Responses of Wheat Plants Under Post-Anthesis Stress Induced by Defoliation: I. Contribution of Agro-Physiological Traits to Grain Yield

Abstract

When water stress develops post-anthesis, wheat (Triticum aestivum L.) plants have to rely increasingly on remobilization of previously stored assimilates to maintain grain filling. In two-year field trials, we studied more than 20 agronomic and developmental traits in 61 wheat genotypes (27 F4:5 families, 17 parents used for the crosses and 17 standards), comparing plants that were defoliated (DP) by cutting off all leaf blades 10 days after anthesis with intact control plants (CP). Estimated contributions of stem and sheath assimilate reserves to grain weight/spike were from 10-54% and from 24-84% in CP and DP plants, respectively. Stem-related traits were among key traits determining stem reserve contribution (SRC). The most important genetic variables in differentiating genotypes for stress tolerance were biomass/stem, stem reserves mobilization efficiency and grain filling rate (GFR). Balance among traits related to yield maintenance in DP were more important than their high values. In general F4:5 families (FAM), that had been crossed to combine typical breeding traits such as biomass and yield components, showed better tolerance under moderate stress than standards and parents.

Vandenyje tirpių angliavandenių kaupimasis kviečio žiedynkotyje ir jų ryšys su morfoanatominiais bei produktyvumo požymiais

“…Average grain weight reduction across 44 genotypes and two years due to leaf blades removal was 19% (Dodig et al, 2016), which agrees well with results of the wheat experiments in field conditions under natural terminal drought (Amiri et al, 2013;Dias de Oliveira et al, 2015).…”

“…Accumulation of water-soluble carbohydrates usually occurs between anthesis and the completion of endosperm cell division (Slewinski, 2012). This period, which in our case occurred in May and June, was on average similar in both years by temperature, but rainfall and sunshine hours were higher in 2011 than in 2012 (Dodig et al, 2016). High environmental effects on WSC at athensis were reported also in other studies (Shearman et al, 2005;Ruuska et al, 2006).…”

“…Only those lines that were phenotypically adapted on the basis of medium height, early/medium flowering date, large grains and good disease resistance were kept. Genotype names, origin, parentage and criteria for crosses are given elsewhere (Dodig et al, 2016).…”

“…All samples and standards were determined as a mean value of three replicate measurements that differed by less than 5%. Measurements of morphological, anatomical and productive traits used in this study for their effect on WSC-related traits were described in Dodig et al (2016).…”

Dry matter accumulation of winter wheat and barley at different sowing dates

“…Significant relationships between biomass at maturity and grain yield have been reported both in wheat (Agegnehu et al, 2014) and barley (de San Celedonio et al, 2014). Moreover, during grain filling period, a substantial part of grain dry matter can originate from different vegetative parts of the plants (Aynehband et al, 2011;Dodig et al, 2016). Therefore, biomass accumulated during pre-and post-anthesis period has an important role in the final grain yield determination (Koutroubas et al, 2012), especially under unfavourable environmental conditions (Madani et al, 2010;Dodig et al, 2017).…”