Context. Although waterlogging is known to decrease grain yield in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), its effect on plant N traits is still unknow.

Aims. This study evaluated biomass N dynamics and partitioning to grains, in wheat and barley plants subjected to waterlogging.

Methods. Under contrasting environmental conditions, two pot experiments exposing wheat and barley plants to waterlogging events for 15–20 days at five different developmental stages, from emergence to maturity were performed. Grain N concentration, grain N content, biomass N concentration, N utilisation efficiency (NUE) and N remobilisation were recorded.

Key results. Both species responded similarly to waterlogging for most N traits. Reductions in grain N content differed according to the moment waterlogging occurred. The greatest reductions (46–77% compared to the control) being for waterlogging from the beginning of stem elongation to anthesis, which also showed the highest reductions in N remobilisation, N uptake at maturity, and N partitioning to the grains, but only a slight decrease in NUE. Grain N concentration raised drastically (up to 45 mg N g DW⁻¹) with minimal grain yields. N concentration of aboveground biomass decreased during waterlogging, recovering control values at maturity. N content at maturity was related to the total biomass.

Conclusions. Waterlogging differentially reduced N uptake and remobilisation to grains of wheat and barley depending on the developmental stage when water excess occurred.

Implications. The impact of waterlogging on N economy of wheat and barley appears indirect and predominantly related to carrying effects of the stress on carbon economy due to growth reductions.

In wheat (Triticum aestivum L.), S-type cytoplasmic male sterile (S-CMS) lines can mainly transform from sterility to fertility at the mononuclear pollen stage. Observations from microscopy revealed an inhibition of starch accumulation within the pollen grain, suggesting that an alteration in carbohydrate metabolism or assimilate supply may be involved in S-CMS pollen abortion. We measured levels of various carbohydrates and activities of key enzymes of sucrose metabolism at the mononuclear pollen stage in anthers collected from an S-CMS line and its maintainer line and found that nonreducing sugars increased in S-CMS anthers. Sucrose accounted for part of the nonreducing sugar accumulation. The activity of invertase declined significantly, whereas sucrose synthase activity during starch accumulation in pollen showed no significant change in S-CMS anthers at the mononuclear pollen stage. The results suggest that sucrose conversion and inhibition of invertase were probably responsible for the pollen abortion. Because there is a high correlation between the rate of ethylene evolution and sucrose content, ethylene anabolism was determined. TaACS2 regulates sucrose metabolism in pollen probably through catalysing the synthesis of ethylene precursor 1-aminocyclopropane-1-carboxylic acid in wheat. In this study, ethylene production of anthers underwent accumulation, revealed by gas chromatography, and expression levels of TaACS2 were upregulated in the S-CMS line, as determined by quantitative real-time PCR. We investigated the DNA methylation pattern of TaACS2 in the core promoter region using bisulfite genomic sequencing, and lower methylation was observed in the S-CMS line. These results suggest that DNA methylation of the TaACS2 gene may be involved in the sterility–fertility transition by regulating the synthesis of ethylene in S-CMS anthers.

Context. The depth-to a constraint determines how much of the soil profile, and the water it contains, can be accessed by plant roots. Information describing the impacts of soil constraints on available water capacity (AWC) and yield is important for farm management, but is rarely considered in a spatial context.

Aims and methods. The depth-to three yield-limiting constraints (sodicity, salinity, and alkalinity) was mapped across ∼80 000 ha in northern New South Wales, Australia using machine learning and digital soil mapping techniques. Soil AWC was calculated using soil data and pedotransfer functions, and water use efficiency equations were used to determine potential yield loss due to the presence of soil constraints. From this, the most-limiting constraint to yield was mapped.

Key results. One or more constraints were found to be present across 54% of the study area in the upper 1.2 m of the soil profile, overall reducing the AWC by ∼50 mm and potential yield by an average of 1.1 t/ha for wheat and 0.8 bales/ha for cotton. Sodicity (Exchangeable Sodium Percentage > 15%) was identified as the most-limiting constraint to yield across the study area.

Implications. The simplification of multiple sources of information into a single decision-making tool could prove valuable to growers and farm managers in managing soil constraints and understanding important interactions with available water and yield.

Lodging is an important agronomic trait related to crop yield and is easily susceptible to environmental influences. In this study, a recombinant inbred line population from soybean (Glycine max (L.) Merr.) Hefeng 25 × Dongnong L28 including 109 lines was used to identify quantitative trait loci (QTLs) related to soybean lodging. Seven QTLs were identified in the three environments (Harbin in 2017, 2018 and 2019), and these could explain 2.21–20.17% of the phenotypic variation. Among these QTLs, qLDG-I-1 (Chr20_24146101–Chr20_24297321) was stable for multiple environments. A residue heterozygous line, which was heterozygous at the qLDG-I-1 locus, was used to verify qLDG-I-1, and the results showed that this QTL could significantly improve lodging resistance of soybean. Meanwhile, 13 pairs of epistatic QTLs were detected, which could explain 3.26–18.24% of the phenotypic variation. QTL × environment interaction mapping was also used, and it detected 31 QTLs, which could explain 1.61–7.94% of the phenotypic variation. In total, 122 pairs of epistatic QTLs were detected, and they could explain 5.39–27.81% of the phenotypic variation. Additionally, candidate genes related to soybean lodging in the qLDG-I-1 interval were predicted, and Glyma.20g068000 was mined as a candidate gene based on quantitative real-time PCR analysis. The QTLs and candidate genes identified in this study are of great significance to position cloning, and could accelerate the progress of breeding resistance to lodging in soybean.

Context. Soil salinity is a major constraint in crop production in arid and semiarid regions where saline water is the main irrigation source affecting soil quality and crop productivity.

Aims. A pot experiment was conducted to study the impact of alternate application of saline water (electrical conductivity (EC): 6.0 dS m⁻¹) and fresh water on soil salinity indicators and salinity build-up under four seed spices (Anethum graveolens L., Nigella sativa L., Pimpinella anisum L. and Trachyspermum ammi L.).

Methods. Soil samples were collected from a pot experiment (0–15 cm depth) conducted at ICAR-Central Soil Salinity Research Institute, Karnal, Haryana, and analysed for different physicochemical properties (pH and EC), cationic (Ca²⁺, Mg²⁺, Na⁺ and K⁺) and anionic (CO₃²⁻, HCO₃⁻, Cl⁻, SO₄²⁻) concentration and their contribution to salinity build-up in soil.

Key results. Soil EC varied between 0.45 and 8.27 dS m⁻¹ (EC_1:2) and between 1.20 and 24.90 dS m⁻¹ (EC_e) irrespective of the seed spice species. The application of saline water in the early stages of growth followed by fresh-water irrigation resulted in a comparatively low EC_e, and cation and anion concentrations over continuous saline-water irrigation irrespective of the seed spice crop. EC_e, sodium adsorption ratio, potassium and pH_s are the important indicators identified by principal component analysis and better explained soil salinity under this situation.

Conclusions. Keeping these in view, there is a need for cyclic use of saline and fresh water in growing seed spice crops to prevent soil degradation. Study recommends that these four seed spice crops should be irrigated with fresh water during crop establishment and flowering stage, whereas, in between, saline water can be applied.

Implications. Such management of saline water irrigation could help to reduce salinity and maintain soil health for sustaining crop productivity, specifically for seed spices, in arid and semiarid regions.

Lucerne (Medicago sativa L.) is a major perennial forage legume worldwide. In Greece, new cultivars have been introduced mainly from the USA, Australia and Italy. However, some of these cultivars have not been tested locally before their widespread release. A field experiment was conducted from 2013 to 2016 in central Greece to compare the performance of 22 lucerne genotypes, including both local Greek and introduced genotypes, under irrigated Mediterranean conditions. There were three harvests in 2013 and five in each of the following years. Measurements included annual and total dry matter (DM) yield, harvest ratios, quality traits and agronomic parameters. Yields after the second year declined by 11.9–26.4%, possibly due to summer heat stress and reduced plant survival. However, several semi-winter-active cultivars were more persistent (by 19.4%) than highly winter-active cultivars. Three local, semi-winter-active cultivars and one introduced highly winter-active cultivar were the top performers for total DM yield (63.8–67.3 t DM/ha). Forage nutritive values showed small differences among cultivars. Evaluation of seasonal yield distribution was effective for comparing adaptive responses of genotypes in relation to the winter activity effect. Spring harvest ratio was more indicative (r = 0.92) of genotype total DM yield than was plant survival (r = 0.70). Specifically, highly winter-active cultivars showed higher autumn and spring harvests (by 36.4% and 7.9%, respectively) than semi-winter-active cultivars, which produced higher summer yields (by 35.7%). A regional program to breed more winter-active genotypes, which can capitalise on the longer preceding season with greater stand persistence, heat tolerance, summer productivity and height (>82 cm) and with more nodes (>18), could be beneficial for forage yield increase under the anticipated climatic changes.

Context. Grazing management strategies affect sward structure, changing patterns of foraging and intake, and consequently animal performance.

Aims. The objective of this study was to evaluate the relationship between sward structure and forage intake rate by cattle grazing elephant grass (Pennisetum purpureum Schumach) cv. Napier subjected to strategies of rotational stocking management.

Methods. The experiment was conducted in Piracicaba, SP, Brazil, from January 2011 to April 2012. Treatments corresponded to all combinations between two post-grazing conditions (post-grazing heights of 35 and 45 cm) and two pre-grazing conditions (95% and maximum canopy light interception during regrowth; LI). The response variables evaluated at both pre- and post-grazing conditions were: (1) vertical distribution of morphological components; (2) bite rate; (3) bite mass; (4) intake rate; and (5) forage nutritive value (morphological and chemical composition of oesophageal extrusa samples).

Key results. Bite mass was smaller and bite rate was greater for LI_95% swards at pre- and post-grazing, resulting in greater rate of forage intake. The post-grazing height targets affected the morphological and the chemical composition of the forage consumed.

Conclusions. In general, pastures managed with targets LI95% (pre-grazing) and 45 cm (post-grazing height) resulted in greater leaf percentage and nutritive value of the consumed forage.

Implications. Adequate grazing management strategies allow for high residual leaf area in pastures, ensuring rapid recovery after grazing. For grazing elephant grass cv. Napier, this corresponded to the combination between the LI95% pre-grazing target and the 45 cm post-grazing height.

Context. The yield and quality of Leymus chinensis, a major forage resource with high nutritional value, is strongly affected by chemical fertiliser application.

Aims. Comprehensive estimation of the effects of different fertilisation practices on the yield and quality of L. chinensis.

Methods. In this study, we conducted a meta-analysis using 206 valid datasets extracted from 10 studies on L. chinensis growth responses to chemical fertilisation in China.

Key results. Yield increases resulting from fertilisation were higher on alkaline soil with a pH >7.0 and aeolian soil with a coarse texture. Forage yield and quality were also associated with the fertiliser combinations and the fertiliser types. Compared with no fertiliser treatment, the yield increase was higher under NP (NPK) fertiliser application (74.7%; P < 0.05) than N or P fertiliser alone. Application of NP (NPK) fertiliser significantly increased the crude protein content, while N fertiliser reduced the crude fiber content and increased the crude fat content. Moreover, the combined application of macro-and micronutrient fertilisers resulted in a substantial increase in yield and quality. The optimal benefits of fertilisation were achieved in aeolian soil with a pH of 7.9–9.5.

Conclusions. Reasonable selection of fertilisers should therefore, be implemented to ensure high-yielding, high-quality L. chinensis based on local soil conditions in different regions.

Implications. The results of this study provide essential information for the formulation of reasonable fertilisation regimes and sustainable production of L. chinensis.

Context. The Australian dairy industry largely relies on grass-based pastures to feed cattle, yet these pastures also host dynamic invertebrate communities that can damage or benefit pasture productivity. While Australian dairy managers have traditionally focused on invertebrates that damage pastures (i.e. pests), invertebrates that provide valuable ecosystem services by acting as natural enemies to pests or delivering other beneficial functions (e.g. nutrient cycling) have received less attention.

Aim. Surveying the natural enemies and other beneficial invertebrate communities in pastures across seven Australian dairy regions and to explore how environmental and farm management factors impact these.

Method. Fifty seven pastures samples were collected during spring and autumn over two years. In doing so, we identified and counted 2 661 315 invertebrates or invertebrate colonies.

Key results. We found natural enemies and other beneficial invertebrate communities have a similar taxonomic composition across regions, with a small number of taxa dominating all regions, and rainfall the most consistent environmental driver in the abundance of these dominant taxa.

Conclusions. Farm management strategies to maintain or promote existing communities of beneficial taxa will likely be similar across regions. Associations between invertebrate communities suggest pest communities may indirectly impact the abundance and/or diversity of natural enemies and other beneficial invertebrates.

Implications. Although still an early step, our findings provide important baseline information that can be used to provide dairy managers with strategies to promote communities of beneficial invertebrates, and consequently maximise the benefits these invertebrates provide.