DIVISION S-4-SOIL FERTILITY & PLANT NUTRITION Accumulation of Sodium and Potassium by Flax

Flax (Linum usitatissmum L.) accumulates Na but little is known about factors influencing Na accumulation in seed of this species. We investigated the influence of added Na (0, 44, and 88 mg NaCl-Na kg -1 soil) and K (0, 75, and 150 mg KC1-K kg -1 soil) on accumulation of these elements by 'Omega' flax grown on an Aerie Calciaquoll in the greenhouse. The principal findings were: (i) vegetative tissue and seed contained up to 5960 and 754 mg Na kg-1, respectively, in the absence of added K; (ii) added Na increased and added K decreased Na concentration in both vegetative tissue and seed; (iii) negative Na x K interactions for Na concentration were due to ion antagonism and were largely unrelated to dilution effects; (iv) seed K concentration was increased by added K and little affected by added Na; (v) Na, in contrast to K, accumulated preferentially in older leaf and stem tissues; and (vi) added Na and K had little influence on seed Ca and Mg concentration. Analysis of seed from five flax nursery trials indicated that both genotype and location influenced seed Na concentration. Commercial flax seed is likely to vary considerably in Na concentration due to edaphic factors, particularly Na and K availability, and genetic factors. Author's Abstract.