Data from all traits were analyzed to detect the effects of intermating cycles and crosses for all of the yield components evaluated. The combined analysis of all crosses demonstrated a significant effect on most variables for all traits. A representative example of this analysis is shown in Table 2 for mean pod rating at S2 and S3 (ANOVA tables for all other traits can be found in Appendix 1).
A bivariate scatter plot shows the relationship between the five traits for all crosses combined (Fig. 4). As expected, yield has a linear positive correlation with and pod number (r = 0.85) (Fig. 4 d) and seeds per pod (r = 0.80) (Fig. 4 j) (Table 3). A negative correlation was found for seeds per pod and thousand seed weight (r = -0.25). The calculated correlation values between pod rating and the other traits was negative because the pod rating scale goes from 1 – 9 where one represents a plant with the best pods and 9 a represents a sterile plant (in contrast to all the other traits in which a higher number indicated a better performing plant). Pod rating exhibited a positive relationship with yield (r = -0.43) (Fig. 4 f) and seeds per pod (r = -0.44) (Fig. 4 i).
Regarding cycles of selfing, differences were found between the two greenhouse experiments (S2 and S3). In the S3 generation, the means for pod number, yield and seeds per pod for all three cycles were higher compared to the S2 generation (Table 4).
Highlights of the significant intermating effects for both experiments and each cross are presented for each trait individually (Table 5). Cross three had significant effects for the intermating cycles in all traits and both experiments; thus, cross three will be used to illustrate results for most traits. Data for all other crosses can be found in appendix 2.
The analysis of the complete data set showed the largest mean pod number among all intermating cycles at C0S2 (Table 4). Mean pod number was the highest among all intermating cycles after the first cycle of full-sib intermating (C1) in three of the five crosses evaluated at S2 (Table 5). In the second experiment (S3), cross 3 showed a larger mean pod number at C2. An evaluation of the individual number of families with improved mean pod number when compared to the best parent showed 7 improved families at C1S2 and no significant improvements between cycles at S3 except for C1 in cross 2 (Table 6). Data for the individual families at each intermating cycle in both experiments is shown in Table 7.
During analyses of the entire data set, no significant differences were found between the intermating cycles in either experiment for pod rating (Table 4). Differences in the overall mean pod rating were found in three of the five crosses at S2 and one cross in S3 (Table 5). At S2, cycles 0 and 1 had the best mean pod rating scores. In contrast at S3, cross 3 showed an improvement in pod rating when compared to the best parent after two full-sib intermating cycles (C2). Cross 5 included a parent with the worst field rating score (Table 1). However, a significant improvement was found at S2 after one cycle of full-sib intermating (C1) and at S3 after one intermating cycle (C0) (Table 5). Comparison of the mean pod rating for the individual families in cross 5 showed a similar trend with the improvement of one out of 12 families at S2 after one cycle of full-sib intermating and 5 families out of 12 when compared to the best parent at C0S3 (Table 8).
Thousand seed weight
The analysis of the complete data set showed the largest mean TSW among all intermating cycles at C0S2 (Table 4). Cross 1 had a higher mean thousand seed weight at S2 after one cycle of full-sib intermating (C1) (Table 5). No significant mean TSW differences were found in the other four crosses for any intermating cycles in either experiment (Table 5). For cross 5, C2 had the highest number of improved families (5/12) at S2. The same number of improved families (2/12) was observed in C0 and C1 at S3 (Table 9).
Seeds per pod
No significant differences for SPP were found between the intermating cycles on either experiment when analyzing the total data set (Table 4). The cycle means for SPP showed one cycle of full-sib intermating (C1) was better than the other intermating cycles for 2 of the 5 crosses at S2 (Table 5). When comparing the means of individual families in every cycle at S2, only C1 and C2 had an improved number of seeds per pod when compared to the best parent (Table 10). No significant differences were found for the overall cycle means or the number of improved families when compared to the best parent at S3 (Table 10).
The analysis of the complete data set showed the highest mean yield among all intermating cycles at C0S2 (Table 4). Mean yield was highest following the initial intermating cycle (C0) for crosses 1 and 2. Cross 2 showed an improved mean yield of 1.09 g. while the best parent had a mean yield of 0.77 g. in S2 (Table 5). Crosses 3 and 5 exhibited higher mean yield at C1. The cycle with the highest number of improved families from all crosses was C0 at S2 (Table 11). The largest number of improved families for a single cross was found at C1S2 for cross 3. Data for the individual families of cross 3 at each intermating cycle in both experiments is shown in Table 12.
Improvement of individual families
Two of the crosses with the greatest improvements were crosses three and five. At least one of the twelve families from each of these crosses showed an increase of >36 % in pod number and yield when compared to the best parent after one cycle of full-sib intermating (C1S2) (Table 13).