Mena-Alí Jorge I, Rocha Oscar J
Escuela de Biología, Universidad de Costa Rica, Ciudad Universitaria Rodrigo Facio, San José, Costa Rica.
Ann Bot. 2005 Feb;95(3):449-55. doi: 10.1093/aob/mci044. Epub 2004 Dec 13.
It has been claimed that ovules linearly ordered within a fruit differ in their probabilities of reaching maturity. This was investigated by studying the effect the position of an ovule within the pod has on seed abortion and seed production in Bauhinia ungulata.
Fruits collected during the dry seasons of 1999, 2000 and 2001 were opened, and the number, position and status of each ovule within the fruit were recorded. A GLM model was used to assess the effects of population, tree identity and ovule position within the pod on ovule fertilization, seed abortion, seed damage and seed maturation in two populations of B. ungulata.
Nearly 30% of the ovules were not fertilized in 1999; this percentage dropped to 5% the following two years. Seed abortion (50%) and seed damage (15%) were the same every year during the study period. Only 15% of the initial ovules developed into mature seeds in 1999; this value increased to 35% in 2000 and 2001. However, seed survivorship was dependent on the position of the ovule within the pod; non-fertilized and early aborted ovules were found more often near the basal end of the ovary. The frequency of seed damage was not affected by position. Mature seeds were found mainly in the stylar half of fruits, where ovules are likely to be fertilized by fast pollen tubes.
The pattern of seed production in B. ungulata is non-random but is dependent upon the position of the ovule within the pod. The results suggest that the seeds produced within a fruit might differ in their vigour.
有人声称，果实内呈线性排列的胚珠达到成熟的概率不同。通过研究紫荆属植物中胚珠在豆荚内的位置对种子败育和种子产量的影响，对此进行了调查。
打开1999年、2000年和2001年旱季收集的果实，记录果实内每个胚珠的数量、位置和状态。使用广义线性模型（GLM）评估两个紫荆属植物种群中种群、树的个体身份以及胚珠在豆荚内的位置对胚珠受精、种子败育、种子损伤和种子成熟的影响。
1999年近30%的胚珠未受精；接下来的两年中这一比例降至5%。在研究期间，每年的种子败育率（50%）和种子损伤率（15%）相同。1999年只有15%的初始胚珠发育成成熟种子；2000年和2001年这一数值增加到35%。然而，种子的存活率取决于胚珠在豆荚内的位置；未受精和早期败育的胚珠更多地出现在子房基部附近。种子损伤的频率不受位置影响。成熟种子主要出现在果实花柱端的一半，胚珠可能在此处被快速生长的花粉管受精。
紫荆属植物的种子生产模式并非随机，而是取决于胚珠在豆荚内的位置。结果表明，果实内产生的种子在活力上可能存在差异。
