Growth and Development in Range Grasses. I. Early Development of Bouteloua curtipendula in Relation to Water Supply

Abstract

1. The growth of seedlings of Bouteloua curtipendula in a coarse sandy loam soil, in 2-gallon crocks 9 inches deep, watered at intervals of 3, 6, 12, and 20 days, was followed for 4 months. All plants received supplementary illumination to provide a 16-hour photoperiod. 2. At the end of the experiment, plant height, and total numbers of: leaves and nodes, and elongated internodes on the primary axis; primary, secondary, and tertiary tillers; adventitious root primordia differentiated; primordia differentiated on lower nodes of primary axis; and living functional adventitious roots all were correlated directly with the amount of water supplied, although to different degrees. Numbers of: mature basal unelongated internodes; basal nodes bearing roots; and root primordia on upper crown nodes were correlated inversely with water supply, to a limited degree. 3. Height or length, as measured to tips of leaves, of both primary and secondary axes, was much more affected by water supply than was the number of leaves, buds, or roots differentiated on corresponding axes. 4. No plants flowered, although primary culm elongation began in the 3's and 6's within 60 days and had begun in the 20's at 4 months. 5. Both size and numbers of axes of the third and fourth order were much lower in the drier series than in the wetter ones. 6. The primary root system developed rapidly, but consisted only of a single taproot and its branches. It became nonfunctional in most 3's and 6's within 2 months, but remained alive in 12's and 20's until the close of the experiment, and in some cases persisted as the only functional part of the root system. 7. Adventitious roots require approximately 3 consecutive days of surface soil wetness to penetrate sufficiently to become established. A tendency was noted for a relative increase in the numbers of primordia differentiated, at the upper crown nodes and on tillers, by plants on which no nodal roots had become established.