Continued starch accumulation in the endosperm has now caused the milky inner fluid to thicken to a pasty consistency. Usually four embryonic leaves have formed by this time and the R4 embryo has greatly increased in size from the R3 stage. The shelled cob is a light red to pink color due to beginning color changes of the surrounding materials (lemmas and paleas).

Toward the middle of R4, the embryo side width will stretch across over half of the kernel side width. Kernels must be dissected longitudinally through the center as with the far right kernel in fig. 46 to observe this. The reduced fluid and increased solids within the kernel at this time produce a doughy consistency .

Just prior to R5 kernels along the length of the ear begin to dent or dry on top. The fifth and last embryonic leaf, and the lateral seminal roots have formed by this time. These five embryonic leaves are the same first leaves to appear the following season after germination and VE.

Management Guides - R4 Stage - Dough

The embryo continues to develop very rapidly through this stage. The kernels are now about 70 percent moisture and have accumulated close to half of their mature dry weight.

fig. 45

fig. 46

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