Soil–Root Interface Water Potential in Sweet Corn Affected by Organic Fertilizations and Effective Microbe Applications

Abstract

We examined effects of organic fertilizations and effective microbes (EM, mainly Lactobacillus, Rhodopseudomonas, Streptomyces, and Aspergillus) applications on soil-root interface water potential Ψs-r of `Honey-Bantam' sweet corn. The contributions to Ψs-r from root amount and root activity were analyzed using the Ohm's law. Plants were grown in 1/5000 a Wagner's pots filled with Andosol and six treatments were made as follows: 1) organic materials fermented anaerobically with EM added; 2) anaerobic organic materials; 3) organic materials fermented aerobically with EM added; 4) aerobic organic materials; 5) chemical fertilizers with EM applied, and 6) chemical fertilizers. One month after sowing, as soil water decreased, Ψs-r was maintained higher in organic fertilized plants than chemical fertilized ones and also higher in plants with EM applications than those without EM. The relatively high Ψs-r was contributed by both their large root amount and high root activity. As a consequence, photosynthesis under soil water deficit conditions were also maintained relatively high in these plants. Maintenance of a high Ψs-r favored plants to resist against water deficits. Moreover, the Ψs-r analysis is a practicable additional means to examine the soil-plant water status under undisturbed conditions.