Improved method for vegetative propagation of mature Pinus halepensis and its hybrids by cuttings

Joseph Riov,Rotem Attias,Robert Sitbon,Rakefet David-Schwartz,Hagar Fox,Mohamad Abu-Abied,Lilach Farkash-Haim,Galina Shklar,Einat Sadot,Yosef Moshe

doi:10.1163/22238980-20191118

Joseph Riov, Rotem Attias + Show 8 more

Open Access

https://doi.org/10.1163/22238980-20191118

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Abstract

Forest trees possess high genetic diversity and high heterozygosity which allow adaptation to changing environmental conditions. There is a tendency to propagate successful and unique genotypes, which are identified at their mature stage in the forests, for future improvement programs and conservation purposes. However, vegetative propagation of mature forest trees is still a challenge in many conifers. In this study, we focused on improving the rooting of cuttings of mature and old Pinus halepensis and its hybrids. We observed that storage of cuttings before rooting at 4°C for 4 weeks and prolong immersion of cuttings in a solution containing 400 mg/l of indole-3-butyric acid, 5 mg/l of the auxin conjugate 2-(2,4-dichlorophenoxy)propanoic acid-glycine methyl ester, and 0.01% of Amistar fungicide significantly improved rooting of mature cuttings. The active ingredient in Amistar is azoxystrobin, an uncoupler of respiration, which seems to directly promote rooting. Rooted cuttings of selected clones demonstrated unique and uniform growth performance, most likely delivering the intrinsic growth parameters of the mother trees. It was also observed that trees growing under drought stress possess improved rooting ability. By using rooted cuttings, it will be possible to study the relationship between growth rate and adaptation to semi-arid climate conditions. The ability to clonal propagate mature and old P. halepensis trees not only enables vegetative propagation of elite trees for improvement programs, but also provides an opportunity to preserve unique naturally occurring old P. halepensis genotypes.

Highlights

The global warming and the frequent drought events that occur in the recent years have led to an increase in forest tree mortality in different regions of the world (Allen et al 2010)
Pine cuttings Cuttings of P. halepensis and hybrids of P. brutia x P. halepensis were prepared from upper shoots, which exhibited vigorous growth, collected during January from mature and old trees of different ages grown in experimental plots or planted forests
In order to test the effect of low temperature storage on the rooting ability, cuttings collected from 7-yearold P. halepensis trees were stored at 4°C for 0, 2, or 4 weeks prior to rooting

Summary

Introduction

The global warming and the frequent drought events that occur in the recent years have led to an increase in forest tree mortality in different regions of the world (Allen et al 2010). Pinus halepensis Miller (Aleppo pine) is a widespread native forest tree species in the Mediterranean basin, which has been widely used for afforestation, in semi-arid regions, due to its well-known drought resistance (Ne’eman et al 2000; Quezel 2000; Chambel et al 2013; Dorman et al 2013; Klein et al 2013; David-Schwartz et al 2016; Voltas et al 2018). The decrease in annual precipitation that is expected to occur in the Eastern Mediterranean (Giorgi and Lionello 2008) poses a threat to the existence of P. halepensis populations in semi-arid regions (Alfaro et al 2014; Fady et al 2016; Voltas et al 2018). The populations of P. halepensis in the Mediterranean basin contain genotypes which exhibit exceptional growth performance under sub-optimal conditions compared to other pine species.

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