一年生短命植物疏齿千里光果实异形性的生态学意义

doi:10.3724/SP.J.1258.2011.00663

摘要/Abstract

摘要：

疏齿千里光(Senecio subdentatus)是分布在新疆北部古尔班通古特沙漠中的一种具异形瘦果的菊科一年生短命植物。将野外观测与室内实验相结合, 对该物种异形瘦果的形态、扩散和萌发特性, 以及异形瘦果产量与植株大小的关系进行了研究, 并对其生态学意义进行了探讨。结果表明: 疏齿千里光果序中的外围果和中央果均为柱形, 但前者为淡黄色, 后者为褐色, 且二者在大小、冠毛长度及果皮微形态等方面均存在明显差异。两种瘦果均以单个果实为扩散单元, 且在静止空气中的降落速度和在1 m·s^-1与2 m·s^-1风速下的扩散距离无显著差异, 说明虽然果实大小和冠毛长度对瘦果扩散具有不同的影响, 但对其整体扩散能力无明显影响。在各温变周期(5/2、15/2、20/10、25/15和30/15 ℃)处理中, 淡黄色外围果的萌发率均高于褐色中央果的, 且不同温度间两种瘦果的萌发率均存在显著差异, 但光照条件对其无显著影响。果序中的中央瘦果数明显多于外围果的, 且植株中外围果所占比例与植株大小间呈显著负相关关系, 而中央果所占比例与植株大小间呈显著正相关关系。这些特点说明, 该物种的小植株倾向于产生较多较易萌发的外围果, 大植株倾向于产生较多不易萌发的中央果。在古尔班通古特沙漠不可预测的极端环境中, 疏齿千里光可通过异形瘦果间的萌发差异及调节其不同大小植株中异形瘦果的比例, 来减少同胞后代之间的竞争, 增加其对不同微环境条件的生态适应性。

关键词: 瘦果产量, 一年生短命植物, 扩散, 生态适应, 萌发, 果实异形性, 形态特征, 疏齿千里光

Abstract:

Aims Senecio subdentatus (Asteraceae) is an annual ephemeral in the Gurbantunggut Desert, northern Xinjiang, China. It produces two morphs of achenes in the same infructescence. Our aim was to determine the morphological, dispersal and germination characteristics of the heteromorphic achenes and the relationship between size and yield of plants produced by them.

Methods Shape, size, surface ornamentation (via SEM micrographs), dispersal, germination of the two morphs of achenes, number of peripheral and central achenes per infructescence and per plant and plant biomass were determined in the laboratory. The mode and duration of achene dispersal were measured in the field.

Important findings The peripheral and central achenes are columnar, but they are significantly different in size, color, length of pappus and pericarp micro-morphology. Peripheral achenes are pale yellow and central ones brown. There are no differences in rate of descent in still air or dispersal distance at wind speeds of either 1 or 2 m·s^-1. Therefore, the dispersal ability of the two achene morphs was not significantly affected by achene size or length of pappus. The germination percentages were higher for 1-month old peripheral achenes at 5/2, 15/2, 20/10, 25/15 and 30/15 °C, and there were significant differences among temperatures in both achene morphs. Light did not affect germination significantly. There are more peripheral than central achenes in a capitulum. The proportion of peripheral achenes in an individual was negatively correlated with plant size, while the proportion of central achenes was positively correlated with plant size. This suggests that small plants produce more peripheral achenes with higher germination percentages, while large plants produce more central achenes with lower germination percentages. In the unpredictable environment of the Gurbantunggut Desert, plant size of S. subdentatus is closely related to micro-habitat. This species can reduce competition among siblings and increase adaptive responses to different micro-environmental conditions by making full use of germination differences between peripheral and central achenes and regulating yield of both achenes in different plant sizes.

Key words: achene yield, annual ephemeral, dispersal, ecological adaptations, germination, fruit heteromorphism, morphology characteristics, Senecio subdentatus

吉乃提汗·马木提, 谭敦炎, 成小军. 一年生短命植物疏齿千里光果实异形性的生态学意义. 植物生态学报, 2011, 35(6): 663-671. DOI: 10.3724/SP.J.1258.2011.00663

JANNATHAN Mamut, TAN Dun-Yan, CHENG Xiao-Jun. Ecological significance of fruit heteromorphism in the annual ephemeral Senecio subdentatus. Chinese Journal of Plant Ecology, 2011, 35(6): 663-671. DOI: 10.3724/SP.J.1258.2011.00663

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链接本文: https://www.plant-ecology.com/CN/10.3724/SP.J.1258.2011.00663

https://www.plant-ecology.com/CN/Y2011/V35/I6/663

图/表 4

图1 疏齿千里光外围果和中央果的形态与微形态特征(A, C, 外围果。B, D, 中央果)。

Fig. 1 Morphology and micrographs of peripheral and central achenes of Senecio subdentatus. A, C, peripheral achenes. B, D, central achenes.

表1 疏齿千里光外围果和中央果的形态和大小(平均值±标准误差)

Table 1 Morphology and size of peripheral and central achenes of Senecio subdentatus (mean ± SE)

观测指标 Parameter	外围果 Peripheral achenes	中央果 Central achenes	F	p
形状 Shape	柱形, 近直立 Columnar and approximately straight	柱形, 近直立 Columnar and approximately straight	-	-
颜色 Colour	淡黄色 Pale yellow	褐色 Brown	-	-
果体长 Length of achene (mm)	5.36 ± 0.08^a	4.99 ± 0.09^b	10.05	< 0.01
果体宽 Width of achene (mm)	0.39 ± 0.01^a	0.31 ± 0.01^b	22.73	< 0.01
冠毛数量(个) No. of pappi	175.80 ± 5.53^a	164.80 ± 4.31^a	10.66	0.12
冠毛长 Length of pappi (mm)	5.26 ± 0.16^a	4.67 ± 0.05^b	14.60	< 0.01
果实百粒重 Mass per 100 achenes (mg)	0.44 ± 0.00^a	0.38 ± 0.00^b	27.95	< 0.01
胚百粒重 Mass per 100 embryos (mg)	0.19 ± 0.00^a	0.18 ± 0.00^a	0.19	0.67

图2 在不同温度和光照下室内干藏1个月的疏齿千里光外围果和中央果的萌发率(平均值±标准误差)。同一温度下的不同字母表示差异显著(p < 0.05)。

Fig. 2 Germination of one month dry-stored peripheral and central achenes of Senecio subdentatus at different temperatures in light (12-h photoperiod) and in darkness (mean ± SE). Different letters at the same temperature indicate significant differences (p < 0.05).

图3 疏齿千里光植株大小与外围果和中央果产量的相关关系。

Fig. 3 Relationships between plant size and yield of peripheral and central achenes of Senecio subdentatus.

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