Yield stability differences among sweetpotato genotypes under field and controlled environments

Two studies were conducted in 1995 and 1996 in the field and under controll ed environments to test the yield and dry matter (DM) content stability of selected sweetpotato genotypes. In the field study, initial screenings of o ver 300 genotypes were conducted. Six genotypes were selected and further t ested under a controlled environment for their adaptability in the Tuskegee University Nutrient Film Technique system for inclusion in crop production for long-duration space missions. In both studies, plants were grown for 1 20 days. Data collected over the two-year period were combined and comparis ons of genotype performance were done between the two growing conditions. R egression analysis on overall mean for the two environments showed that yie ld for the six selected genotypes were highest when plants were grown under field conditions. For all six genotypes, there were differences shown in y ield performance when they were grown in the greenhouse or under the contro lled environment. There was a significant interaction between environment a nd genotypes for root yield while DM accumulation was independent of enviro nment. Yield stability analysis indicated that lower-yielding genotypes reg ress closer to unity than higher-yielding genotypes, while variance due to deviations from regression was closest to zero for genotypes whose mean yie lds were closest to the grand mean.