Phenotyping Almond Orchards for Architectural Traits Influenced by Rootstock Choice

Álvaro Montesinos,Jérôme Grimplet,Grant Thorp,María Rubio-Cabetas

doi:10.3390/horticulturae7070159

Abstract

The cropping potential of almond (Prunus amygdalus (L.) Batsch, syn P. dulcis (Mill.)) cultivars is determined by their adaptation to edaphoclimatic and environmental conditions. The effects of scion–rootstock interactions on vigor have a decisive impact on this cropping success. Intensively planted orchards with smaller less vigorous trees present several potential benefits for increasing orchard profitability. While several studies have examined rootstock effects on tree vigor, it is less clear how rootstocks influence more specific aspects of tree architecture. The objective of this current study was to identify which architectural traits of commercially important scion cultivars are influenced by rootstock and which of these traits can be useful as descriptors of rootstock performance in breeding evaluations. To do this, 6 almond cultivars of commercial significance were grafted onto 5 hybrid rootstocks, resulting in 30 combinations that were measured after their second year of growth. We observed that rootstock choice mainly influenced branch production, but the effects were not consistent across the different scion–rootstock combinations evaluated. This lack of consistency in response highlights the importance of the unique interaction between each rootstock and its respective scion genotype.

Highlights

Accepted: 17 June 2021Since its development, reported around 1800 BCE, grafting has been a crucial part of the propagation process for tree and vine crops [1]
Clonal rootstocks are utilized in numerous fruit and nut species of economic significance [7]. Their usage is widespread in almond (Prunus amygdalus (L.) Batsch, syn P. dulcis (Mill.)) orchards, and varieties are generally graft-compatible with both almond and peach (P. persica (L.) Batsch) rootstocks and their interspecific hybrids [2,8]
A scion–rootstock interaction was observed for the diameter at the base of the scion (d_Base), which is equivalent to the trunk cross sectional area (TCSA), even though it could be expected that a more vigorous rootstock should have an effect on this trait

Summary

Introduction

Accepted: 17 June 2021Since its development, reported around 1800 BCE, grafting has been a crucial part of the propagation process for tree and vine crops [1]. As well as conferring traits of agronomic interest to trees in the orchard, the use of grafting and clonal rootstocks has facilitated the independent selection of scion and rootstock traits, improving breeding techniques. Rootstocks can influence scion phenotype such as fruit quality, yield, flowering time and tree vigor [3,4,5,6,7]. Clonal rootstocks are utilized in numerous fruit and nut species of economic significance [7]. Their usage is widespread in almond (Prunus amygdalus (L.) Batsch, syn P. dulcis (Mill.)) orchards, and varieties are generally graft-compatible with both almond and peach (P. persica (L.) Batsch) rootstocks and their interspecific hybrids [2,8]. Several new dwarfing rootstocks have been developed, conferring low and medium vigor to establish new more intensive and sustainable cropping systems

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