Journal of Resources and Ecology ›› 2022, Vol. 13 ›› Issue (2): 319-327.DOI: 10.5814/j.issn.1674-764x.2022.02.014

• Soil and Agriculture-Forest Ecosystem • Previous Articles     Next Articles

Seed and Fruiting Phenology Plasticity and Offspring Seed Germination Rate in Two Asteraceae Herbs Growing in Karst Soils with Varying Thickness and Water Availability

LIU Junting1,2(), LI Suhui1,2, SONG Haiyan1,2, LEI Ying1,2, CHEN Jinyi1,2, WANG Jiamin1,2, GUO Xuman1,2, LIU Jinchun1,2,*()   

  1. 1. Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing 400715, China
    2. Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
  • Received:2021-03-24 Accepted:2021-10-19 Online:2022-03-30 Published:2022-03-09
  • Contact: LIU Jinchun
  • About author:LIU Junting, E-mail: 1109547757@qq.com
  • Supported by:
    The Chongqing Natural Science Foundation(cstc2020jcyj-msxmX0244);The Special Funds for Basic Scientific Research in Central Universities(XDJK2020B037);The National Natural Science Foundation of China(31500399)

Abstract:

Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions. Annual herbs are pioneers adapted to these areas; however, little is known about the responses of their seeds and infructescence, and the germination of their offspring to these limited water and soil resources. In this study, we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs (Xanthium sibiricum and Bidens pilosa) respond to the harsh karst soil environment, by assessing the seed number, seed biomass and offspring seed germination rate. X. sibiricum and B. pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design. The key results were as follows: (1) The number and biomass of progenies (infructescence and seeds) of X. sibiricum decreased with the decline of soil thickness and/or water availability (P <0.05). The infructescence and seed biomass of B. pilosa increased with the decline of water availability. (2) Seed quantity and seed biomass of X. sibiricum showed no correlation after their parents experienced resource reductions. A significant positive relationship between seed number and seed biomass was observed in B. pilosa (P <0.05). (3) The offspring seed germination rate of X. sibiricum did not change with the decrease of soil thickness under three levels of water treatment. However, the offspring seed germination rate of B. pilosa decreased significantly with the decrease of soil thickness under the control water level (P<0.05). The results show that X. sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats. In contrast, B. pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy. B. pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment, but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.

Key words: karst drought, shallow soil, seed number, parental environment, seed biomass