Effects of parent species type, flower color, and stamen petaloidy on the fruit-setting rate of hybridization and selfing in lotus (Nelumbo)

Abstract Understanding the relationship of fruit-setting rate (FSR) with species type, flower color, and stamen petaloidy (tepal number) of the parents in the crossing and selfing of lotus (Nelumbo) can improve breeding efficiency. In this study, 193 artificial crosses with 1.932 flowers and selfing (artificial and non-interference selfing) with 1.120 flowers were carried out in 218 lotus accessions. There were no differences in the cross FSR between Asian lotus (Nelumbo nucifera) and American lotus (N. lutea), but both of their cross FSRs were significantly higher than that (7.9 %) of Asian-American hybrids. The selfing FSRs were highest in American lotus, followed by Asian lotus and Asian-American hybrids. Regardless of whether they were used as the female or male parents in crosses, lotus accessions with pink tepals had higher FSRs than those with white tepals. While the yellow-flowered American lotus obtained the highest FSRs among all flower colors in both of selfing. As the tepal number increased, the FSRs of cross and artificial selfing did not continuously decrease. Cultivars with 91–120 tepals had the highest cross FSR in the double-tepalled lotus, regardless of whether they were used as the male or female parents. Therefore, the cross and selfing FSRs of lotus were associated with parent species type, flower color, and stamen petaloidy. Generally, the results of this study provide useful insights into parent selection, cross design, and sample sizes for reducing costs and improving efficiency in lotus breeding.