464 Distribution of Sugars in Sweet Corn

Abstract

Sweet corn (Zea mays L.) kernels are sinks, and sugars found in kernels must be translocated from a source. Stalk tissues can act as a source and a sink as sweet corn plants age. Quantity and types of sugars present in various sweet corn tissues during plant development are not well documented. Concentrations of fructose, glucose, sucrose, and their total were determined in the ninth stalk internodes (I9) from the 12-leaf stage (V12) to fresh-market maturity (R3) in sweet corn cultivars carrying either the su1se1, su1, or sh2 endosperm genotype. Developing ears were sampled at tassel emergence (VN) and silking (R1). Kernels and cob tissue were sampled separately at blister stage (R2) and R3. Correlation analysis was performed on concentrations of sugars at all developmental stages. In I9, from V12 to R3, levels of fructose and glucose declined and sucrose increased. In developing ears, concentrations of fructose and glucose increased from VN to R1. Concentrations of sugars in cobs in all cultivars were generally the same at R2 and R3. In kernels from R2 to R3 in the su1se1 cultivar, glucose decreased while the other sugars were unchanged; in the su1 cultivar, fructose decreased while levels of the other sugars stayed the same; and in the sh2 cultivar, fructose decreased, glucose was unchanged and sucrose increased. Correlation analysis suggested that the cultivars moved sugars to the kernels differently. The pattern of movement of sugars to kernels was most complex in the su1se1 cultivar than in the su1, which was more comlex than in the sh2 cultivar. Knowing how sugar content changes in the plant may be used to predict sugar content in kernels.