Root Growth and Biological, Chemical, and Physical Gradients in CIPS

Abstract

Verticle gradients of moisture, salinity, specific fertilizer ions, and pH in the root zone in the closed, insulated pallet system (CIPS) are relatively stable compared with those in the open container system (OCS). Establishment of the VA mycorrhizal fungus Glomus intraradices and maintenance of the biocontrol fungus Trichoderma harzianum and the entomopathogenic nematode Steinernema carpocapsae were greater in CIPS than in control OCS. In CIPS, percent corn root length colonized by G. intraradices was greatest in roots in the top stratum of the root medium. Colonization was significantly greater in copper-coated root-containment pouches. Population maintenance in CIPS of T. harzianum, initially uniformly inoculated throughout the root medium, was highest in the top stratum of the root medium where K+ and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document} concentrations were highest. Efficacy of S. carpocapsae in parasitizing Galleria mellonella larvae, while greater in CIPS, was significantly related to host plant in CIPS but not in OCS. Inoculation with bacterial antagonists Bacillus cereus, Enterobacter aerogenes, and Serratia plymuthica significantly increased plant growth in CIPS, but not in OCS. Phytophthora cinnomomi root rot infection readily occurred in inoculated plants, but did not spread to noninoculated plants in CIPS when roots were contained within plant pouches. Because of the stability of the root zone parameters and the lack of leaching-dilution of exudates, volatiles, and other materials from the root zone, CIPS is an excellent system for evaluating effects of microorganism and other factors on root growth and development.