Heat stress in temperate and tropical maize hybrids differences in crop growth, biomass partitioning and reserves use

Maize [Zea mays L.] hybrids with tropical genetic background are a promising source of heat stress tolerance, but their performance in high yielding environments remains poorly understood. Our objective was to assess [i] genotypic differences in the ecophysiological determinants of grain yield; i.e., fraction of light intercepted by crop [fIPAR], radiation use efficiency for biomass production [RUE], and harvest index [HI], and [ii] the responses of mentioned traits to brief episodes of high temperature. The contribution of stored reserves to grain yield was also analyzed. Field experiments included three contrasting maize hybrids [Te: temperate; Tr: tropical; TeTr: Te×Tr] grown under two temperature regimes [control and heated] during daytime hours. We tested heating [ca. 33-40°C at ear level] along three 15-d periods [GS 1: pre-silking; GS 2: from silking onwards: GS 3: active grain filling]. Heat stress had no effect on leaf area and fIPAR, but heating during grain filling affected light capture through reduced cycle duration, especially for the Te hybrid [average of -16.5 d]. Heating caused a large reduction in RUE, but this trait had a rapid recovery after heat removal and final shoot biomass was not much affected [between -3 percent and -33 percent]. HI was markedly reduced by heating and its variation was associated with changes in reserves use [r 2=0.61]. Grain yield in heated plots was better explained [r 2 greater than or equal to 0.92] by the variation in HI than by the variation in final shoot biomass [r 2 greater than or equal to 0.59]. Heat effects on grain yield were larger [i] when they occurred around flowering [-527gm -2 for GS 1 and -545gm -2 for GS 2] than during grain filling [-352gm -2 for GS 3], and [ii] for the Te hybrid [-599gm -2] than for the TeTr [-440gm -2] and the Tr hybrids [-384gm -2]. Heating around silking [GS 1 and GS 2] caused apparent accumulation of reserves during the effective grain-filling period. The opposite trend was detected among plots heated during active grain formation [GS 3]. The tropical genetic background did not penalize yield potential and conferred an enhanced capacity for enduring heat effects.

Bibliographic Details

Main Authors:	Rattalino Edreira, Juan Ignacio, Otegui, María Elena
Format:	Texto biblioteca
Language:	eng
Subjects:	BIOMASS PRODUCTION, GRAIN YIELD, HEAT EFFECTS, HYBRIDS, MAIZE, ZEA MAYS L., BIOMASS ALLOCATION, CROP PRODUCTION, CROP YIELD, ECOPHYSIOLOGY, GROWTH RATE, HIGH TEMPERATURE, LEAF AREA, TEMPERATE ENVIRONMENT, TEMPERATURE TOLERANCE, TROPICAL ENVIRONMENT, ZEA MAYS,
Online Access:	http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46552
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