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Leticia Santos-Hernández, Martha Martínez-García, Jorge E. Campos, and Ernesto Aguirre-León

1 To whom reprint request should be addressed; e-mail eall@servidor.unam.mx . We thank the people and local governments of six communities of the Tehuacan-Cuicatlan Valley for their guidance and help in the field

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Yung-I. Lee, Chia-Fu Lu, Mei-Chu Chung, Edward C. Yeung, and Nean Lee

vitro ( Lee, 2003 ). We attempted to gain a better insight into the role of endogenous ABA in orchid seeds, and the relationship between ABA and various pretreatments before germination. The objectives of this study are to 1) document key anatomic

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Scott Reid, Judy Harrington, and Harrison Hughes

Distichlis spicata var. stricta (Torrey) Beetle is a native grass that tolerates salt, high pH, and some heavy metals. It has been proposed for use in several challenging environments, including mine spoils and salt-impacted areas of golf courses. But, its widespread use has been hindered by several factors, one of which is poor seed set. Because chromosome numbers are variable and some genotypes are aneuploids, there was concern that pollen viability in some genotypes was low. Pollen from several genotypes failed to germinate in vitro on four artificial media prepared with various levels of osmoticum. However, hand pollination in vivo resulted in profuse pollen germination for all genotypes tested. Germination on pollinated stigmas was observed at intervals beginning 2 h after pollination with a fluorescence microscope using aniline blue and acridine orange stains and in bright field using toluidine-O stain. Very young stigmas seemed unreceptive and, while pollen would germinate, the pollen tubes would not grow down through the style. On receptive stigmas, many pollen tubes grew down toward the egg and some reached it within 24 h. There was no evidence of impaired fertility. Aniline blue was the best method for observing pollen tube growth through the style, although toluidine-O was adequate for observing germination on the stigmatic surface.

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Boris Andrés Bran Barrientos and Jong-Yi Fang

orchid species. Successful in vitro seed germination has been reported for S. plicata using various medium formulations. Hossain and Dey (2013) found that the maximum seed germination percentage was observed with the Phytamax medium (95%) followed by

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R.B. Rogers, M.A.L. Smith, and R. Cowen

The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

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R.B. Rogers, M.A.L. Smith, and R. Cowen

The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

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Luisa Santamaria and Sherry Kitto

Solanum quitoense, also known as naranjilla or lulo, is a native species of Ecuador and Colombia. Its value is based on the uncommon sweet-sour flavor of its fruits, which is appreciated in the national and international markets. The worst problem for this crop is the root-knot nematode Meloidogyne incognita. The main objective of our research is to develop root-knot nematode–resistant naranjilla via somaclonal variation. Seeds of Solanum quitoense `Baeza' germinated quicker than those of `Dulce'. Seeds given a 2-week dark treatment had 100% germination compared to 75% germination for seeds placed under lights (16-h photoperiod, 60 mmol·m–2s–1). Single-node explants proliferated an average of nine nodes after 1 month of culture. Microcuttings (two nodes, 3.5 cm) stuck in sand and placed under a humidity dome under mist had an average of five roots averaging 25 cm in length after 3 weeks. Stems regenerated shoots better than petioles or leaves and explant orientation/polarity had no effect on regeneration. Root cultures of Solanum quitoense inoculated in vitro with Meloidogyne incognita showed susceptibility to root-knot nematodes.

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Konstantinos F. Bertsouklis and Maria Papafotiou

, San Diego, CA Bertsouklis, K.F. Papafotiou, M. 2009 In vitro propagation of Arbutus andrachne L Acta Hort. 813 477 480 Bertsouklis, K.F. Papafotiou, M. 2010 Effect of storage on Arbutus andrachne L. seed germination Acta Hort. 885 65 71

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José G. Levy and Dina A. St. Clair

High temperatures during flowering have been implicated in reducing seed set and fruit set in tomatoes (Lycopersicon esculentum). Pollen viability and vigor were studied by measuring in vitro germination and pollen tube development in pollinated pistils of four processing tomato cultivars under normal (25° C day/15° C night) and high (32° C day/23° C night) temperatures. Preliminary studies were carried out to determine the length of pollen tubes in styles collected in times ranging from 3 to 48 hours after pollination. Under normal temperatures the pollen tubes reach the end of the style between 12 and 18 hours. At high temperatures there are fewer pollen tubes moving through the style and the time to reach the end of the style is longer. In pollen vigor studies, crosses were made between pollen and pistils of plants grown under different temperature treatments, then pollinated pistils were collected at 4, 8 and 12 hours after pollination. There were differences in in vitro pollen germination percentage and pollen tube length in the pollinated pistils, suggesting that high temperatures act to slow down pollen activity.

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W. Msikita, R.M. Skirvin, J.A. Juvik, W.E. Splittstoesser, and N. Ali

1 Graduate Student. 2 Professor. 3 Associate Professor. This research was supported in part by the Univ. of Illinois Agricultural Experiment Station (Hatch 65-0323), the Swedish International Development Authority (SIDA), and the Zambian