Is maize kernel weight limited by its capacity to expand?

GAMBÍN, B.L.; BORRÁS, L.; OTEGUI, M.E.

MAYDICA

Maydica

Lugar: Bergamo, Italia; Año: 2007 vol. 52 p. 431 - 441

0025-6153

Maize (Zea mays L.) kernel weight (KW) hardly responds to increased assimilate availability per kernel once the early grain-filling stages have elapsed. We studied if this lack of response could be related to a limited kernel capacity to expand due to physical restrictions. Two experiments (Exp) were conducted to modify space availability for kernel expansion. In Exp I, a physical restriction was applied to decrease the capacity to expand. The restriction started at different grain-filling stages, and was maintained for differing periods to test the kernel capacity to recover growth. In Exp II, the space available for kernel expansion was increased by removing kernels from adjacent rows. Kernel dry weight, water content and kernel volume were measured throughout grain filling. Decreasing the space available for expansion reduced final KW. The earlier the physical restriction was imposed, the higher the reduction in final KW. Removing the restriction was not always followed by a recovery in kernel expansion, especially when removed after kernels achieved maximum water content.  Increasing space availability by removing neighbor kernels had no effect on increasing KW at maturity, although kernels were shorter and wider. We concluded that kernel-to-kernel proximity was not limiting KW. Increasing the space available for expansion would not increase KW beyond the potential set early in grain filling, but further restricting the kernel capacity to expand would decrease KW.