Shock Pulse Effects on Wheat Growth

Wheat seedlings (Triticum aestivum cv. Pacific Blue Stem) grown under continuous low-level illumination were used to study the effects of pressure variation and its duration. Growth was determined by dry weights, leaf length, and types of secondary roots produced. Two sublethal shock pulses (1.41 and 2.82 kg cm ^?2) and three pressure duration intervals (0.1, 1.0 and 10.0 seconds) were studied. The results indicated a general overall reduction in growth associated with the shock pulse and that the pressure duration interval influenced the shock- growth response. The long pressure duration interval was found to be the most influential on shock pulse response. Present knowledge indicates that a pulse rise-time of 1 ms and a pressure duration interval of at least 1.0 second affect plant growth at sublethal shock pulses, such that the growth response is linear or bi-directional, depending on the magnitude of the shock pulses, and either linear or complex with respect to pressure duration interval for any shock pulse level.