Pedogenic carbonate recrystallization assessed by isotopic labeling: a comparison of 13C and 14C tracers

The C isotopic composition (δ¹³C) of pedogenic carbonates reflects the photosynthetic pathway of the predominant local vegetation because pedogenic (secondary) CaCO₃ is formed in isotopic equilibrium with soil CO₂ released by root and rhizomicrobial respiration. Numerous studies show the importance of pedogenic carbonates as a tool for reconstructing paleoecological conditions in arid and semiarid regions. The methodological resolution of these studies strongly depends on the time scale of pedogenic carbonate formation, which remains unknown. The initial formation rate can be assessed by ¹⁴C labeling of plants grown on loess and subsequent incorporation of ¹⁴C from rhizosphere CO₂ into newly formed carbonate by recrystallization of loess CaCO₃. We tested the feasibility of ¹⁴C and ¹³C tracers for estimating CaCO₃ recrystallization rates by simultaneous ¹⁴C and ¹³C labeling and comparison with literature data. ¹⁴C labeling was more efficient and precise in assessing recrystallization rates than ¹³C labeling. This is connected with higher sensitivity of ¹⁴C liquid scintillation counting when compared with δ¹³C measurement by IRMS. Further, assessment of very low amounts of incorporated tracer is more precise with low background signal (natural abundance), which is true for ¹⁴C, but is rather high for ¹³C. Together, we obtained better reproducibility, higher methodological precision, and better plausibility of recrystallization rates calculated based on ¹⁴C labeling. Periods for complete CaCO₃ recrystallization, extrapolated from rates based on ¹⁴C labeling, ranged from 130 (125–140) to 240 (225–255) y, while it was ≈ 600 (365–1600) y based on the ¹³C approach. In terms of magnitude, data from late‐Holocene soil profiles of known age provide better fit with modeled recrystallization periods based on the ¹⁴C approach.     

Effects of Supplemental Calcium on Ion Accumulation,Transport and Plant Growth of Salt Sensitive Brassica Rapa Landrace

ABSTRACT

Effects of three supplemental calcium (Ca⁺⁺; 2.5, 5.0, and 10 mole m^?3) concentrations on ion accumulation, transport, selectivity, and plant growth of salt-sensitive species, Brassica rapa ‘Sani’ in saline medium were investigated. Supplemental Ca⁺⁺ in the presence of 125 mol m^?3 sodium chloride (NaCl) did not improve the dry weight and leaf area indicating no role played by Ca⁺⁺ in the alleviation of salinity induced growth inhibition. However, calcium chloride (CaCl₂) did significantly affect sodium (Na⁺), potassium (K⁺), and Ca⁺⁺ contents of roots and shoots. The ion contents of shoots were significantly greater than those of roots per g dry weight, indicating ion transportation to shoots is greater than ion accumulation in roots. Use of CaCl₂ in 125 mol m^?3 NaCl reduced the Na⁺ content but increased K⁺ and Ca⁺⁺ contents in shoots. Sodium contents in shoots differed among the supplemental Ca⁺⁺ treatments indicating the role of CaCl₂ in Na⁺ ions transportation. Calcium content in shoots declined significantly in the control treatment (0 CaCl₂) but increased significantly in 10 mol m^?3 CaCl₂. The root also showed the effects of Ca⁺⁺ on the reduction of Na⁺ content and the increase of K⁺ and Ca⁺⁺ content. Unexpectedly, 5 mol m^?3 CaCl₂ induced the highest Na⁺ content in roots at 16 days after treatment. Supplemental CaCl₂ application influenced the K⁺ or Ca⁺⁺ selectivity over Na⁺ in two ways, ion accumulation at roots and transport to shoots. However, high CaCl₂ treatments allowed greater Ca⁺⁺ selectivity over Na⁺ than low CaCl₂. Likewise, high supplemental CaCl₂ showed higher K⁺ selectivity over Na⁺ than low CaCl₂. A marked increase in K⁺ versus Na⁺ selectivity for the transport process occurred at 10 mol m^?3 CaCl₂ treatments. The roots and shoots exhibited higher K⁺/Na⁺ and Ca⁺⁺/Na⁺ ratios in high CaCl₂ treatment than in low. The results are discussed in context to supplemental Ca⁺⁺ concentrations, ions accumulation, transportation and selectivity of salt sensitive Brassica rapa cultivar.     

EFFECTS OF FOLIAR AND SOIL CALCIUM APPLICATION ON YIELD AND QUALITY OF TABLE GRAPE CV. ‘THOMPSON SEEDLESS’

Table grape quality and firmness are key parameters for Chile's export, given distances from the main markets. As a consequence, calcium (Ca) fertilization has become a standard practice in the country, although its effects have not been fully evaluated. The objectives in this study were to investigate the effects of calcium fertilization on table grape nutrition and quality. A two-year field trial was conducted in central Chile, using grapevines (Vitis vinifera) cv. ‘Thompson seedless’, grown on an overhead trellis system. Calcium (CaCl₂) application treatments included foliar, soil, foliar plus soil, and a control without Ca fertilization. Calcium and other nutrients concentration were determined afterwards in soil, leaves, and berries. Also, yield and some fruit quality parameters were evaluated. Calcium application method did not have an effect on soil, leaf or fruit Ca content, neither on yield and berry sugar concentration, with levels being similar to the control treatment. Additionally, in treatments where CaCl₂ was applied to soil, chlorides concentration in soil, leaves, and berries were higher. Also, berries were larger, more turgent, with lower dry matter and larger cells. In the second season, in these same treatments, berry firmness at harvest was higher, but this effect disappeared after the storage simulation period. These results question the validity that Ca applications might improve table grape postharvest quality for growing conditions similar to the ones in this experiment. The temporal changes in berry quality parameters were attributed to higher Cl soil content and the associated plant osmoregulatory mechanisms.     

石灰性土壤交换性钙和镁测定方法的研究

石灰性土壤交换性盐基组成的测定,通行的方法是采用70%乙醇溶液反复洗盐,再经pH 8.50.1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液进行多次交换处理,测定交换液中的K+、Na+、Ca2+、Mg2+浓度。但此方法常常受操作步骤繁琐,以及土壤中碳酸盐的溶解量因多次浸提而增加的困扰,最终导致测定结果偏高。基于上述原因,选择不同浓度、不同pH的NH4OAc和NH4Cl 10种交换剂,对比分析10种交换剂中的碳酸盐溶解度和土壤交换性钙镁含量。结果表明,pH=8.5 1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液较适合石灰性土壤交换性盐基的测定。此新方法是先经70%乙醇(CH3CH2OH)溶液洗盐,再用pH8.5 1 mol L-1氯化铵(NH4Cl)-70%乙醇(CH3CH2OH)溶液进行一次性交换处理,然后测定交换液的K+、Na+、Ca2+、Mg2+浓度,简化了操作程序的同时有效抑制了土壤碳酸盐的溶解,降低了测定结果的偏差。     

Effect of Preharvest Sprays of Calcium on Cracking and ‘Schattenmorelle’ Sour Cherry Fruit Quality Harvested Mechanically

The aim of the study was to examine effect of preharvest sprays of calcium (Ca) in the form of Ca-chloride (CaCl₂), Ca-nitrate [Ca(NO₃)₂], or a mixture of Ca-formate, Ca-acetate, CaCl₂, and Ca(NO₃)₂ on cracking and quality of ‘Schattenmorelle’ sour cherry fruit harvested mechanically. The experiment was conducted in 2008–2009 at a commercial orchard in central Poland. Mature trees grew on a coarse-textured soil poor in organic matter, at a spacing of 4.0 × 1.5 m. The spray treatments of Ca were performed at 7-day intervals, starting 28 days before harvest, at the rates of 5.0–5.6 kg Ca ha^?1 per season. The trees sprayed with water were treated as the control. Fruit were harvested mechanically when peduncle-fruit detachment force dropped below 3 N. The results showed that preharvest Ca sprays caused no leaf damage. This measure did not affect yield, mean fruit weight, soluble solids concentration and titratable acidity of fruit, and weight loss of fruit during 24 h after harvest. Fruit sprayed with Ca had improved status of this nutrient, and were less liable to juicy leakage from the stem scar, rain-induced cracking, and preharvest decay caused by Glomerella cingulata. The above effects of Ca sprays did not depend on the tested material. It was concluded that preharvest sprays of Ca as CaCl₂ and/or Ca(NO₃)₂ should be recommended in ‘Schattenmorelle’ sour cherry orchards to reduce fruit losses resulting from rain-induced cracking, leakage of juice, and the incidence of cherry bitter rot.     

Ameliorative effect of potassium on mice and tomato subjected to sodium salinization

Rice (Oryza sativa L. cv. Yamabiko) and tomato (Lycopersicon esculentum Mill cv. Saturn) plants subjected to Na-salinization (NA: 80 mmol( + ) kg^-1 Na) in hydroponics were grown after the addition of K at five concentrations (K1: 10, K2: 20, K3: 30, K4: 40, K5: 50 mmol( + ) kg^-1). The effect of K on their growth was analyzed in terms of transpiration, cation uptake, and transport. A similar tendency for the above parameters was obtained in both species. The addition of 10 mmol( + ) kg^-1 K improved the growth by decreasing the content of Na and increasing the K content of the plants. The growth of the plants, however, was reduced along with the increase of the K concentration and became comparable to that of NA at K5. The total cation content increased with the increase of the K concentration, which was due to the increase of the K content.

A close relationship was observed among the osmotic potential of the solution, cumulative transpiration, and dry weight for both species among the K treatments.

Addition of K suppressed the uptake of other cations by rice and tomato in the order of Na>Mg>Ca, with a very small suppression for Ca and Mg. The depression of Na uptake by K could be due to the antagonism between the two cations.

In rice, the addition of K resulted in a decrease of the uptake concentration (UC) of Na and an increase of that of K, but did not bring about any changes in the UC of Ca and Mg. It was worth noting that K1 and K2 led to a higher UC of Na than NA in tomato, while the trend of the UC of K, Ca, and Mg was similar to that in rice. The transport of Na and Ca to the tops of rice was not affected by the addition of K, while that of Mg increased by K addition. In tomato, the transport of all the cations was promoted by the increase of the K concentration.     

Effect of calcium concentration in nutrient solution before and after inoculation with Ralstonia solanacearum on resistance of tomato seedlings to bacterial wilt

We previously reported that calcium (Ca) nutrition in tomato (Lycopersicon esculentum Mill.) significantly affected the resistance to bacterial wilt caused by Ralstonia solanacearum Smith. To elucidate the mechanisms underlying the Ca-dependent resistance, the effect of the Ca concentration in the nutrient solution applied before and after inoculation with the pathogen on the resistance of tomato seedlings to bacterial wilt was studied. One week before inoculation, seedlings were transferred to nutrient solutions containing Ca at concentrations of 0.4, 4.4, or 20.4 mM. Soon after inoculation, the seedlings that were treated with each concentration of Ca before inoculation were transferred to solutions containing the same three concentrations of Ca. Although the disease development was not affected by the concentration of Ca in the solution before inoculation, a higher concentration of Ca after inoculation reduced the disease severity. This result suggests that the concentration of Ca in the host, especially in the cell walls, before infection may not be directly involved in the Ca-dependent resistance of tomato seedlings to bacterial wilt.     

心土培肥犁改良瘠薄土壤的效果

研究根据心土培肥的改土技术要求研制出心土培肥犁,并分别在瘠薄黑土和碳酸盐草甸黑钙土上开展大面积机械改土试验,明确自主研发的心土培肥犁改土后对土壤理化性质影响及对作物产量的效果,为其广泛应用到低产土壤改良提供机械及技术支持。试验设深松、心土培肥和常规对照耕作,采用大田对比方法。研究结果表明:心土培肥和深松在不同类型土壤上对土壤理、化性质,对作物产量及产量性状影响后效不完全一致;心土培肥降低土壤抗剪强度后效明显,碳酸盐草甸黑钙土10~30 cm土层土壤抗剪强度比对照降低6.65~12.16 k Pa,黑土比对照降低8.20~11.31 k Pa,碳酸盐草甸黑钙土改土后效果明显,黑土改土后效长,心土培肥改土效果优于深松;土壤容质量和硬度趋势同上;心土培肥提高土壤透气系数为2.78~14.28倍,饱和导水率为2.38~11.62倍;深松和心土培肥可提高下层土水分消耗比例,30~60 cm土层耗水量为心土培肥区深松区对照区,心土培肥耗水量比照高10%;心土培肥处理可提高土壤磷含量和供磷强度,20~30 cm和30~40 cm土层土壤供磷强度比对照分别提高4.19~5.17倍和4.96~17倍,碳酸盐草甸黑钙土高于黑土;心土培肥可提高玉米产量,碳酸盐草甸黑钙土上心土培肥增产幅度为6.82%~18.01%,黑土增产幅度为6.45%~11.18%,平均增产效果碳酸盐草甸黑钙土薄层黑土,但黑土持续增产效果好。     

氯化钠和氯化钙对玉米淀粉-瓜尔胶复配体系的影响

通过测定分析玉米淀粉-瓜尔胶复配体系在有无氯化钠和氯化钙存在条件下的糊化特性、动态与静态流变学特性,研究氯化钠和氯化钙对玉米淀粉-瓜尔胶复配体系的影响。结果表明,氯化钠和氯化钙的加入,提高了玉米淀粉-瓜尔胶复配体系的成糊温度,降低了崩解值和回升值,峰值黏度也略微下降;玉米淀粉-瓜尔胶复配体系的弹性模量G′值显著减小,黏性模量G″值的频率依赖性较大;氯化钠和氯化钙使玉米淀粉-瓜尔胶复配体系的假塑性增强,且氯化钙的作用大于氯化钠。     

不同保鲜剂喷雾处理对冰箱贮藏期间西兰花保鲜效果的影响

以西兰花为试材,在冰箱贮藏条件下(温度(5±1)℃、相对湿度76%±10%),通过测定失重率、VC含量、多酚氧化酶(PPO)、过氧化氢酶(CAT)、脂氧合酶(LOX)活性等指标,研究丙酸钙和纳他霉素喷雾处理对西兰花品质和相关酶活性的影响。结果表明,与对照相比,3.0 g/L丙酸钙和1.2 g/L纳他霉素喷雾处理均能有效保持冰箱贮藏期间西兰花的感官品质、硬度、VC含量和CAT活性,并且减少失重,抑制PPO活性和LOX活性的升高,其中丙酸钙喷雾处理的保鲜效果优于纳他霉素。