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Submitted to: HortScience
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/22/2008 Publication Date: 10/1/2008 Citation: Mou, B. Evaluation of Oxalate Concentration in the U.S. Spinach Germplasm Collection. HortScience 43(6):1690-1693.2008. Interpretive Summary: In addition to its high nutrient content, spinach (Spinacia oleracea L.) is also known to have greater amount of oxalic acid than most crops. Oxalic acid may form crystals with minerals to reduce the bioavailability and absorption of calcium and iron in diets, and calcium oxalate may deposit in the kidney of certain people as a common form of kidney stone. Genetic improvement to reduce the amount of oxalic acid must start from germplasm evaluation to identify sources of low oxalate content. The entire USDA spinach germplasm collection (338 accessions) and 11 commercial cultivars were screened for oxalate levels. There were significant differences in oxalate concentration among the varieties evaluated, ranging from 5.3 to 11.6% on a dry weight basis. None of the two Spinacia tetrandra and four Spinacia turkestanica wild spinach accessions screened contained low levels of oxalate. Two accessions from Syria, PI 445782 (cultivar name Shami) and PI 445784 (cultivar name Baladi), consistently had low oxalate concentration. When expressed on a fresh weight basis, oxalate concentration may be affected by the moisture content of the plant. Oxalate concentration had little correlation with types of leaf surface and leaf weight per plant. With the genetic variation and sources of low oxalate concentration found, breeding of spinach for a low level of oxalate seems feasible. Technical Abstract: In addition to its high nutrient content, spinach (Spinacia oleracea L.) is also known to have greater amount of oxalic acid than most crops. Oxalic acid may form crystals with minerals to reduce the bioavailability and absorption of calcium and iron in diets, and calcium oxalate may deposit in the kidney of certain people as a common form of kidney stone. Genetic improvement to reduce the amount of oxalic acid must start from germplasm evaluation to identify sources of low oxalate content. The entire USDA spinach germplasm collection (338 accessions) and 11 commercial cultivars were screened for oxalate concentration in a preliminary experiment with two replications. Putative accessions with low oxalate levels that were identified, plus controls and commercial cultivars, were included in another test with five replications to confirm the results. There were significant differences in oxalate concentration among the genotypes evaluated, ranging from 5.3 to 11.6% on a dry weight basis. The low-oxalate genotypes identified in our experiments are all Spinacia oleracea. None of the two Spinacia tetrandra and four Spinacia turkestanica accessions screened contained low levels of oxalate. Two accessions from Syria, PI 445782 (cultivar name Shami) and PI 445784 (cultivar name Baladi), consistently had low oxalate concentration. When expressed on a fresh weight basis, oxalate concentration may be affected by the moisture content of the plant. Oxalate concentration had little correlation with types of leaf surface and leaf weight per plant. With the genetic variation and sources of low oxalate concentration found, breeding of spinach for a low level of oxalate seems feasible. |
