Yield generation and radiation use in hybrids with and without a genetic alteration in height.

VILLAVICENCIO, J.; PLUDA, P.; ROTILI, D.H.; URIBELARREA, M.; ROIG, J; MADDONNI, G. A.; CAGNOLA, J.I.

Rosario

Congreso; XXXIV Reunion de la Sociedad Argentina de Fisiología Vegetal; 2023

SAFV

Brachytic maize hybrids (br2) reduce internode growth, and their shorter stature prevents costly yield losses due to lodging, especially in late plantings or windy regions. However, the impact of br2 on yield in a given site and season, which depends on cumulative intercepted radiation (related to interception efficiency, IE), its conversion into biomass (through radiation use efficiency, RUE), and its partitioning to ears (harvest index, HI), remains unknown. Plant height modifies these efficiencies. Our objective was to compare the br2 hybrids and their traditional iso-hybrids (same genetic base without short-stature mutation), analyzing IE, RUE, and HI. We cultivated two pairs of maize hybrids (1 and 2), each in the br2 (S) and traditional (T) versions, planted at 4, 8, and 16 pl m-2 in a split-plot design under irrigation, with high fertilization levels. An alfa = 0.05 was considered for comparisons between iso-hybrids. The hybrid x density interaction was non-significant for yield. Grain yield was higher for T1 than for S1, while there were no differences between T2 and S2. Also, the yield was lower at 4 pl m-2 and maximized at 8 and 16 pl m-2. All hybrids reached the critical leaf area index (IE > 0.95), and iso-hybrids had similar cumulative intercepted radiation. By contrast, density affected these variables, as the 4 pl m-2 only reached IE = 0.9, determining a lower cumulative intercepted radiation (IE: 4 < 8 < 16 pl m-2). RUE was higher for T1 than for S1 but similar between T2 and S2, while HI did not differ between iso-hybrids. For both hybrid pairs, RUE increased with density, while HI was similar across densities for pair 2 and lower at 16 pl m-2 than 4 or 8 pl m-2 for pair 1. In conclusion, br2 did not affect IE, RUE, HI, or yield for hybrid pair 2, but a lower RUE was determinant of a lower yield for S1 versus T1, suggesting that br2 could be a beneficial technology against lodging without negative effects on yield depending on the hybrid.