Testing for pollinator recognition in multiple species of Heliconia

Plant-pollinator generalization increases the robustness of plant-pollinator communities to fluctuations in the availability of mutualistic partners. However, natural selection may reinforce floral traits that filter pollinator communities to promote pollination by efficient pollinators, which reduces the number of potential partners. We tested the generality of a recently described, cryptic pollinator filter termed ‘pollinator recognition’ (PR) which could reduce the realized number of pollinators compared to the number of floral visitors. PR was first documented experimentally in Heliconia tortuosa whereby pollen tube germination – a proxy for reproduction – was enhanced following visits from morphologically specialized pollinators, but not generalists. We tested for PR in four taxa spread widely across the Heliconiaceae. With aviary experiments that standardized pollen quality and minimized variation in pollen quantity, we demonstrated that visits by pollen-free hummingbirds increased pollen tube rates compared to hand pollination alone in two species; we also corroborated previous results that visits by long-billed, but not short-billed hummingbirds increased pollen tubes in H. tortuosa . Based on these results, we suggest that the PR mechanism likely exists beyond a single species in the Heliconiaceae and could promote outcrossing in two ways. First, promoting pollen tube growth following a cue from a visiting pollinator could allow a plant to invest in seed production when pollen on the stigma is less likely to be composed entirely of self pollen. Second, because hummingbirds with long, decurved bills tend to be less territorial and more mobile than those with short, straight bills, pollinator recognition could act in conjunction with physical exploitation barriers, such as long and curved corolla tubes, to filter the community of floral visitors in favor of those that are more likely to carry pollen from geographically and therefore genetically distance sources. While the mechanism underlying PR remains equivocal, cryptic pollinator filters may be more common than previously anticipated and could alter perspectives on redundancy in plant-pollinator communities.

JUMLAH, UJI VIABILITAS DAN DAYA KECAMBAH POLEN 31 AKSESI PISANG (Musa sp.) KOLEKSI KEBUN PLASMA NUTFAH PISANG LIPI

Cross pollination is one of the plant breeding techniques to create a better cultivar with desired traits. A successful cross pollination is affected by quality and quantity of the pollen used. The aim from this study is to know amounts, viability and germination from various banana accessions. This study was conducted by using 31 banana accessions. Pollen quantity per anther, pollen viability, pollen germination growth were measured. The results showed that pollen amounts were ranged between 5.032 and 118.181 pollens per anther. In addition, pollen viability ranged from 30% in Tingalun accession (Musa sp. cv. Tingalun) to 99% in Malaccensis 2x accession. Furthermore, pollen germination level varied from 1% in Mambee Thu OS accession to 48% in Rutilifes 2x accession. We also found that negative correlation between pollen viability and pollen germination were moderate with correlation coeeficient value of -0,59 ( p-value = 0,00051). From 31 banana accessions tested in this research, pollen source from Malaccensis 2x and Rutilifes 2x banana accessions have the highest potential to be used as the male parent.

Pollen Quantity and Viability in 65 Litchi (Litchi chinensis Sonn.) Cultivars

The characteristics of litchi pollen have drawn increasing attention in recent years. Previous studies indicated that there are significant differences in the quantity and viability of litchi pollen grains among different varieties and flowering stages. Moreover, the same variety may show a different quantity of pollen grains and viability in different years. There is still a lack of systematic studies on the change of pollen germination rate and pollen amount in different varieties and at different flowering stages. In this study, the changes in the germination rate of pollen at different development stages were studied. It was primarily revealed that the pollen germination rate already approached its peak upon the filament extends fully, but the anther does not dehisce the developmental stage. In 2009 and 2010, the viability and number of pollen grains per anther were investigated in 65 litchi cultivars, and a difference was observed among cultivars. The pollen germination rate ranged between 20.14% (‘Wuchali’) and 54.69% (‘Donlongmili’). The number of pollen grains per anther ranged between 1555 (‘Zhongshanzhuangyuanhong’) and 7455 (‘Houye’). Sixty-five litchi cultivars were classified into six clusters based on the pollen quantity and germination rate. Most litchi cultivars can produce large amounts of viable and compatible pollen grains during the flowering period. Thus, our results indicate that the pollen amount and germination rate might not be the only factors restricting the successful pollination of litchi.

Flowering, pollen characteristics and insect foraging on Campanula bononiensis (Campanulaceae), a protected species in Poland

This study investigated the floral biology and pollen quantity and quality of <em>Campanula bononiensis </em>L. (Campanulaceae), a protected species in Poland. Observations and measurements were made during the years 2007–2009 in natural phytocoenoses from the Festuco-Brometea class situated within the Lublin area, SE Poland. A considerable decrease (approx. 87%) in population density was observed. Significant variations both in the amount of pollen (18.5%–34.8% of pollen in the total anther dry weight, i.e. 0.5–1.5 mg per 10 anthers) and in pollen viability (38.8–97.0%) were noted. Both a low amount of pollen and low pollen viability may reduce the reproductive success of individuals. The most frequent visiting insects were bees (<em>Apoidea</em>), including solitary bees 45.7%, honeybees 20.4%, and bumblebees 11.4%. Dipterans, coleopterans (weevils), lepidopterans and ants were also recorded, implying a strong impact of <em>C. bononiensis </em>on insect biodiversity within grasslands.