Changes in drought tolerance of Pinus radiata in Chile associated with provenance and breeding generation

Abstract

Key message In Chile, breeding radiata pine for growth has led to drifts in the degree of drought tolerance of the seedlings. Interior provenances gained a larger tolerance to drought after three breeding generations as shown by larger survival and root/shoot ratio under water shortage, while coastal provenance displayed an opposite trend.• Context Given that rainfall is predicted to decrease and to affect establishment and early survival of radiata pine (Pinus radiata D. Don) in Chile, there is a need to identify more drought tolerant genotypes at seedling stage.• Aims The aim of this study was to test whether provenances of P. radiata originating from interior or from coastal provenances, displayed different responses to short-term water shortage, and whether these responses differed from the first to the third breeding generation.• Methods Three generations of breeding families from two sites in Central Chile were compared. The seedlings were grown during 100 days and subjected to two watering regimes for 45 days. Survival, growth, and biomass allocation to roots and shoots were recorded.• Results The two provenances displayed different responses to drought. Biomass allocation to shoots and survival were significantly reduced by water shortage. The first generation seedlings from the coastal provenance displayed a larger survival rate when exposed to water shortage (i.e., 60 %); this rate decreased in the following breeding generations. On the contrary, the survival rate increased from the first to the third generation in the interior provenance.• Conclusions We observed an important local adaptation to water shortage in the interior provenance. This response may be due to the fact that parent tree populations of the interior provenance have successfully adapted to sites with periodic drought.

Field performance of various Pinus radiata breeding families established on a drought-prone site in central Chile

“…A phenotypic ranking based on height for seedlings under nursery water stress conditions was constructed using the same data set of Espinoza et al (2014Espinoza et al ( , 2016. A subset of 30 families were then selected from the total 98 families used in the previous nursery experiment (10 families from each of the upper, middle and lower portions of the ranking).…”

“…Pinus radiata has undergone three generations of breeding for growth rate and form to date. Some unintended changes in wood properties associated with breeding (Li and Wu 2005) and evidence of important differences among populations and breeding generations in response to water stress at the nursery stage (Espinoza et al 2013(Espinoza et al , 2014(Espinoza et al , 2016 have been reported. However, no studies have investigated if such differences persist when different breeding generations of the species are established in complex field environments, where multiple stresses co-occur.…”

“…This paper examines the possible consequences of breeding on growth and gas exchange in P. radiata populations in Chile, by examining phenotypic variation in early growth and physiological performance of trees established on a drought-prone site. We chose two populations and three breeding generations of P. radiata, because population-and breeding-generation differences in growth, morphology and biomass allocation under drought stress in nursery conditions have been well documented (Espinoza et al 2013(Espinoza et al , 2014(Espinoza et al , 2016. Espinoza et al (2013) reported that interior and coastal breeding populations of P. radiata in Chile displayed different responses to drought, which were also related to the breeding generation of the families under study (Espinoza et al 2016).…”

“…We chose two populations and three breeding generations of P. radiata, because population-and breeding-generation differences in growth, morphology and biomass allocation under drought stress in nursery conditions have been well documented (Espinoza et al 2013(Espinoza et al , 2014(Espinoza et al , 2016. Espinoza et al (2013) reported that interior and coastal breeding populations of P. radiata in Chile displayed different responses to drought, which were also related to the breeding generation of the families under study (Espinoza et al 2016). First-generation seedlings from the coastal population displayed a higher survival than the interior population when exposed to water shortage, but survival decreased in the following breeding generations.…”

“…However, there is less understanding of whether differences observed between breeding families in response to water stress in a nursery then persisted in the field. The present study reports on early results from a long-term field experiment involving a subset of the families used by Espinoza et al (2016). Above-ground growth and some additional ecophysiological traits were examined.…”