Assessment of grain starch content and responses to CMS-S and CMS-C in high-starch maize hybrids

Background. Increasing the production of native and modified starch from maize requires raw materials with high starch content in grain. Materials and methods. An experimental panel of 780 simple high-starch maize hybrids produced with CMS-S and CMS-C lines underwent two-year testing. Starch content in the grain of the lines and their hybrids was assessed with IR spectrometry. Native starch content in the grain of hybrids with highest yields was measured at the All-Russian Research Institute of Starch and Starch-Containing Raw Materials Processing using the method proposed by L. P. Nosovskaya with coauthors. Responses to CMS were scored according to G. S. Galeev’s scale. Results. Grain starch content was found to vary from 58% to 72% DMB throughout the tested panel. IR spectrometry helped to identify 22 hybrids with high (72.03–72.67%) starch content, and 5 hybrids promising for deep grain processing, combining high protein (10.3–13.53%) and oil (3.77–5.03%) levels with high starch content (69.02–70.4%) in their grain. Native starch extraction using L. P. Nosovskaya’s method showed that grain starch content in the best 68 hybrids ranged from 70.03 to 71.95% DMB. The collection was ranked according to the main heterotic groups: 57 lines of Iowa Dent, 26 lines of Stiff Stalk Synthetic, and 28 lines of Lancaster. For CMS-S and CMS-C types, 33 and 6 maintainers, and 9 and 8 restorers were selected, respectively. The hybrids were distributed across the following FAO maturity groups for maize: FAO 200–299 (14 hybrids), FAO 300–399 (7), FAO 400–449 (21), and FAO 450–500 (29). Conclusion. Assessing agronomic and breeding prospects of the best 68 hybrids between high-starch maize lines and sterile testers proved their potential for producing native starch to at least 70–72% DMB. Five hybrids were identified as promising for yielding native starch (69.02–70.4% DMB), as well as protein (10.3–13.5% DMB) and oil (3.77–5.03% DMB) by-products during deep grain processing.