Endosperm Development in Maize and Related to Photosynthate Supply

Maize ( Zea mays , L. Sweet Corn) plants were given shaded, partially shaded and control light treatments during 10 days or 20 days periods around the time of pollination. Glucose, sucrose, starch and dry matter (DM) contents were measured at intervals in composite samples of pericarp/nucellus (PN), and in endosperms taken from developing kernels. Total kernel DM per ear at maturity was higher in the partially shaded treatment than control and shaded treatments due to higher kernel set in apical regions of ears. In PN at 11 days after pollination (DAP), DM and sucrose contents were slightly greater in partially shaded than control and shaded plants. Glucose contents were substantially greater than controls in PN of partially shaded plants and were less than control in shaded plants. In endosperms from apical kernels at 5 to 10 DAP (during cell division), DM, glucose and sucrose contents were substantially less in shaded than control and partially shaded plants, sucrose contents were greater in endosperms of partially shaded than control plants. Sugar contents in endosperms from basal kernels were nearly the same in the three light treatments. At 10 DAP, apical and basal endosperms in shaded plants had fewer nuclei than those of the other light treatments. The light treatments appeared to effect apical kernel growth by influencing the extent of cell division.