两种互逆资源梯度影响下刺叶锦鸡儿的种子选择性败育格局

种子的选择性败育在被子植物中普遍存在，开展结籽格局及其影响因素的研究有助于深入了解种子的形成机制及多样化的生殖对策。以刺叶锦鸡儿Caragana acanthophylla为材料，通过传粉过程、胚珠发育动态和资源分配状况的研究，以探讨种子的选择性败育格局及相关影响因素。结果显示：(1)刺叶锦鸡儿具高度自交不亲和性，为泛化的传粉系统，蜂类是主要的传粉者。自然状态的结实率为(86.00±4.96)%,不存在传粉限制，但受精具明显的时间效应。(2)刺叶锦鸡儿单花期4—5d,每朵花有(14.00±0.14)粒胚珠。胚珠的发育从荚果顶部开始，其中，开花后第3天荚果顶部胚珠开始膨大；第11天绝大多数胚珠出现了膨大，此时，在荚果基部的胚珠开始败育，随后荚果顶端受精后的胚珠也出现败育，最终仅荚果中部形成2—3粒种子。其结籽格局为成熟荚果中部胚珠，而败育荚果顶部和基部胚珠的选择性败育类型。(3)受微地形影响，居群内开花植株具斑块分布，对较少开花植株通过添加水肥进行资源调控后，结籽率显著提高，说明在种子形成过程中存在资源限制。综上所述，受精顺序和资源限制两个互逆的资源梯度决定了刺叶锦鸡儿的结籽格局。其中，...

Seed selective abortion pattern under the influence of two reciprocal resource gradients in Caragana acanthophylla

The selective seed abortion (SSA) universally exists in angiosperm plants. It is helpful to understand the formation mechanism of SSA and various reproductive strategies for analyzing the seed setting pattern and its influencing factors. To explore the pattern of SSA and related influencing factors, we carried out studies on pollination process, dynamics of ovule development and resource allocation in Caragana acanthophylla. The results showed that:(1) Caragana acanthophylla had a mating system of obligate outcrossing due to the highly self-incompatibility, in which the main pollinators were bees with a general pollination system. There were no pollination limitations in the pollen source and pollination intensity with a natural fruit setting of (86.00±4.96)%. But there were significant timing effects in fertilization. (2) Caragana acanthophylla had (14.00±0.14) ovules per flower, and individual flower remained open for 4-5 days. Seed development started from the top of the pod, and the ovules at the top the of pod began to expand on the 3rd day after flowering. On the 11th day, most of ovules were enlarged. At the same time, those ovules at the base of the pod become aborted, and then ovules fertilized at the top of the pod were aborted. Finally, only 2-3 seeds were formed in the middle of the pod. It was a seed setting pattern of selective abortion type in Caragana acanthophylla, in which ovules in the middle of the pod were matured preferentially and ovules at the top and base of the pod were aborted firstly. (3) The flowering plants in the population had a patchy distribution, in which some plants had many flowers, while others had a few flowers due to the influence of microtopography. Seed setting rate was significantly increased when the resources were regulated by applying water and fertilizer for a few flowering plants. It indicated that there were resource limitations in the process of seed formation. In conclusion, the seed setting pattern was determined by resource allocation of two reciprocal gradients:fertilization order and resource limitations in Caragana acanthophylla, in which the time gradient of fertilization led to the first abortion of ovulesat the basal, while the position effect of resource allocation led to the abortion of ovules fertilized at the top of the pod. The middle ovules had a better development due to the location of intersection of two resources transportation, in which it was a tradeoff of fertilization time and location effect of resource allocation.