Influence of Root System Characteristics on Black Spruce Seedling Responses to Limiting Conditions.

Clémentine Pernot,Nelson Thiffault,Annie Desrochers

doi:10.3390/plants8030070

Abstract

Roots directly affect planted seedling adaptation to new growing conditions at reforestation sites. To test the influence of root characteristics on the short-term response of seedlings to limiting resources (water, nutrient, or oxygen), we conducted two experiments. We compared (1) the growth and physiology of three types of four-year-old black spruce (Picea mariana (Mill.) BSP) seedlings (Containerized, highly developed initial roots restricted to a plug; bareroot, less developed but unrestricted initial roots; deeply-planted containerized, restricted initial and adventitious roots) to different combinations of irrigation and fertilization. We also investigated (2) the cellular plasticity of adventitious and initial roots to three irrigation regimes including flooding. Bareroot seedlings had better relative growth rates in height than containerized seedlings, probably due to their larger initial size. On the other hand, containerized seedlings took better advantage of fertilization, as shown by a higher relative growth rate in diameter compared to bareroot seedlings and were less affected by water limitation, possibly due to the root plug acting as an additional water reserve capacity. For containerized seedlings, the presence of adventitious roots was beneficial to height growth and physiological performances compared to seedlings with initial roots only. Adventitious roots showed great cell plasticity, particularly under flooding conditions.

Highlights

RGRheight was influenced by the interaction between fertilization increase of 24% (Figure 2A)
RGRheight was influenced by the interaction between fertilization and and irrigation treatments (Table 1)
Our results show that the physiological advantage provided to seedlings by adventitious roots occurred mainly under limited water conditions and could be related to the greater cellular plasticity of adventitious vs. initial roots

Summary

Introduction

BSP) is a dominant species of North American boreal forests. It has a large ecological spectrum [1], able to grow in conditions ranging from peatlands [2,3] to mesic well-drained sites [4]. The root system plays a key role in tree establishment [6] This is especially important when outplanting seedlings from nursery to field conditions, because the range of changing conditions can be considerable. Seedling ability to develop new roots impacts the time required to establish direct contact with the planting site [7,8,9], which is necessary to have direct access to soil resources. The ability to produce new roots is an important criterion for selecting the most vigorous seedlings [13,14,15]

Methods

Results

Conclusion