The superior yielding ability of PSC 355 has been demonstrated by head-to-head comparisons with 1998 and 1999 university data from Texas to North Carolina. Sustained superior performance over a range of environments is essential to the success of a new variety. The summer of 2000 in the Mid-South provided a stressful environment for the evaluation of varieties for yield stability. The average daily high from July 1 to Sept. 8 was 5.4 ^o F higher than normal and only 0.72” of rain fell during this entire period. Six checks from Phytogen’s AST were compared at four irrigated and four dryland locations in the Mid-south. DP Pearl was the highest yielding variety when averaged over both the irrigated (1253 #/acre) and the dryland (858 #/acre) locations, but PSC 355 was not statistically different from it with 1208 and 836 #/acre, respectively. DP Pearl had the highest yield at the highest yielding irrigated locations of Leland, MS and Crowville, LA. PSC 355 was the highest yielding check at St. Joseph, LA, Marianna, AR, and at Brownsville, TN.

Differential plant mapping reflected that DP 388 produced slightly more bolls on the bottom nodes and fewer bolls on the middle and top nodes than did PSC 355. The trend for SG 747 was similar. The differential boll distribution of ST 474 and FM 958 was opposite that of DP 388 and SG 747 with fewer bottom and slightly more middle and top bolls than PSC 355. The boll distribution for DP Pearl was similar to that for FM 958, but the magnitude of the difference from PSC 355 was greater. These differences were reflected in the analysis of map index with DP 388 having the highest and DP Pearl having the lowest map index means over locations. These mapping data suggest that ST 474 and FM 958 were slightly later than PSC 355 and that DP Pearl was significantly later maturing than PSC 355. The slight yield advantage observed for DP Pearl over PSC 355 in 2000 would probably be reversed in a more normal year in the Mid-south with fewer accumulated heat units.