Kernel Abortion and Distribution of Mineral Elements Along the Maize Ear

Kernel abortion, especially prevalent at apical ear positions, results in malformed (nubbin) ears and substantial yield reduction in maize ( Zea mays L.). Although deficiencies of N, P, K, Mn, Zn, and B are reported to cause nubbin ears, it is not known whether the concentrations of these or other elements are different in the aborted and normal (fully developed) kernels. In this study, the concentrations of 12 mineral elements in the kernel and cob tissue from apical, middle, and basal positions in normal and nubbin maize ears having aborted kernels at their tips were compared. The concentrations of N, P, K, Mg, Ca, Na, B, Zn, Cu, and Mn in the kernels and P, Na, Ca, Fe, B, Zn, Cu, Mn, and Mo in the cobs were the same in nubbin and normal ears. Kernel concentration of Mo and cob concentrations of N, K, and Mg were significantly higher in nubbin than in normal ears. In the normal ears, concentrations of K and Zn in the kernels and N, P, K, and Zn in the cobs were higher in apical than in basal ear positions. In nubbin ears, concentrations of N and Zn were higher in apical (aborted) than in basal (normal) kernels. In cobs of nubbin ears, however, concentrations of N, P, K, Mg, Ca, Zn, and Mn were higher in apical positions adjacent to aborted kernels as compared with basal positions adjacent to fully developed normal kernels. Since the concentration of no element was lower in the nubbin ear than in the normal ear, an insufficient supply of the tested mineral elements was ruled out as a cause of kernel abortion. From this study, it is not certain whether accumulation of elements in the apical portion of the cob precedes or follows kernel abortion. A malfunction in the transport of mineral elements and carbohydrates from the leaves to the kernels via phloem or a disturbance in the transfer of mineral elements between cob and kernel tissues at their junction may be concomitant with (but not necessarily the cause of) kernel abortion.