Dry Matter Accumulation and Carbohydrate Concentration Patterns of Field-Grown and in Vitro Cultured Maize Kernels from the Tip and Middle Ear Positions1
- J. M. Hanft,
- R. J. Jones and
- A. B. Stumme2
Tip and middle position kernels from field-grown ears and in vitro cultured maize (Zea mays L.) were compared for dry matter accumulation and pedicel and endosperm carbohydrate concentration patterns. The experiment was designed to determine whether the growth of tip kernels is limited by their inherent potential to accumulate dry matter or by the supply of assimilate entering the kernel. Tip kernels from field-grown ears had the lowest linear dry matter accumulation rate, the shortest duration of kernel growth, and therefore, the lowest maximum mass. The mass of tip kernels cultured in vitro was three times greater than tip kernels from field-grown ears, which indicated that tip kernels on field-grown ears fail to attain maximum potential mass. The mass of tip kernels cultured in vitro was lower than the mass of middle kernels cultured in vitro or from field-grown ears. Tip kernels that developed on field-grown ears had a much lower pedicel fructose, glucose, and sucrose concentration throughout kernel growth than did tip kernels cultured in vitro and middle kernels of both field grown and in vitro culture. Tip kernels from the field also had a reduced maximum endosperm sucrose concentration as compared to tip and middle kernels cultured in vitro and middle kernels from field-grown ears. The relative endosperm starch accumulation of field-grown tip kernels was comparable to that of tip kernels cultured in vitro. Starch synthesis in the endosperm of tip kernels from the field was initiated 4 days later than in tip and middle kernels cultured in vitro and middle kernels from field-grown ears. The low sugar concentrations in the pedicel and the decreased endosperm sucrose concentration in tip kernels from field-grown ears indicate that an inadequate assimilate supply reaching these kernels may be limiting their growth more than their inherent potential to accumulate dry matter.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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