EFFECT OF SOIL TYPE AND AERATION UPON ROOT SYSTEMS OF CERTAIN AQUATIC PLANTS

Abstract

Hibiscus militaris, Typha latifolia, Acorus calamus, and Sagittaria latifolia developed bulkier root systems and larger tops in aerated cultures. Relative growth and development of all species were greatest in muck, second in clay, and least in sand with the following exceptions. H. militaris had a maximum growth in unaerated sand, and S. latiJolia attained maximum growth in unaerated and aerated sand cultures. The root systems of all spp. showed aero-tropic response. In unaerated cultures the plants established shallow and surface root systems, while with aeration the roots ramified the soil with the greatest growth in the region of the aerating coils. Increased root elongation was accompanied by corresponding increment in root diameters in aerated soils, with this exception: root diameters of Acorus calamus were greater in unaerated muck than in aerated. Laterals were longer and branched nearer the root tips in all aerated soils than in unaerated. Second-rank laterals occurred in H. militaris roots in all cultures except unaerated sand, and on T. latifolia roots in all aerated soils but never in unaerated ones. Roots of S. latifolia and A. calamus remained singly branched in all cultures. Branched surface-growing roots were developed by H. militaris, T. latifolia, and A. calamus in all unaerated soils. Root hairs did not occur on surface-growing roots in unaerated sand or clay, but were found in unaerated muck. They were much more numerous on roots from all aerated soils.