Effect of irrigation in growth and fruit production in stone pine (Pinus pinea L.) in Chile

Pinus pinea L. is an interesting conifer because of its fruits, pine nuts or pinoli, the most expensive nut in international markets, and a productive alternative for owners/companies. However, in spite of the historic use of the species, fruit harvesting occurs mostly in natural forests located in the Mediterranean zone, there being only limited advance in semi intensive and intensive techniques for its cultivation as a fruit tree. The species is characterized by a long cycle of fruit development, with cones of 1, 2 and 3 years of age being simultaneously on the tree, making the nutritional and water management more complex than in other cultivated trees. In Chile, the species was introduced more than a century ago and was used in soil stabilization, erosion control and cattle shading. In order to promote its cultivation, we performed a multi environment study including irrigated and non-irrigated 3-18-year-old plantations; later, in order to assess the consistency of results, we also evaluated 13-, 15- and 28-year-old irrigated plantations and allometric measurements were compared to one non irrigated plantation located in the same region. We observed that irrigation has a significant effect both on growth traits (higher DBH up to 84%) and fruit production (higher cone production up to 15.2 times), concluding that irrigation is an important practice in zones with water limitations. Results confirm the convenience of implementing intensive orchards with irrigation in order to increase growth and fruit production.