Varietal Differences in Grain Filling at the Distal end of Sweet Corn Ear

Abstract

The bases of varietal differences in the frequency of unfilled grains at the distal end of sweet corn cultivars in relation to : (i) the dry matter production, (ii) partitioning of dry, matter within the ear, and (iii) changes in the florets with emerged silk were investigated.
1.Cultivars with delayed silk emergence had the largest total plant dry weight at silking time, the fastest dry matter accumulation rate during grain filling, heaviest ear weight at the harvesting, and the maximaum number of filled grains. A low negative correlation was obtained between the percentage of unfilled grains and dry matter accumulation during grain filling period.
2.A positive correlation exists between percentage of the decrease of a single grain weight (SGW) at the distal positions and percentage of the occurrence of unfilled grains on the ear. Ears on cultivars which have significantly lighter SGW at the ear distal end compared to the basal grains had large proportions of unfilled grains.
3.A negative correlation exists the percentage of the florets with silk emerging 5 days after the first silk appearance and percentage of the decrease of a SGW at the distal end of the corn ear. The difference in SGW within an ear was small in the cultivars in which silk emerged relatively early, proceeding from the basal to the distal florets.
Therefore, the varietal difference in the frequency of unfilled grains are caused, not only by the dry matter accumulation during grain filling, but also by the partitioning of assimilates to the distal grains. Cultivars in which, silk emerged relatively early had : (i) uniform partitioning of dry matter within ear, (ii) greater translocation of assimilate to the distal grains, and (iii) fewer unfilled distal grains.