Intensive agronomic practices such as deep and repeated tillage and applying high mineral fertilization rates to improve crop yields have gradually determined soil resource degradation. A study was carried out over a two-year period (2015 and 2016) to assess effects of tillage (plough; subsoil; and spading) and fertilization (mineral vs. organic) on soil health relative to carbon and nitrogen dynamics in potato crop in the Mediterranean environment. Microbial indices could be successfully used as tool for assessing soil health in terms of predictors and indicators of carbon sequestration and nitrogen availability. The microbial quotients, calculated as percentage of the microbial-C to total organic C (C_mic:C_org), was significantly higher in subsoiling than in plowing and spading soil tillage, and higher in 2016 (3.19%) than 2015 (1.72%). The activity of enzymes involved in C cycle was significantly higher in subsoiling and spading than in plowing, while acid phosphatase was positively affected by spading and arylsulfatase increased with plowing. The whole enzyme activity expressed as synthetic enzymatic index (SEI) was positively affected by subsoiling and plowing in 2015 (4254) compared to spading tillage (3934). A general decrease in soil enzyme activity in 2016 than 2015 was observed. The subsoiling in potato crop favored the immobilization of carbon and nitrogen during the wet spring–summer period. Conversely, the plowing favored the mineralization process when the spring–summer period became more dried.

Crop yield under reduced tillage (RT) practices is a concern for sustainable production worldwide because it is related to different environmental and agronomic factors than conventionally tilled soils. This study aimed to evaluate how climate, soil, and farming practices could affect crop yield under RT, especially under different sources of fertilisation [mineral (M), mineral + organic (MO), and organic (O)]. Multilevel meta-analysis was adopted. The analysis was performed taking into consideration environmental conditions, soil properties, crop rotation, and crop species. Only studies that reported the interaction effect of soil tillage and nutrients management on grain yield were included. The results suggest that the impact of soil tillage and fertilisation sources on crop yield depended on crop species. Using reduced tillage practices, adopting only organic nutrient sources could produce enough grains for legume crops. However, combining both inorganic and organic fertilizers added benefits for cereal crops in terms of grain yield production. This study highlights how conservation tillage practices could be affected by environmental and agronomic factors.

Agricultural intensification may cause significant changes in weed density due to high weed competitiveness. Therefore, sustainable practices are to be designed to get maximum benefits of plant biodiversity in the agro-ecosystems. Field experiments were conducted in 2013/2014 and 2014/2015 to evaluate the impact of fertilizer source and soil tillage on weed spectrum in durum wheat (Triticum durum Desf.). Treatments in this study were: (i) two fertilizer sources (mineral fertilizer (MIN) and municipal organic waste (MOW)), and (ii) three tillage regimes (plowing (Plo), subsoiling (Sub) and spading (SM)). A randomized complete block design with three replications was adopted. Data on weed density and biomass were collected at the wheat tillering stage. Weed density was higher in MOW than MIN (53.8 vs. 44.0 plants·m⁻²), especially in 2014/2015, while S was the highest among tillage regimes (58.2 plants·m⁻²). Annual and monocots species were always the highest in subsoiling (43.5 and 10.1 plants·m⁻²). The density of perennial and dicots species was higher in MOW compared with MIN plots, regardless of soil tillage management. Weed community, in terms of weed species composition, varied between the two fertilizer sources, while among soil tillage regimes, it only differed between plowing and subsoiling. Based on the analysis of weed community composition, annual dicot species were mainly associated with plowing, while monocots tended to be associated with MIN fertilizer. Spading tillage may be a useful strategy for managing weed diversity under organic fertilization, where mineral soil nitrogen availability was limited. Conversely, the spading machine produced lower grain yields than plowing with mineral fertilizer application.

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 < 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.

Agricultural practices should be approached with environmental-friendly strategies, able to restore soil organic matter and reduce the greenhouse gas emissions. The main objective of this study is to evaluate the environmental benefits, in terms of CO₂ emissions and carbon balance, of some agricultural practices for potato cultivation. A randomized complete block design was adopted where the treatments were: (a) tillage systems (plowing; subsoiler and spading); (b) fertilizer sources (mineral and organic). All treatments were replicated three times. Potato yield and its carbon content, soil CO₂ emissions, temperature, and volumetric water content were measured. The CO₂ emissions were higher in organic than in mineral fertilizer (0.60 and vs. 0.77 g m⁻² h⁻¹, respectively), while they were low in spading compared to the other soil tillage (0.64 vs. 0.72 g m⁻² h⁻¹, respectively). Carbon input was the highest in plowing and organic fertilizer 4.76 and 5.59 Mg C ha⁻¹, respectively. The input/output ratio of carbon varied according to the main treatments. The findings suggest that spading tillage and organic fertilizer might result in environmental and agronomical benefits, further research should be performed to evaluate to possibility to extend the results to other environments and crops.

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.

Understanding how biological systems evolve across changing conditions has been a crucial focus of research. Mutations change the genetic context in which genes are expressed and yet the mechanisms underlying mutation fitness are still unclear. We use the sweet corn mutant sugary1 (su1) as a model for understanding the genetic regulation of mutant fitness, focusing on the mutant × genotype interaction across diverse environments. In a previous work, we identified quantitative trait loci (QTLs) affecting fitness in a mapping population of recombinant inbred lines (RILs) derived from a cross between field corn (B73) × sweet corn (P39 or IL14h) parents; however, the epistatic effects of these QTLs on su1 fitness were not investigated. In the present study, we estimated fitness for two seed production environments. Viability of su1 is under genetic and environmental controls, regulated by multiple genes with minor contributions, and these genes depend on the genotype into which the mutation is introduced and on the environment. Some QTLs were in linkage disequilibrium with the maize gene Su1 and had epistatic effects on su1 fitness. These QTLs could be used by sweet corn breeders by combining the most favorable alleles associated with su1 viability in breeding new genotypes from field × sweet corn crosses. These results also have implications for mutagenesis breeding or genome editing because the epistatic effects of the target genome on the new alleles generated by these techniques could affect the success of the breeding program.