Juvenile–mature genetic correlations in Pinus radiata D. Don. under different nutrient × water regimes in Spain

Individual and family heritabilities and juvenile–mature genetic correlations were estimated for growth and biomass traits recorded in treatment with optimal and limiting water and/or nutrient availability to study how the different growth environments affected genetic parameter estimates. Thirty open-pollinated families, randomly selected among the 58 families used in field progeny tests in Galicia, were cultivated for 30 weeks in a climatic chamber under controlled conditions. Two water regimes (high and low water supply) combined with two nutrient regimes (high and low nutrient supply) were applied by subirrigation. Several growth, branching and dry mass traits were assessed 30 weeks after sowing and compared with field performance (height, diameter and volume) of 4-year-old progeny tests established at three different sites in Galicia (NW Spain). Both the irrigation and the fertilization treatments had a strong effect in all the assessed traits except irrigation for the number of branches. Heritabilities for growth and biomass traits were moderate to high (0.13–0.77) in individual treatments. However, when analyzing all treatments together, the impact of the family × treatment interactions led to a reduction (0.20–0.35) in the heritability estimates. The results indicated that the genotype × water and genotype × nutrient interactions may be important and could not be ignored in the Galician radiata pine breeding program. Climatic chamber–field correlations were different between different traits measured at climatic chamber experiments and the three field tests. The correlations were larger with the well-watered treatments, suggesting that further development of early testing methods for radiata pine in Galicia should include treatments with no limiting water availability.