Cultural Conditions and Propagule Type Influence Relative Chloride Exclusion in Grapevine Rootstocks

Breeding for salt resistance in grapevines and other crops has made slow progress despite decades of research. One factor contributing to this problem in grapevines is the weak or nonexistent correlation of field and greenhouse performance observed in some studies when salt resistance is assessed by chloride accumulation in leaf tissue. To develop a rapid chloride exclusion assay for use in rootstock breeding, multiple systems were tested. Results were obtained wherein the well-established field performance of specific genotypes was augmented, equalized, or reversed when in containerized culture. One assay using fritted clay media and herbaceous cuttings yielded a rank order and relative chloride uptake among the tested genotypes that was similar to published values from long-term studies in experimental vineyards. This assay used only 14 days of high salt exposure, was inexpensive, required relatively little space and maintenance, and has continued to provide reliable data in subsequent experiments. The results demonstrate the potential for considerable plasticity in chloride exclusion exhibited by ungrafted grapevines when assayed in containers. This underscores the importance of system design wherein genotypes of known capacity for chloride exclusion are accurately calibrated to their established field performance. This study describes an empirically derived assay that replicates these conditions closely enough to be used in a rootstock breeding program for improved chloride exclusion.