Acclimating commercial tree seedling root system architecture to drought

Planting seedlings is the first step to reforest recently disturbed sites, yet seedling performance can be poor if they do not quickly acclimate with the planting site. This limits forest productivity and requires substantial investment. One frontier in forestry is identifying tree seedling genotypes and phenotypes that maximize seedling survival and early growth. Projects examining root system of architecture (RSA) are limited for seedlings even though extensive research for agriculture plants shows its importance for maximizing productivity by optimizing resource capture. RSA can be manipulated in the nursery by modifying growing regimes that may affect the RSA following planting. Testing cultural regimes that modify the RSA in the nursery to better acclimate seedlings to drought conditions is important for seedling productivity and many become more important with more frequent, severe, and longer duration droughts. This project will focus on western larch and black walnut for the following objectives: (i) Characterize RSA of seedlings growth under different drought acclimation regimes in the nursery, (ii) Examine partitioning of RSA between intact root plugs and egressed roots in the field, and (iii) Assess the effects of drought acclimation on survival and growth of seedlings in relation to RSA. Our approach to studying seedling RSA includes greenhouse, laboratory, and field studies. RSA will be manipulated in the greenhouse by imposing drought acclimation treatments followed by examining maximum RSA in lab grown seedlings, and finally examining RSA in the field. Results will improve nursery practices and identify RSA traits important for seedling productivity.

(Funding: USDA NIFA, NSF CAFS, Digital Forestry)