Fig. 3. Associations between yield and ¹³C among wheat breeding lines grown under rain-fed conditions at Condobolin, eastern Australia, in 1992 and 1993. The breeding lines were F₆ (1992) and F₇ (1993) progeny of two crosses between parents with low and high values of ¹³C (Rosella x Matong and Quarrion x Cranbrook). The values of ¹³C plotted are genotype means for leaf material of F₅ lines sampled early in the 1991 season when there was no water stress. Least-squares linear fits are plotted where correlation coefficients were statistically significant (P < 0.05, n = 30). Among the lines within each cross there was only small variation for either flowering date or height but lines from the Rosella x Matong cross on average flowered one week later than the lines from the Quarrion x Cranbrook cross. (Adapted from Condon and Hall, 1997.)