Mowing is one of the most effective methods of pasture management, and frequency plays a critical role in management strategies. Bermudagrass (Cynodon dactylon (L.) Pers.) is a highly valuable forage grass due to its exceptionally high mowing recovery rate and its high potential to be used as a forage crop. In China, bermudagrass is increasingly becoming a crucial forage crop because of the growing demand from the livestock industry. The objective of the present study was to determine the effect of mowing frequencies on forage bermudagrass (‘Wrangler’) yields and nutritive value. Four treatments with different mowing frequencies (2, 4, 6 and 12 weeks) were evaluated. Harvested grasses were assessed for yield and nutritive value. The shoot dry weight, crude fibre and N content did not exhibit any difference at various mowing frequencies. The highest content of crude protein was attained at the 2-weeks mowing frequency, although the 4-weeks mowing frequency resulted in a relatively higher shoot fresh weight, crude fat content, water content, P concentration and plant height. A persistently high upregulation of NRT1, PHT1, PHT2, AOC, AOS, MYC2 and NCED1 genes were observed at 4-weeks frequency. Yield was highest at 4- and 6-weeks mowing frequencies. Consequently, the 4-weeks frequency was considered to be the optimal mowing frequency in view of the forage quality and regrowth capacity.

Our aim was to identify temperature and moisture modifications needed for improvement of seed germination, growth and establishment of the protein-rich forage legume Vicia unijuga A.Br. so that it could become large enough and store sufficient root reserves to survive in subalpine conditions. Germination tolerance of scarified V. unijuga seeds to various temperatures and water potentials was tested in the laboratory, and a 3-year field experiment was conducted in the subalpine region of China to evaluate the effects of modified soil temperature and moisture conditions generated by mulching with plastic film and barley straw on seedling emergence, growth, root nutrient reserves and subsequent overwinter performance. The highest germination percentage and rate occurred at the optimum temperature of 15–20°C, which improved these germination traits at low water potentials between –0.6 and –1.0 MPa. Higher soil temperature and water content were recorded in the plastic mulch treatment than in the control and straw mulch treatments. This enhanced establishment and accumulation of biomass and root reserve pools in the plastic mulch treatment, with nearly 100% of the plants surviving overwinter. The relative contribution of soil temperature was greater than of soil-water content to the variation in biomass and root nutrient reserves. Root starch content explained the most variation in overwinter survival. In conclusion, scarified V. unijuga seeds can germinate over a wide range of conditions, including those in the subalpine zone in spring. The plastic mulch treatment provided adequate soil temperature and water resources to improve growth and root starch reserves in first-year plants of V. unijuga, thereby improving overwinter survival in the subalpine environment.

Maize (Zea mays L.) is one of the most important crops worldwide. However, low temperature limits seed germination and seedling growth of maize, which can in turn affect grain yield. The calcium ion (Ca²⁺) is the second messenger involved in the response to environmental-stimuli-induced signal transduction networks. The underlying physiological mechanisms related to the effects of exogenous Ca²⁺ treatment of different maize cultivars under low temperature are unclear. We selected two inbred lines, cold-sensitive cv. C546 and cold-tolerant cv. Y478, for studying the effects of Ca²⁺ on seed germination, photosynthesis, antioxidant enzymes and the osmotic regulation of seedling resistance to low temperature. The optimal concentration of CaCl₂ was 80 mmol L^-1, which significantly improved the germination percentage at temperatures <10°C. Application of CaCl₂ at this concentration under cold stress mitigated the degree of membrane injury and improved the antioxidant enzyme system through reduced relative electrolyte conductivity and malondialdehyde content, increased the soluble protein content, and enhanced superoxide dismutase and peroxidase activity. CaCl₂ also significantly increased chlorophyll fluorescence indicators (F_v/F_o, F_v/F_m) and the photosynthetic rate. We conclude that exogenous CaCl₂ at a concentration of 80 mmol L^-1 protects the function and structure of the membrane and photosystems, improves antioxidant enzyme activity and increases osmotic regulatory substances under cold stress. These results improve our understanding of the mechanisms of Ca²⁺ and contribute to the development of cold-tolerant maize varieties.

The increased incidence of extreme temperature events due to global climate change poses a major challenge for crop production. Ability to increase temperature tolerance through genetic improvement requires understanding of how crops and their wild relatives respond to extreme temperatures. We developed a high-throughput technique to evaluate tolerance to freezing stress (FS) and heat stress (HS) in wild, crop–wild hybrid and cultivated sunflower (Helianthus annuus L.). We also investigated whether trade-offs exist between stress tolerance and growth under benign conditions. Eleven experiments were performed under a combination of growth-chamber and field conditions. In growth-chamber experiments, FS and HS consisted of exposing acclimated plants at the 2–4-leaf stage to temperatures ranging from to –2.5°C to –4°C for 2–4 h and from 52°C to 54°C for 2–3 h. In the field, plants were grown for 32 days during midwinter (FS: average T_mean = 9.9°C and T_min = 3.8°C) or for 10 days in a heat tent (HS: average T_mean = 30.1°C and T_max = 43.3°C). We observed large differences in tolerance to FS and HS between wild and cultivated sunflower. Wild sunflower showed higher FS tolerance than cultivated in both growth-chamber and field experiments, whereas cultivated sunflower showed higher HS tolerance in growth-chamber experiments. No differences in HS tolerance were observed in the field. Crop–wild hybrids generally showed intermediate HS and FS tolerance. We found no evidence of a growth-tolerance trade-off, which suggests that tolerance might be introgressed into elite germplasm without growth penalties. The study reveals that wide genetic variation for the tolerance to extreme temperatures exists in the primary gene pool of sunflower.

Drought stress, especially at the reproductive stage, is a major limiting factor that compromises the productivity and profitability of canola in many regions of the world. Improved genetics for drought tolerance would enable the identification and development of resilient cultivars, resulting in increased canola production. The main objective of the present study was to dissect the genetic basis of seed yield of canola under water-limited conditions. A doubled haploid population derived from a cross between two Australian parental lines, RP04 and Ag-Outback, was evaluated to identify the genetic variation in fractional normalised deviation vegetative index (NDVI), aboveground shoot biomass accumulation, flowering time and plasticity in seed yield under irrigated and rainfed field conditions in two consecutive years. An irrigation treatment was applied at the 50% flowering stage and an incremental drought tolerance index (DTI) was estimated for seed yield. By utilising a genetic linkage map based on 18 851 genome-wide DArTseq markers, we identified 25 genomic regions significantly associated with different traits (logarithm of odds (LOD) ≥ 3), accounting for 5.5–22.3% of the genotypic variance. Three significant genomic regions on chromosomes A06, A10 and C04 were associated with DTI for seed yield. Some of the quantitative trait loci (QTL) were localised in the close proximity of candidate genes involved in traits contributing to drought escape and drought avoidance mechanisms, including FLOWERING LOCUS T (FT) and FLOWERING LOCUS C (FLC). Trait-marker associations identified herein can be validated across diverse environments, and the sequence-based markers may be used in a marker assisted selection breeding strategy to enhance drought tolerance in canola breeding germplasm.

Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is the most important disease affecting yield of soybean (Glycine max (L.) Merr.). In China, among the main physiological races of SCN causing serious economic loss of soybean, HG Type 0 is the most widely distributed. Breeding SCN-resistant varieties is one of the safest and most effective ways to manage SCN. Soybean cv. Dongnong L-204 has a green seed coat and is a resource for resistance to SCN; however, the transcriptional variation and main molecular mechanism of resistance of Dongnong L-204 are not clear. We obtained 66.42 Gb of raw reads by using Illumina HiSeq high-throughput sequencing of Dongnong L-204. Transcriptional changes at Days 3, 7 and 10 after HG Type 0 stress are described. In total, 11 279 differentially expressed genes were responsive to HG Type 0 stress, including 6407 SCN-induced and 4872 SCN-suppressed genes. Gene Ontology analysis emphasised the important roles of the terms metabolic process, single-organism process, catalytic activity and binding under HG Type 0 stress. Among them, the terms related to extracellular matrix, extracellular region part, membrane-enclosed lumen, protein-binding transcription factor activity, and symplast and cell junction existed only in pairwise comparisons Day 7 vs Day 0 and Day 10 vs Day 0. KEGG enrichment analysis showed that metabolic pathway played an important role in the stress response to HG Type 0. Cellular processes, metabolism and organismal systems and other pathway-related genes increased significantly after 7 days. Transcription factor analysis showed that transcription factors such as MYB, AP2-EREBP, bHLH, WRKY and NAC may be involved in the anti-HG Type 0 response of Dongnong L-204. At the same time, few transient inducible transcription factors were found and more transient inhibited transcription factors in Dongnong L-204 in the early stage of HG Type 0 syncytial establishment. RT-qPCR was used to analyse expression of 10 genes closely related to the HG Type 0 stress response. The expression of GmWRKYX1 was >60 times higher at Day 10 after HG Type 0 stress than at Day 0. The WRKY transcription-factor family may play an important role in the resistance of Dongnong L-204 to HG Type 0 stress.

‘Translational research’ became an increasingly common term when it was realised that much agriculturally inspired basic research failed to contribute to the improvement of crops. Most of the failure has come from laboratory-based attempts to ameliorate abiotic stresses. Dealing with biotic stress has been much more successful; the control of pests and weeds is often enabled by transforming crops with single genes, for such genes have little or no influence on a crop’s metabolism. By contrast, abiotic stress varies with the weather; i.e. crops respond systemically, over a range of levels of organisation (e.g. cells, tissues, organs), with many feedbacks and feedforwards. Drought is the most pervasive form of abiotic stress. There are 4600 papers that have searched, ineffectively, for ‘drought resistance’, a term that usually defies useful definition. By contrast, dealing with a measured, limited water supply (e.g. seasonal rainfall), rather than with ‘drought’, has effectively increased water-limited yield through agronomic innovation based on improving water-use efficiency. ‘Salt tolerance’ has similar difficulties; nevertheless, physiological knowledge has revealed effective single genes, in contrast to the failures of empirical gene prospecting. Another important goal has been to increase potential crop yield by exploring mechanistic opportunities to improve photosynthetic efficiency. These attempts have not, so far, succeeded, perhaps because they have rarely broached physiological responses beyond carbon balance, such as metabolic responses to environmental challenges that may affect meristematic development. A major reason for the predominant failure of translational research from laboratory to field is that the peer-review system is too narrow; i.e. reviewers have the same backgrounds as the authors. Effective translation will require the addition of reviewers who can assess the pathway from laboratory to field.

Flavour is an essential quality characteristic of soymilk; however, it contains volatile compounds unacceptable to consumers. Hexanal is the most important flavour compound that gives a sensory beany, grassy flavour in the soymilk. An effective way to reduce hexanal content in soymilk is to screen for and utilise cultivars of soybean (Glycine max (L.) Merr.) with lower hexanal content. The objective of the present study was to dissect the genetic basis of hexanal content in soybean seed by using genome-wide association analysis (GWAS), thereby providing guidance for the selection and breeding of soybean varieties with low hexanal content. We used 24 651 single-nucleotide polymorphisms (SNPs) and screened seeds from 111 cultivated soybean accessions to identify quantitative trait nucleotides (QTNs) affecting hexanal content. We discovered 14 novel QTNs located on five different chromosomes that are significantly associated with hexanal content in soybean seed. Among these, 11 QTNs co-localised with quantitative trait loci previously found in linkage or association mapping studies related to protein, oil and/or fatty acid content in soybean seed. We also identified some candidate genes involved in amino acid metabolism, protein content, lipid metabolism and hormone metabolism. Six cultivars with low hexanal content were identified by screening. This is the first GWAS study on hexanal content in soybean seed, and a number of QTNs and candidate genes were identified. Some of these may be useful to breeders for the improvement of marker-assisted breeding efficiency for low hexanal content and may be useful for exploring possible molecular mechanisms underlying hexanal content in soybean seed.