At Prosper, Prowl 3.3 EC (pendimethalin) was preplant applied and incorporated on 3 May 2001 at 1.5 quarts/acre (1.25 lbs a.i./acre). The soil type was a Houston Black Clay with pH 8.1. Fourteen soybean cultivars were planted on 16 May 2001. The cultivars were selected because their upper leaves varied in size. The objective of the study was to determine whether leaf size was related to a cultivar’s response to row spacing. Plots were 20 feet long and 12 rows wide using 14-inch rows and 6 rows wide using 28-inch rows. Prowl 3.3 EC, was the only pesticide applied. Poast (at 1.5 pt per acre) and Asana XL at 0.5 pint/acre was applied on 6 July due to grass and grasshopper pressure, respectively. Rain was plentiful through June 30, but there was little rain in July. By mid August, the weather was unseasonably cool and wet and it remained that way through September. Plots were end trimmed to 10 feet just prior to harvest. The four center rows of each 14-inch row plot and the two center rows of each 28-inch row plot were harvested using a mechanical plot harvester. Yield was determined by obtaining seed moisture and adjusting weights to 13% moisture. No clear relationship between leaf size and response to tow spacing was found. The 28-inch rows tended to outyield the 14-inch rows.

Please see results page.

Leaf Morphology-by-Row Spacing Study – Dallas, TX 2001 (planted 16 May 2001).

R8 dap = days after planting when crop was mature. The row spacing and interaction effects on maturity were not significant. Therefore, maturity dates are averaged across row spacing.

Acknowledgements:

We thank the seed companies for supplying the seed, Lipha Tech, Inc. for supplying the Cell-Tech 2000 inoculant, and the Texas Soybean Board for funding the project.