ‘Chaozhou 5’ was partly self-compatible, and ‘Orejona’ and ‘F11’ were completely self-incompatible. Hand cross-pollination significantly increased the fruit set percentages and mean fruit fresh weights (FWs) in ‘Chaozhou 5’ and ‘Orejona’. Pollen source also significantly affected the fruit set percentage and fruit FW. ‘VN-White’ (after self-pollination) and ‘Chaozou 5’ (after crossing with ‘VN-White’) gave superior fruit set percentages and fruit FWs. Reciprocal crosses between ‘Orejona’ and ‘F11’ also resulted in high fruit set percentages as well as large fruit in both cultivars. Therefore, the source of pollen and the method of pollination can affect fruit production in some cultivars of pitaya. Self-compatibility in ‘VN-White’ concurs with the morphology of its flowers in which the anthers lie in close proximity to the stigma.The distance between the anthers and the stigma may be used an indicator of whether hand pollination is necessary for a pitaya cultivar.     

Crop failure in gooseberry due to poor pollination

Some commercial plantations of gooseberry (Ribes uva-crispa L. cultivar ‘Careless’) recently carried poor crops of small fruit with few seeds. The flowers appeared normal and there was an effective pollination period of at least 11 days. Hand pollination resulted in a good set of normal fruits. Few pollinating insects were recorded on a typical affected site, but on trouble-free sites insects, particularly honey bees, were plentiful and effective in transferring pollen. On trouble-free sites, excluding pollinating insects by caging bushes resulted in a typical crop failure, but caging had little effect on the problem site. Introducing honey-bee colonies to the affected site increased fruit set and seed number by comparison with caged bushes.     

Eignen sich die Mauerbienen Osmia bicornis und Osmia cornuta als Best?uber im Obstbau?

Mason bees have been successfully managed as orchard pollinators in Japan and USA for many decades. Recently, the European species Osmia bicornis (L.) and Osmia cornuta (Latr.) attract more interest as pollinators in fruit orchards in Germany. Several studies indicate the potential of these mason bees as pollinators of pome and stone fruit. Here, we investigated the composition of the pollen loads in the brood cells of these two mason bees in fruit orchards different in habitat characteristics. At eight study sites, trap nests and cocoons of O. bicornis and O. cornuta were installed. During fruit tree blossom, pollen was sampled every two weeks and the percentage of Rosaceae pollen was identified. Landscape characteristics were assessed in a radius of 250 m from the trap nests. At all eight study sites, O. bicornis and O. cornuta collected pollen of Rosaceae. The percentage of Rosaceae pollen in the samples and the local habitat quality of the foraging sites were negatively correlated. In fruit orchards with a low diversity of suitable foraging habitats, brood cells contained a relatively high percentage of fruit tree pollen. These results indicate the potential of O. bicornis and O. cornuta as efficient pollinators in intensively managed fruit orchards. However, intensive fruit orchards appear less suitable as habitats for these mason bees to establish an endogenous pollinator population. Hence, the introduction and management of mason bees in orchards will improve pollination.     

Honigbienen zur Bestäubung von verfrühten Süßkirschen im geschützten Anbau

The objective of the present work was to study ways of additional foraging of honey bees in a sustainable production of forced sweet cherries in a polytunnel in order to reduce any loss of bees and to substitute the annual re-introduction of new bumble bees (Bombus terrestris L.) which are lost after use. Three honey bee (Apis mellifera L.) hives were employed during the three weeks flowering in April 2006 in a closed, unheated polytunnel to pollinate sweet cherry cvs ‘Burlat’, ‘Earlise’, ‘Samba’, ‘Souvenir des Charmes’ and an unnamed clone on dwarfing GiSelA 5 rootstock at Klein Altendorf research station near Bonn, Germany. The central position of hive A allowed the honey bees to collect pollen and nectar exclusively from the flowering sweet cherries in the tunnel. Hive B also inside the tunnel had apertures inside and outside the tunnel, while hive C outside the tunnel adjacent to its wall, had inside and outside apertures; honey bees from the latter two hives were allowed to forage both inside the tunnel or outside. Differences in air temperatures between the inside and outside the tunnel were no more than 5?°C due to effective ventilation. A portable gas heater for automated frost protection maintained the night temperature in the polytunnel in April above 0?°C. Measurements of the flight activity showed a close correlation with the ambient temperature at the respective hive location. The two bee hives A and B within the tunnel showed larger flight activities of an averaged 540 bees per hour compared with 180 bees per hour outside due to low spring temperatures. Honey bee population A in the centre of the tunnel declined after three weeks pollination to ca. 9,200 individuals and produced only 46?kg honey due to shortage in food reserves and intense flight activity. The outdoor bee population C with ca. 15,000 individuals yielded also only 49?kg honey due to lack of flight activity during the cold April 2006 compared with 68?kg honey from population B with ca. 16,000 individuals but continuous flight activity within the tunnel and additional foraging outside. Control bee hives D and E with ca. 22,000 individuals each, which had remained at the institute at Bonn, produced 82–93?kg honey during the same time. Cherry forcing resulted in a 12–18 days earlier flowering in April 2006 relative to the 12–16 days earlier harvest in June 2006. Large fluctuations in yield of 0.3–15.4?kg/tree were due to commensurate S-alleles causing intersterility, insufficient fertilisation and location of the cherry cultivars relative to each other and the bee hive.     

Study on Fruitset and Pollen-Compatibility Status in Sweet Cherry (Prunus avuim L.) Cultivars

Prunus avium L. is one of the most important temperate zone fruits in the world. Most of the cherry cultivars always have difficulties of fertilization and fruit set due to self-incompatibility, so they need suitable and compatible pollinizers for commercial fruit production. In this experiment, pollination compatibility of cherry cultivars of ‘Napoleon’, ‘Burlat’, ‘Zhan’, and ‘Lambert’ was studied as both pollen recipients and donors. To determine the compatibility or incompatibility of pollinizers, percent of fruit set was calculated. This research was carried out as a factorial experiment in a randomized complete block design. The final average fruit set in studied cultivars was different under self or cross-pollination. The results showed that ‘Napoleon’, ‘Zhan’ and ‘Lambert’ cultivars are the suitable pollinizers for ‘Burlat’. Also, ‘Burlat’ is a cultivar which produced many fruits under self-pollination. Therefore, ‘Burlat’ can be used as monoculture for orchard establishment. Results showed that cultivar ‘Napoleon’ was cross-incompatible with ‘Lambert’. ‘Zhan’, ‘Napoleon’ and ‘Lambert’ cultivars are founded self-incompatible and require cross-pollinations to obtain fruits.

     

Blooming phenology and self-incompatibility of some commercial cherry (Prunus avium L.) cultivars in Iran

Self-sterility in cherry (Prunus avium L.) is one of the most important problems in commercial cherry orchards in Iran and many other countries. The main objective of this research was to determine self-fertility rate and blooming phenology of 25 commercial cherry (P. avium L.) cultivars in Iran. This study was conducted during 2006–2007.Results revealed that the stage of bud swell in all cultivars began late second decade of March, which lasts 8–11 days. In all cultivars the duration end bloom to petal fall stage took 5 days. Cherry cultivars were classified into three groups considering their overlapping pollination. The cultivars each group had a great overlapped pollination toward each other. The results also showed that there was a significant difference among cultivars in respect of the fruit set (P < 1%). The fruit set of open pollination treatment among the cultivars varied in range of 7.36–41.58%. However fruit set was not observed in isolated pollination (artificial and natural self-pollination). In open pollination, the cultivars were also classified into four groups, i.e. weak fertility (Moreau and Ferracida), mean fertility (Siah Mashhad, Napelon, Proteva, Haj usefy, Lambert, Roshun, Sefid Ghermeze Baghno, Arak, Belamarka, Siah Shabestar, Ghermeze Rezaeyeh, Abardeh, Soraty Lavisan and Victoria), good fertility (Peshrase Mashhad, Dovoumras Mashhad, Bing, Shesheiy Mashhad, Siah Ghazvin and Sefid Rezaeyeh), very good fertility (Zarde Daneshkadeh, Dirrase Italia and No. 1 karaj). All cultivars were found to need cross-pollination and included in self-sterile group.     

Physiological Breakdown in Stored Monarch Plums

Summary

Several pollination studies carried out on different, self-incompatible almond cultivars and seedlings have shown the presence of variable levels of fruit set following self-pollination that could be attributed to partial self-incompatibility (PSI). PSI is an intermediate reproductive behaviour, described in some angiosperm species, which indicates that self-incompatibility is a quantitative and plastic trait. The present study was performed to substantiate the occurrence of PSI in almond by studying ten cultivars that are traditionally considered to be self-incompatible (four of which had previously shown fruit set after self-pollination). These cultivars were analysed by microscopic observations of the progression of pollen tubes through the pistil following controlled self-pollination, determinations of fruit set after bagging flower buds, and molecular identification of the parentage of the fruits obtained using consensus PCR-primers for Prunus S-RNase alleles. The results showed that, in nearly all cases, the pollen tubes did not enter the ovary and, from a total of 5,349 bagged flower buds, only 17 fruits were obtained. In all cases, PCR analysis of the plants obtained after germination of these seeds showed a band corresponding to an S-RNase allele not present in the maternal progenitor, clearly indicating that they could only have arisen from cross-pollination.Therefore, the low fruit set values observed in some of the cultivars studied were not due to a breakdown in the self-incompatibility response that confers PSI, but to very low rates of contamination with foreign pollen. These results corroborate the self-incompatibility phenotype of the cultivars studied here, and highlight the importance of ascertaining the identity of the parentage in any progeny obtained after bagging.     

Flowering and fruit set in cherimoya (Annona cherimola Mill.) as affected by the tree-training system

Summary

Management of flowering and fruit set are of prime importance in order to obtain high yields in cherimoya (Annona cherimola Mill.) due to floral dichogamy. This phenomenon is largely dependent on environmental conditions such as temperature, relative humidity, and light intensity, which usually make hand-pollination of flowers necessary in order to achieve acceptable levels of fruit set and yield. Nevertheless, these factors can be modified by means of the growing system. In this work, we studied the effects of two tree-training systems on the environment inside the canopy, on flowering, on pollination, and on fruit set in mature ‘Concha Lisa’ cherimoya trees. The open-centre vase training system (6 m 4 m) and the high-density slender-spindle (tunnel) training system (4 m 1 m) were used. The high-density tunnel training system increased the relative humidity, as well as reducing the temperature and the level of photosynthetically active radiation, inside the canopy, which resulted in an earlier onset of the male floral stage and in an extended maintenance of the highly-receptive female stages. This resulted in an overlap of the sexuallycompatible floral stages, thus increasing the incidence of natural cross-pollination and maintaining the viable, receptive sexual stages and pollen, over time, to improve hand-pollination.     

The effect of temperature on certain chemical changes and the storage behaviour of jujube fruits (Zizyphus spinachristi (L.), Willd.)

Summary

Jujube fruits (Zizyphus spinachristi (L.) Willd.) cv. Bambawi were harvested at the mature green stage and stored at 10°C and 27–30°C. Titratable acidity and total chlorophyll decreased as the fruit matured, the rate of decline being more rapid at the higher temperature. Total soluble solids, carotenoids and ascorbic acid contents of the fruit increased towards maturity, the increase being faster at the higher temperature. Jujube fruits could be stored for six days at room temperature and twenty-five days under refrigeration at 10°C.     

Comparative studies on the postharvest physiology of fruit from different species of Annona (custard apple)

Summary

Fruit of three Annona species, viz. cherimoya (A. cherimola Mill), sugar apple (A. squamosa L.) and custard apple (atemoya, Annona X) were ripened in ethylene-free air and under propylene. Differences were found in patterns of respiration, ethylene production and fruit firmness changes during ripening. Cherimoya and custard apple fruits showed two successive rises in respiration rate whereas sugar apple fruits showed only one. Ethylene production showed one main peak but the onset of rapid ethylene production occurred after the beginning of the respiration climacteric in all three species. Custard apple fruit had acceptable eating quality (as judged by sensory assessments and chemical analyses of pulp) for up to four days after first detectable softening, when ripened at 20°C in ethylene-free air or under propylene. Fruit ripened in ethylene-free air had better ripe fruit quality than fruit ripened under propylene.     

Influence of pollination methods on fruit development and sugar contents of oriental melon (Cucumis melo L. cv. Sagyejeol-Ggul)

This study was conducted at the Seongju Fruit Vegetable Experiment Station for 2 years, 2002–2003 to investigate the effect of pollination methods on development and sugar content of oriental melon fruits. Oriental melon fruit was pollinated by honeybees (Apis indica) and bumblebees (Bombus ignitus) and fruit setting growth regulators was used as a control treatment. Fruits pollinated by honeybees and bumblebees has lesser length and width of fruit compared to the control. Pollinated by bumblebees increased hardness and soluble solids of fruits by 27% and 4–5% and that of honeybees increased hardness and soluble solids of fruits by 12% and 5–10% compared to the control, respectively. Fermented fruit ratio (%) of oriental melon fruit pollinated by honeybees, bumblebees, and growth regulator was 6.7%, 9.1%, and 28.1%, respectively. Glucose, fructose and sucrose contents of fruits by HPLC (high performance liquid chromatography) were very low throughout the ripening stage, but abruptly increased at harvesting stage. In fructose content of fruits, pollination of bumblebees and honeybees was higher by 9% and by 13% than those of control, respectively. The amount of total sugar content in fully ripen fruits of oriental melon was not different between the treatments (P > 0.05). Total sugar content (%) of fruits pollinated by bumblebees was slowly decreased until 15 days after storage compared to that of other treatment. For the low fermented fruit ratio (%) and slowly reduced total sugar content at storage of fruits, the pollination of bees was more useful than fruit setting growth regulators in early cultivation of oriental melon under plastic houses. The economic analysis according to the pollination method will be needed in the near future.     

Rootstock influence on the incidence of rind breakdown in ‘Navelate’ sweet orange

Summary

The influence of three rootstocks, Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), Cleopatra mandarin (Citrus reshni Hort. ex Tanaka) and sour orange (Citrus aurantium L.) on the incidence and severity of rind breakdown in ‘Navelate’ sweet oranges was studied over seven years in four orchards. The proportion of affected fruit was greater in trees on Carrizo citrange (60% on an average) followed by Cleopatra mandarin (38%) and then on sour orange (9%). There were also significant differences in the severity of the disorder among rootstocks; more than 35% and 20% of fruit from trees on Carrizo citrange and Cleopatra mandarin, respectively, were rejected for commercialization, whereas only 4% of fruit on sour orange was rejected. Cryo-scanning electron microscopy (SEM) of fruit peduncles showed that average diameter of xylem vessel elements of peduncles of fruits on Carrizo citrange rootstock were 6% and 17% larger than those on Cleopatra mandarin and sour orange, respectively. Defoliation of fruit-bearing branches reduced water loss from fruit, maintained fruit peel water potential at a higher value than that of fruit on undefoliated branches and reduced the proportion and severity of affected fruit. It is concluded that fruit-tree water relationships are related to rind breakdown in ‘Navelate’ oranges and low fruit water content might be responsible for the disorder.     

Some physiological characteristics of fruits of jujube (Zizyphus spina-christi L., Willd.) at different stages of maturity

Summary

Jujube fruits (Z. spina-christi L., Willd.) of the three cvs Bambawi, Zaytoni and Mallasey were harvested at three stages of maturity and their physiological characteristics measured. Moisture content, titratable acidity, total chlorophyll and pectic substances decreased with fruit maturity. Total soluble solids, carotenoids and vitamin C contents increased as the fruit matured.     

Changes in endogenous gibberellins during fruit growth in guava,with a general discussion

Levels of endogenous gibberellins were determined in seeded and seedless fruits of guava (Psidium guajava L.) in relation to fruit development. The gibberellin content in the seeded fruit was at all times higher than that in the seedless fruit. The peak concentrations of gibberellins in both kinds of fruits occurred at 15 days after pollination and thereafter declined rapidly. This suggests that these substances are involved in the early phase of fruit growth.     

Einfluss der Bestäubung durch die Honigbiene (Apis mellifera) auf Ertragsparameter der Kulturheidelbeere (Vaccinium corymbosum)

The influence of honey-bees’ pollination on parameters of yield of the three highbush blueberry varieties ‘Bluecrop’, ‘Reka’ and ‘Brigitta Blue’ was investigated. Four pollination variants were realized: 1. without cage; 2. cage with bees; 3. cage without bees; 4. fine-meshed bag. Total yield, fruit weight, seed production and phenology of the three varieties were examined. An enormously positive influence of honey-bees on yields of ‘Bluecrop’ and ‘Reka’ was found: total yield was by 500–560% higher in cages with bees compared to cages without bees. The results of fruit weight and seed production were similarly clear. However, ‘Brigitta Blue’ hardly responded to different intensities of pollination: regardless of the variant, total yield was extremely low (in cage with bees only 35% of the ‘Bluecrop’-yield) and couldn’t be improved by intensive pollination. The same applied to number of seeds per fruit. However, the mean fruit weight resembled that of ‘Reka’, but wasn’t influenced by the intensity of pollination, either. ‘Bluecrop’ lived up to its reputation as most profitable standard grade with highest yields in all variants (3.7?kg/m³ bush in cage with bees), highest fruit weight (1.6?g) and maximum number of seeds per fruit (98). A direct correlation between fruit weight and number of seeds per fruit couldn’t be established.     

Evidence for a major role of honeybees (Apis mellifera) rather than wind during avocado (Persea americana Mill.) pollination

Summary

The purpose of this study was to determine the relative importance of honeybee (Apis mellifera) activity and wind in the pollination of avocado (Persea americana Mill.) trees. Data on the pollination rates of five cultivars of avocado, honeybee densities, ambient temperatures, and wind velocities were recorded in an orchard in Israel on 61 d over a period of 7 years. The effect of wind velocity on avocado-flower pollen under laboratory conditions was also studied. Rates of pollination showed highly positive correlations with honeybee density, whereas no correlations were observed with wind velocity. Under laboratory conditions, no effect of wind velocities equivalent to those measured in the field was observed on avocado-flower pollen. Our results agree with earlier work in which wind contributed only slightly to avocado yield. Hence, we conclude that contrasting data which show the effectiveness of wind pollination in avocado are not relevant to most avocado-growing regions, including Israel and California. It is, therefore, strongly recommended that avocado growers continue using honeybees for pollination.     

Fruit set evaluation for self-compatibility selection in almond

Self-compatibility was assessed in 19 almond selections by genetic and physiological means, such as PCR with specific primers for the S_f allele, pollen tube growth, and fruit set after self-pollination and in bagged branches. Although all genotypes possessed the S_f allele and showed a similar pollen tube growth after self-pollination than after cross-pollination with cross-compatible pollen, fruit sets showed a different behaviour between years, ranging from 16.2 to 24.7%, as well as between treatments, with the highest after self-pollination. The differences between genotypes could be due to the genetic constitution of each genotype, where inbreeding may reduce set by the accumulation of deleterious genes in different members of a progeny. Flower morphology may also affect sets in bagged branches. Thus, in addition to bud density, flower sterility, pollination success and environmental conditions, other traits must be taken into account when evaluating yield in self-compatible almond cultivars, such as the inbreeding effect and the effective autonomous self-pollination.     

Cross-pollination improves ‘Orri’ mandarin fruit yield

‘Orri’, a selection of ‘Orha’ mandarin [Temple (Citrus temple hort. ex Y. Tanaka) × Dancy (Citrus tangerina hort. ex Tanaka)], is a new high-quality Israeli mandarin which, in the last decade, has become one of the leading varieties in Israel. ‘Orri’ has an excellent taste, the rind is deep orange in color and easily removed, and it contains few or no seeds. However, ‘Orri’ grown in Israel suffers from inadequate yield and no published studies have yet addressed this problem. In the present study we determined that ‘Orri’ productivity depended on conditions being favorable to cross-pollination. Under cross-pollination conditions a positive correlation (R² = 0.97) was found between yield per tree and number of fruits per tree, and more than 90% of the fruits exceeded 60 mm: the most profitable size range. These data suggest that the number of fruits per tree, and not fruit size, is the limiting factor for yield improvement in ‘Orri’ orchards. Studying seed set showed that ‘Michal’ mandarin (Citrus reticulata Blanco) is a compatible pollenizer for ‘Orri’ flowers: the number of seeds per ‘Orri’ fruit increased as the distance from ‘Michal’ trees decreased. The present study demonstrated that cross-pollination of ‘Orri’ resulted in yield improvement, yet at the price of increased seed set.