Abstract

Increasing maize production is vital in many developing countries. One way of increasing production is through adoption of high planting densities. However, high planting densities are associated with intra-specific competition between plants for resources like nutrients, water and sunlight, as a result weak stalks develops which are susceptible to lodging. The challenge of lodging in high planting densities can be reduced by ethephon (2-chloroethylphosphonic acid). A 3 x 2 factorial experiment in randomised complete block design was carried out at New Donnington Farm, Zimbabwe in the 2011/12 rainy season to study the effects of ethephon rates and planting densities on maize. Ethephon rate had the following levels 0 l/ha (control), 0.56 l/ha and 0.84 l/ha while the density consisted of 53,333 and 80,000 plants/ha. Ethephon rate significantly (p˂0.05) reduced the plant height of maize as compared to the control plants across different levels of planting densities. Also a significant increase (p˂0.05) in internode diameter in the treated stands over the control plants across different levels of planting densities was recorded. Ethephon treatment significantly reduced (p˂0.05) the percentage of lodged plants from 6.54 (control) to 4.34 and 2% for medium and high rate, respectively. Grain yield increased significantly in response to increased rates of ethephon at high planting density by 28.5 and 29.1 tons/ha for medium and high rate, respectively.

Key words: Maize, ethephon, planting, density, lodging.