Nutrition and biochemical responses of chickpea (Cicer Arietinum L.) to vermicompost fertilizer and water deficit stress

Vermicompost can have an effective role in plant growth and nutrition. It can also reduce the harmful effects of stress caused by environmental factors. This study was a factorial experiment with a completely randomized plot design and three replications. The results showed that the calcium concentration (+40% +39%) of root and calcium (+71% +67%) and potassium contents (+49% +59%) of leaf under conditions of moderate and severe water stress increased under vermicompost treatments at the ratio of 30%. Sodium absorption (?37% ?21%) in moderate and severe conditions was significantly reduced by vermicompost treatment. In moderate and severe water stress, the growth medium of 30% vermicompost significantly enhanced proline (+39%) and soluble protein content (+28%) compared to the control. In conclusion, our results proved vermicompost fertilizer due to its structural properties and components, served to reduce the negative effects of water stress by increasing the absorption of calcium (Ca) and potassium (K), and decreasing sodium (Na) absorption that resulted in increased evaluations for proline and protein content.     

Interactive Effect of Sulfur and Nitrogen on Nitrogen Accumulation and Harvest in Oilseed Crops Differing in Nitrogen Assimilation Potential

ABSTRACT

Field experiments were conducted to determine the interactive effect of sulfur (S) and nitrogen (N) on nitrogen accumulation, its distribution in various plant parts, and nitrogen harvest of oilseed crops viz. rapeseed (Brassica campestris L. cv. ‘Pusa Gold’) and taramira (Eruca sativa Mill.) differing in their N-assimilation potential. Two combinations of S and N (in Kg/ha): 0S + 100N (?S+N) and 40S + 100N (+S+N) were used. The results showed that combined application of S and N (+S+N) significantly (P < 0.05) increased the nitrogen accumulation in both the genotypes at all the growth stages compared with N applied alone (?S+N). This increase in nitrogen accumulation was due to the improvement in the reduction of nitrate into reduced nitrogen as evident from higher nitrate reductase (NR) activity in the leaves of plants grown with both S and N, compared with N alone. Nitrate-N content in the leaves of plants grown with only N (?S+N) was higher compared to those grown with both S and N (+S+N), showing that combined application of S along with N (+S+N) appreciably reduced the nitrate content in the leaves due to higher NR activity. This decline in nitrate (NO₃ ^?) was followed by an overall increase in N-accumulation in the plants. Consequently, the nitrogen content in the plant was increased by 29–148% in rapeseed and 38-166% in taramira with +S+N treatment. Combined application of S along with N (+S+N) also increased seed protein content and nitrogen harvest index of both the genotypes. It is concluded that combined application of S along with N (+S+N) not only increased the N-accumulation, but also its mobilization towards economic sinks.     

The combined effects of enhanced UV-B radiation and selenium on growth, chlorophyll fluorescence and ultrastructure in strawberry (Fragaria × ananassa) and barley (Hordeum vulgare) treated in the field

The possible ameliorative effects of selenium (Se) addition to soil on the detrimental effects of enhanced UV-B radiation were tested on strawberry and barley during 4 months of field experiment in Kuopio, Central Finland. Control plants were exposed to ambient levels of UV radiation, using arrays of unenergized lamps. A control for UV-A radiation was also included in the experiment. Added Se, applied as H₂SeO₄, at the level of 0.1 mg kg⁻¹ soil (low dosage) and 1 mg kg⁻¹ soil (high dosage) increased Se concentrations in plants more than 10 and 100 times, respectively. After 4 months of exposure, strawberry and barley plants were harvested for biomass analysis. Chlorophyll fluorescence was measured using the Hansatech FMS2 fluorescence monitoring system. Leaf anatomy and ultrastructure were observed by light and transmission electron microscope. Several effects of UV and Se as well as their interaction were found, mostly for strawberry, but not for barley, indicating species-specific responses. Our results provided evidence that the high Se concentration in soil had no ameliorative effect but increased the sensitivity of strawberry to enhanced UV-B radiation in the field. Under ambient radiation, Se did not alter leaf growth of strawberry, whereas under UV-B radiation, the high Se addition significantly decreased leaf growth. Strawberry runner biomass was affected by the interaction of Se and UV. Under ambient radiation Se did not change dry weight of runners, but in combination with UV-A or UV-B radiation the high Se dosage decreased dry weight of runners by about 30%. Although the high Se concentration positively influenced on quantum efficiency of photosystem II (PSII) in strawberry leaves, it reduced runner biomass, leaf number and ratio of starch to chloroplast area. This suggests that the harmful effects of the high Se dosage on photosynthetic processes occurred as a result of changes in activity or/and biosynthesis of enzymes, rather than alteration of PSII. At the low concentration, Se effects were slight and variable.Although barley leaves accumulated higher Se concentrations than strawberry, there were no apparent changes in their growth, biomass or chlorophyll fluorescence due to Se effect either alone or in combination with UV-B. However, at the ultrastructural level, an enlargement in the peroxisome area was found due to combination of UV radiation with Se, suggesting the activation of antioxidative enzymes, possibly catalase. Decrease in mitochondrial density in barley cells in response to Se might be attributed to alteration of mitochondrial division. Increase in the proportion of cells with cytoplasmic lipid bodies due to combined effect of UV-B and Se indicated the alteration of lipid metabolism and the acceleration of cell senescence in barley. Main UV-B effects were found, mostly at the tissue and ultrastructural level in strawberry, but not in barley, indicating species-specific susceptibility to enhanced UV-B radiation. UV-B-treated strawberry plants developed marginally thinner leaves with reduced ratio of starch to chloroplast area in their cells, suggesting negative influence of UV-B on photosynthetic processes.     

不同价态硒缓解小油菜镉胁迫的生理机制

【目的】 硒有利于提高植物对环境胁迫的抗性,缓解植物受到的非生物胁迫。研究不同价态硒对小油菜缓解重金属镉胁迫的影响,可为治理农田土壤重金属镉污染提供参考。 【方法】 采用盆栽试验,选取三种价态硒,分别为硒代甲硫氨酸 Se (–2)、亚硒酸钠 Se (+4) 和硒酸钠 Se (+6),硒浓度均为 1 mg/kg,设置镉胁迫浓度 0、低浓度镉 (2 mg/kg) 和高浓度镉 (5 mg/kg),共计 12 个处理,采用原子吸收光谱法测定植物的镉含量,分析调查了对小油菜生长及生理特性的影响。 【结果】 未加外源镉时,与对照 (CK₀) 相比,各价态 Se 均能显著促进小油菜生长,且 Se (–2) 处理对小油菜生物量、株高、根长的促进效果优于无机硒 Se (+4) 和 Se (+6) 处理;低浓度镉胁迫下,与对照 (CK₂) 相比,经 Se (–2) 和 Se (+4) 处理后,小油菜地上部镉含量分别降低 13% 和 5%,而 Se (+6) 处理却增加了 25%;在高镉胁迫下,与对照 (CK₅) 相比,经 Se (–2) 和 Se (+4) 处理后,小油菜根部及地上部镉含量降幅可达 13%～41%,而 Se (+6) 处理后,小油菜根部及地上部镉含量分别增加了 38% 和 17%。当存在镉胁迫时,施用 Se (–2) 和 Se (+4) 处理可有效提高植物体内超氧化物歧化酶 (SOD)、过氧化物酶 (POD) 和过氧化氢酶 (CAT) 等酶的活性,增加小油菜叶片内抗坏血酸 (AsA) 和还原型谷胱甘肽 (GSH) 的含量,但Se (+6) 降低了其抗氧化酶的活性,减少了小油菜叶片中 AsA、GSH 的含量。 【结论】 在镉胁迫下,Se (–2) 在促进小油菜生长、抑制镉在小油菜体内的积累及增强小油菜生理特性方面的作用均优于 Se (+4) 和 Se (+6)。因此,Se (–2) 处理最能有效缓解小油菜镉胁迫,Se (+4) 次之,Se (+6) 却增加了镉对小油菜的胁迫作用。      

Influence of iron nutrition on sulphur uptake and metabolism in maize (Zea mays L.) roots

Abstract

Recent research has evidenced a relationship between Fe nutrition and S nutrition. Aim of the present work was to investigate the effect of Fe deficiency on the capacity of maize roots to take up and metabolize S. Maize (Zea mays L. cv. Cecilia) plants were grown for 10 d in nutrient solution (NS) with (+S) or without (?S) sulphate and Fe was added as Fe^III-EDTA at 80 μm. After removing the extraplasmatic Fe pool, half of the plants of each treatment (+S and ?S) were transferred to a new Fe-free NS. Roots were collected 4 and 24 h from the beginning of Fe deprivation. Fe deprivation slightly increased root thiols content in both nutritive conditions (+S and ?S). ATP sulphurylase activity was enhanced by sulphur deprivation, but greatly depressed when Fe and S were both omitted from the nutrient solution. O-Acetylserine sulphydrylase activity was also enhanced by S deprivation; this activity was increased by Fe starvation in +S plants, while it was unaffected by Fe nutrition in ?S plants. S deprivation greatly increased uptake rates of ³⁵SO₄ ^2? (1.9 ± 0.1 vs. 5.2 ± 0.2 μmol g^?1 root d.w. h^?1); furthermore, Fe deficiency increased ³⁵SO₄ ^2? uptake rates by 11 and 55% in +S and ?S plants, respectively. Data show that Fe-deficiency in maize results in a higher ability to take up sulphate, while limiting the first step of S assimilation in S deprived plants.     

外源硒对铅污染下荞麦生长及生理特性的影响

以荞麦‘右玉26’为材料,在防雨棚下进行盆栽试验,研究外源硒对土壤铅污染下荞麦幼苗的农艺性状及生理特性、成熟期各器官铅累积和产量的影响,旨在探讨硒对土壤铅胁迫下荞麦的生长发育、产量及铅在荞麦体内富集量的影响,为发现硒缓解重金属铅对植物的毒害作用提供理论依据,以期为农业区铅污染治理及荞麦生产提供有价值的思路和方法。试验采用2因素完全随机设计,设置3个土壤铅浓度(0 mg·L-1、500 mg·L-1、1 000 mg·L-1)、5个硒浓度(0 mg·kg-1、1 mg·kg-1、2.5 mg·kg-1、5 mg·kg-1和10 mg·kg-1)。研究结果表明:1)随铅浓度增加,荞麦的株高、总根长、干重、根系总面积、根系活力、叶绿素含量、叶绿素荧光参数、经济产量(千粒重、株粒数)均呈降低趋势。2)低浓度硒(1~2.5 mg·L-1)可缓解铅对荞麦的毒害,高浓度硒(5~10 mg·L-1)和铅为协同作用,加剧了对荞麦的毒害。3)硒浓度为2.5 mg·L-1时,缓解铅对荞麦毒害的效果最为明显,显著降低了铅胁迫下荞麦幼苗SOD和POD活性;降低成熟期荞麦各器官铅含量,各处理下荞麦各器官铅含量均表现为根茎叶种子;产量达到最大值。由此可见,外源硒可通过抑制荞麦对铅的吸收和转运,促进荞麦幼苗叶片的光合作用、提高叶片叶绿素含量和根系活力等途径来增强荞麦对铅胁迫的耐性。对本研究所用的5种浓度来说,缓解效果最佳的硒浓度为2.5 mg·L-1。     

Does the Sulfur Assimilation Pathway Play a Role in the Response to Fe Deficiency in Maize (Zea mays L.) Plants?

Abstract

The finding that the methionine is the sole precursor of the mugineic acid family phytosiderophores induced us to evaluate whether sulfur assimilation pathway has a role in plant response to Fe deficiency. Maize plants were grown for 10 days in nutrient solution (NS) containing 80 µM Fe in the presence (+S) or absence (?S) of sulfate. After removing the root extraplasmatic iron pool, half of the plants of each treatment (+S and ?S) were transferred to a new Fe deficient NS (0.1 µM final Fe concentration) (?Fe). The remaining plants of each pre‐culture condition (+S and ?S) were transferred to a new NS containing 80 µM Fe (+Fe). Leaves were collected 4 and 24 hours from the beginning of Fe deprivation period and used for chemical analysis and enzyme assays. Results showed that iron content in the leaves was lower in plants grown in S‐deficiency than in those grown in the presence of the macro‐nutrient. Iron deprivation produced an increase in the level of SH compounds in both nutritive conditions (+S and ?S). These observations are suggestive of some relationship between S nutrition and Fe uptake. For this reason, we next investigated the influence of Fe availability on S metabolism through the evaluation of changes in ATPs and OASs activity, the first and the last enzyme of S assimilation pathway respectively. Results showed that S‐starvation increased the activity of both enzymes, but this effect disappeared in plants upon Fe deficiency suggesting that S metabolism is sensitive to Fe availability. Taken together these evidences suggest that S metabolism is sensitive to soil Fe‐availability for plant nutrition and support the hypothesis of S involvement in plant response to Fe deprivation.     

硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响

采用盆栽试验探讨土壤施硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响。结果看出,在土壤施硒0.5～2.0 mg/kg范围,苦荞根在苗期（40 d）大量吸收并累积硒,全生育期各器官硒含量极显著提高;在生长中后期(60～80 d) 硒的累积最快,累积量最多。硒在苦荞各器官中的分布为:在40 d时,根＞叶＞茎;60 d时Se0.0处理为叶＞根＞花＞茎,施硒各处理则为花＞根＞叶＞茎;80 d时Se0.0处理以花＞根＞叶＞茎＞子粒,Se0.5处理以花＞叶＞子粒＞茎＞根,施硒≥1.0 mg/kg的处理则为花＞叶＞茎＞根＞子粒。土壤施硒≤1.0 mg/kg促进苦荞生长,提高地上部各器官干重和植株总干重以及各器官总黄酮和芦丁含量与累积量,不改变总黄酮和芦丁的器官分布,增加苦荞中后期对总黄酮的累积;以Se0.5处理效应最佳,各差异达显著水平。过量的硒（Se1.5～2.0 mg/kg）显著抑制苦荞生长,降低各器官干重、总黄酮和芦丁含量与累积,不利于硒在子粒中富集和总黄酮在子粒中分布。表明在低硒土壤上栽培苦荞,土壤施硒以不超过1.0 mg/kg为宜,既能最大限度的提高苦荞各器官硒、总黄酮和芦丁含量和累积量,又可降低施用硒肥的成本和减少硒肥对环境的影响。     

Interactive effects of salinity and two phosphorus fertilizers on growth and grain yield of Cicer arietinum L.

Chickpea is considered among the most sensitive grain legumes to salinity. The improvement of tolerance of lines in combination with tolerant rhizobial strains depends on various environmental and cultural conditions such as soil properties. This investigation was undertaken to evaluate the effect of phosphorus fertilization (0, 90 and 200 kg ha^?1 of P₂O₅) on biomass, nodular traits and grain yield (GY) of chickpea (cv. Flip 84-79C) growing under salinity (0 and 150 mM NaCl). The trial was laid out following a randomized block design with three replicates during 2010–2012, at the experimental farm of Oued Smar (Algiers). Salinity did not significantly decrease the dry biomass of the plants but the relative shoot growth was more affected than control, P and SP1 treatments. Besides, salinity significantly reduced GY (?20%) and nodulation traits compared to the control plants while an inversely proportional relationship was found between protein, leghemoglobin and MDA content, K/Na ratio and the increase in salt concentration. Application of two P levels to saline soil enhanced growing conditions of plants. Particularly, the (90?kg?ha^–1 of P ×?150?mM?NaCl) combination significantly increased leghemoglobin (92%), reduced proline content (?69%) and protected membranes against peroxydation compared to saline conditions. A significant increase was observed in the GY (about 30%) of plants at both P doses combined with salt stress compared to other cases. Statistically, the low P level combined with salinity induced similar responses of plants and sometimes better responses to control plants. Finally, our results support the roles of phosphorus fertilizer in the alleviation of salt stress and enhancing the soil quality for better symbiosis efficiency and yield of chickpea.     

Uptake and utilization of applied phosphorus in oilseed rape (Brassica napus L. cv. Hayola) plants at vegetative and reproductive stages: Comparison of root with foliar phosphorus application

ABSTRACT

In order to compare plants’ response to phosphorus (P) application through roots and leaves, oilseed rape (Brassica napus L. cv. Hayola) plants were cultivated until vegetative or reproductive stages and were pretreated with an adequate (+P) or low (?P) supply of P. Thereafter, these plants were treated with 0.3 mM P as sodium dihydrogen phosphate (NaH₂PO₄) either through roots (root application, RA) or leaves (leaf application, LA). Shoot biomass was observed to be suppressed under ?P conditions at both stages, whereas root growth was comparatively improved in ?P plants at the vegetative stage but not at the reproductive stage. Both RA and LA were able to compensate for the growth of vegetative shoot and roots at both stages; however, LA reduced P and dry matter partitioning into the fruits. At the vegetative stage, recovery of applied P was similar between RA and LA treatments, and was extensive in ?P plants compared with the +P ones. At the reproductive stage, in contrast, significantly lower recovery of P was observed likely due to the lower capacity of leaves for P absorption and/or their lower re-translocation ability through the phloem. Data of P utilization efficiency showed that ?P plants, at both vegetative and reproductive stages, efficiently use leaf-applied P for biomass production when compared with the +P plants. Activity of acid phosphatase was sharply inhibited by RA in ?P plants, whereas it was preferably increased by LA in both +P and ?P plants. Results indicated that under P-deficiency conditions, plants had higher ability to utilize foliar-applied P, and in contrast to RA, LA may enable plants for a continuous higher capacity of P uptake from P-deficient soil; however, RA was superior to LA in terms of fruit growth.     

Root biomass dynamics in a semi-natural grassland exposed to elevated atmospheric CO2 for five years

The effects of elevated atmospheric CO₂ on root dynamics were studied in a semi-natural grassland in central Sweden during five consecutive summer seasons. Open-top chambers were used for ambient and elevated (+350 μmol mol^?1) concentrations of CO₂, and chamberless rings were used for control. Root dynamics were observed in situ with minirhizotrons during the five summers and root biomass production was measured with root in growth cores during the last two years, from which total root biomass was estimated for each of the five years. The elevated CO₂ treatment showed both a greater increase in root numbers during the early summer and a greater decline in root numbers during autumn and winter than the ambient CO₂ treatment. Mean root production under elevated CO₂ was 50% greater than ambient CO₂ during the five years, and the difference increased from +25% in the first year to +80% in the last two years. Conversely, during the same period, the elevated to ambient CO₂ difference in shoot biomass decreased from +50% to +5%. This resulted in a dramatic change in root to shoot ratios in elevated CO₂ compared with the ambient treatment, which increased from ?15% in 1996 to +70% in 2000. Similar differences were seen between elevated CO₂ and the chamberless grown control plants, where root to shoot ratios increased steadily from ?47% in 1996 to +27% in 2000. Less dynamically, the root to shoot ratios of ambient CO₂ grown plants compared with the chamberless control plants were consistently ?29%±6% during the experimental period. In conclusion, during the 5 years this grassland was studied, there was a clear shift in plant biomass partitioning from above to below ground for plants exposed to elevated CO₂.     

Distribution of Vitamin E, squalene, epicatechin, and rutin in common buckwheat plants (Fagopyrum esculentum Moench)

Buckwheat leaves and young parts of the plant are consumed in some countries as a vegetable. Green flour, obtained by milling of the dried plants, is used as a natural food colorant. The distribution of vitamin E, squalene, epicatechin, and rutin (as the most important antioxidants) within buckwheat plants, as well as changes of their content within leaves during the growing season, were determined by GC-MS and HPLC analyses. alpha-Tocopherol was found as the main component of vitamin E in all parts of the plant; epicatechin and squalene were also detected. For the use of buckwheat as an antioxidant source in the human diet, the most suitable part of the plants seems to be the leaves and the flowers at the stage of full flowering due to the considerable amounts of rutin and epicatechin. alpha-Tocopherol content correlates positively with temperature, drought, and duration of solar radiation. Certain differences appear among varieties of buckwheat, especially in their squalene and rutin contents.     

Evaluation of vermicompost fertilizer application on growth,nutrient uptake and photosynthetic pigments of lentil (Lens culinaris Medik.) under moisture deficiency conditions

Vermicompost can play an effective role in plant growth and also in reducing harmful effects of various environmental stresses on plants due to its porous structure, high-water storage, having hormone-like substances and also high levels of macro and micro nutrients. Application of vermicompost in soil, especially at the levels of 15 and 25 Wt% significantly increased all studied traits under non-stress conditions. Under temperate and severe stress conditions, vermicompost at 25 Wt% treatment resulted in a significant increase in plant height (+10% +21%), number of pod (+44% +65%), root dry weight (+63% +66%), shoot dry weight (+50% +89%), leaf area (+6% +7%), root area (+65% +35%). The leaf calcium (Ca) (+62% +67%), leaf potassium (K) (+39% +45%) and root Ca (+33% +34%) under temperate and severe stress, increased using of 25% vermicompost. In conclusion, we suggested that application of vermicompost had a positive effect on lentil under moisture deficit stress.     

Influence of soil redox potential on nitrogen uptake and growth of wetland Oak seedlings

A study was conducted to determine ammonium nitrogen uptake by cherrybark oak and overcup oak as affected by soil redox conditions. Seedlings of the two species were grown in laboratory microcosms for 60 days in soil suspensions incubated at three separate Eh levels (+560, +340, and + 175 mV). In both species, uptake of added ¹⁵N labeled nitrogen (N) (NH₄Cl) and photosynthesis activity decreased with decreasing soil redox potentials. Net photosynthesis in cherrybark oak decreased by 72.9 and 100% in response to the +340 and + 175 mV treatments as compared to control plants, respectively. Similarly, net photosynthetic rates were reduced by 53.7 and 65.8% in overcup oak under + 340 and + 175 mV treatments, respectively. A significant correlation between net photosynthesis and leaf ¹⁵N content was found in cherrybark oak (r=0.866, P=0.01) but not in overcup oak (r=0.648, p>0.05). However, in overcup oak, the correlation between net photosynthesis and total leaf N content was significant (r=0.911, P=0.01). Maximum ¹⁵N uptake was measured at the highest soil redox level (+560 mV). Uptake of ¹⁵N in cherrybark oak decreased from a maximum of 1.83 mg under aerated (+560 mV) treatment to 0.11 mg under reduced conditions (+175 mV). Similarly, ¹⁵N uptake in overcup oak decreased from 2.37 mg under the + 560 mV treatment to 0.28 mg under + 175 mV treatment. Greater uptake of soil and fertilizer nitrogen was measured under the soil redox conditions in which adequate plant growth was recorded. Moderately reducing soil redox conditions (+340 and + 175 mV) adversely affected both plant nitrogen uptake and net photosynthetic activities of the two species.     

硒镉伴生对富硒土壤柑橘生长及生理代谢的影响

为保障富硒柑橘的安全生产,明确富硒土壤硒镉伴生现象对柑橘生长、硒镉吸收转运和抗氧化能力的影响,采用盆栽试验,以一年生大雅柑橘为试验材料,研究添加硒代蛋氨酸(SeMet,CK,模拟富硒土壤)和添加SeMet与镉(模拟富硒土壤硒镉伴生)对富硒土壤柑橘的生长指标、硒镉含量、叶片还原型抗坏血酸-谷胱甘肽(AsA-GSH)循环效率的影响。结果表明,与CK相比,富硒土壤中,硒镉伴生增加了柑橘叶片叶绿素a+b、叶绿素a、叶绿素b和类胡萝卜素含量,但对株高、新梢长度、新梢数量以及根茎叶的干物质量影响不显著;在富硒土壤中,硒镉伴生显著增加了大雅柑橘硒含量和硒的富集系数(BCF),降低了硒的转运系数(TF);硒和镉主要分布在根系,其次是叶片和茎;在AsA-GSH循环中,硒镉伴生使过氧化氢(H₂O₂)和还原型抗坏血酸(AsA)含量显著上升,脱氢抗坏血酸(DHA)含量上升但未达到显著水平,抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)活性和脱氢抗坏血酸还原酶(DHAR)活性显著上升,而GSH和氧化型谷胱甘肽(GSSG)含量下降,AsA/(AsA+DHA)和GSH/(GSH+GSSG)比值降低,谷胱甘肽过氧化物酶(GPX)活性显著降低。本研究为阐明镉胁迫对富硒土壤柑橘的生理影响机制提供了理论依据。     

EFFECT OF CADMIUM ON PHYSIOLOGICAL RESPONSES OF WHEAT AND CORN TO IRON DEFICIENCY

This work evaluated the effect of cadmium (Cd) on the physiological responses of corn (Zea Mays L.) and wheat (Triticum aestivum L.) to iron (Fe) deficiency. For this purpose, seedlings of corn and wheat were cultivated under controlled conditions, plants were grown in different strength Hoagland's solutions for one month. In the fifth week, some seedlings were still in full strength Hoagland's solution (+Fe) and others were in full strength Hoagland's solutions without iron (?Fe). The plants were exposed to different cadmium (Cd) concentrations for four days. The plant chlorophyll content of young leaves, Fe and Cd content in shoots and roots, biomass production, and phytosiderophores (PS) release by roots were assessed. Results showed that Cd decreased the chlorophyll content of young leaves, accompanied by a significant shoot and root biomass reduction for Fe-deficient and Fe-sufficient wheat and corn across all Cd treatments. However, chlorophyll content and shoot and root biomass of Fe-deficient wheat and corn were lower than Fe-sufficient plants at different Cd concentrations. Iron-deficiency induced Cd accumulation compared to Fe-sufficient in wheat and corn; however, a depressive effect of Cd on iron acquisition in shoots and roots of Fe-deficient and Fe-sufficient wheat and corn across all Cd treatments was observed. Cadmium also inhibited PS release in Fe-deficient and Fe-sufficient wheat and corn. Iron-deficient PS release was higher than Fe-sufficient corn and wheat across all Cd treatments. These results suggested that Cd might reduce capacity of plants to acquire iron from solution by inhibiting PS release.     

Autumn growth and cold hardening of winter wheat under simulated climate change

Abstract

Plant responses to elevated CO₂ are governed by temperature, and at low temperatures the beneficial effects of CO₂ may be lost. To document the responses of winter cereals grown under cold conditions at northern latitudes, autumn growth of winter wheat exposed to ambient and elevated levels of temperature (+2.5°C), CO₂ (+150 µmol mol^?1), and shade (?30%) was studied in open-top chambers under low light and at low temperatures. Throughout the experiment, temperature dominated plant responses, while the effects of CO₂ were marginal, except for a positive effect on root biomass. Increased temperature resulted in increased leaf area, total biomass, total root biomass, total stem biomass, and number of tillers, but also a lower content of total sugars and a weaker tolerance to frost. The loss of frost tolerance was related to the larger size of plants grown at elevated temperature. The 30% light reduction under shading did not affect the growth, sugar content, or frost tolerance of winter wheat. At the low temperatures found at high latitudes during autumn, the atmospheric CO₂ increase is unlikely to enhance autumn growth of winter wheat to any significant extent, while a temperature increase may have important and major effects on its development and growth.     

Olive mill wastewater spreading and AMF inoculation effects in a low-input semi-arid Mediterranean crop succession

ABSTRACT

The study aimed to evaluate, in a marginal semi-arid Mediterranean agro-ecosystem (Sicily-Italy), the effects of arbuscular mycorrhizal fungi (AMF) inoculation and raw olive mill wastewater (OMW) (40 and 80 m³ ha^?1) on forage (durum wheat-snail medick intercropping) yield, and grain production of broad bean and chickpea. AMF inoculation significantly increased (+13.6%) forage dry biomass and durum wheat nitrogen (+22.8%) and phosphorus (+32.5%) uptake. AMF inoculation, significantly promoted broad bean phosphorus uptake (+11.5%) and root nodule number (+13.9%) in the absence of OMW. OMW spreading reduced weeds in the forage (?31.3%), root nodule number (?29.7%) and dry weight (?22.7%) in broad bean. OMW also significantly increased snail medick dry biomass (+19.3%) as compared to control treatments (0, 40 and 80 m³ H₂O ha^?1, average production 361 g m^?2), and broad bean grain yield with a production of 2.46 ± 0.12 and 1.94 ± 0.09 Mg ha^?1 with and without OMW, respectively. During the experiment AMF colonization was not affected by OMW volumes. The results obtained showed that in a marginal Mediterranean agro-ecosystem: 1) OMW, notwithstanding spreading volumes, is a valuable amendment to maximize legume yield while 2) AMF inoculation is a valuable practice to improve biomass production and N and P uptake in wheat.     

Influences of ultra‐violet (UV)‐blue light radiation on the growth of cotton. II. Photosynthesis,leaf anatomy,and iron reduction

Cotton (Gossypium hirsutum L.) plants grown under low pressure sodium lamps (LPS) developed chlorosis which was similar in appearance to iron‐stress induced chlorosis, while plants under cool white fluorescent lamps (CWF) at the same level of photosynthetically active radiation (PAR) developed normally. These illumination sources differ in spectral irradiance; CWF lamps emit ultra violet (UV), whereas LPS lamps do not. Ultraviolet radiation is capable of reducing Fe³⁺ to Fe²⁺ through a chlorotic leaf which may be important in establishing an active iron fraction in the leaf. Root reduction of Fe³⁺ to Fe²⁺ was lacking in Fe‐stressed cotton under LPS light, but was present under CWF light. Net photosynthesis, photosynthetic electron transport, and leaf chlorophyll content were lower under LPS than CWF light in most of the growing media studies (soil or solutions with nitrate‐ or ammonium‐nitrogen supplied). Chloroplast ultrastructure and leaf thickness were also altered by LPS irradiance. Electron microscopic studies with plants grown in nutrient solutions for 4 weeks suggested that chioroplastic granal disorganization was more directly associated with diminished iron supplies than with light source. However, plants grown in soil for 6 weeks under LPS light had granal disorganization similar to that found in iron‐stressed plants. These studies suggest an important role for UV radiation in influencing the activity of iron in plants.     

土壤增施蛋氨酸硒对厚皮甜瓜生理特性和品质的影响

【目的】本研究探究了蛋氨酸硒对厚皮甜瓜生长与生理特性的调控作用,硒在厚皮甜瓜中的富集效益,以及硒在土壤中的变化趋势。【方法】以‘M135’厚皮甜瓜为试材,蛋氨酸硒为硒源,采用盆栽试验,以土壤本底硒为对照,通过向土壤中增施蛋氨酸硒使土壤中的总硒含量分别增加4、 10和16 mg/kg,研究了蛋氨酸硒对厚皮甜瓜生长、 产量、 光合特性、 产品品质及果肉硒含量的影响,对厚皮甜瓜不同组织器官中总硒含量的影响,以及对土壤中不同形态硒含量变化的影响。【结果】施硒4、 10和16 mg/kg均可显著提高甜瓜叶片光合色素含量、 叶片光合速率、 植株生长量以及甜瓜产量; 另外,不同浓度施硒处理还显著提高了果肉中有机硒、 无机硒、 可溶性糖、 可溶性蛋白、 游离氨基酸和维生素C的含量,并以10 mg/kg施硒处理的效果最佳。10 mg/kg施硒处理的单株产量比对照提高了19.53%,果肉中的可溶性糖、 可溶性蛋白、 游离氨基酸和维生素C的含量比对照分别提高了14.82%、 49.88%、 23.42%和25.03%,果肉中硒的总含量为44.74 μg/kg,其中有机硒含量36.87 μg/kg,占到总硒含量的82.91%,达到富硒标准。进一步的研究发现,虽然果肉中硝酸还原酶活力、 硝酸盐和亚硝酸盐含量均随施硒浓度的增加而增加,但4、 10和16 mg/kg施硒处理后的亚硝酸盐含量分别为1.499、 1.907和2.131 mg/kg,均远低于国家标准的上限(20 mg/kg)。对施硒后厚皮甜瓜不同组织器官中硒含量的研究发现,厚皮甜瓜各组织器官(根、 茎、 叶柄、 叶、 果皮、 果肉和种子)的总硒含量也随施硒浓度的增加而增加。对根、 茎、 叶柄和叶的比较发现,在未增施蛋氨酸硒时叶中的硒含量最高,其次为根、 茎和叶柄; 而增施蛋氨酸硒后则表现为根中最多,其次为茎、 叶和叶柄。对果皮、 果肉和种子的比较发现,各处理果实内各组织的总硒含量均表现为种子中最多,其次为果肉和果皮。对施硒后土壤中不同形态硒含量的研究发现,定植后未施蛋氨酸硒的上层土壤中总硒、 无机态Se6+的含量均呈下降趋势,土壤中有机硒和无机态Se4+的含量变化不大; 4、 10和16 mg/kg施硒处理的土壤中有机硒、 总硒以及无机态Se4+含量都呈先下降后趋于平缓的趋势,而无机态Se6+的含量则呈先上升后下降的趋势。【结论】土壤增施蛋氨酸硒后提高了厚皮甜瓜果肉的硒含量,增强了光合能力,促进了厚皮甜瓜植株的生长,从而提高了产量和综合品质,其适宜的土壤施硒浓度为10 mg/kg。