Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, and State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, 650504, Yunnan, China.
Key Laboratory of Grassland Ecosystem of Ministry of Education, and Sino-U.S. Centers for Grazingland Ecosystem Sustainability, College of Grassland Science, Gansu Agricultural University, Lanzhou, 730070, China.
Am J Bot. 2022 Jul;109(7):1191-1202. doi: 10.1002/ajb2.16001. Epub 2022 Jun 25.
Spatial and temporal resource allocations within inflorescences have been well-studied in many plants based on flowering sequence or floral position. However, there had been few attempts to investigate architectural effects and resource competition in species where the blooming pattern does not follow a linear positional pattern within the inflorescence. Moreover, most flowering plants show female-biased sex allocation in early or basal flowers, but it is unclear in species with inherent and changeless ovule production.
We investigated intra-inflorescence variation in reproductive traits of Salvia przewalskii, a perennial herb with 4-ouvle ovary flowers and flowering sequence-floral position decoupled inflorescences. To detect the effects of resource competition and architectural effects on reproductive success, we manipulated inflorescence (removed floral buds by position and flowering sequence) and pollination (opened and supplemented pollination).
Pollen production and dry mass deceased from bottom to top flowers but did not significantly differ following flowering sequence, resulting in male-biased sex allocation in basal flowers. The seed production, fruit set, and bud development exhibited significant declining trends from proximal to distal positions regardless of the thinning and pollen treatments. Meanwhile, the seed production, fruit set, and bud development success did not significant differ when thinning was conducted according to flowering sequence.
Architectural effects plays a crucial role in resource allocation within decoupled flowering inflorescences. Moreover, our results highlighted that inherent floral traits such as changeless ovule production, may modify architectural effects on sex allocation.
在许多植物中，基于开花顺序或花位，已经很好地研究了花序内的空间和时间资源分配。然而，在开花模式不符合花序内线性位置模式的物种中，很少有尝试研究建筑效果和资源竞争的情况。此外，大多数开花植物在早期或基部花朵中表现出雌性偏爱的性别分配，但在具有固有且不变的胚珠产量的物种中，情况尚不清楚。
我们调查了多年生草本植物鼠尾草的花序内生殖特征的变化，该植物具有 4 个胚珠的子房花和与开花顺序-花位解耦的花序。为了检测资源竞争和建筑效果对生殖成功的影响，我们操纵了花序（按位置和开花顺序去除花芽）和授粉（打开和补充授粉）。
花粉产量和干物质从下到上的花朵减少，但开花顺序后没有显著差异，导致基部花朵中出现雄性偏爱的性别分配。种子产量、结实率和芽发育无论变薄和花粉处理与否，从近端到远端位置都呈现出显著的下降趋势。同时，当根据开花顺序进行变薄处理时，种子产量、结实率和芽发育成功率没有显著差异。
建筑效果在解耦开花花序内的资源分配中起着至关重要的作用。此外，我们的结果强调了固有花的特征，如花序不变的胚珠产量，可能会改变建筑效果对性别分配的影响。
