Table_1_Variability of Flowering Sex and Its Effect on Agronomic Trait Expression in White Guinea Yam.DOCX

White Guinea yam (Dioscorea rotundata) is mainly a dioecious tuberous crop that produces flowers of varying sex phenotypes. Agronomic traits in Guinea yam differ according to the sex phenotype, but the precise interaction between the traits and sex phenotype is not clearly understood. This might be due to the high heterozygosity of yam where cultivars with different flowering sex have different genetic backgrounds, which mask the sole effect of sex phenotype on the agronomic traits. This study used F1-derived clonal progenies from a bi-parental cross to minimize the impact of different genetic backgrounds among the plants with different sex phenotypes. The impact of plant sex on agronomic traits, specifically tuber yield, was evaluated through field trials conducted for four years. The results showed that only plants with a female genotype exhibited varying sex phenotypes even within the clones of same accession grown in the same experimental field. The significant effects of sex genotype and phenotype on agronomic traits were detected. Our results revealed that the flowering date was delayed in the plants with female genotypes compared to male genotypes, even when compared only among the plants with male phenotypes. The flowering date is the most important reason for the sexual differences in tuber yield. A high tuber yield was obtained when plants with the female phenotype flowered before tuber enlargement. This result can be attributed to the fact that the low flowering intensity in female plants increases the availability of carbon resources for leaf development. Female plants also showed a large negative effect of late flowering on tuber yield owing to resource competition between flowering and tuber enlargement. These findings demonstrate the feasibility of yield improvement by controlling the flowering time, with a higher effectiveness achieved in female than in male plants.

白几内亚薯蓣（Dioscorea rotundata）为雌雄异株型块根作物，其花序具有多样化的性别表型。几内亚薯蓣的农艺性状随性别表型的不同而存在差异，但农艺性状与性别表型间的确切互作机制尚未明确。这一现象可能源于薯蓣极高的基因组杂合性：不同开花性别的栽培品种具有各异的遗传背景，这会掩盖性别表型对农艺性状的独立效应。本研究采用双亲杂交获得的F1代无性克隆株系，以尽可能消除不同性别表型植株间遗传背景差异带来的影响。通过为期四年的田间试验，本研究评估了植株性别对农艺性状（尤其是块根产量）的影响。结果显示，仅携带雌性基因型的植株，即便在同一试验田种植的同一无性系株系中，仍表现出多样化的性别表型。本研究检测到性别基因型与性别表型均对农艺性状存在显著效应。研究发现，即便仅在雄性表型植株中进行比较，携带雌性基因型的植株开花日期也晚于雄性基因型植株。开花日期是导致块根产量出现性别差异的最关键因素。当雌性表型植株在块根膨大期前完成开花时，可获得较高的块根产量。该结果可归因于：雌性植株较低的开花强度提升了可用于叶片发育的碳资源供应量。此外，雌性植株若开花过晚，会因开花过程与块根膨大期之间的资源竞争，对块根产量产生显著的负向影响。上述研究结果证实，通过调控开花时间可实现产量提升，且该策略在雌性植株中的实施效果优于雄性植株。