Comparative kernel growth and yield components of two- and six-row barley (Hordeum vulgare) under terminal drought simulated by defoliation

Abstract

Barley (Hordeum vulgare L.) is often grown in sites with low rainfall and high temperature during grain filling. Because spike architecture is one of basic footprints of barley domestication, the importance of spikes in adaptation to different environments or abiotic stresses can be hypothesised. In order to compare different barley spike types in terms of kernel growth and yield components, we tested 15 two-row and 10 six-row winter genotypes in eight environments where terminal drought was simulated by defoliation at 7 days after heading (7 DAH). Control plants were grown intact. On average, two-row genotypes outyielded six-row genotypes by 17% under control conditions and 33% under simulated late drought. Observations of kernel dry weights from 7 DAH through to harvest maturity at 5-day intervals were regressed onto a measure of thermal time. After preliminary evaluation of four nonlinear (S-shaped) models for kernel dry-weight accumulation, the ordinary logistic model was deemed the most appropriate in most cases and was finally applied to all plant-growth curves. Four parameters were estimated from the logistic model. Whereas two earliness estimators (inflection point and thermal time needed to reach maximum kernel weight) were similar for the two barley types, maximum kernel weight (Ymax) and mean rate of kernel growth (RG) were higher (P<0.05) in two-row than in six-row barleys. Differences in Ymax and RG among six-row barley genotypes were greater between control and defoliation treatments than between years, whereas among two-row barley genotypes, differences between years were greater, suggesting better stability of six-row types and better drought tolerance of two-row types in the tested barley set.

Post-Anthesis Mobilization of Stem Assimilates in Wheat under Induced Stress

“…Presented results depicted statistically significant variation among genotypes in response to chemically-induced stress. These results are in line with previous reports suggesting genotype-specific responses towards induced stress in different crops [44][45][46][47]. After the development of semi-dwarf genotypes with increased yield, the post-green revolution era resulted in reduced accumulation of water-soluble carbohydrates in the stem [44].…”

Breeding progress in grain filling and grain yield components of six-rowed winter barley

“…In cereal crops, grain weight is determined by two major parameters, namely duration and rate of grain filling. As previously reported (Kandić et al, 2018;Dodig et al, 2019), environmental factors had a strong influence on grain weight, grain filling rate and duration in Pannonian cereal crops. Environmental conditions in the Pannonian Plain are characterized by appearance of high temperatures and water deficit after anthesis, resulting in decreased duration of grain filling period and grain weight reduction (Pržulj et al, 2015).…”

“…Time to maximum grain filling rate (TMGFR) was calculated from the non-linear equation as time from anthesis to the maximum grain filling rate and expressed in GDD. Rate of grain growth (RGG) was calculated according to Dodig et al (2019). Grain yield (GY) in t ha -1 was determined at maturity after mechanical harvesting and adjusted to 13% moisture.…”

Impact of Rising Temperature in the Deposition Patterns of Bioactive Compounds in Field Grown Food Barley Grains

“…The effective grain filling phase (between the end of the lag phase and physiological maturity) is when dry matter and bioactive compounds accumulate, determining the final weight and nutrient composition and the quality of the grain [ 9 ]. It is well documented that the accumulation of dry matter during grain filling follows a sigmoid pattern [ 10 ]. This is characterized by three phases: lag phase (fertilization and rapid cell division), the effective grain filling period (accumulation of reserve components) and the maturation drying phase (loss of water content and reaching “physiological maturity”, i.e., maximum dry matter accumulation) [ 11 , 12 ].…”