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Vikramjit S. Bajwa* and Curt Rom

Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pistil viability both in vitro and on excised limbs.

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Michael S. Stanghellini and Jonathan R. Schultheis

In 1999 and 2000, a total of 27 diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars and advanced breeding lines (hereafter referred to as cultigens) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant × pollen grains produced per flower) differed greatly among cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0029) and days within years (P = 0.0225), but pollen production between years by cultigens was stable (P = 0.4841). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in choosing a good diploid pollenizer for triploid watermelon production.

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Ghodratollah Riazi, Shahrokh Khanizadeh and Majid Rahemi

The xenial and metaxenial effects of five different male sources on cross pollination of three pistachio cultivars, were studied in 1990 and 1991 in Rafsanjan/Iran. The pollen grains used were P. atlantica Desf., P. mutica F.& M., P. vera L. (Momtaz), P. vera L. (Soltani), and an open pollination. The female cultivars chosen were `Owhadi', `Kalleh-ghuchi', and `Momtaz', which occupy the largest cultivation area. Experiment was done in two successive years in a completely randomized design. Results of this study agreed with previous studies regarding the retardance of pistachio nut development by wild pollen species rather than P. vera L. The greatest change in various characteristics of nuts, e.g., kernel weight and shell splitting, occurred when P. mutica F.& M. pollen grains used followed by P. atlantica Desf. pollen grains. Thus, some manifestations of xenia and metaxenia could be inferred. In general, larger kernels and increased shell dehiscence resulted from the use of P. vera L. pollen grains. Greater kernel weight of `Kalleh-ghuchi', higher shell splitting of `Momtaz', and higher blank of `Owhadi' produced by pollination with P. vera L. in some extent could also be cultivar characteristics.

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Mike Stanghellini and Jonathan R. Schultheis*

In 1999 and 2000, a total of 28 diploid watermelon cultigens (released cultivars and advanced breeding lines) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant x pollen grains produced per flower) differed greatly between cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0003) and days-within-years (P = 0.0094), but pollen production between years by cultigens was stable (P = 0.3845). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in selecting an optimal diploid pollenizer for triploid watermelon production.

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A. Talaie, B. Goleyn, A. Vezvaei and Y. Ebrahimi

`Page' mandarin is a complex hybrid between `Minneola' tangelo and `Clementine' mandarin. Because of self-incompatibility, this cultivar severely needs pollinizers and, if a suitable pollinizer does not exist, it will produce few and small fruit. In this study, the effects of pollen grains of nine cultivars of citrus ['Sour' orange, `Duncan' grapefruit, `Sweet' lemon, `Salustiana' orange, `Local' mandarin, `Hamlin' orange, `Siavaraz III Locan' orange, `Marrs' orange, and `Shell' mahaleh (natural hybrid)] on the quantitative and qualitative characteristics of fruit (weight, diameter, length, volume, peel thickness, juice content, developed seeds, undeveloped seeds, total soluble solids, acidity, pH, vitamin C, and percentage of final fruit set) were investigated and evaluated. After artificial pollination and during fruit growth and development, seven times abscission and fruit color and diameter were recorded. Fruit were harvested 29 weeks after pollination and were analyzed. The results showed that this cultivar, in addition to the complete self-incompatibility, has the ability of week parthenocarpy, which results in small and low-quality fruit and also parthenocarpy is induced. `Page' mandarin is cross-compatible with some cultivars, such as `Marrs' orange. There is a positive and significant correlation between developed seed number and fruit weight. The pollen of `Siavaraz III Local' orange has the most effects on percentage of final fruit set. The pollen of `Shell' mahaleh (natural hybrid) has the most effect of the quantitative characteristics, and the pollen of `Marrs' orange has the most effects on qualitative characteristics. It was concluded that `Hamlin' orange is the best pollinizer for `Page' mandarin in northern Iran. The results of this study were analyzed with the use of a randomized complete-block design.

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Christopher S. Cramer

Determination of ploidy is an essential plant breeding technique. Laboratory exercises for teaching students how to determine ploidy in plant tissues using various techniques are described for geranium and onion. The different methods include root tip squashes, pollen mother cell squashes, pollen grain size and germinal pore counts, stomata size and density determination, and gross morphology.

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Wol-Soo Kim* and Sang-Hyun Lee

In order to investigate the cause of differences of mature pollen in Asian pear (Pyrus phyfolia) that are collected from various sources for the artificial pollination, various factors were measured as below: the composition of nonstructural carbohydrate in bud at 30 days after full bloom, the contents of crude protein in skin, cytosol and membrane, and the affinity for lectin (CON-A: Concanavalin, type III A) of glycoprotein in cytosol of pollen were measured. Contents of sucrose and glucose in buds influenced pollen germination rate and pollen tube growth, respectively. Therefore, soluble types of carbohydrates stored in bud were regarded as influencing on pollen germination rate and pollen tube growth. Pollen, which showed low activity, had low affinity on CON-A, lectin of glycoprotein, because it had fragile membrane, proteins in cells were denatured to pollen surface and certain enzymes concerned in pollen germination lost stability and activity. Pollens that showed high activity contained 92 kDa protein while others not. This was assumed as influencing on control of pollen viability.

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Cevriye Mert

sativa Mill.) ( Mert and Soylu, 2007 ). Pollen grains are the male gametophytes and take part in the reproductive biology. Fruit set is also dependent mainly on the fertilization process in the cornelian cherry cultivars. For this reason, the viability

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Lihong Hao, Hui Ma, Jaime A. Teixeira da Silva and XiaoNan Yu

level of detail in pollen grain surface sculpture that is discernable. The detail that is available from SEM is often required for taxonomic studies ( Kodela, 2006 ). In this study, the pollen morphology, including shape, size, and surface sculpture, of

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Jiefang Wu, Danwen Fu, Jiezhen Chen, Changhe Cai, Qian Yan and Liangxi Ou

pollen grains deposited on the stigma depends on the number of pollinator visits received by a floret during a certain period (visit rate) and the proportion of viable pollen in the pollen loads carried by the pollinators ( Dafni et al., 2005 ). Litchi is