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•WEY increased from 56.92 to 315.42 % in 100 % N under bi cropping system.•Net returns increased from US $ 188.5 to US $ 224.0/ha in 100 % N in bi-cropping system.•Soil OC, available ...N and P increased significantly in bi-cropping system.•100 % N application in bi-cropping had highest stability in wheat equivalent yield.•Bi-cropping system recorded higher LER (18.01 to 57.65 %) over sole cropping.
We studied the integration of white clover (Trifolium repens) with nitrogen management practices in wheat (Triticum aestivum L.) - maize (Zea mays L.) cropping sequence to find optimum level of N and to enhance forage production. This experiment was laid out in Randomized Block Design with three replications comprising of 12 treatments viz., (T1) wheat-maize; (T2) white clover + wheat -maize (0 N); (T3) white clover (sole); and (T4 to T12) 50, 75 and 100 % of recommended N to wheat, maize or both. Application of 100 % N to white clover + wheat - maize (bi-cropping) recorded the highest crude protein in white clover. Wheat equivalent yield (WEY) was computed by multiplying the white clover and maize yields with their respective per unit price to compare the system productivity. The system productivity was found 2.67 (56.92 %) and 5.93 t/ha (315.42 %) higher in 100 % N application to bi-cropping over wheat-maize (0 N) and sole white clover, respectively. Highest net returns (US $ 188.5 and 224.0/ha at farmers’ field and research farm, respectively) were also recorded in the same bi-cropping treatment. Bi-cropping along with N application resulted in higher Land equivalent ratio (LER) (18.01–57.65%) over sole cropping. The treatment and treatment x environment (TTE) bi-plot also explained 99.84, 98.70 and 99.63 % of treatment and treatment × environment variation for WEY, Benefit: Cost Ratio (BCR) and LER, respectively. Soil fertility improved significantly in sole white clover and bi-cropping treatments with N application. However, when upto 75 % N of recommended dose of fertilizers (RDF) was applied to bi-cropping system resulted in higher WEY, BCR and LER, which were at par with 100 % N. Thus, cereal-clover bi-cropping system along with 75 % N of RDF can be recommended for sustainable forage and food production; and better soil health in temperate, sub-temperate climatic regions of the world.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Increasing water-soluble carbohydrate (WSC) content in white clover is important for improving nutritional quality and reducing environmental impacts from pastoral agriculture. Elucidation of genes ...responsible for foliar WSC variation would enhance genetic improvement by enabling molecular breeding approaches. The aim of the present study was to identify single nucleotide polymorphisms (SNPs) associated with variation in foliar WSC in white clover. A set of 935 white clover individuals, randomly sampled from five breeding pools selectively bred for divergent (low or high) WSC content, were assessed with 14,743 genotyping-by-sequencing SNPs, using three outlier detection methods: PCAdapt, BayeScan and KGD-F
. These analyses identified 33 SNPs as discriminating between high and low WSC populations and putatively under selection. One SNP was located in the intron of
, a gene coding for a sugar transporter located on the vacuole membrane. A genome-wide association study using a subset of 605 white clover individuals and 5,757 SNPs, identified a further 12 SNPs, one of which was associated with a starch biosynthesis gene, glucose-1-phosphate adenylyltransferase,
. Our results provide insight into genomic regions underlying WSC accumulation in white clover, identify candidate genomic regions for further functional validation studies, and reveal valuable information for marker-assisted or genomic selection in white clover.
Key messageThe widely divergent species 4xTrifolium ambiguum and 2xT.occidentale are inter-fertile long after speciation (including polyploidisation) has occurred. Tri-species hybrids (T. repens × T. ...ambiguum × T. occidentale) have the potential to achieve introgression of stress resistant traits from both wild species into white clover.Trifolium ambiguum and T. occidentale are geographically, adaptionally and phenotypically contrasting species in the white clover section (Trifoliastrum) of the genus. T. ambiguum occurs as a high-altitude polyploid series (2x, 4x, 6x) in W Asia and NE Europe. T. occidentale is a diploid coastal species, occurring at sea level in W Europe. This study investigated hybridisation between 4xT. ambiguum and 2xT. occidentale and considered the significance of the hybrids for introgression breeding of white clover. Partially fertile F1 hybrids between 4xT. ambiguum and 2x and 4xT. occidentale were generated by embryo rescue. Hybrid plant morphology and fertility varied widely and hybrids generally expressed traits from both species. Advanced generation (F2–F5) 4x hybrids were highly fertile and constitute a new synthetic allotetraploid species. FISH analyses of 4x hybrids showed multivalent chromosome configurations with homoeologous associations between T. ambiguum and T. occidentale chromosomes. Crosses of the hybrids with T. repens produced fertile tri-species progeny. These very divergent species remain inter-fertile long after speciation (including polyploidisation) has occurred. Tri-species hybrids have the potential to achieve introgression of stress resistance traits from both wild species into white clover.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
There is increased demand for dairy products worldwide, which is coupled with the realization that consumers want dairy products that are produced in a sustainable and environmentally benign manner. ...Forage legumes, and white clover (Trifolium repens L.; WC) in particular, have the potential to positively influence the sustainability of pasture-based ruminant production systems. Therefore, there is increased interest in the use of forage legumes because they offer opportunities for sustainable pasture-based production systems. A meta-analysis was undertaken to quantify the milk production response associated with the introduction of WC into perennial ryegrass swards and to investigate the optimal WC content of dairy pastures to increase milk production. Two separate databases were created. In the grass-WC database, papers were selected if they compared milk production of lactating dairy cows grazing perennial ryegrass-WC (GC) swards with that of cows grazing perennial ryegrass-only swards (GO). In the WC-only database, papers were selected if they contained milk production from lactating dairy cows grazing on GC swards with varying levels of WC content. Data from both databases were analyzed using mixed models (PROC MIXED) in SAS (SAS Institute, Cary, NC). Within the grass-WC database, where mean sward WC content was 31.6%, mean daily milk and milk solids yield per cow were increased by 1.4 and 0.12 kg, respectively, whereas milk and milk solids yield per hectare were unaffected when cows grazed GC compared with GO swards. Stocking rate and nitrogen fertilizer application were reduced by 0.25 cows/ha and 81 kg/ha, respectively, on GC swards compared with GO swards. These results highlight the potential of GC production systems to achieve similar levels of production to GO systems but with reduced fertilizer nitrogen inputs, which is beneficial from both an economic and environmental point of view. In the context of increased demand for dairy products, there may be potential to increase the productivity of GC systems by increasing fertilizer nitrogen use to increase stocking rate and carrying capacity while also retaining the benefit of WC inclusion on milk production per cow.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Main conclusion
This study leads to advances in the field of heat tolerance among different plant species. We concluded that a coordinated, increased antioxidant defense system enabled white clover ...to reduce heat-induced oxidative damage.
The rise in global ambient temperature has a wide range of effects on plant growth, and, therefore, on the activation of various molecular defenses before the appearance of heat damage. Elevated temperatures result in accelerated generation of reactive oxygen species (ROS), causing an imbalance between ROS production and the ability of scavenging systems to detoxify and remove the reactive intermediates. The aim of this study was to determine the role of antioxidant defense systems in the alleviation of heat stress (HS) consequences in white clover (
Trifolium repens
L.), which is cultivated worldwide. We evaluated how temperature and time parameters contribute to the thermotolerance of white clover at different growth stages. We revealed HS protection in white clover from 37 to 40 °C, with 40 °C providing the greatest protection of 3-day-old seedlings and 28-day-old adult plants. Heat-provoked oxidative stress in white clover was confirmed by substantial changes in electrolyte leakage, malondialdehyde (MDA), and chlorophyll content, as well as superoxide anion (O
2
·−
) and hydrogen peroxide (H
2
O
2
) production. Furthermore, superoxide dismutase (SOD) and ascorbate peroxidase (APX) as well as a high level of GSH non-enzymatic antioxidant were the most responsive, and were associated with acquired thermotolerance through the regulation of ROS generation. We demonstrated, by studying protoplast transient gene expression, direct genetic evidence of endogenous antioxidant-related genes that confer HS tolerance in white clover. Our present study clearly establishes that oxidative stress ensues from HS, which triggers the induction of antioxidant defense systems for ROS scavenging in white clover.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of the present study was to analyze the effects of two arbuscular mycorrhizal fungi (AMF), Funneliformis mosseae and Paraglomus occultum, on leaf water status, root morphology, root sugar ...accumulation, root abscisic acid (ABA) levels, root malondialdehyde (MDA) content, and root antioxidant enzyme activities in white clover (Trifolium repens L.) exposed to well-watered (WW) and drought stress (DS) conditions. The results showed that root colonization by F. mosseae and P. occultum was significantly decreased by 7-week soil drought treatment. Under drought stress conditions, mycorrhizal fungal treatment considerably stimulated root total length, surface area and volume, as compared with non-mycorrhizal controls. In addition, inoculation with arbuscular mycorrhizal fungi also increased leaf relative water content and accelerated the accumulation of root glucose and fructose under drought stress. Mycorrhizal plants under drought stress registered higher activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) and ABA levels in roots, while lower MDA contents, relative to non-mycorrhizal plants. As a result, mycorrhiza-inoculated plants represented better physiological activities (e.g. antioxidant defense systems, root morphology, and sugar accumulation) than non-inoculated plants in response to soil drought, whilst P. occultum had superior effects than F. mosseae.
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IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UL, UM, UPUK
•Rumen undegradable protein increased during wilting but decreased during ensiling.•Silages had lower true protein concentration than unwilted and wilted herbage.•Acid-treated silage had greater true ...protein concentration among the silages.•Acid-treated silage had the lowest dry matter losses among the silages.
This study evaluated the effects of wilting and ensiling of a lucerne-white clover mixture with or without additives on protein quality and fermentation characteristics. We hypothesized that wilting will increase the rumen undegradable protein (RUP) of a lucerne-white clover mixture and that the use of additives will decrease proteolysis of lucerne-white clover silage. The experimental design was a completely randomized design with three replicates per treatment. Rapid wilting of the lucerne-white clover mixture increased RUP but ensiling of the wilted mixture decreased the true protein content and the RUP concentration. Addition of acid at the time of ensiling was more effective in decreasing proteolysis and preserved sugar compared with the untreated control and inoculant-treated silages, which potentially can improve N utilisation by ruminants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Premise β‐Cyanoalanine synthase (β‐CAS) and alternative oxidase (AOX) play important roles in the ability of plants to detoxify and tolerate hydrogen cyanide (HCN). These functions are ...critical for all plants because HCN is produced at low levels during basic metabolic processes, and especially for cyanogenic species, which release high levels of HCN following tissue damage. However, expression of β ‐CAS and Aox genes has not been examined in cyanogenic species, nor compared between cyanogenic and acyanogenic genotypes within a species. Methods We used a natural polymorphism for cyanogenesis in white clover to examine β ‐CAS and Aox gene expression in relation to cyanogenesis‐associated HCN exposure. We identified all β ‐CAS and Aox gene copies present in the genome, including members of the Aox1, Aox2a , and Aox2d subfamilies previously reported in legumes. Expression levels were compared between cyanogenic and acyanogenic genotypes and between damaged and undamaged leaf tissue. Results β‐ CAS and Aox2a expression was differentially elevated in cyanogenic genotypes, and tissue damage was not required to induce this increased expression. Aox2d , in contrast, appeared to be upregulated as a generalized wounding response. Conclusions These findings suggest a heightened constitutive role for HCN detoxification (via elevated β‐ CAS expression) and HCN‐toxicity mitigation (via elevated Aox2a expression) in plants that are capable of cyanogenesis. As such, freezing‐induced cyanide autotoxicity is unlikely to be the primary selective factor in the evolution of climate‐associated cyanogenesis clines.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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