QUANTITATIVE-DETERMINATION OF CALCIUM-OXALATE AND OXALATE IN DEVELOPING SEEDS OF SOYBEAN (LEGUMINOSAE)

Developing soybean seeds accumulate very large amounts of both soluble oxalate and insoluble crystalline calcium ( Ca) oxalate. Use of two m ethods of detection for the determination of total, soluble, and insol uble oxalate revealed that at +16 d postfertilization, the seeds were 24% dry mass of oxalate, and three-fourths of this oxalate (18%) was b ound Ca oxalate. During later seed development, the dry mass of oxalat e decreased. Crystals were isolated from the seeds, and X-ray diffract ion and polarizing microscopy identified them as Ca oxalate monohydrat e. These crystals were a mixture of kinked and straight prismatics. Ev en though certain plant tissues are known to contain significant amoun ts of oxalate and Ca oxalate during certain periods of growth, the acc umulation of oxalate during soybean seed development was surprising an d raises interesting questions regarding its function.