Chromosomal analysis of photosynthesis rate and stomatal conductance and their relationships with grain yield in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) under water-stressed and well-watered conditions

A series of substitution lines of variety ‘Timstein’ (Tim) into genetic background of Chinese Spring (CS) were used in this study. Analysis of variance indicated that significant differences exist among the substitution lines for all the traits under study except stomatal width (SW) in the water-stressed condition and stomatal length, and photosynthesis rate (PR) in the well-watered experiment. Correlation analysis indicated that PR and stomatal conductance (SC) were most important in affecting yield under the both experiments. Chromosomal analysis indicated that grain weight was affected by many chromosomes as it was expected due to its complexity under both well-watered and water-stressed conditions. In well-watered experiment, no substitution line was significantly different from recipient variety for PR. Despite results in well-watered experiment, chromosomes 3A, 3B, 4B, and 3D from variety Timestin increased PR when substituted into variety CS under the water-stressed experiment. In well-watered experiment, chromosome 7D of variety Timetin had the main effect on increasing SC, and chromosome 1A had a diverse effect on this character when substituted into recipient variety. However chromosomes 3A, 3B, 4B, and 1D of Timestin increased SC under water-stressed conditions. It was also revealed that in general the chromosomes expressed their independent effects on the characters regardless of environment. Nonetheless, some chromosomes indicated similar effects under the two conditions. Among them, chromosome 1A of Timestin reduced yield, chromosomes 2B, 7B, and 5D increased the amount of grain yield, and chromosome 1D increased SC under both conditions.