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S. Brooks Parrish and Zhanao Deng

, we examined their leaf morphology, stomata size and density, pollen stainability, chromosome number and nuclear DNA content, and SSR banding pattern. These findings will have major implications on caladium breeding, their possible origins, and

Open access

Dan E. Parfitt and S. Ganeshan

Abstract

Seven assays (hanging-drop slide and agar-plate germination, acetocarmine, three tetrazolium-based stains, and Alexander’s staining procedures) were used to estimate pollen viability in Prunus armeniaca L., P. avium L., P. dulcis Webb, P. persica (L.) Batsch, and P. salicina Lindl. The two in vitro germination tests (hanging-drop and agar-plate) were the most reliable and were highly correlated (r = 0.96). The pollen staining procedures were not reliable or consistent and were not positively correlated with the in vitro assays. Acetocarmine and Alexander’s stains stained dead pollen.

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Mark K. Ehlenfeldt and James L. Luteyn

composed of 50:50, peat:sand mixture. At approximately a three true-leaf stage, seedlings were transplanted to 36-cell flats. All primary hybrids were transferred to 3-L pots in their second season. Male fertility. Pollen samples were stained with

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Kelly M. Oates, Thomas G. Ranney, and Darren H. Touchell

evaluate male fertility, pollen was collected from newly opened florets from each plant between 1030 hr and 1130 hr . Pollen was placed on a glass slide and stained with 40 μL of acetic-carmine (1%), covered with a coverslip, and incubated at room

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Josh H. Freeman, Stephen M. Olson, and Eileen A. Kabelka

Seedless watermelons account for 78% of the watermelons sold in the United States ( U.S. Department of Agriculture, 2006 ). Triploid watermelon plants do not produce sufficient viable pollen to pollenize themselves and a diploid cultivar must be

Open access

L. E. Cockerham and G. J. Galletta

Abstract

Pollen stainability, frequency of unreduced pollen grains, and pollen diameter were examined in 13 species and 4 interspecific hybrids of Vaccinium comprising 3 ploidy levels. Pollen in the tetraploid species was potentially more fertile (as judged by stainability) than in the diploid species. Pollen stainability in the hexaploids was not different from the diploids or tetraploids. Four pollen viability classes (good, fair, poor, and very poor) were established among species. Practically all of the species studied produced unreduced pollen grains. Mean pollen diameter was 11% larger in the tetraploids than in the diploids and 11% larger in the hexaploids than in the tetraploids. The normal pollen diameter ranges for the 3 ploidy levels of Vaccinium were calculated and presented as a possible taxonomic tool.

Genetic, rather than seasonal or environmental differences, appeared to account for the major portion of the interclonal and interspecific variation observed in pollen stainability and in the frequency of unreduced pollen grains.

Frequent irregularities observed were empty pollen grains and granular, unstained pollen, which were assumed to represent early postmeiotic abortions. Meiosis was studied in a representative species of each ploidy level. Pairing and segregation were essentially normal, but a few multivalents or pseudo-multivalents (bivalents secondarily associated) were observed in the hexaploid species.

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M. L. Meyer and F. A. Bliss

Kiwifruit (Actinidia deliciosa) is a functionally dioecious plant where fruit size is dependent on number of seeds set. Pollen fertility was estimated in 1990 and 1991 by percentage stainability and percentage germinability in vitro. Profiles of the isozymes AAT, GPI and PGM were used to assess if any large differences in pollen fertility could be attributed to genotypic variation. Based on these three isozymes, eight different genotypes were discovered. Although significant differences were found among vines within orchards and among orchards, all vines can be considered good pollenizers (stainability > 87%). A positive correlation was found in 1991 between percentage stainability and percentage germination.

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Sandra M. Reed

Little information is available on the reproductive behavior of Hydrangea macrophylla (Thunb. Ex J.A. Murr.) Ser. The objectives of this study were to investigate time of stigma receptivity, viability of pollen from sterile flowers, and self-incompatibility in this popular ornamental shrub. Pollen germination and pollen tube growth in styles were examined using fluorescence microscopy. Stigma receptivity was examined in cross-pollinations made from 1 day before anthesis to 8 days after anthesis. Maximum stigma receptivity for the two cultivars examined occurred from anthesis to 4 days after anthesis. Viability of pollen from sterile flowers was evaluated through pollen staining and observations of pollen tube growth. No significant difference in percent stainable pollen between fertile and sterile flowers was observed in any of the six taxa examined. Pollen germination and pollen tube growth were studied in cross-pollinations made using pollen from fertile and sterile flowers of two cultivars. For both cultivars, pollen tubes from fertile and sterile flowers grew to the same length and had entered ovules by 72 hours after pollination. Self-incompatibility was evaluated by comparing pollen germination and pollen tube growth in cross- and self-pollinations. In the five taxa examined, self pollen tubes were significantly shorter than cross pollen tubes in flowers that were examined 72 hours after pollination. This finding indicates the presence of a gametophytic self-incompatibility system in H. macrophylla.

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Asad Tavakkoli and Enayat Tafazoli

Hand pollinated pistilate date palm flowers were removed 2, 6, 10, 16, 20 hours after pollination, fixed. cleared with 8N NaOH and stained with aniline blue. The Fluoresced pollen tubes were abserved under ultra violet microscope. It was noted that under natural conditions with mean temperature of 19C pollen tube reached the ovary after 16 hours.

Viability test of fresh and stored pollen grains using Brewbaker & Kwack's media at room temperature was 85 and 52.5%. respectively.

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A. Tenkouano, J.H. Crouch, H.K. Crouch, and D. Vuylsteke

We attempted to determine ploidy level in the gametophyte and the sporophyte of Musa using pollen and chloroplast characteristics, respectively. In the gametophyte, interploidy differences accounted for 63.8% of the genetic variance for pollen diameter and 87.5% for pollen stainability, the remainder being attributable to intraploidy differences among clones. While pollen count and stainability effectively separated triploid accessions from diploids or tetraploids, they did not discriminate between diploids and tetraploids. In the sporophyte, the relative contributions of interploidy and intraploidy differences to genetic variation in the number of chloroplasts in stomatal guard cells were 70.8% and 29.2%, respectively. Although pollen diameter and chloroplast number increased with ploidy, the use of the sporophytic parameter appears to provide a more satisfactory means of estimating ploidy status in Musa.