The relation of lignification of the outer glume to resistance to shattering in wheat
1938
Vogel, O.A.
The breaking point of the outer glume of a wheat spikelet, when broken off, was between 0.1 and 0.2 mm above the inside base. The proportion of lignified tissue in the base of the glume is practically the same in the early dough stage as at maturity. The areas of greatest lignification were near the edges of the glume base. This is important because the edges are broken first when the glume is forced outward. The varieties more resistant to shattering were found to have the greater proportion of lignified tissue at the breaking point of their outer glumes. Among varieties similar in shattering resistance differences in lignification could not be determined because of variability among individual glumes. Longitudinal sections of the glume showed that the lignified band at the inner epidermis did not continue above the breaking point so prominently in varieties susceptible to shattering as in the resistant varieties. The enlargement of the grain in a spikelet during the dough stages often causes a buckling at the breaking point of the outer epidermis of one or both glumes. This may explain the fact that in an individual wheat spike the outer glumes of spikelets containing very plump grains often are removed more easily than from spikelets with smaller kernels. Although the measurement of lignification provides a better understanding of shattering, it is concluded that a direct measurement of the tenacity of mature glumes would be a better determination of shattering resistance.
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