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Pulses form an important component of the human diet, provide animal feed, and replenish soil fertility through biological nitrogen fixation. However, pulse breeding is a time consuming process. Most of the traditional breeding programs take 10–15 years to release an improved cultivar. In the breeder’s equation, a model of the expected change in a trait in response to selection, cycle time is the most powerful parameter for increasing genetic gain. Shuttle breeding, double haploids and in vitro culture are some of the methodologies that have been developed; however, they have not been able to be implemented efficiently in the breeding programs for pulses. In this context, speed breeding emerges as a technology that allows increased efficiency of the programs, reducing costs and the work required. The technique uses optimal light quality, light intensity, daylength and temperature control to accelerate photosynthesis and flowering, coupled with early seed harvest. It can be integrated with other breeding technologies, does not include transgenesis or gene editing, and is presented as a revolution to increase the efficiency of the programs. We present different advances in pulse breeding programs and propose a speed breeding system for pea (Pisum sativum L.) that includes hybridisations and advancing generations in a growth chamber. This review concludes by highlighting the opportunities and challenges to incorporating speed breeding into pulse breeding programs.
NGS-based multiplex assay has accomplished a valuable status as a means of high throughput research, rapid screening functional markers in wheat breeding programs. Accordingly, we applied a total of 42 locus-specific markers from Indel and SNP-mediated categorisations coupled with the agronomic important genes or quantitative trait loci (QTL) in bread wheat. The amplicons were analysed by an Ion Torrent Proton Sequencer. Then, an allele detection custom pipeline was applied to process the genotype of a total of 99 Iranian cultivars and 270 landraces. On the whole, 29 markers were positively incorporated and achieved 100% SNP call rates. Assessment of sequence-tagged site (STS) and competitive allele-specific PCR (KASP) markers concerning the same loci confirmed the genotype calls of all markers altogether. It was revealed that the Iranian cultivars and landraces supply a rich genetic resource capable of resisting Hessian fly, leaf rust, fusarium head blight, adult plant leaf diseases, stem rust, wheat soilborne mosaic virus, wheat streak mosaic, pre-harvest sprouting, high grain protein, and gluten strength traits. This finding can be developed to improve and enrich bread wheat. Further, it is advocated that NGS-based multiplex assay can be a promising approach for high throughput in examining trait-linked markers in wheat germplasm collections.
Increasing wheat yield and grain quality is crucial for achieving profitable production systems. Genotype has an important role in determining potential grain end-use quality, because it defines the protein subunits stored in the endosperm. Nitrogen (N) and sulfur (S) availability modulate the expression of the genotype by determining variations in quantitative gluten composition. The aim of this work was to analyse the responses of grain quality to N and S fertilisation and relate them to the relative quantitative composition of different subunits of gliadins and glutenins in 24 Argentinean bread wheat cultivars differing in apparent S recovery (ASR), cycle length and protein pattern. Two field experiments were conducted in the Humid Pampas of Argentina. Gluten composition was analysed by electrophoresis and densitometry, and grain quality by N/S ratio, protein content, sedimentation test, and alveograms. Most genotypes presented high quality potential according to their pattern of high molecular weight glutenin subunits, although they differed in grain quality performance. Under an environment of low soil fertility (i.e. where the soil has a low capacity to supply N and S), N fertilisation reduced the sedimentation test values at low S level (67 vs 54 mm, on average) and increased this parameter at high S level (62 vs 81 mm, on average), with different responses among genotypes. Also, S fertilisation at high N level increased dough strength by 52% for long cycle genotypes and decreased it by 9% for those of short cycle. Genotypes with contrasting ASR, cycle length and protein pattern modified the responses of baking strength to S fertilisation in different ways (positive, neutral or negative), whereas genotype × N interaction modified the responses only in their magnitude. Outstanding genotypes (e.g. Klein Proteo) were identified according to baking quality stability. We conclude that S fertilisation had a notable effect on baking quality, especially in long cycle genotypes and a low soil-fertility environment, correcting S deficiency at high N availability. ASR was not a useful classificatory trait for predicting grain quality. Instead, the study of variants for the protein subunits coded by particular genes (e.g. Glu-A3, Glu-B3, Glu-D1x and Glu-D1y) that partially determine baking quality should be intensified, in order to optimise genetic improvement in wheat.
Balancing nutrient inputs and exports is essential to maintaining soil fertility in rainfed crop and pasture farming systems. Soil nutrient balances of land used for crop and pasture production in the south-west of Western Australia were assessed through survey data comprising biophysical measurements and farm management records (2010–15) across 184 fields spanning 14 Mha. Key findings were that nitrogen (N) inputs via fertiliser or biological N2 fixation in 60% of fields, and potassium (K) inputs in 90% of fields, were inadequate to balance exports despite increases in fertiliser usage and adjustments to fertiliser inputs based on rotations. Phosphorus (P) and sulfur (S) balances were positive in most fields, with only 5% returning losses >5 kg P or 7 kg S/ha. Within each of the three agroecological zones of the survey, fields that had two legume crops (or pastures) in 5 years (i.e. 40% legumes) maintained a positive N balance. At the mean legume inclusion rate observed of 20% a positive partial N budget was still observed for the Northern Agricultural Region (NAR) of 2.8 kg N/ha.year, whereas balances were negative within the Central Agricultural Region (CAR) by 7.0 kg N/ha.year, and the Southern Agricultural Region (SAR) by 15.5 kg N/ha.year. Hence, N budgets in the CAR and SAR were negative by the amount of N removed in ∼0.5 t wheat grain, and continuation of current practices in CAR and SAR fields will lead to declining soil fertility. Maintenance of N in the NAR was achieved by using amounts of fertiliser N similar to other regions while harvesting less grain. The ratio of fertiliser N to legume-fixed N added to the soil in the NAR was twice that of the other regions. Across all regions, the ratio of fertiliser N to legume-fixed N added to the soil averaged ∼4.0:1, a major change from earlier estimates in this region of 1:20 under ley farming systems. The low contribution of legume N was due to the decline in legume inclusion rate (now 20%), the low legume content in pastures, particularly in the NAR, and improved harvest index of lupin (Lupinus angustifolius), the most frequently grown grain legume species. Further quantifications of the effects of changing farming systems on nutrient balances are required to assess the balances more accurately, thereby ensuring that soil fertility is maintained, especially because systems have altered towards more intensive cropping with reduced legume production.
Chia (Salvia hispanica L.) grain is rich in omega-3 and omega-6 fatty acids, which are important for human nutrition and prevention of cardiovascular disease, as well as dietary fibre and quality protein. Demand for chia grain is increasing worldwide driven by the interest in functional food; however, large gaps exist in our understanding of chia physiology. The objective of this study was to determine the critical period for grain yield in chia. A field experiment was conducted under well-watered conditions during four growing seasons, using sequential shading periods of 7–10 days during the season. Yield of unshaded controls varied from 1418 to 2148 kg ha–1 among seasons. Chia’s critical period for grain yield spanned from 550 degree-days before flowering to 250 degree-days after flowering. Seed number fully accounted for reductions in grain yield, with no responses in grain weight to shading. Shading from 550 to 250 degree-days before flowering reduced yield by as much as 40% and this reduction was associated with reductions in the number of verticillasters on second and third order branches. Shading from 50 degree-days before flowering to 250 degree-days after flowering reduced yield by at least 20% and this reduction was associated with reductions in both the number of verticillasters on second and third order branches and the number of grains per verticillaster on branches of all orders. The findings from this study will aid development of management practices to avoid stresses during periods when grain yield would be penalised, and will contribute to breeding for yield potential and stress adaptation by targeting the critical physiological stages.
Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.
Soil acidification and declining fertility are widespread in sub‐Saharan Africa. Nutrient depletion is mainly related to nutrient mining driven by biomass removal without replenishment of nutrients through use of fertilisers. Concomitant acidification is due to the high ash alkalinity of harvested biomass. We determined the nutrient content and ash alkalinity of biomass of the main crops produced in smallholder mixed crop–livestock farming systems in the Malagasy Highlands of Madagascar and calculated the soil acidification/alkalinisation occurring through biomass transfer. Samples of rice and forage were collected from 70 rice plots and 91 cultivated forage plots, and 70 manure samples were collected from farms. Nutrient exports induced by crop harvesting resulted in annual losses of 57 kg nitrogen (N), 6 kg (phosphorus) P and 33 kg potassium (K) ha–1 for rice (grain + straw), and 31–51 kg N, 8–9 kg P and 29–57 kg K ha–1 for each forage cut (with three cuts per year on average). The ash alkalinity of samples, calculated as the difference between cation and anion contents, was 49–100 cmolc kg–1 for forage crops, 31 cmolc kg–1 for rice straw, and only 4 cmolc kg–1 for rice grains. Biomass removal caused a loss of nutrients and an increase in soil acidity. Owing to low nutrient retention efficiency during the handling and storage of manure, the traditional input of manure at 5 t fresh matter ha–1 is insufficient to balance nutrient and alkalinity losses in Malagasy mixed crop–livestock farming systems. Maintaining productive and sustainable mixed crop–livestock farming systems requires greater attention to ensuring a nutrient balance at both plot and farm levels.
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