High night temperature during post-flowering in field-grown maize increases night respiration and reduces kernel number and photosynthesis

BELÉN KETTLER; CONSTANZA CARRERA; FEDERICO NALLI; FERNANDO ANDRADE; NICOLÁS NEIFF

Santa Fe

Congreso; XXXIII Argentinian Meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología Vegetal

This study aimed to evaluate the effect of high night temperature (HNT) during maize post-flowering (R1+2d to R1+16d) on kernel number (KN), crop growth rate expressed in thermal units (CGRTU), night respiration (Rn), photosynthesis (Amax), and cell membrane stability (CMS). An experiment was conducted at Corrientes (27°28?45??S; 58°47?06??W) in a split-plot design with three replications during the 2019 spring season without water-nutrient restrictions. Two thermal conditions were assayed using polyethylene shelters (main plots): (i) HNT from 1900-0700h, and (ii) ambient night temperature (ANT). Two hybrids (Te, temperate; and St, subtropical) were randomly assigned to subplots within each main plot. At R1+2d and R1+16d, CGRTU was estimated through aboveground biomass sampling. The KN was estimated at harvest. Leaf gas exchange was measured in ear leaves during the night (Rn) and midday (Amax). The CMS was estimated by the electrical conductivity of ear leaf discs. Night mean temperature during post-flowering period was 27.7°C and 23.3°C for HNT and ANT, respectively. The KN was reduced by 9% (p