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Accueil du site → Doctorat → États-Unis → 1994 → Seedling performance in selected fourwing saltbush (Atriplex canescens) (Pursh) Nutt.) populations and their F(1) hybrids under arid land conditions in New Mexico

New Mexico State University (1994)

Seedling performance in selected fourwing saltbush (Atriplex canescens) (Pursh) Nutt.) populations and their F(1) hybrids under arid land conditions in New Mexico

Oushy, Hamdy Soliman

Titre : Seedling performance in selected fourwing saltbush (Atriplex canescens) (Pursh) Nutt.) populations and their F(1) hybrids under arid land conditions in New Mexico

Auteur : Oushy, Hamdy Soliman

Université de soutenance : New Mexico State University

Grade : Doctor of Philosophy (PhD) 1994

Résumé
Mass selection was compared with intraspecific hybridization of selected parental materials and their hybrids for their effectiveness in improving fourwing saltbush (Atriplex canescens (Pursh) Nutt.). Selected fourwing saltbush (4n) tetraploid populations from six different sites in New Mexico were established in a breeding nursery at the Plant Science Research Center, NMSU, in July 1990. A top-cross scheme was used to perform intercrossing between the common pollinator and the five female populations in 1992. Entries, including six parents and five hybrids with four differed plants were investigated in three experiments. In the first experiment, rate of seed germination and percentage were determined in a greenhouse. Growth characteristics (height, shoot number, seed weight, internode number, root length, leaf number, leaf/stem ratio, root/shoot ratio, leaf DM, stem DM, root DM, and dry forage yield on 5-month-old seedlings) were also measured. Percentage of seed germination and survival of seedlings were analyzed in the field in September 1993. Percentage of seed germination and seedling height of parents were significantly higher than their $F\sb1$ hybrids. The reduced germination of hybrids appeared to be influenced by the genotype of the common pollinator and suggests that the crossing scheme was effective. No differences were observed in shoot number and 100-seed weight between or within parents or the hybrids, indicating no genetic differences. Similar response was exhibited by internode number, root length, leaf number, leaf/stem ratio, stem DM, root DM, root/root ratio and forage yield Leaf DM expressed significant differences between both groups. No differences in survival were observed for seedlings of the parents or their $F\sb1$ hybrids at Jornada Experimental Range. However, there were significant differences in the percentage of germination. A high correlation coefficient between seed germination in the greenhouse versus the field indicated that a greenhouse could be used for germination tests. These results indicate that mass selection may be more effective for improving native fourwing saltbush population than hybridization, especially with such unselected, and highly genetically variable populations. Hybridization generally suppressed seedling character expression. Mass selection within adapted populations should be implemented for each ecological site with similar environmental conditions.

Mots clés : Genetics, Range management, Plant propagation, Biological sciences

Annonce (NMSU)

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