Effects of stone pine (Pinus pinea L.) plantation spacing on initial growth and conelet entry into production

Abstract

Stone pine (Pinus pinea L.) is well-known for its fruits, the pine nuts, which are considered a delicacy and are the most expensive dry fruits in the world. This fruit is harvested mostly from natural forests, and limited advances have been made for cultivating it as a fruit tree. This study was aimed at assessing the effect of plantation spacing and seed source on early fruiting of stone pine plantations for pine nut production in Chile. We tested two plantation spacings (5 × 5 and 7 × 7 m) and three local seed sources (Tanumé, Cáhuil and Chillán), selected according to the current cultivation practices in Chile in a multi-environment trial involving four sites. Plantations were repeatedly measured annually for 6 years after establishment. High environmental effects as well as interactions between environment and management techniques were observed for all growth variables. Spacing had effects on crown development at all sites except for the most limiting one, but not on height or root-collar diameter. The lowest density (7 × 7 m) was associated with the highest crown diameter. Effects of seed source varied across environments, being significant for growth variables in both environments with poor growth. Young plantations (5 and 6 years old) showed a trend that suggests a higher precocity of entry into fruiting and higher strobili production for the 7 × 7 m than for 5 × 5 m spacing. Our results suggest that plantations can be effective for stone pine fruit production in Chile, and the convenience of developing environment-specific plantation designs, considering spacing as a relevant parameter for orchard establishment and management.