| Abstract: | The properties of starches during development of several endosperm mutants of maize were investigated. Starch contents of normal and waxy (wx) kernels were higher than those of dull (du), sugary-2 (su2), and amylose-extender (ae) kernels, and in general the greater increase in starch contents occurred earlier in kernel development. The normal, du, su2, and ae mutants in that order, respectively, increased the apparent amylose concentration of the starches as measured by the “blue value” method. Within each of these genotypes, absorption intensity increased and λ max. of absorption curves shifted to a longer wavelength region with increasing maturity. Waxy starches did not change in either of these properties at any of the developmental stages. Few detectable differences were observed in X-ray diffraction intensity, gelatinization temperature, heat of gelatinization, and the photopastegrams within these genotypes during development. Exhaustive degradation of starch granules by glucoamylase showed that ae starches were more resistant to amylase than the other starches. Except for wx, the starches tended to be more resistant to amylase with increasing maturity. |
