The objective of this work was to characterize the morphology and viability of the pollen of 15 genotypes of castor bean (Ricinus communis L.) and to generate information that can assist in the selection of highly promising male parents for future use in genetic improvement programs aimed at producing seeds for oil extraction. Acetolysis and scanning electron microscopy was used to characterize...

With the aid of osmium tetroxide vapour, dry pollen and pollen at various stages of hydration has been fixed anhydrously for examination with the transmission electron microscope (TEM). In addition to establishing features characteristic of grains at different states of hydration, this technique has enabled the detection of a superficial layer investing both the exine and the pollen coating. Th...

Little is known about the levels of exposure to grass pollen in urban environments. We assessed the spatio-temporal variation of grass pollen concentrations and the role of urbanity as a determinant of grass pollen exposure in the Helsinki Metropolitan area. We monitored grass pollen concentrations in 2013 at 16 sites during the peak pollen season by using rotorod-type samplers at the breathing...

Many flowering plants are unable to set seeds with their own pollen because a system known as gametophytic self-incompatibility is operating. The basis of this system is a single multiallelic locus S, and if the S allele carried by a pollen grain matches one of the two S alleles carried in the style, as it is certain to do upon self-pollination, then pollen tube growth is inhibited. Should one ...

In previous studies, we have shown that the temperature dependent vibrational frequency of the CH(2) stretch in hydrocarbons in intact pollen grains can be recorded with Fourier transform infrared spectroscopy and used to measure phase transition temperatures (T(m)) in these hydrocarbons. Circumstantial evidence was provided that the major contribution to the signal seen in these samples was fr...

Based on qualitative and quantitative melissopalynological analyses, 19 Chinese honeys were classified by botanical origin to determine their floral sources. The honey samples were collected during 2010-2011 from the central region of Shanxi Province, North China. A diverse spectrum of 61 pollen types from 37 families was identified. Fourteen samples were classified as unifloral, whereas the re...

Pollen grains are the mature male (haploid) gametophyte of higher plants. These tiny organs (10-100 IJ.m in diameter) develop in the anthers (Stanley and Linskens, 1974). When the flower opens the anthers become exposed to the environment and dehydration triggers a mechanism for release of the pollen. In the process, the pollen also dehydrates. Though the pollen of most species can withstand dr...

The objective of this year's work was to confirm the role of pollen in pistillate flower abscission (PFA) of Serr walnut. Pistillate flower abscission was evaluated in individual trees along transects, beginning close to po11enizers and extending up to 640 feet away, in 12 orchards. It was also evaluated in controlled pollinations of bagged and unbagged Serr flowers with varying levels of Serr ...

High quality of bee pollen for commercial purpose is required. In order to attend the consumer with the best identification of the botanical and floral origin of the product, 25 bee pollen batches were investigated using two techniques of pollen grain preparation. The first started to identify pollen loads of different colors in two grams of each well mixed batch, and the second to identify pol...

High Pinaceae pollen concentrations in the air and on the surface of puddles before the main pollen season started were observed in Kraków (southern Poland) in May 2013. The paper presents the results of detailed studies of the composition and source of the "yellow rain" in 2013, and as a comparison, the Pinaceae pollen concentrations and samples collected from the ground surface in 2014 were c...