Adventitious Root Initiation in Kleingrass in Relation to Seedling Size and Age

Abstract

Successful establishment of grasses depends on initiation and growth of adventitious roots. This study was undertaken to determine the minimum size and/or age requirement for adventitious root development in kleingrass (Panicum coloratum L.) seedlings, and also to determine which of these two factors is more important in controlling or regulating adventitious root development. Shoot mass was modified in dependently of age through use of populations having different seed mass. These were ‘Selection 75’ (low seed mass), ‘Verde’ (intermediate seed mass), and 79‐35 (greatest seed mass). Seeds were planted in soil in plastic cones and were germinated and grown in a growth chamber. Resulting plants were sampled at 5, 6, 8, 10, 12, and 14 d after emergence. Shoot masses of the three entries (at all sampling dates) were in the same relative order as seed masses of the entries, and Selection 75 initiated adventitious roots at the lowest shoot mass. Seedling age at first adventitious root development was not related to seed weight differences. However, Verde and 79‐35 were superior to Selection 75 in primary root length, number of adventitious roots, and length of longest adventitious root (data averaged over all sampling days). Because seedling age in kleingrass is apparently more important than seedling mass in influencing adventitious root initiation, selecting for rapid seedling growth will not necessarily shorten the interval between planting and development of the first adventitious root. However, selection for rapid seedling growth may concomitantly improve other root characteristics.