Leaf Area, Nonstructural Carbohydrates, and Root Growth Characteristics of Blue Grama Seedlings

Abstract

Establishment of blue grama [Bouteloua gracilis (H.B.K.) Lag ex Steud.] seedlings requires extension of adventitious roots into the soil profile. The objectives of this study were to determine the effects of leaf area and total nonstructural carbohydrates (TNC) on root growth characteristics of blue grama. Seedlings supported by the seminal root only were treated with 3 days of reduced light and then with 0, 1, 2, and 3 days of full sunlight to alter TNC percentage in crowns. Seedlings within each of these treatments were then clipped at a height of 3, 6, 9, and 12 cm, or left unclipped to alter leaf area. Adventitious root growth was studied during a 3-day test. Path coefficients indicating the effects of leaf area on number of roots per seedling, depth of roots, and root weight per unit length (diameter) were 0.72, 0.47, and 0.77, respectively. The TNC had smaller effects on root growth than did seedling leaf area. Clipping treatments probably reduced root growth because of a deficiency of photosynthetic products. But, the reduction was explained by an adjustment in all components of growth rather than in root depth only. Thus, blue grama seedlings maintained a reasonable rate of root elongation even under severe clipping treatments.