Enhancing Pinus pinea cone production by grafting in a non-native habitat

Pinus pinea is an interesting species for its valued pine nuts. Despite the high demand for this nut, the species is mostly harvested from natural forests, because the time elapsed until the trees come into production hinders advances toward a more intensive cultivation. The grafting technique has been used to favor an earlier production in native Mediterranean habitats. In Chile, stone pine has been recently included in orchards. The objective of this study was to assess the initial performance in terms of growth, entry into production and cone yield of three grafting trials of the species established in Chile; two of the trials included nursery-grafted plants and the other, in situ grafting of P. pinea on a 3-year-old P. radiata plantation. An earlier entry into production and a higher number of female strobili and 1-year-old conelets (up to 2.9 times) were found in nursery-grafted plants compared with control seedlings. Growth was higher in trees in situ grafted onto radiata pine than in seedlings; eight years after grafting, the trees had achieved reproductive maturity, 67% had on average three cones per tree, and the presence of female strobili and 1-year-old conelets was 6.6 and 15.6 times higher than in seedlings, respectively. Radiata pine could be a feasible rootstock for either in-nursery or in situ stone pine grafting. Grafting accelerated stone pine entry into production, showing to be an effective tool for stone pine propagation and cropping.

Automated summary

Pinus pinea, valued for its pine nuts, is often harvested from natural forests due to slow production in cultivated environments. Grafting onto radiata pine accelerated entry into production, with grafted trees showing higher growth and cone yield compared to control seedlings. This study suggests radiata pine as a feasible rootstock for stone pine grafting.