Ca Supply Research Articles

Effects of feed particle size, calcium concentration and phytase supplementation on InsP6 degradation in broiler chickens fed pelleted diets

ABSTRACT 1. The objective of the trial was to study the single and interactive effects of feed particle size in pelleted feed, dietary calcium (Ca) concentration and microbial phytase supplementation in broiler chickens. The studied traits were myo-inositol (1,2,3,4,5,6) hexakis (dihydrogen phosphate) (InsP6) degradation, pre-caecal digestibility of phosphorus (P), Ca and amino acids (AA) and retention of P, Ca and nitrogen (N). 2. Male Ross 308 broiler chickens were housed in metabolism units in groups of 10 and allocated to one of eight diets with seven pen replicates per diet. The 2 × 2 × 2-factorial arrangement included coarse and fine feed particle size (309 or 222 µm), low and high Ca concentration (4.9 and 7.2 g/kg) and without or with phytase supplementation (1,000 FTU/kg). 3. Pre-caecal InsP6 disappearance was higher with coarse than fine feed particle size when no phytase was added (54 vs. 48%) but not when phytase was added (74%; p = 0.046). High dietary Ca feeds decreased pre-caecal InsP6 disappearance (67 to 59%) and P digestibility (65 to 55%; p < 0.001). Gizzard pH was lower with coarse than fine feed particle size and higher with high Ca than low Ca (p < 0.001). Pre-caecal digestibility of most AA was approximately 3.5%-points lower with high Ca without phytase compared to the other treatments (p ≤ 0.047). Coarse feed particle size caused higher pre-caecal AA digestibility than fine particle size (~2%-points; p ≤ 0.031). InsP6 disappearance in the crop increased at high Ca concentration when phytase was added (22 vs. 37%; p = 0.011). 4. Coarser feed particle size in pellets increased gastrointestinal InsP6 degradation and nutrient digestibility, likely owing to effects on the gizzard functions. Additional Ca supply exerted antinutritive effects that was not compensated for by using coarser feed particles.

Effect of dietary calcium and vitamin D supplements on plasma bone turnover biomarkers, bone mineralization, bone strength, and lameness score in gilts.

This study investigated the impact of calcium (Ca) and vitamin D supplements on bone metabolism, bone measurement, lameness, and selection rate in gilts fed five dietary treatments. Two Ca levels (6.85/6.42 [adequate; ACa] or 8.99/8.56 [high; HCa] g/kg) were combined with either 856 IU/kg vitamin D3 (Danish feeding standards; adequate; AD3) or 50 μg/kg 25-hydroxyvitamin D3 (high; HHyD) to create ACaAD3, HCaAD3, ACaHHyD, and HCaHHyD diets. The values 6.85/6.42 and 8.99/8.56g/kg correspond to adequate and high Ca supply for gilts weighing 32 to 100 and 100 to 180kg body weight (BW), respectively. The fifth diet was a combination of HCa and 2,000 IU/kg vitamin D3 (high; HD3) to create HCaHD3. Two hundred gilts were phase fed the dietary treatments from 32 to 100 and 100 to 180kg BW until they were slaughtered, either at 100 or 180kg BW. The gilts were weighed fortnightly, and plasma and urine samples were collected at 100 and 180kg BW. At slaughter, the 2nd and 3rd metacarpal bones were collected for bone parameters measurements. Lameness and selection rate were assessed within the last 7 d at 100 and 180kg BW. Dietary treatments did not affect gilts' growth performance and plasma concentration of Ca, but urinary concentration of Ca was greater in HCa-supplemented gilts at both 100 (P = 0.003) and 180 (P = 0.05) kg BW. Plasma concentration of vitamin D3 (P < 0.001) and 25-hydroxyvitamin D3 (P < 0.001) showed dose-dependent responses at both 100 and 180kg BW. Bone-specific alkaline phosphatase was greater (P = 0.02) in the plasma sample collected at 180kg BW in gilts fed the HCaHD3 diet and tended to be greater in gilts fed the ACaAD3 diet (P = 0.06). The bone ash content (P = 0.02) was greater in gilts fed the HCaAD3 diet and slaughtered at 100kg BW compared with gilts fed the ACaAD3 and ACaHHyD diets. However, bone weight, length, thickness, dry matter, and mineral content did not differ among the dietary treatments at both 100 and 180kg BW (P > 0.05). Neither lameness nor selection rate was affected by the dietary treatments. The average daily gain of gilts weighing 32 to 100 and 100 to 180kg BW showed a positive correlation with bone strength (r = 0.37; P < 0.001) and bone ash content (r = 0.24; P = 0.02), respectively. In conclusion, higher Ca and vitamin D3 supplementation slightly increased bone ash content but had no effect on lameness or selection rate of the gilts compared to those fed according to the Danish nutrient standards.

Insights into the antagonistic effects of calcium on cadmium accumulation in peanuts (Arachis hypogaea L.)

Peanut (Arachis hypogaea L.) plant has a high requirement for calcium (Ca) during its growth and development, and possesses the ability to accumulate cadmium (Cd) from soil. However, the precise mechanisms underlying the antagonistic effects between Ca and Cd remain unclear. This study aimed to explore the dynamic changes in Cd accumulation in peanut seedlings by varying the Ca-to-Cd concentration ratio (CRCa/Cd) from 250 to 3500. Additionally, the influence of ion channel competition and cell wall fixation in the root on Cd accumulation in peanuts was explored by analyzing Cd chemical forms, subcellular distribution, pectin content, and Cd2+ fluxes using a non-invasive micro-test technique (NMT). The findings revealed that Cd accumulation in peanut seedlings was significantly lower when the CRCa/Cd was higher than 2000. In the Ca-pretreated seedlings (cell wall fixation treatment), Cd content in the shoots and roots decreased by 18.9% and 25.0%, respectively, compared with the simultaneous exposure to Ca and Cd (ion channel competition treatment). Cd2+ influx in peanut roots decreased by 55.8% in the Ca-pretreated group. However, increasing the competitive strength of Ca2+ and Cd2+ did not affect Cd2+ influx under normal Ca conditions (>2 mM Ca). Meanwhile, Ca pretreatment significantly increased Cd distribution in the root cell wall, pectate, and protein-binding forms, while significantly reducing Cd distribution in root soluble components and inorganic Cd forms. The pectin content in the roots increased by 128% and 226% in the Ca and Cd simultaneous exposure treatment and Ca pretreatment, respectively. These results suggest that Ca pretreatment enhanced Cd retention in the root cell wall. Overall, exogenous Ca effectively mitigated Cd accumulation in peanut plants when the CRCa/Cd was below 2000, and Ca2+ channels partially facilitate the entry of Cd2+ into peanut roots. Under normal Ca supply conditions, exogenous Ca reduced Cd accumulation in peanuts primarily through root cell wall fixation rather than ion channel competition. Our findings provide insights into the mechanism by which Ca alleviates the uptake and transfer of Cd in peanuts.

Metasomatic Interaction of Ultramafic Mantle Xenoliths with their Felsic HP–UHT Granulite Host (Moldanubian Domain, Bohemian Massif in Lower Austria)

Abstract The St. Leonhard granulite massif in Lower Austria, dominantly formed by kyanite-bearing felsic granulite, encloses countless up to 5 cm sized mantle xenoliths of garnet clinopyroxenite and peridotite. The mineralogical, textural and chemical consequences of a mutual metasomatic interaction at the contact between these xenoliths and the host orthopyroxene-bearing felsic granulite are described. Movement of Mg, Al and, especially, Ca from the garnet clinopyroxenite to the granulite and migration of K and Na in the opposite direction, caused the breakdown of clinopyroxene and formation of orthopyroxene–plagioclase symplectite coronae at the expense of the garnet clinopyroxenite xenoliths. Around the peridotite xenoliths, monomineralic orthopyroxene coronae have developed due to the supply of Si from the host granulite. The P–T conditions of this interaction were established to 900°C to 1000°C and 1.0 to 1.2 GPa by thermodynamic modelling. The duration of coronae growth was constrained to 13 to 532 ka based on modelling of Fe–Mg interdiffusion underlying secondary compositional zoning of garnet from the garnet clinopyroxenite xenolith extending to the coronae. The most significant change in the host granulite was caused by the supply of Ca from the garnet clinopyroxenite xenolith, which led to the breakdown of the Al2SiO5 phase—probably kyanite—and stabilization of orthopyroxene. K-feldspar-poor haloes surrounding mantle xenoliths formed due to the depletion of K in the granulite adjacent to the garnet clinopyroxenite. The observed origin of felsic–intermediate orthopyroxene-bearing granulite by transformation of felsic kyanite-bearing granulite through the metasomatic interaction with mantle xenoliths implies that the deep crustal chemical exchange between mantle- and crust-derived lithologies may have an important consequences on composition, thermal structure and geodynamic evolution of orogenic lower crust especially in hot collisional orogens, such as the European Variscides.

Utility of in situ ion‐exchange membranes to assess nutrient availability, productivity, and fertilizer response of coastal Douglas‐fir of the Pacific Northwest

AbstractDouglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] is the predominant forest plantation species in the Pacific Northwest (PNW), with site productivity and fertilizer response influenced by climate and soil variations. This study investigates the utility of in situ 12‐week supply measurements of nitrogen (N), calcium (Ca), and phosphorus (P) to ion‐exchange resins (specifically Plant Root Simulator [PRS] probes) to estimate carbon (C):N ratios, soil nutrient contents (0–1 m), foliar nutrient concentrations, Douglas‐fir productivity (site index and basal area mean annual increment), and fertilizer volume response. PRS nutrient supply rates were correlated with N, Ca, and P soil nutrient contents (0–1 m), C:N ratios, and foliar nutrient concentrations. Low PRS NO3 supply rates (&lt;25 mg N·m−2·burial period−1) were correlated with lower Douglas‐fir productivity and greater fertilizer volume response. PRS NO3 supply rates performed as well as total soil N contents and foliar N concentrations at estimating volume growth response to fertilizer. Twelve weeks after fertilization, PRS NO3, NH4, and Ca supply rates were significantly elevated compared to the unfertilized treatment. This research found that PRS probes were an effective in situ tool and are recommended for understanding N, Ca, and P nutrient availabilities, site productivity, and fertilizer response in Douglas‐fir plantations and for developing fertilizer prescriptions.

Integrated Ca, Mg, Cu, and Zn supply upregulates leaf anatomy and metabolic adjustments in Eucalyptus seedlings

Adaptive responses to abiotic stresses such as soil acidity in Eucalyptus—the most widely planted broad-leaf forest genus globally—are poorly understood. This is particularly evident in physiological and anatomical disorders that inhibit plant development and wood quality. We aimed to explore how the supply of Ca and Mg through liming (lime), combined with Cu and Zn fertilization (CZF), influences physiological and anatomical responses during Eucalyptus grandis seedlings growth in tropical acid soil. Therefore, related parameters of leaf area and leaf anatomy, stomatal size, leaf gas exchange, antioxidant system, nutrient partitioning, and biomass allocation responses were monitored. Liming alone in Eucalyptus increased specific leaf area, stomatal density on the abaxial leaf surface, and Ca and Mg content. Also, Eucalyptus exposed only to CZF increased Cu and Zn content. Lime and CZF increased leaf blade and adaxial epidermal thickness, and improved the structural organization of the spongy mesophyll, promoting increased net CO2 assimilation, and stomatal conductance. Fertilization with Ca, Mg, Cu, and Zn positively affects plant nutrition, light utilization, photosynthetic rate, and antioxidant performance, improving growth. Our results indicate that lime and CZF induce adaptive responses in the physiological and anatomical adjustments of Eucalyptus plantation, thereby promoting biomass accumulation.

Knockout of a rice K5.2 gene increases Ca accumulation in the grain.

Rice is a staple food for half of the world's population, but it is a poor dietary source of calcium (Ca) due to the low concentration. It is an important issue to boost Ca concentration in this grain to improve Ca deficiency risk, but the mechanisms underlying Ca accumulation are poorly understood. Here, we obtained a rice (Oryza sativa) mutant with high shoot Ca accumulation. The mutant exhibited 26%-53% higher Ca in shoots than did wild-type rice (WT) at different Ca supplies. Ca concentration in the xylem sap was 36% higher in the mutant than in the WT. There was no difference in agronomic traits between the WT and mutant, but the mutant showed 25% higher Ca in the polished grain compared with the WT. Map-based cloning combined with a complementation test revealed that the mutant phenotype was caused by an 18-bp deletion of a gene, OsK5.2, belonging to the Shaker-like K+ channel family. OsK5.2 was highly expressed in the mature region of the roots and its expression in the roots was not affected by Ca levels, but upregulated by low K. Immunostaining showed that OsK5.2 was mainly expressed in the pericycle of the roots. Taken together, our results revealed a novel role for OsK5.2 in Ca translocation in rice, and will be a good target for Ca biofortification in rice.

Nitrogen addition increases the glucose-induced priming effect of the particulate but not the mineral-associated organic carbon fraction

Nitrogen availability affects the mineralization of soil organic matter differently depending on soil type and soil layer. It is unknown whether such differences result from different responses of individual carbon fractions to N supply. This study examined the priming effect (PE) on the decomposition of particulate organic matter (POM) and mineral-associated organic matter (MAOM) fractions in response to N addition. Two soils, one from a woodland and the other from a cropland, were fractionated to obtain two POM fractions differing in C:N ratio and two MAOM fractions differing in mineral C protection. Two fractions of each soil were incubated for 14 days after the initial supply of 13C-glucose and Ca(NO3)2 at 0, 20 and 60 mg N kg−1. Glucose addition induced a stronger PE per unit soil organic C in the MAOM than POM, particularly in the woodland soil (6.2 vs. 0.8 mg C g−1 C). The glucose-stimulated increases in the abundances of bacteria, fungi, and four functional genes (LMCOs, ureC, npr and chiA) were also larger in the MAOM than POM. The PE was similar in the MAOM (C:N 11.6–12.4) from the two soils and was not affected by N addition. By contrast, N addition increased the PE in the POM (C:N 21.6) of the woodland soil (e.g., by 7-fold at 60 mg N kg−1), along with marked increases in the abundances of fungi, the four functional genes, and the ratio of fungi to bacteria. Compared with the woodland soil, the addition of 60 mg N kg−1 to the POM of the cropland soil (C:N 16.9) stimulated the PE to a lesser extent (by 30%). These results suggest that N input may have a greater potential in stimulating the PE in soils with a higher proportion of POM with a greater C:N ratio.

Proximate composition and mineral content analysis of Curcuma caesia rhizome

In Ayurveda, Curcuma caesia Roxb. (Zingiberaceae) plants are used as medicines and nutritional supplements. Because of its variety of phytochemicals and beneficial nutritional properties, the native flora species C. caesia has been subjected to current research work. This study performed a preliminary phytochemical screening, physicochemical studies, proximate analysis, and element identification in C. caesia rhizomes using standard techniques. Preliminary phytochemical screening revealed that plants have a variety of secondary metabolites like curcumine, coumarin, carbohydrates, and phenol present in each extract. The findings proved that C. caesia has a greater ratio of crude protein, crude fiber, crude fat, and carbohydrates. The results also revealed a rich supply of mineral elements, including Fe, K, Co, Na, Ca, Mg, P, and Al, which emphasized its good nutritional value. This research would help to identify and formulate pharmaceutical medications as well as quality control aspects.

Effects of Ca Sprays on Fruit Ca Content and Yield of Tomato Variety Susceptible to Blossom-End Rot.

Several factors are involved in the incidence of blossom-end rot (BER) in tomato fruit, but the main one is insufficient Ca uptake and transport through the plant, resulting in Ca deficiency in the fruit. Sprays of Ca-containing products are considered to be a possible measure to overcome the local Ca deficiency in tomato fruit. Therefore, the main objective was to evaluate the effectiveness of additional Ca supply to tomato fruits for increasing Ca content and reducing fruit damage. Sprays of five different commercial preparations containing (Brexil Duo, Calmax Zero N, Ca(NO3)2, CaCl2) or promoting (Greenstim) Ca uptake were tested using BER-sensitive large-fruit variety 'Beorange'. The experiment was conducted in the commercial greenhouse 'Getlini EKO', Latvia, during the autumn-spring season of 2020/2021 under controlled conditions, eliminating the adverse impact of external factors. The results revealed that none of the preparations were effective in increasing Ca content, preventing BER, and did not promote the tomato yield. As good agricultural practices were followed in the greenhouse to manage BER, we concluded that a non-marketable yield of around 15% should be expected for 'Beorange' when grown under artificial light, possibly due to the impact of abiotic stresses and genetically determined susceptibility.

Effects of exogenous calcium on cadmium accumulation in amaranth

Calcium oxalate (CaOx) crystals in plants act as a sink for excess Ca and play an essential role in detoxifying heavy metals (HMs). However, the mechanism and related influencing factors remain unclear. Amaranth (Amaranthus tricolor L.) is a common edible vegetable rich in CaOx and a potential Cd hyperaccumulation species. In this study, the hydroponic experiment was carried out to investigate the effect of exogenous Ca concentrations on Cd uptake by amaranth. The results showed that either insufficient or excess Ca supply inhibited amaranth growth, while the Cd bioconcentration factor (BCF) increased with Ca concentration. Meanwhile, the sequence extraction results demonstrated that Cd mainly accumulated as pectate and protein-bound species (NaCl extracted) in the root and stem, compared to pectate, protein, and phosphate-bound (acetic acid extractable) species in the leaf. Correlation analysis showed that the concentration of exogenous Ca was positively correlated with amaranth-produced CaOx crystals but negatively correlated with insoluble oxalate-bound Cd in the leaf. However, since the accumulated insoluble oxalate-bound Cd was relatively low, Cd detoxification via the CaOx pathway in amaranth is limited.

Effects of Drought Stress and Ca Supply on the Biomass Allocation Strategies of Poplar and Mulberry

In order to investigate the effect of Ca on the biomass allocation strategies of tree species with different growth rates under drought conditions, we treated poplar (Populus canadensis cv) cuttings and mulberry (Morus alba) seedlings with two soil moisture levels (40 ± 5% and 80 ± 5% maximum water holding capacity) and two soil Ca levels (0 and 200 mg·kg−1 Ca2+) in a greenhouse experiment, and then measured the Ca uptake, growth, gas exchange parameters, biomass allocation, and leaf traits. Drought induced a reduction in biomass accumulation of poplar cuttings and mulberry seedlings, and the cuttings and seedlings exhibited different biomass allocation patterns in response to drought stress. Under Ca0 treatment, poplar cuttings allocated more biomass to leaves and less biomass to stems under drought conditions, leading to an increased leaf/stem (L/St) ratio and higher SLA than under moist conditions in order to maintain higher Pn, and had enhanced WUE to cope with drought stress. Under the same treatment, mulberry seedlings allocated more biomass to roots and less biomass to stems, leading to an increased root/shoot (R/S) ratio and lower SLA, to improve drought resistance. Ca200 treatment decreased the growth of poplar cuttings and mulberry seedlings, whereas it enhanced the WUE, root growth, and R/S ratio of poplar cuttings and the WUE of mulberry seedlings, and alleviated drought stress in both species.

Exogenous calcium regulates the growth and development of Pinus massoniana detecting by physiological, proteomic, and calcium-related genes expression analysis

Pinus massoniana is an important industrial crop tree species commonly used for timber and wood pulp for papermaking, rosin, and turpentine. This study investigated the effects of exogenous calcium (Ca) on P. massoniana seedling growth, development, and various biological processes and revealed the underlying molecular mechanisms. The results showed that Ca deficiency led to severe inhibition of seedling growth and development, whereas adequate exogenous Ca markedly improved growth and development. Many physiological processes were regulated by exogenous Ca. The underlying mechanisms involved diverse Ca-influenced biological processes and metabolic pathways. Calcium deficiency inhibited or impaired these pathways and processes, whereas sufficient exogenous Ca improved and benefited these cellular events by regulating several related enzymes and proteins. High levels of exogenous Ca facilitated photosynthesis and material metabolism. Adequate exogenous Ca supply relieved oxidative stress that occurred at low Ca levels. Enhanced cell wall formation, consolidation, and cell division also played a role in exogenous Ca-improved P. massoniana seedling growth and development. Calcium ion homeostasis and Ca signal transduction-related gene expression were also activated at high exogenous Ca levels. Our study facilitates the elucidation of the potential regulatory role of Ca in P. massoniana physiology and biology and is of guiding significance in Pinaceae plant forestry.

Exogenous calcium promotes growth of adzuki bean (Vigna angularis Willd.) seedlings under nitrogen limitation through the regulation of nitrogen metabolism

Plants exhibit lower nitrogen use efficiency (NUE) under N-limitation conditions. Although the function of calcium (Ca) has been widely studied in plants, it remains to be explored whether regulation of nitrate uptake and reduction is needed. A hydroponics experiment on adzuki beans (Vigna angularis Willd.) was used as a test material to determine the interactions between Ca and three levels of nitrogen supply. The height of the plant, the leaf area per plant, the biomass of the plant, the morphology of the roots, the hydraulic conductivity of the roots, the level of gas exchange, and the level of N metabolism of the adzuki beans were evaluated. Furthermore, RT-qPCR was conducted to explore the expression of genes related to nitrate transporter responses to Ca under N-limitation stress conditions. The rate of accumulation of N in plant tissue increased with the application of Ca. However, plant biomass, photosynthetic parameters, and root activity peaked for Ca2+ supply under N-marginal conditions. Further investigation revealed that the activities of nitrate reductase and glutamine synthetase were relatively high. The transcription of the nitrate transporter (VaNRT1.1; VaNRT2.5) was up-regulated in the roots of the Ca-treated plants. Both N-marginal conditions and N deficiency inhibit N absorption and utilization. The favorable effects of Ca on seedling growth and N metabolism under N-marginal conditions were more significant than those under N-deficiency conditions. The supply of Ca2+ is optimal, as it increases NUE by enhancing photosynthesis, N-metabolizing enzyme activities, and NO3 uptake and transport under N-marginal conditions.

Foliar fertilizers with Ca prolong the firmness of Sweet Grape tomatoes during the post-harvest period

The objective of this study was to evaluate the post-harvest quality of Sweet Grape tomatoes, with and without nutritional deficiency, subjected to sources and frequency of application of foliar fertilizers based on Ca. Two experiments were conducted with storage of the fruit in different climate chambers: 25 and 11 ºC. The experiments were conducted in a randomized block design with subdivided plots. The Ca sources used via foliar fertilization were allocated to the plots: calcium chloride and calcium acetate at a concentration of 0.3% Ca, and deionized water. In the sub-plots the frequencies of foliar fertilizer application (7 or 14 days) were allocated. The sub-sub-plots received the periods of fruit evaluation during storage (0, 9, 18, and 27 days). In each experiment and evaluation period, firmness, pH, soluble solids content, and titratable acidity of the fruit were determined. In both plants that received adequate and low Ca supply in the nutrient solution. Foliar fertilizer applications increased initial fruit firmness, regardless of the frequency of application, enabling longer storage time at both temperatures. There were no differences between the treatments in the evaluations referring to the taste of the fruits during the storage periods.

Estimates of Dietary Mineral Micronutrient Supply from Staple Cereals in Ethiopia at a District Level.

Recent surveys have revealed substantial spatial variation in the micronutrient composition of cereals in Ethiopia, where a single national micronutrient concentration values for cereal grains are of limited use for estimating typical micronutrient intakes. We estimated the district-level dietary mineral supply of staple cereals, combining district-level cereal production and crop mineral composition data, assuming cereal consumption of 300 g capita−1 day−1 proportional to district-level production quantity of each cereal. We considered Barley (Hordeum vulgare L.), maize (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench), teff (Eragrostis tef (Zuccagni) Trotter), and wheat (Triticum aestivum L.) consumption representing 93.5% of the total cereal production in the three major agrarian regions. On average, grain cereals can supply 146, 23, and 7.1 mg capita−1 day−1 of Ca, Fe, and Zn, respectively. In addition, the Se supply was 25 µg capita−1 day−1. Even at district-level, cereals differ by their mineral composition, causing a wide range of variation in their contribution to the daily dietary requirements, i.e., for an adult woman: 1–48% of Ca, 34–724% of Fe, 17–191% of Se, and 48–95% of Zn. There was considerable variability in the dietary supply of Ca, Fe, Se, and Zn from staple cereals between districts in Ethiopia.

Improving Bell Pepper Crop Performance and Fruit Quality under Suboptimal Calcium Conditions by Grafting onto Tolerant Rootstocks

Calcium deficiency or its inefficient translocation to pepper fruits leads to considerable economic loss by reducing the number of marketable fruits. The present study proposes grafting as an environmentally friendly technique to effectively reduce such loss. A commercial variety (Al-cudia F1; V) was grafted onto two pepper (Capsicum annum L.) accessions (V/A6 and V/A8), a hybrid rootstock (V/N) and was also self-grafted (V/V). All rootstock–scion combinations were cultivated under greenhouse conditions with optimal and suboptimal Ca supply and assessed for fruit yield and biomass production, gas exchange and chlorophyll fluorescence, mineral concentration in leaves and fruits as well as several fruit quality parameters. The V/N plants demonstrated an enhanced capacity for increased biomass, higher yield and number of commercial fruits and greater mean fruit weight compared with the other rootstock–scion combinations. These improvements are attributed primarily to increased intrinsic water efficiency. Additionally, a significantly higher Ca concentration in leaves was found under suboptimal Ca conditions in the V/N combination than that found in the other rootstock–scion combinations indicating a higher capacity for Ca uptake and translocation. Under the same conditions, the concentration of organic acids in fruits, such as citric and tartaric, which impact the organoleptic quality, was also higher in V/N plants. Consequently, we can conclude that grafting pepper onto tolerant rootstocks is a successful tool for ameliorating the negative impact of suboptimal Ca conditions on pepper crop performance and fruit quality.

The geomorphological distribution of subaqueous tufa columns in a hypersaline lake: Mono Lake, U.S.A.

Abstract Understanding the flow of carbon through hyperalkaline lakes is a key means of understanding their biogeochemistry, sedimentology, and their paleoenvironmental and paleoclimatic records. Furthermore, understanding how mineral precipitation is regulated in these lakes can provide insights into how their sequestration of carbon can be managed. We report geophysical surveys of Mono Lake, California, USA, which show unanticipated geomorphological control on the recent/contemporary formation of lacustrine carbonate formations (“tufa”). Acquired shallow-penetration seismic data show a fault zone below the lake floor, but despite the regional evidence for geothermal waters rising up these fractures, we find no evidence for tufa precipitation at the surface exposure of this structure, either in the seismic data or in the swath bathymetry. However, we do find sub-lacustrine tufa columns in these data elsewhere, which is the first time these have been reported directly. We find and report on a strong link between column location and meteoric Ca supply to the lake, with the latter sourced either through surface runoff or groundwater. For example, a region close to a creek inlet has more frequent and larger tufa bodies, which grow at a wider depth range than another region far from an inlet but close to the fault. This demonstrates the importance of meteoric water ingress in regulating carbonate mineral formation in these basins, and raises the possibility that management of water within the catchment could be a means to enhance carbon capture in natural and artificial hyperalkaline lakes.

Three OsMYB36 members redundantly regulate Casparian strip formation at the root endodermis.

Plants have evolved a lignin-based Casparian strip (CS) in roots that restricts passive diffusion of mineral elements from the soil to the stele. However, the molecular mechanisms underlying CS formation in rice (Oryza sativa), which contains a CS at both the exodermis and endodermis, are poorly understood. Here, we demonstrate that CS formation at the rice endodermis is redundantly regulated by three MYELOBLASTOSIS (MYB) transcription factors, OsMYB36a, OsMYB36b, and OsMYB36c, that are highly expressed in root tips. Knockout of all three genes resulted in a complete absence of CS at the endodermis and retarded plant growth in hydroponic conditions and in soil. Compared with the wild-type, the triple mutants showed higher calcium (Ca) levels and lower Mn, Fe, Zn, Cu, and Cd levels in shoots. High Ca supply further inhibited mutant growth and increased Ca levels in shoots. Transcriptome analysis identified 1,093 downstream genes regulated by OsMYB36a/b/c, including the key CS formation gene OsCASP1 and other genes that function in CS formation at the endodermis. Three OsMYB36s regulate OsCASP1 and OsESB1 expression by directly binding to MYB-binding motifs in their promoters. Our findings thus provide important insights into the mechanism of CS formation at the endodermis and the selective uptake of mineral elements in roots.

69 Impact of DON in a Protocol of Calcium Depletion and Repletion in Piglets

Abstract This study aimed to evaluate factors that modulate phosphorus (P) use, such as calcium (Ca) intake that is well known and deoxynivalenol (DON) contamination which has been the subject of few studies until now. A total of 64 piglets (2 piglets per pen) received 1 of 4 treatments distributed into 8 blocks during an initial 13-d phase: control (DON-) or DON-contaminated treatment (DON+, 2.72 mg/kg) with either a low Ca (Ca-, 0.39%) or normal Ca (Ca+, 0.65%) level with a constant digestible P level (0.40%). During a second 14-d phase, piglets that received Ca+ and Ca- were fed a similar diet containing 0.65% Ca and 0.35% P without DON contamination. Growth performance and apparent total tract digestibility (ATTD) of Ca and P for piglets and bone mineral content (BMC) of 1 pig per pen were evaluated. After phase 1, ATTD P was higher for Ca-DON+ (DON x Ca interaction, P &amp;lt; 0.01). The ATTD Ca was higher for DON+ (( P &amp;lt; 0.001). The DON+ increased BMC in Ca+ but opposite effect was observed in Ca- (DON x Ca interaction, P &amp;lt; 0.001). The plasma P concentration was greater for Ca- (P = 0.05). After phase 2, average daily gain (P = 0.08) and average daily feed intake (P = 0.09) tended to be less for Ca- than for Ca+. The Ca- piglets recovered their BMC deficit in DON-, but not those receiving DON+ (DON x Ca interaction, P = 0.06). ATTP P in DON- was lower in Ca+ but increased in DON+ regardless of Ca level (DON x Ca interaction, P = 0.04). Plasma P and Mg were greater for Ca- (P = 0.05). The results show that piglets can regain the BMC caused by Ca depletion in DON non-contaminated feed. DON contamination increased Ca and P digestibility and modified BMC depending on Ca supply.