Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Master → Etats Unis → 1979 → Growth and development patterns of black grama in southern New Mexico

New Mexico State University (1979)

Growth and development patterns of black grama in southern New Mexico

Gadzia, Kirk Leslie

Titre : Growth and development patterns of black grama in southern New Mexico

Auteur : Gadzia, Kirk Leslie

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 1979

Résumé
The objectives of this study were to 1) provide an accurate description of growth and development of black grama ; 2) determine reproductive potential of all stem types within this species ; and 3) distinguish the most important factors influencing new plant establishment by vegetative means. Three years of black grama shoot production were classified according to their position of growth during a two-year period. Horizontal shoots, which have generally been referred to as stolons included shoots growing along or near the soil surface. Vertical shoots, generally classified as flower stalks or floral culms, included shoots in a position +/- 25 degrees from the vertical ; while angular shoots included those shoots which occur throughout the plant at approximately a 45 degree angle and have been referred to as either stolons or floral culms. Shoots were permanently marked with non-restricting color rings and changes in development and position were evaluated over a two-year period. No apparent morphological differences were noted between the three categories of shoots. All shoots followed the general phenological pattern of vegetative growth, floral development, quiescence and senescence. The period of time shoots remained in these phases appeared to depend upon prevailing conditions of precipitation, temperature and day length. Amounts of axillary branching, which are the potential for vegetative reproduction in black grama, were nearly equal for all categories. Of the three categories of shoot position, proportions of axillary branches which became rooted during the study period were greatest for the horizontal category. Angular shoots rooted about 30% of the total, while vertical shoots only rarely contributed to vegetative reproduction. Differences in proportion of positional change within the three categories appeared responsible for the observed difference in rooted axillary branching. These differences were also related to the amount of time axillary branches were in position to take advantage of the relatively short periods during the growing season when conditions were favorable for rooting. Comparison of grazed and ungrazed plants suggests that the chances for establishment of axillary branches on shoots in the horizontal position are not severely impaired under a moderate grazing regime, although a greater percentage were broken by trampling. Angular shoots were less susceptible to trampling, but about 30% were consumed during the 1978 growing season. Practically all vertical shoots were removed under moderate grazing. Hoof action may improve the chances for establishment of rooted axillary branches by covering their crown bases with loose soil and providing more favorable rooting conditions through breakup of the hard-surfaced soil crust.

Mots Clés : Bouteloua, phenology, cattle grazing, Bouteloua, grass, Bouteloua, grassland, Bouteloua, phenology, phenology,Bouteloua

Présentation (Jornada NMSU)

Page publiée le 28 avril 2016, mise à jour le 18 décembre 2017