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Cecilia E. McGregor and Vickie Waters

2009 ( U.S. Department of Agriculture, 2011 ). The seedless fruit is produced on triploid plants, but because pollination and fertilization are required for fruit set, and these plants produce negligible amounts of viable pollen, diploid pollen sources

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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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R.A. Stern, S. Gazit, R. El-Batsri, and C. Degani

Fruits produced in two orchards, each consisting of adjacent blocks of `Floridian' and `Mauritius' lychee (Litchi chinensis Sonn.), were unequivocally identified as selfed or outcrossed by phosphoglucose isomerase (PGP; EC 5.3.1.9) isozyme analysis. The average rate of hybrid production in each orchard was 69% and 87% for `Floridian' and 17% and 65% for `Mauritius', respectively. The percentage of hybrids produced on trees adjacent to those of the other cultivar was invariably significantly higher than that produced on the more distant trees. However a significant correlation between hybrid percentage and proximity to the other cultivar, as well as between hybrid percentage and yield, was found only for `Floridian' in one of the orchards. A significant correlation was found between pollen source and the weights of fruits and seeds in both cultivars. Fruits originating from cross-pollination were heavier and contained heavier seeds than selfed fruits. The most pronounced effect of pollen parent on seed weight was found in `Floridian', which appears to exhibit inbreeding depression.

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Thomas Gradziel and Bruce Lampinen

cultivar Nonpareil, and is being released as a pollenizer for ‘Nonpareil’. ‘Kester’ kernels have a similar appearance to ‘Nonpareil’, but have a darker seedcoat. Trees have an upright spreading and open architecture that produce high yields with tolerance

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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

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Thomas Gradziel, Bruce Lampinen, Franz Niederholzer, and Mario Viveros

source of self-compatibility and disease resistance. Selection SB13,36-52 was selected for regional testing as an early bloom pollenizer for ‘Nonpareil’ based on its desirable early flowering and high kernel quality with an average kernel lipid content of

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Patrick J. Conner

pecan, breeding programs often must make use of stored pollen to achieve particular crosses. Efficient and reproducible viability testing is essential to facilitating the use of stored pollen because nut set cannot be determined until after the end of

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Gaetano Distefano, Giuseppina Las Casas, Stefano La Malfa, Alessandra Gentile, Eugenio Tribulato, and Maria Herrero

when cultivated near other sexually compatible cultivars. To avoid seed formation, several strategies have been explored ( Vardi et al., 2008 ). Open pollination factors such as pollen flow ( Chao et al., 2005 ) or the pollination efficiencies of wind

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Khalil R. Jahed and Peter M. Hirst

Pollination is an essential process for fruit set, fruit growth, fruit quality, and seed set of most apple cultivars. The first step of successful apple pollination is the transfer of pollen to the stigmatic surface (typically vectored by bees

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Shawn A. Mehlenbacher

one production zone to another, contrasts sharply with the situation with the major food crops. Pollen–stigma incompatibility in hazelnut is of the sporophytic type and controlled by a single locus, designated the S-locus, with multiple alleles