Barley Leaf Area and Leaf Growth Rates Are Maximized during the Pre-Anthesis Phase

Abstract

Leaf developmental traits are an important component of crop breeding in small-grain cereals. Surprisingly, little is known about the genetic basis for the differences in barley (Hordeum vulgare L.) leaf development. The two barley row-type classes, i.e., two-and six-rowed, show clear-cut differences in leaf development. To quantify these differences and to measure the genetic component of the phenotypic variance for the leaf developmental differences in both row-type classes we investigated 32 representative spring barley accessions (14 two-and 18 six-rowed accessions) under three independent growth conditions. Leaf mass area is lower in plants grown under greenhouse (GH) conditions due to fewer, smaller, and lighter leaf blades per main culm compared to pot-and soil-grown field plants. Larger and heavier leaf blades of six-rowed barley correlate with higher main culm spike grain yield, spike dry weight, and harvest index; however, smaller leaf area (LA) in two-rowed barley can be attributed to more spikes, tillers, and biological yield (aboveground parts). In general, leaf growth rate was significantly higher between awn primordium and tipping stages. Moderate to very high broad-sense heritabilities (0.67-0.90) were found under all growth conditions, indicating that these traits are predominantly genetically controlled. In addition, our data suggests that GH conditions are suitable for studying leaf developmental traits. Our results also demonstrated that LA impacts single plant yield and can be reconsidered in future breeding programs. Six-rowed spike 1 (Vrs1) is the major determinate of barley row-types, the differences in leaf development between OPEN ACCESSAgronomy 2015, 5 108 two-and six-rowed barleys may be attributed to the regulation of Vrs1 in these two classes, which needs further testing.

Genomic dissection of plant development and its impact on thousand grain weight in barley through nested association mapping

“…QTLs that affect early development are characterized by their influence on SHO and SEL. SEL is strongly related to the phase from awn primordium to tipping, which was shown to be the most decisive developmental phase for spikelet survival ( Alqudah and Schnurbusch, 2014 ) and leaf growth rate ( Alqudah and Schnurbusch, 2015 ) in barley. The length of this phase is therefore assumed to play a key role in determining a plant’s yield potential.…”

“…This phase is terminated with anthesis resulting in the onset of the grain-filling phase. The length of different preanthesis subphases has been shown to be under genetic control ( Kernich et al , 1997 ; Borras et al , 2009 ; Borras-Gelonch et al , 2010 ; Borras-Gelonch et al , 2012 ; Alqudah et al , 2014 ) and impacts yield-related traits ( Miralles et al , 2000 ; Alqudah and Schnurbusch, 2014, 2015 ). The postanthesis phase is also assumed to have a major impact on yield by determining the time frame for grain-filling ( Evans and Wardlaw, 1976 ; Egli, 2004 ), which controls the yield component grain weight ( Distelfeld et al , 2014 ).…”

Leaf primordium size specifies leaf width and vein number among row‐type classes in barley

“…Barley exists in two morphologically distinct spike forms, referred to as ‘two‐rowed’ and ‘six‐rowed’, which also differ in their leaf blade area (LA) (Alqudah and Schnurbusch, ). To study the natural genetic variation of LA in spring barley, 218 worldwide accessions (125 two‐rowed and 93 six‐rowed, Table S1) under greenhouse conditions (Methods S1) at four developmental stages (Zadoks stage, Z): awn primordium (Z31–33), awn tipping (Z49), heading (Z55) and anther extrusion (Z65) (Zadoks et al ., ; Alqudah and Schnurbusch, ) were analysed. A significant difference ( P ≤ 0.05) in the main culm LA between row‐types, in which six‐rowed forms had significantly larger LA at all developmental stages after awn primordium (AP) (Figure a), was detected.…”

“…weight per unit leaf area) has been shown to be associated with increased net photosynthetic capacity ( A max ) and leaf nitrogen (N) (Reich et al ., ). Interestingly, Alqudah and Schnurbusch () found that six‐rowed barley (wide leaf) also had significantly lower LMA than two‐rowed types under different growth conditions, implying that six‐rowed forms may have higher leaf nitrogen (N) than two‐rowed. The observed significant increase of leaf nitrogen (%) during the important pre‐anthesis phase in six‐rowed barleys supported this.…”

Barley yield formation under abiotic stress depends on the interplay between flowering time genes and environmental cues

“…During shoot elongation, which captures the growth period between establishing awn primordia and ear emergence, the leaf growth rate and the potential grain number per area are defined 51,53,58 . An extended shoot elongation phase may thus improve grain yield by increasing leaf size, i.e.…”