Nomenclature


2.3.3. Thousand kernel weight

286 Wheat Improvement, Management and Utilization

moisture content [13, 44].

Acknowledgements

Nomenclature

L Length (mm) W Width (mm) T Thickness (mm) FFD Factor-form-density φ<sup>s</sup> Sphericity (%)

Di any measured dimension (mm)

Ap Largest projected area (mm<sup>2</sup>

<sup>X</sup> r Sum radios of curvature

N Number of measurements (Eq. (2)) Total numbers of corners (Eq. (4))

D Average dimension or equivalent diameter (mm)

Ac Area of smallest circumscribing circle (mm<sup>2</sup>

R Radius of the maximum inscribe circle (mm) (Eq. (4)) Mean radius of the object (mm) (Eq. (5))

weight, due to a greater endosperm to bran ratio [29].

Ponce-García thanks to CONACyT for postdoctoral scholarship support.

)

)

Thousand kernel weight (TKW) measures the mass of the wheat kernel and is an essential parameter for the selection of cultivars with the best physical and physiological seed quality. Generally, higher TKW values are positively related to potential flour extraction or yield [46], because this property is closely related to grain size and proportion of endosperm to germ and pericarp tissues [5]. Wheat breeders and flour millers employ this method as a complement to test weight to better describe wheat kernel composition and potential flour extraction [16]. TKW could be used as an index of wheat milling value and is a good parameter for evaluation of kernels as seed material [11]. When the grain is undamaged may be expected high test

Finally, it is important to highlight that grain moisture content has deep influence on the physical properties, particularly those related with volumetric grain weight and density in bulk as it modifies surface properties of seed-coat as well as the properties of kernel endosperm. Several studies [34, 42, 43, 47] have reported the effect of moisture content on different wheat kernel physical properties and concluded that increasing of moisture content level increased axial dimensions, thousand kernel weight, porosity, kernel volume and sphericity, while bulk density decreased. Higher grain moisture content results in an increase in susceptibility of grains to deformation, thus physical properties of cereal grains vary as a function of

