Kernel weight responses to the photothermal environment in maize dent × flint and flint × flint hybrids

Abstract

Maize (Zea mays L.) grain yield is assumed to be source limited during the flowering period but sink limited during grain growth; however, environmental restrictions during active grain filling may strongly affect final kernel weight (KW). In this study, we evaluated the effect of natural changes in photothermal conditions during lag phase (LP) and effective grain‐filling period (EGFP) on KW, its physiological determinants, and the post‐flowering source–sink relationships of flint and semident germplasm. F1 hybrids of flint × flint and dent × flint background were tested during four seasons (Y1, Y2, Y3, and Y4). Across years, the highest KW (286 mg) was obtained under the maximum photothermal quotients during LP (PTQLP = 1.18 MJ m−2 °C−1) and EGFP (PTQEGFP = 1.07 MJ m−2 °C−1) of Y2, whereas the smallest KW (252 mg) and source–sink ratio during grain filling was obtained under the lowest PTQEGFP (.79 MJ m−2 °C−1) of Y3. Supra‐optimum temperatures during LP of Y3 negatively affected potential KW determination, and hence kernel growth rate (P < .001) as a result of reduced assimilate availability per kernel. Hybrids dent × flint exhibited higher grain yield, kernel number, and plant growth around flowering than flint × flint throughout evaluated seasons but had reduced source–sink relationship during grain filling (P < .05) and increased KW sensitivity (P < .001) to changes in the photothermal conditions. Results emphasized the importance of the photothermal environment during grain filling on KW determination (particularly for seasons with great photothermal imbalance between filling subphases) as well as the dependency of KW responses on the genetic background.

Importance of sowing date optimization for morphological properties and grain yield of maize inbred lines

“…Limited environmental conditions during grain filling can strongly affect yield. Photothermal conditions are important, especially seasons with photothermal imbalances that affect kernel weight and yield (Hisse et al, 2021).…”

Diallel analysis of kernel weight and grain‐filling traits in maize grown under contrasting nitrogen supply

“…The F 1 × E component corresponding to each N level was entirely represented by the F 1 × Y interaction. In this sense, both experimental years differed notably in the photothermal conditions during grain filling (Hisse et al., 2021), affecting, to a greater extent, the potential condition corresponding to the N200 treatment. For this N level, a higher response degree to the changes in the photothermal environment is expected, with the subsequent increase in the F 1 × E component (Table S1), and hence, in the reduction of heritability (Figure 2).…”

“…KW, KGR, and durations of the effective grain‐filling (EGFD) and lag ‐phase (LPD) periods were estimated by fitting a bilinear model relating kernel dry weight and TT after silking (Borrás & Otegui, 2001). Maximum kernel volume (KV MAX ) was estimated by fitting a bilinear model relating kernel volume and TT after silking (Hisse et al., 2021). Maximum kernel water content (KWC MAX ) was computed by fitting a trilinear model relating kernel water content and TT after silking (Gambín et al., 2007).…”