RESPONSE OF NONIRRIGATED MATURITY GROUP-V DETERMINATE SOYBEAN TO END-TRIMMING

Obtaining accurate seed yield information from soybean [Glycine max (L .) Merr.] field research environments and concurrently conserving valu able held space is desirable. The purpose of this study was to determi ne the effect of plot length and alley width on the response of short- and tall-statured Maturity Group (MG) V soybean cultivars to end-trimm ing after maturity. Experiments were conducted in 1995 and 1996 at the Delta Research and Extension Center at Stoneville, MS, (lat. 33 degre es 26').'Hutcheson' (relatively short stature) and 'DP 3589' in 1995 a nd 'DP 3588' in 1996 (both relatively tall stature) were planted on 9 May 1995 and 15 May 1996. Treatments were plot length (6.10 or 15.25 m ), alley width (0.90 or 2.45 m), and end-trim length (0, 0.45, or 0.90 m). Average height of Hutcheson at maturity was 52 cm in 1995 and 55 cm in 1996, while average height of DP 3589 in 1995 and DP 3588 in 199 6 was 88 cm. All cultivars responded similarly in yield to all factors in this experiment. End-trim length was the only factor that signific antly affected average yield. Not end-trimming resulted in an average yield of 2573 kg ha(-1) while end-trimming either 0.45 or 0.90 m resul ted in average yields that were nearly identical (2356 and 2337 kg ha( -1) respectively). Contrary to our hypothesis, increasing plot length from 6.10 to 15.25 m and decreasing alley width from 2.45 to 0.90 m di d not negate the end-of-plot effect on yield of soybean grown in nonir rigated field plots. These results indicate that soybean grown in plot s with row lengths and alley widths that are within the confines of th e dimensions used in our experiment should be end-trimmed to eliminate end-of-plot effects. Also, field space can be conserved by using the 6.1-m plot length and the 0.90-m alley width.