An exogenous cytokinin supply in the ornamental fern Asplenium nidus L. induces an unusual post-transplant biomass accumulation

Jorge Molinari,Adalberto Di Benedetto,Alberto Pagani,Ernesto Giardina,Danilo Carnelos

doi:10.1590/2447-536x.v27i2.2259

Jorge Molinari, Adalberto Di Benedetto + Show 3 more

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https://doi.org/10.1590/2447-536x.v27i2.2259

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Abstract

Abstract Ferns are ornamental plants with a low relative growth rate and long production cycles, which are grown at small pot volumes to optimize the commercial space for sale. However, the root restriction effects under this plant management can limit biomass accumulation and frond area. Since an exogenous spray with cytokinin (6-benzyl aminopurine (BAP)) has been suggested as a tool to override the root restriction in plants grown in pots, this study aimed to evaluate the effect of different BAP doses (5, 50, 100 or 200 mg L-1) once (7 days after transplant), twice (7 and 30 days after transplant) or three times (7, 30, and 60 days after transplant), on plant growth and frond area development in spore-propagated Asplenium nidus fern plants grown in pots. Both increasing the BAP doses and number of applications led to an unusual response: an excessive decrease in the frond plastochron and a significant increase in the frond number initiated at the apical shoot meristem. This large frond number was not sustained due to the low net photosynthetic rate of the younger fronds and significantly limited outward appearance.

Highlights

Ornamental plants with a low relative growth rate and long production cycles (24 months or more), such as ferns (Page, 2002; Liao et al, 2017), are grown in small pot volumes and frequently transplanted before sale
Since an exogenous spray with cytokinin (6-benzyl aminopurine (BAP)) has been suggested as a tool to override the root restriction in plants grown in pots, this study aimed to evaluate the effect of different benzyl amino purine (BAP) doses (5, 50, 100 or 200 mg L-1) once (7 days after transplant), twice (7 and 30 days after transplant) or three times (7, 30, and 60 days after transplant), on plant growth and frond area development in spore-propagated Asplenium nidus fern plants grown in pots
When BAP dose increased, SAM differentiated a significantly higher number of lateral growth areas (290.91% compared to controls) (Figure 2), while rate of leaf appearance (RLA) increased (120.89%), but rate of leaf area expansion (RLAE) (100.20%) and specific leaf area (SLA) (70.60%) decreased (Table 1)

Summary

Introduction

Ornamental plants with a low relative growth rate and long production cycles (24 months or more), such as ferns (Page, 2002; Liao et al, 2017), are grown in small pot volumes and frequently transplanted before sale. Asplenium nidus fern plants grown in small pots suffer from root restriction (Pagani et al, 2020), in agreement with previous reports in other ornamental potted plants (Di Benedetto et al, 2020a) In this regards, Pagani et al (2020) showed that the use of large pots (1500-cm3) in A. nidus increases fresh weight (FW), dry weight (DW) and frond area (the main commercial aesthetic trait). They found higher frond appearance rate, frond area expansion, frond thickness, relative growth rate and net assimilation rate. The main effects of exogenous cytokinin on fern growth in culture have been described in detail

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