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Oregon State University (1997)

Performance of perennial ryegrass (Lolium perenne L.) seed crops under water stress conditions

Velloza, Theodosius Marmaduke

Titre : Performance of perennial ryegrass (Lolium perenne L.) seed crops under water stress conditions

Auteur : Velloza, Theodosius Marmaduke

Université de soutenance : Oregon State University

Grade : Doctor of Philosophy (Ph. D.) in Crop Science 1997

The purpose of this study was to analyze strategies for sustainable development, and especially the opportunities and constraints for sustainable development in arid lands. This study examines how environmental, economic, political, and social factors influence regional development. Because of the complexity of the problem, a two-perspective interdisciplinary approach was used. First, from a historical perspective, a farming systems approach focuses on understanding the interaction of population, environmental, technological and institutional factors. Second, and from an economic perspective, a linear progranuning model examines the interaction of the North American Free Trade Agreement (NAFTA) as well as the Amendment to Article 27 of the Mexican Constitution in regional-level current and expected transformations. Research was conducted in central Sonora, located in northwest Mexico, one of the arid zones of the Sonoran desert. From colonial times to the early 20th century chaotic changes occurred in Sonora. These changes were influenced by cultural, environmental, and technological factors. Cultural differences between the indigenous Sens and Spaniards prompted a long period of conflict. Seris were a hunter-gatherer nomadic group, the Spanish conquerors searched for gold and minerals, and the later Mestizos were farmers and ranchers. The strategy of hunting-gathering not only permitted the Seris to cope with a hostile, arid climate, but also helped them resist Spanish efforts to colonize or exterminate them. In contrast, environmental barriers limited the introduction of agricultural systems into the Seri territory and limited the rapid conquest of the Sens as well. Nonetheless, the Seris were nearly exterminated as a result of this conflict, and their territory reduced to the coastal margins of the Gulf of California.

Mots clés : Lolium perenne — Effect of stress on — Lolium perenne — Drought tolerance


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