Introduction:

In Pinus radiata D. Don, one of the most widely planted pines globally, frost damages plantations at the seedling stage.

Objective:

To determine differences in growth and tolerance to low temperatures of native populations (Guadalupe and Cedros islands) of P. radiata in greenhouse and outdoors conditions, under different levels of soil moisture.

Materials and methods:

Low-temperature tolerance was determined through the damage index (DI) in freezing tests at -12 °C during 4 h. In each environment (greenhouse and outdoors) two soil moisture treatments were defined (irrigation and drought). The DI was evaluated with the method of electrical conductivity in primary needles during winter and spring. The absolute growth rate (AGR) of the terminal shoot was obtained by measuring the total height of the seedlings.

Results and discussion:

Average DI of 50 and 64 % were obtained in winter and spring, respectively. In greenhouse, DI was different (P ≤ 0.05) between populations, being higher in Guadalupe (>59 %) than in Cedros (<42 %), both in winter and spring. Outdoors, Cedros (64.1 %) had a higher DI than Guadalupe (36.5 %) only during winter. DI was similar in both favorable soil moisture and drought conditions. The Guadalupe population presented higher AGRs in both environments and moisture conditions.

Conclusion:

The population of Guadalupe is more sensitive to low temperatures with greater variation in DI, due to its growth dynamics. Differences between populations are useful in the genetic improvement of the species.

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