Short-stature and tall maize hybrids have a similar yield response to split-rate vs. pre-plant N applications, but differ in biomass and nitrogen partitioning

Context: Development of semi-dwarf wheat (Triticum aestivum) and rice (Oryza sativa) led to increased yields and agronomic efficiencies with less lodging. While these short-stature cereals have become common in global crop production, commercial maize (Zea mays L.) hybrids remain tall. There is no information currently available on plant N uptake or yield responses to N timing for short stature maize hybrids. Objective: We tested three hypotheses on short-stature and tall maize hybrids 1) short-stature maize hybrids would have similar yield response to in-season N application compared to tall hybrids, 2) short-stature maize hybrids would have similar dry matter and N uptake patterns to tall hybrids, and 3) there would be significant partitioning differences between short-stature and tall hybrids in dry matter and N within the plants at multiple growth stages. Methods: In ten side-by-side field trials across eight site-years in the Midwestern USA, we tested the yield response and underlying nitrogen physiology of short-stature maize hybrids and tall comparators to split-rate N application. Results: We show that split-rate application of 50% of the total N at mid-vegetative stages (V6) averaged 0.24 t ha-1 more grain yield across 10 field trials (positive yield response in 6 out of 10 trials) compared to a single 100% up-front N application, with the same pattern for short-stature and tall hybrids. In both hybrid statures, V6 N applications showed more frequent improvement in grain yield than V12 N applications. Total N uptake at maturity was not different between short-stature hybrids and their tall counterparts (p = 0.62). N partitioning differed between short-stature and tall hybrids; leaves in short-stature hybrids had 5% higher N concentration and 13% more N content in early vegetative development, stalks had 18-27% less dry matter and 5-25% less N content, depending on growth stage, while R1 ears averaged 18% more dry matter and N accumulation (p < 0.10 in all cases). At maturity short-stature hybrids had 4% higher harvest index and 3% higher N harvest index (p < 0.10). Conclusions: Based on these results, we expect that N management recommendations in short-stature maize hybrids would be similar to their tall counterparts, but that short stature mitigates logistical risk by providing more flexibility for in-season N applications. Implications: This study provides a unique, robust dataset on yield and physiological response to split-rate N treatments in commercially relevant maize hybrids.

Automated summary

The study found that short-stature maize hybrids have similar yield responses to in-season nitrogen application compared to tall hybrids, and there are partitioning differences in dry matter and nitrogen within the plants between the two hybrid statures. Short-stature hybrids also provide more flexibility for in-season nitrogen application.