Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings.

Wenhui Shi,Mark Bloomberg,Shuchai Su,Guolei Li,Liming Jia

doi:10.1371/journal.pone.0177002

Wenhui Shi, Mark Bloomberg + Show 3 more

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https://doi.org/10.1371/journal.pone.0177002

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Journal: PloS one	Publication Date: May 18, 2017
Citations: 11	License type: CC BY 4.0

Affiliation: Lincoln University, Beijing Forestry University

Abstract

Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T0 to T2 for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation.

Highlights

Oak (Quercus) species are widely distributed in the northern hemisphere [1]
Cotyledon excision improved the total emergence of Q. variabilis seedlings (Fig 2A, S2 Table)
Greatest emergence occurred in the Intermediate excision rather than either Slight or Extreme excision treatments

Summary

Introduction

Oak (Quercus) species are widely distributed in the northern hemisphere [1]. Matured acorns feature large size, and are found by animals such as rodents, rabbits and birds [2], which results in preferential dispersal for acorns and high returns for predators [3]. The embryo parts of acorns commonly escape from being eaten due to the bitter and astringent taste [4], and have the potential to develop into seedlings [5,6,7,8,9,10,11] In this way, acorns achieve both dispersal and plant regeneration, paying a price of acorn damage by the seed predators [12,13,14,15,16]. There are many studies focused on these problems that have used a series of pre-germination techniques, such as stratification or exposure of seeds to cold or warm temperatures for variable time periods [22,23] These techniques normally increased acorn emergence but did not promote germination synchronicity. Forest managers have imitated this by excising distal ends of acorns before sowing them into soil to improve seedling emergence [28]

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