Mitigating Salinity Stress in Barley (<i>Hordeum vulgare</i> L.) through Biochar and NPK Fertilizers: Impacts on Physio-Biochemical Behavior and Grain Yield

Increased soil salinity significantly inhibits crop production around the world. Over the last decade, biochar has been used in agriculture to improve plant productivity, soil quality, and as an alternative to plant amendment. This study was aimed to study the effect of biochar, NPK, and their combination on the growth, physio-biochemical traits, mineral contents, and grain yield of barley (Hordeum vulgare L.). Thus, a pot factorial experiment based on a completely randomized design with three replications was performed. Experimental treatments included four levels of biochar (0, 2, 5 and 10% of total pot mass), four different NaCl levels (0, 75, 125, and 200 mmol L−1), and with or without NPK fertilizer. The results showed that a negative effect on gas exchange parameters, photosynthetic pigments, SPAD value, minerals contents, and grain yield of barley under salinity treatments. In addition, our funding showed the negative effect on biochemical traits such as proline, soluble sugars, individual sugar, and phenolic compounds. The use of biochar, combined with NPK fertilizers, considerably increases these parameters and especially improves barley grains yield under severe salinity conditions (200 mM) with a dose of 2% and 5% (394.1 and 280.61 g m−2, respectively) of total pot mass. It is concluded that biochar amendment could be a promising practice to enhance barley growth under severe saline irrigation and NPK fertilization regimes

Dissecting the Genetic Basis of Lateral and Central Spikelet Development and Grain Traits in Intermedium-Spike Barley (Hordeum vulgare Convar. Intermedium)

Barley (Hordeum vulgare L.) is one of the major grain crops worldwide and considered as a model plant for temperate cereals. One of the barley row-type groups, named intermedium-barley, was used in our previous study where we reported that other genetic loci rather than vrs1 and Int-c could play a role in lateral spikelet development and even in setting grains. To continue this work, we used phenotypic and genotypic data of 254 intermedium-spike barley accessions aimed at dissecting the genetic basis of development and grain traits of lateral and central spikelet using genome wide association (GWAS) analysis. After genotypic data filtering, 8,653 single-nucleotide polymorphism (SNPs) were used for GWAS analysis. A total of 169 significant associations were identified and we focused only on the subset of associations that exceeded the p &lt; 10−4 threshold. Thirty-three highly significant marker-trait-associations (MTAs), represented in 28 different SNPs on all seven chromosomes for the central and/or lateral spikelet traits; such as kernel length, width, area, weight, unfilled spikelet and 1000-kernel weight, were detected. Highly significant associated markers were anchored physically using barley genome sequencing to identify candidate genes to either contain the SNPs or the closest gene to the SNP position. The results showed that 12 MTAs were specific for lateral spikelet traits, nine MTAs were specific for central spikelet traits and seven MTAs for both central and lateral traits. All together, the GWAS and candidate gene results support our hypothesis that lateral spikelet development could be regulated by loci different from those regulating central spikelet development

Spike developmental stages and ABA role in spikelet primordia abortion contribute to the final yield in barley (Hordeum vulgare L.)

Background: Salinity is a significant environmental stress factor limiting crops productivity. Barley (Hordeum vulgare L.) has a natural tolerance to salinity stress, making it an interesting study object in stress biology research. In the present study, for the first time the effect of salinity stress on barley inflorescence developmental stages was investigated. Five spring barley genotypes irrigated with saline water (12.5 ds/m NaCl) were compared to controls treated with normal tap water. We measured abscisic acid (ABA) concentrations in the apical, central and basal sections of the immature inflorescence at green anther (GA) stage. The role of ABA in spikelet primordia development, atrophy and abortion and final yield was evaluated. Results: A time course experiment starting from double ridge until green anther (GA) stages revealed that salinity reduced the length of spike developmental stages in all genotypes causing shortened of the plant life cycle. The shortened plant life cycle negatively affected plant height and number of tillers/plant. Salinity also affected spikelet primordia development. In both control and salinity treated plants apical spikelet abortion started in late awn primordium (AP) stage. However, under salinity treatment, significantly more spikelets were aborted, thus directly affecting plant yield potential. ABA, which plays a role in the spikelet/floret abortion process, was markedly elevated in the base and apex of salt treated spikes correlating with an increased spikelet abortion in these regions. Conclusions: Overall, salinity treatment reduced all plant and yield-related parameters investigated and turned some of the correlations among them from positive to negative or vice versa. Investigations of ABA role in floral development and phase duration of barley spike showed that, ABA regulates the spikelet/floret abortion process affecting the yield potential under salinity and control conditions