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Seed Ecology on Ephemeral Lachnoloma Lehmannii (Brassicaceae)

Author: JiNaiTiHan·MaMuTi
Tutor: TanDunYan
School: Xinjiang Agricultural University
Course: Botany
Keywords: Lachnoloma lehmannii fruit morphology dispersal settlement seed dormancy seed germination salinity Jungger desert
CLC: Q948
Type: Master's thesis
Year: 2011
Downloads: 56
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Abstract

Lachnoloma lehmannii is an annual ephemeral in Brassicaceae species and distributed in salinity desert of the northern Junggar Basin of Xinjiang Province. Fruits of this species are ovoid indehiscent silicles with a thick and hard pericarp, which is cowered densely trichomes, and intact silicles are the dispersal units. In this paper, effect of the fruit morphology on dispersal, settlement and seed germination, also, dormancy and germination characteristics, tolerance to salinity of this species were studied manipulatively both in field and laboratory, and the ecological adaptive strategies of this species in the harsh environment of Jungaer desert were analyzed. The main results are as follows:(1)Silicles of Lachnoloma lehmannii are ovoid,5.05±0.15 mm in length and 3.13±0.04 mm in width. The pericarps of fruits are pale yellow and have muddy white trichomes. In field, fruits were began to disperse on Mid-June by wind after matured, the duration time of dispersal was approximately one month; The dispersal ability of three kinds of dispores after treatment were intact fruits> fruits without trichomes >seeds. The intact fruits were afloat for longer than fruits without trichomes and seeds on the water. This suggests that the pericarp and trichomes not only had enhanced the dispersal ability of fruit by wind, but also promote the dispersal by water.(2)Intact fruits have a batter adherence ability to soil particles, the fruits with trichomes and pericarp can more easily settelment on soil via increasing fruit mass than fruits without trichomes and seeds. MC of seeds of from intact fruits was slowly rised and decreased than seeds from fruits without trichomes and seeds during the imbibition and dehydration, which indicating that trichomes and pericarp of intact fruits has batter keep-water ability on seed. Date from test seed viability of three kinds of dispores indicated that pericarp take adventage in keep seed viability under high temperature conditions. Seeds from intact fruits and fruits without trichomes were do not germinate optimal temperature (15/2℃) in light (12-h daily photoperiod), however, removing the fruit coats was significantly improved the germination percentage to 90.0% from 0.0%, which indicating that the pericarp had mechanically inhibited seed germination. Also, the germination of seeds in other treatments at the same conditions were> 60.0%, but which are lower than seeds without fruit coat, suggesting that water-soluble germination inhibitors were leached from pericarp and trichomes.(3)Fresh seeds had non-deep physiological dormancy and needed dry storage and GA3 treatments to break dormancy. Germination percentage affected significantly by light, temperature, and their interactions.Seed was do not germinated in high concentration of PEG, however, some non-germinable seeds germinated after redydration, suggesting that drought stress inhibited seed germination.(4)Salinity inhibited seed germination, seedling growth and development. Seed germination decreased with the increase of salinity, low concentration of NaCl induce secondary dormancy, hawever, high concentration of NaCl coused lost viability of some seeds. Seedling survival significantly decreased with increased concentration of NaCl, height of seedlings, fruit/seed-set, biomass, and root/shoot ratio inhibited significantly by salinity. In seedling stage, NaCl concentration>150 mmol·L-1 could not grow, but in the development stage, the plant was still survive and set some fruits when NaCl concentration reached 200 mmol·L-1, suggesting that tolerance to salinity was estimated at various life stages. The seedling growth can endure at lower salinity than developing and germination stages.The fruit morphology has an effect on dispersal, settlement, and seed germination. Dormancy/germination characteristics and response to salinity have significant ecological consequences in seedling development, good to successful establishment and population expansion of species in Jungger desert.

Seed Ecology on Ephemeral Lachnoloma Lehmannii (Brassicaceae)

Abstract

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