Respiration and Nutrient Absorption of Plant Roots Growing under Aerobic or Anaerobic Condition : 1. Respiration and nutrient absorption of rice roots growing under anaerobic condition.

Abstract

Attached roots and detached roots of rice plants were kept submerged for 8 hours in a culture solution to which nitrogen gas was bubbled. The amount of CO2 evolved from respiration was analyzed in 1-hour period by way of absorbing CO2 in N/50 KOH solution. Before and after the experiment, nutrients solved in the culture solution were measured to determine the amount of nutrients absorbed by the roots. The components analyzed were NH4-N, P2O5, K2O, and CaO. The results obtained are summarized as follows: 1. The rates of respiration and nutrient absorption of attached roots kept submerged in the culture solution to which nitrogen gas was bubbled were almost nearly the same as normal, while a considerable depression in the rate of respiration and a marked decrease in nutrient absorption were revealed when 10-2M NaN3 was applied to the culture solution. 2. The rates of respiration and nutrient absorption of detached roots were far less than those of attached roots, when they were treated with nitrogen gas without addition of NaN3 to the culture solution, but they were nearly the same rates as those of attached roots kept submerged in the culture solution containing 10-2M NaN3. A tendency of somewhat accelerated depression in the rates of respiration and nutrient absorption was seen, providing detached roots were exposed to the culture solution containing 10-2M NaN3. 3. Resting on the facts obtained from this experiment it should be inferred that the intact rice roots are able to sustain aerobic respiration and to absorb nutrients quite normally under anaerobic condition so far as any materials harmful to respiration are not included in the solution and, eventually, that molecular oxygen may be transported from the top to the roots of rice plants through the well-developed ventilating system.