Stigma receptivity and anther dehiscence in ornamental pepper

ABSTRACT The objective of this study was to evaluate stigma receptivity and anther dehiscence in three floral development stages in F3 population of ornamental pepper (Capsicum annuum). A total of 162 plants (81 of purple corolla and 81 of white corolla) were used in this study. To analyze the stigma receptivity and anther dehiscence, three floral stages were analyzed: bud, pre-anthesis, and open flower. For each stage, 33 flowers of each phenotypic class were collected. The receptivity of the stigma was detected by dripping hydrogen peroxide solution (3%). For the evaluation of the level of receptivity, scores of 0 to 3 were assigned, varying according to the bubbles percentage found on the stigmatic surface. Scores of 1 to 5 were assigned for the reference of the amount of pollen released by the stamens. The data were subjected to analysis of variance (p≤0.05) following a 2x3 factorial scheme: two classes of flower colors and three development stages, with 33 replicates (flowers) with later separation of means by Tukey’s test at the same probability level. For the analysis of divergence, the data were clustered according to Tocher’s method based on generalized Mahalanobis distance. Despite the not significant differences between the means for pollen dehiscence of both flower colors, the purple flowers presented higher stigma receptivity than the white ones. The ornamental pepper flowers displayed stigma receptivity since the bud phase, but the highest level of receptivity was observed after anthesis. Anther dehiscence prevailed after anthesis of the flowers regardless of color, and the presence of pollen grains was superior after anthesis. For the manual crossing, the buds at pre-anthesis phase are the most indicated irrespective of the color, as they show high stigma receptivity and greater ease at handling.

摘要 本研究旨在评估观赏辣椒（Capsicum annuum）F3群体三个花发育阶段的柱头可授性与花药开裂情况。本研究共纳入162株植株，其中紫花冠与白花冠类型各81株。为分析柱头可授性与花药开裂情况，本研究选取三个花发育阶段：花蕾期、开花前期与盛开期。每个阶段中，每种表型类别的33朵花被采集。通过滴加3%过氧化氢溶液检测柱头可授性：根据柱头表面气泡占比，将可授性等级赋值为0至3分；依据雄蕊释放的花粉量参考标准，将花粉释放量赋值为1至5分。数据采用2×3因子设计（两种花冠颜色与三个发育阶段）进行方差分析（p≤0.05），每组设置33次重复（花朵样本），后续采用Tukey检验在同一显著性水平下进行均值多重比较。对于群体分化分析，基于广义马氏距离采用Tocher聚类法进行样本聚类。尽管两种花冠颜色的花粉开裂均值无显著差异，但紫花冠植株的柱头可授性高于白花冠植株。观赏辣椒的花自花蕾期即具备柱头可授性，但可授性最高水平出现在开花后。无论花冠颜色如何，花药开裂均在花开放后占主导，且开花后花粉粒检出量更高。对于人工杂交实验而言，无论花冠颜色如何，开花前期的花蕾均为最适宜的材料，因其具备较高的柱头可授性且操作难度更低。