Relationship Between Photosynthate Supply and Endosperm Development in Maize

Abstract

Maize (Zea mays L., cultivar Pioneer 3925) plants were given shaded, thinned and control light treatments during 10 d or 20 d periods surrounding 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 thinned treatment than control and shaded treatments due to higher kernel set in apical regions of ears. In PNs at 11 d after pollination (DAP), DM and sucrose contents were slightly greater in thinned than control and shaded plants. Glucose contents were substantially greater than controls in PNs of thinned plants and were less than controls in shaded plants. In endosperms from apical kernels at 8 to 12 DAP (during cell division), DM, glucose and sucrose contents were substantially less in shaded than control and thinned plants. Sucrose contents were greater in endosperms of thinned than control plants. Sugar contents in endosperms from basal kernels were nearly the same in the three light treatments. At 12 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.