Assessment of allelopathy effects of Johnson grass (Sorghum halepense) on the germination and growth parameters of corn (Zea mays) CV. 704

Allelopathy is known as direct or indirect effect of released chemicals in to the environment by a plant species on another one. The effect mostly has harmful for others. Johnson grass is a common weed in corn farm in Isfahan. It has critical impact on growth and development of the crop. On behalf of assessment of allelophatic effect of the weed on seed germination and growth parameters of corn, an experiment was accomplished based on Completely Randomized Design with four treatments by five replications in Agriculture Jahad Education Centre of Isfahan. Factors were extracts of different parts of Sorghum halepense in three type (arial parts, underground parts, whole plant) with five levels of concentrations (25, 50 and 100%). Distilled water considered as control (concentration 0%). Seed corn cultivar single cross-704, used for cultivation. Parameters such as percent and rate of germination, root length, shoot length, fresh and dry weights were measured. Data were analyzed by SAS software through Duncan test. Results showed that germination and growth parameters affected by treatments, showed different results to the concentrations. Results showed that extract had negative effect on all measured parameters except in percentage of germination, as, the most effect showed in concentration of 100 and the lowest in control. Comparison between different parts of the plant showed that underground organs have the most effect on the seedling growth.