J Plant Ecol ›› 2023, Vol. 16 ›› Issue (4): rtad004.DOI: 10.1093/jpe/rtad004

• Research Articles •    

Does a tragedy of the commons due to individual competition arise from genetically fixed traits or plastic traits in dryland wheat? An experimental verification

Li Zhu1,2, Jun Xiang1, Da-Yong Zhang3, Wei Wang2, Shuang-Guo Zhu2, Bao-Zhong Wang2, Li-Yuan Yang4, Meng-Ying Li2, You-Cai Xiong2,*   

  1. 1Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization, College of Biology and Agricultural Resources, Huanggang Normal University, Huanggang 438000, China;
    2State Key Laboratory of Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou 730000, China;
    3Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, China;
    4Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, School of Landscape and Architecture, Zhejiang Agricultural and Forestry University, Hangzhou 311300, China
  • Received:2022-07-08 Revised:2022-08-27 Accepted:2023-01-29 Online:2023-02-08 Published:2023-08-01
  • Contact: E-mail: xiongyc@lzu.edu.cn


Abstract: Growth redundancy, the overgrowth of resource-foraging organs in crop stands, is often detrimental to yield and is thus called a ‘tragedy of the commons’. A tragedy can also arise owing to the plastic overproduction of competitive structures when intra-variety individuals forage in close proximity to each other. However, little is known about the sensitivity of crop varieties and resource availability to this ‘plastic’ tragedy. Pot experiments were designed to investigate this issue. The root competition environment was imposed by growing two plants of the same variety in mesh and plastic partitions. Two wheat varieties (old Monkhead and modern 92-46) were used, and two resource levels were established. Compared with 92-46, Monkhead allocated more biomass to stems and leaves and concurrently less to seeds. We identified intra-variety neighbour effects only in 4 out of 24 allometric comparisons with a small magnitude. Allometric data also revealed a lowered response to fertilizer addition in 92-46 than in Monkhead. Based on a limited sample size, our results revealed a trade-off between above-ground vegetative growth and crop yield. This trade-off resulted in a tragedy of the commons in old Monkhead and enhanced yields in modern 92-46. The tragedy of the commons in wheat may generally arise from genetically fixed traits in terms of growth redundancy in old varieties, rather than from the plastic behaviour of individuals. Modern 92-46 may adopt a conservative strategy of resource use, whereas old Monkhead employs an exploitative strategy. Our findings highlight breeders should select genotypes with low individual competitiveness.

Key words: root competition, resource allocation, growth redundancy, tragedy of the commons, trade-off

作物的生长冗余,也就是营养器官的过度生长,常常对作物产量不利,因此被称为作物的‘公地悲剧’。作物品种内相邻植株之间的资源竞争也会导致可塑性的营养器官的过度生长,因此被称为可塑性的公地悲剧。然而,目前有关这种可塑性的公地悲剧如何响应不同作物品种和不同的资源水平的研究较少。本研究设计了盆栽实验来探索这一问题。为设置根系竞争和无竞争两种处理,把同品种两个植株栽种在同一花盆中,分别用尼龙和塑料进行隔离;采用了两个小麦品种(古老品种和尚头和现代品种92- 46),设置了两个资源水平处理。研究结果表明,与92-46相比,和尚头品种把资源更多地分配给茎叶,更少地分配给种子。异速生长数据显示,在24对尼龙隔离和塑料隔离处理的比较中,只有4对显示出程度很小的差异。异速生长数据还显示,相比和尚头品种,92-46品种对增加资源的响应程度更小。基于有限样本大小,本研究揭示了作物地上部分营养生长和繁殖生长之间的权衡关系。正是这种权衡关系,导致了和尚头小麦品种的‘公地悲剧’式生长,同时也使得92-46小麦品种的种子产量得以提升。小麦的公地悲剧更可能是源自遗传性状(比如古老品种的生长冗余),而不太可能是源自植株的可塑性冗余生长。现代小麦品种92-46可能采用了节约型的资源利用方式,而古老品种则采取的是消耗型策略。综上所述,本研究表明育种工作者应当选育个体竞争力低的基因型。

关键词: 根系竞争, 资源分配, 生长冗余, 公地悲剧, 权衡