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K.P. Baiyeri, B.N. Mbah and A. Tenkouano

The additive main effects and multiplicative interaction (AMMI) model was used to evaluate the stability patterns of 36 Musa genotypes in four cropping environments for bunch weight, pulp weight, and dry matter content. Alleycropping generally induced higher means for all traits than did sole cropping. The triploid plantains produced smaller bunch weights and were less stable than dessert and cooking bananas. In this ploidy group, bunch weight was highest for the cooking bananas `Cardaba' and `Fougamou', but only `Fougamou' was stable across environments. Among the hybrids, only `FHIA23' (dessert banana) expressed high and stable bunch weights, while other high-yielding hybrids displayed specific adaptation to alleycropping. Pulp weight was lower but more stable in plantains than in other triploid genotypes. Among the hybrids, pulp weight was high and stable for one cooking banana (`FHIA3'), one dessert banana (`FHIA1'), and three plantains (`PITA1', `PITA2', and `PITA7'). Dry matter content was highest in plantains and lowest in dessert bananas at both triploid and tetraploid levels, and was also more stable than the other traits. Thus, the adaptation patterns of genotypes across environments varied according to the trait studied. When rank changes were not observed across traits for a given genotype, differences were still noted in the relative magnitude of the IPCA1 score. Hence, both farm gate traits and postharvest processing traits should be considered in selecting for broad or specific adaptation. Determination of the genetic relationships between processing traits and farm gate traits could allow Musa breeders to construct selection indices that would facilitate multiple trait selection and enhance breeding efficiency, with respect to cultivar stability and adaptation across environments.

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Jeffrey Adelberg, Maria Delgado and Jeffrey Tomkins

). Furthermore, hybridizers have used colchicine to convert many diploid cultivars, and then used the altered material as tetraploid breeding stock. As a result, the modern germplasm pool is a mix of both diploid and tetraploid cultivars. Four daylily cultivars

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Li-ping Chen, Yan-ju Wang and Man Zhao

In this study, in vitro induction of tetraploid Lychnis senno Siebold et Zucc. and its cytological and morphological characterization were conducted. For polyploid induction, nodal segments with axillary buds from in vitro grown plants were kept for 3 days in MS (Murashige and Skoog, 1962) liquid or solid media added with a series of concentrations of colchicine. Out of total 588 recovered plants, 15 tetraploids and 6 mixoploids determined by flow cytometry analysis were obtained. The tetraploid contained 48 chromosomes, twice the normal diploid number of 24, as observed under light microscope. The tetraploid plants exhibited much larger but less stomata than diploid plants. Moreover, significant differences in stem height and leaf size between the diploid and tetraploid plants were noted. The tetraploid plants were more compact than diploids.

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Marietta Loehrlein and Dennis T. Ray

Triploid watermelon seed are produced by crosses between tetraploid female and diploid male plants. When open-pollinated, the resultant seed can be either tetraploid due to self-pollination or triploid from pollination by a diploid. This work was done to test if triploid and tetraploid seed can be separated on the basis of seed thickness and weight. Open-pollinated seed from a 4n × 2n cross were separated by either thickness (grouped into 0.1-mm increments) or weight (5-mg increments). Seed were germinated in a greenhouse and transplanted into the field. Plants were scored as either triploid or tetraploid by use of a genetic marker system. When separated by either thickness or weight, triploid and tetraploid seed were found in essentially each size category. There were no significant differences between populations for thickness, and the mean weights were essentially equal between triploid and tetraploid seed.

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Bruce W. Wood and Larry J. Grauke

% of taxa) or tetraploid (60% of taxa). Species are grouped by section based on morphology with those within the Carya section being shellbark hickory [ C. laciniosa (2 n = 32)], southern shagbark hickory [ C. carolinae-septentrionalis (2 n = 32

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G. Fassuliotis and B.V. Nelson

`Gulfstream' and `Charentais' muskmelons (Cucumis melo. L.) plants were regenerated by in vitro culture to increase their genetic variability for resistance to root-knot nematodes (Meloidogyne spp.). While no genetic variability for root knot resistance was found, regenerated plants exhibited other traits that varied from the donor cotyledons. Chromosome counts confirmed that >75% of the somaclonal variants were tetraploid (2n = 24; 4n = 48). Tetraploids consistently exhibited micro- and macroscopic morphological changes that enabled distinction between tetraploids and diploids without chromosome counts; tetraploids contained enlarged stomates with more chloroplasts in the guard cells and pollen with a high percentage of square-appearing shapes. Tetraploids exhibited distinctive macroscopic morphological changes, including differences in leaf structure, fruit shape, blossom-end scar, number of vein tracts, and seed size.

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Hae Keun Yun, Kyo Sun Park, Jeong Ho Roh, Yong Bum Kwack, Ji Hae Jun, Seok Tae Jeong, Seung Hui Kim, Han Ik Jang and Yong Uk Shin

‘Suok’ (‘Kyoho’ × ‘Beniizu’) is a tetraploid (4×) table grape cultivar showing large berries with high quality. ‘Suok’ has a mean bud burst on 17 Apr., flowering on 31 May, and fruit maturity on 15 Sept. The mean berry weight is 10.9 g, and mean

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Douglas C Needham and Homer T. Erickson

Mean seed production in tetraploid × diploid crosses of Salpiglossis sinuata R et P. was similar to that in diploid × diploid crosses, but germination of the resultant triploid seeds was low (8%). Parental line selection resulted in some germination improvement. Triploid hybrids from these crosses were vigorous, with floral characteristics resembling tetraploids. The fertility indices of self-pollinations of triploids and pollinations by diploid and tetraploid plants were <1, 22, and 6, respectively, compared with 176 for diploid × diploid crosses. Thus, the self-pollinated triploids were virtually sterile.

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Jeffrey W. Adelberg, Bill B. Rhodes, Halina T. Skorupska and William C. Bridges

Adventitious and axillary shoots of melon (Cucumis melo L.) were cultured from explants on a modified Murashige and Skoog medium containing 10 μm BA. Explants were diversified with regard to genetic source (breeding lines Miniloup, L-14, and B-line), seed parts (apical and cotyledon tissue), seed maturity (10-40 days after pollination; DAP), and cotyledon sections with respect to apical-radicle axis (distal and proximal). Plants were screened for ploidy level by pollen morphometry. Immature cotyledons produced more tetraploid regenerants than mature cotyledons from seed of breeding line Miniloup; the highest frequency of tetraploid regenerant plants was from cotyledons of embryos harvested 18 and 22 DAP. Explants from the apical meristem of the same seeds produced fewer or no tetraploid plants. Proximal sections from immature cotyledons of three genotypes (Miniloup, L-14, B-line) produced higher frequencies of tetraploids than whole mature cotyledons or whole immature cotyledons.

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I. Oiyama and S. Kobayashi

Some undeveloped seeds from mature Citrus fruit of monoembryonic diploid cultivars crossed with a tetraploid selection were observed to be polyembryonic. The multiple embryos formed a small mass the the micropylar end. Plants regenerated in vitro from the embryos in polyembryonic seeds were triploid and showed identical peroxidase banding patterns on acrylamide gels. These results indicate that the multiple embryos found in the undeveloped seed from monoembryonic diploid × tetraploid crosses are genetically identical and of zygotic origin.