Yield determinants, root distribution and soil water uptake in maize (Zea mays) hybrids differing in canopy senescence under post-silking drought

ANTONIETTA M.; MAYDUP M.L.; CANO, M.G.; FANELLO D.D. ; ACCIARESI, H.A.; GUIAMET J.J.

Functional Plant Biology

CSIRO

Año: 2021 vol. 48 p. 1124 - 1138

Delayed canopy senescence or ‘stay-green’ (SG) trait in maize (Zea mays L.) could improve droughttolerance. Two field trials comparing four to six maize hybrids with different senescence rate werecarried out at Buenos Aires, Argentina, varying water availability during the reproductive period.Green leaf area at maturity was related to kernel weight (r2 = 0.94***) but its relationship withyield was weaker (r2 = 0.51–53*) and post-silking dry matter remobilisation was negativelyrelated with the SG trait (r2 = 0.84**). Two additional experiments were carried out in 63 Lpots by withholding irrigation in half of the pots after silking. The SG hybrid achieved lower rootbiomass at silking, a shallower root distribution and larger root growth in the post-silkingperiod. Under drought conditions, stomatal conductance was lower in the SG hybrid butphotosynthetic electron transport rate was higher. Higher post-silking dry matter assimilation inthe SG hybrid was compensated for by higher dry matter remobilisation in the non-SG. Higherkernel number per plant in the non-SG hybrid with no ability to compensate for by higherkernel weight in the SG, resulted in slightly higher yields in the non-SG under drought. A waterconservation strategy associated with a shallower root system could be linked to the SG trait,promoting faster water depletion at upper soil levels and reduced stomatal conductance at theleaf level but with no conclusive yield advantage.