Effects of Plant Growth Regulator on Castor Development and Seed Yield Production on the Texas High Plains.

Petroleum is an essential commodity needed by man for food production, as well as to keep our energy based economy operating at optimum performance and efficiency. Castor ( Ricinus communis L.) has tremendous potential as an oilseed crop to produce biofuels. However, castor plants can reach heights of over three meters in a single growing season, severely reducing mechanical harvest efficiency. The purpose of this research is to evaluate plant growth regulator effects on mature castor plant height and seed yield. The cultivar Hale was planted in May 29, 2007 on plots irrigated by subsurface drip, with tape injected 30 cm below the root zone on 1 meter centers. The trial was arranged in a randomized split block design with three replications. Stance (cyclanilide 22g + mepiquat 88g as/l ), a Bayer Crop Science plant growth regulator used commercially in cotton, was chosen for the treatments. The treatments consisted of four rates, (0, 380ml, 511ml, and 731 ml per hectare), applied with one application at five different growth stages, (6^th node, 8^th node, first flower, 1^st node past flower, and second flower). The data demonstrated highly significant response of castor to the application of the plant growth regulator, resulting in shorter more uniform plants, increased seed set, and higher seed yields. This research will allow farmers to control growth, enhancing mechanical harvest efficiency, and increasing seed yield of castor grown as vegetable oil for feedstock for biofuels.