This proof-of-concept field study investigated whether different phosphorus fertilizer sources (soluble diammonium phosphate (DAP) and slow-release struvite) and application methods (broadcast or near-root placement) can modify maize starch properties for biobased applications. Placement increased shoot P content but decreased starch P/PO43– levels relative to broadcast. Struvite produced smaller starch granules than DAP, and broadcast treatments led to smaller granules than placement─especially with struvite. FTIR (1047/1022 cm–1) revealed contrasting trends in starch structural order depending on the fertilizer type and application method. These structural changes resulted in higher gelatinization onset (T0) and peak (Tp) temperatures in DAP-broadcast and reduced water absorption in DAP-placement. Broadcast and struvite treatments showed higher modulus (G′ and G″ values) with temperature dynamics than placement and DAP, respectively. DAP-placement showed the slowest hydrolysis rates among all treatments, consistent with starch P/PO43– levels. These results indicate a potential route to tailor the starch structure and functionality through P management.
Zhang et al. (Thu,) studied this question.