Phenotypic plasticity of maize grain yield and related secondary traits: Differences between inbreds and hybrids in response to contrasting water and nitrogen regimes

RUIZ, MÓNICA B.; D'ANDREA, KARINA E.; OTEGUI, MARÍA E.

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Año: 2019 vol. 239 p. 19 - 29

0378-4290

Correct characterization of heritability and phenotypic plasticity (PP)is critical for breeding purposes. The latter refers to the variation range of a trait in response to changes in the environment and has been assessed as the difference between percentiles 10th (P 10 )and 90th (P 90 )of each trait, which does not reflect below the median (P 50 )variations to the same extent as the above the median ones. This inconsistency may affect the classification of stable (low PP)or plastic (high PP)given to traits, as well as their relative ranking and PP relationship with heritability. The objectives of current research were to evaluate corrected PP (PP C )variation in grain yield (GY)and related secondary traits among contrasting maize genotypic groups (inbreds and hybrids)grown under contrasting water regimes (WR)and nitrogen (N)availabilities. The relationship between PP C and broad-sense heritability (H 2 )was also assessed. Field experiments were conducted during three (N)or seven (WR)growing seasons at two mid-latitude environments of Argentina. Measured traits were days and thermal time to 50% anthesis (A 50 and TT A )and to 50% silking (S 50 and TT S ), the anthesis-silking interval in days (ASI D )and in TT (ASI TT ), plant height (Ph), prolificacy (Pr), GY, kernel numbers (KN), and kernel weight (KW). Values for percentiles 10th (P 10 ), 50th (P 50 )and 90th (P 90 )of each trait were identified for each treatment combination. P 50 was set to 1, and values obtained for P 10 and P 90 were expressed as ratios with P 50 . P 10 was corrected (P 10C = P 50 ? P 50 /P 10 )to reflect the below P 50 variations to the same extent as those above P 50 . Corrected PP was estimated as PP C = P 90 - P 10C . P 90 values of all traits corresponded to non-stressed plots whereas P 10C values corresponded to stressed plots, except for ASIs (opposite trend). A large plasticity (PP C >mean PP C )was usually verified for ASIs, GY and KN. Mean inbreds PP C had a larger variation than mean hybrids PP C (+19% for WR and +29% for N), except for GY under contrasting WR (hybrids > inbreds). A common trend across all evaluated traits was the markedly larger effect on PP C of P 10C than of P 90 , in agreement with the predominant representation of stressful conditions by the former and in contrast to previous studies where no correction was performed on P 10 . Our results demonstrated the lack of relationship between H 2 and PP and improved current knowledge about the importance of environment modulation on PP of most expansion-related and production traits, highlighting the relevance of the evaluated resource (water or N)as well as of the genotypic group (hybrids or inbreds)on final phenotype expression.