Foliar application of silicon at different growth stages alters growth and yield of selected wheat cultivars

To evaluate the response of some selected wheat cultivars to silicon application at different growth stages under drought stress, an experiment was carried out in the greenhouse of College of Agriculture, Shiraz University, Iran, during 2012 using a completely randomized factorial design with four replications. Experimental treatments included drought stress (100% F.C. as control and 40% F.C. as drought) and foliar application of 6 mM sodium silicate (control, application at mid tillering stage, at anthesis stage, and application at tillering + anthesis stages) and wheat cultivars (Sirvan and Chamran, relatively drought-tolerant, and Shiraz and Marvdasht, drought-sensitive cultivars). Drought stress significantly reduced chlorophyll content, leaf area, relative water content, grains per spike, 1000-grain weight, grain yield and biomass of all wheat cultivars. Furthermore, drought stress increased electrolyte leakage of the flag leaves of all cultivars. In contrast, foliar-applied silicon significantly increased these parameters and reduced electrolyte leakage. Furthermore, highest positive influence of silicon application was observed at combined use of silicon both at the tillering + anthesis stages in wheat plants under both stress and non-stress conditions. Significant differences were found in physiological responses among wheat cultivars. The drought tolerant cultivars (Sirvan and Chamran) had significantly higher growth and yield than those of drought sensitive cvs. Shiraz and Marvdasht under drought stress. In conclusion, foliar application of silicon especially at the tillering + anthesis stages was very effective in promoting resistance in wheat plants to drought conditions by maintaining cellular membrane integrity and relative water content, and increasing chlorophyll content.     

Effect of exogenous application of salicylic acid on salt-stressed sorghum growth and nutrient contents

This study was conducted to investigate the effect of salinity and foliar application of salicylic acid (SA) on sorghum biomass and nutrient contents. Treatments were comprised of salinity levels (0 and 100?mM NaCl) and SA concentrations (0.3, 0.7, 1.1 and 1.5?mM). Salinity increased sodium (Na), chlorine (Cl) and copper (Cu) but decreased nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), iron (Fe), zinc (Zn) and manganese (Mn) contents and the root and shoot dry matter. Fe and Zn were the most affected nutrients by salinity. However, SA reduced Na and Cl but increased plant dry matter and nutrient content. SA had greater positive effects on root than on shoot dry matter. Maximum increases through SA were achieved in N, K, Fe, Mn, Cu, and shoot weight under salt stress but in Zn and root weight under non-saline condition. In most cases 1.1?mM was the most effective SA concentration in reducing the negative effects of salinity.     

Growth,mineral composition,leaf chlorophyll and water relationships of two cherry varieties under NaCl-induced salinity stress

Abstract

Growth, mineral nutrition, leaf chlorophyll and water relationships were studied in cherry plants (cv. ‘Bigarreau Burlat’[BB] and ‘Tragana Edessis’[TE]) grafted on ‘Mazzard’ rootstock and grown in modified Hoagland solutions containing 0, 25 or 50 mmol L^?1 NaCl, over a period of 55 days. Elongation of the main shoot of the plants treated with 25 or 50 mmol L^?1 NaCl was significantly reduced by approximately 29–36%, irrespective of the cultivar. However, both NaCl treatments caused a greater reduction in the dry weight of leaves and scion's stems in BB than in TE plants. Therefore, BB was more sensitive to salinity stress than TE. The reduction of leaf chlorophyll concentration was significant only when BB and TE plants were grown under 50 mmol L^?1 NaCl. Osmotic adjustment permitted the maintenance of leaf turgor in TE plants and induced an increase in leaf turgor of BB plants treated with 25 or 50 mmol L^?1 NaCl compared with 0 mmol L^?1 NaCl. Concerning the nutrient composition of various plant parts, Na concentrations in all plant parts of both cultivars were generally much lower than those of Cl. For both cultivars, leaf Cl concentrations were much higher than the concentrations in stems and roots, especially in the treatments containing NaCl. Finally, the distribution of Na within BB and TE plants treated with NaCl was relatively uniform.     

再生水灌溉对草坪草生长速率、叶绿素及类胡萝卜素的影响特征

为节约城市清洁水源,扩大再生水利用力度,确保高质量的草坪,以草地早熟禾为研究对象,探讨了不同灌溉水源及再生水灌溉不同水分梯度下草坪草生长速率及叶绿素的变化特征。试验采用7种水分处理：清水适宜灌、混合水适宜灌、再生水充分灌、再生水适宜灌、再生水轻微干旱胁迫、再生水中度干旱胁迫、再生水重度干旱胁迫,灌水下限分别70%fc(田间持水量)、70%fc、80%fc、70%fc、60%fc、50%fc、40%fc,灌水定额相同。研究表明：不同灌溉处理下草坪草生长速率差异明显,再生水灌溉促进了草坪草的生长,草坪草生长速率与供水量成正相关;再生水灌溉下草坪草叶绿素及类胡萝卜素含量显著高于清水适宜灌处理下草坪草叶绿素及类胡萝卜素含量,而再生水灌溉草坪草叶绿素及类胡萝卜素含量在处理间差异不显著。     

沸石添加对NaCl胁迫下黄瓜幼苗生长及离子含量的影响

试验研究了沸石添加对NaCl胁迫下黄瓜幼苗生长及离子含量的影响。结果表明,在相同的NaCl溶液浓度下,随沸石量的增加,幼苗的株高、茎粗、叶面积及干物重呈增加趋势;光合色素含量上升,蒸腾速率(E)、光合速率(Pn)和气孔导度(Gs)增加而胞间CO2浓度(Ci)下降;超氧化物岐化酶(SOD)、过氧化氢酶(CAT)活性和可溶性蛋白质含量(Pr)含量增加;K、Mg在根、茎、叶中的含量上升,Ca在茎叶中含量亦增加,Na在根、茎、叶中的含量明显下降。表明沸石可以在一定程度缓解NaCl胁迫对黄瓜幼苗造成的伤害。     

Effect of salinity on growth,mineral composition,and water relations of grafted tomato plants

A greenhouse experiment was designed in order to evaluate growth, water relations, and nutrient concentrations of grafted and ungrafted tomato plants grown under varying levels of salinity (0, 30, or 60 mM NaCl). Two cultivars, ‘Fanny’ and ‘Goldmar’, were grafted onto AR‐9704, using the cleft‐grafting method. Growth of grafted ‘Fanny’ plants was higher than that of ungrafted plants. Growth of ‘Goldmar’ plants was not affected by salinity treatments or grafting, but it was slower than for ‘Fanny’. Leaf turgor showed no significant differences between grafted and ungrafted plants or between salinity levels. The stomatal conductance (G_s) was higher for grafted than for ungrafted plants, and salinity decreased it significantly and progressively in both grafted and ungrafted plants and in both varieties. The concentrations of Na⁺ and Cl^– were significantly higher in ungrafted than in grafted ‘Fanny’ plants. ‘Fanny’ was more tolerant when grafted, probably due to reduced accumulation of Na⁺ and/or Cl^– in the shoot.     

Silicon priming benefits germination,ion balance,and root structure in salt-stressed durum wheat (Triticum durum desf.)

Abstract

Effects of silicon (Si) priming at 0, 0.5, 1.0, and 1.5?mM on germination, ion balance, and root structure of two durum wheat cultivars at 0, 100, and 200?mM sodium chloride (NaCl) was conducted in a laboratory. An aliquot of 200?mM NaCl with 1.5?mM Si improved Behrang cultivar germination from 54 to 88%, but in Yavaros only from 49 to 85%. In Behrang, the control root length at 200?mM NaCl increased from 5.07 to 7.11?mm when treated with 1.5?mM Si, but Yavaros only increased from 3.18 to 4.09?mm. Behrang accumulated less sodium (Na⁺) and more potassium (K⁺). For mean diameter of central and peripheral metaxylem cells, Behrang benefitted more from Si amelioration than Yavaros. Salinity affected the diameter of central and peripheral metaxylem cells to a greater degree compared to vessel number. Si soil application (1.0 and 1.5?mM Si) may help to establish durum wheat seeds grown under saline conditions.     

Interactive effects of salinity and potassium availability on growth,water status,and ionic composition of Hordeum maritimum

The interactive effects of salinity and potassium (K⁺) availability on biomass production, water status, and ionic composition were investigated in Hordeum maritimum, an annual grass growing natively on saline soils. Plants were grown for 7 weeks on Hewitt nutrient solution supplied with NaCl (0, 100, 150, 200, and 300 mM) combined with low (0.232 mM) or high (5.8 mM) K⁺ levels. Independent of potassium availability, dry matter of both roots and shoots decreased consistently with increasing NaCl levels in the culture medium, in association with a significant reduction of the shoot water content. This salt‐induced growth reduction did not result from a restriction of K⁺ nutrition, since H. maritimum expressed similar growth under both low and high K⁺ supply. NaCl decreased shoot K⁺ concentrations. This effect was more pronounced in plants grown at high K⁺ supply than in plants grown at low K⁺ supply. This result suggests that the absorption systems were strongly selective for K⁺, and that this selectivity was enhanced by salt.     

The individual and combined effects of ozone and simulated acid rain on chlorophyll contents,carbon allocation and biomass accumulation of armand pine seedlings

The seedlings of armand pine (Pinus armand Franch.) were applied to exposure, alone or in combination, to charcoal filtered air (CF) or ozone (O₃) at 300±15 nl/l(ppb) for 8 h a day, 6 days a week, and simulated rain of pH 6.8, 3.0 or 2.3, six times a week, alone and in combination, for 14 weeks from June 15 to September 20, 1993. No significant interactive effects of O₃ and simulated acid rain were observed on chlorophyll contents, carbon allocation and biomass accumulation of the seedlings in the present study. The O₃ caused reductions in biomass accumulation of whole-plant and below-ground parts, but not that of above-ground parts without an acute visible foliar injury. At the same time, the O₃ reduced R/S ratio, but raised F/C ratio. Therefore, O₃ also altered carbon allocation pattern. On the other hand, chlorophyll contents were increased by simulated acid rain, but other determined parameters were not altered.     

Shift in physiological and biochemical processes in wheat supplied with zinc and potassium under saline condition

Soil salinity is a serious abiotic factor affecting the production of crops by reducing potassium (K) uptake due to strong competition with sodium (Na) cations in the root regions. In calcareous soils, most of the nutrients precipitate in unavailable forms for plants. This study investigated the physiological and biochemical response of two wheat genotypes salt tolerant Abadghar and salt sensitive Pari-73 supplemented with K and zinc (Zn) nutrition. A factorial experiment with three levels of K (0, 50 and 100 kg ha^?1) and three levels of Zn (0, 25 and 50 kg ha^?1) based on a complete randomized design was employed. The results showed significant effect of treatments on chlorophyll (Chl) contents, water relations, nitrogen metabolism and yield attributes. The treatment K+Zn (100, 25 kg ha^?1) was the most effective in increasing grain yield. The results achieved highlight the importance of K and Zn nutrition in salt-stress conditions.     

Salinity‐induced changes in growth,superoxide dismutase activity,and ion content of two olive cultivars

Olive trees (Olea europaea L.) are considered moderately tolerant to salinity, with clear differences found among cultivars. One‐year‐old self‐rooted olive plants of the Croatian cv. Oblica and Italian cv. Leccino were grown for 90 d in nutrient solutions containing 0, 66, or 166 mM NaCl, respectively. The shoot length and the number of nodes and leaves for both cultivars were not affected by salinity up to 66 mM NaCl. However, at 166 mM NaCl, growth of Leccino was reduced earlier and to a higher extent than growth of Oblica. After 10 d of exposure to 66 and 166 mM NaCl, increased activity of superoxide dismutase (SOD) was observed in Leccino, whereas there was almost no response in Oblica. Reduced SOD activity in Leccino at 166 mM NaCl was observed after prolonged stress (90 d), whereas in Oblica SOD was increased at 66 mM compared to control or 166 mM NaCl. Electrolyte and K⁺ leakage were increased and relative water content decreased as NaCl concentration increased with similar intensity of response measured in both cultivars. Oblica exhibited an ability to keep a higher K⁺ : Na⁺ ratio at all salinity levels compared to Leccino, but since no difference was found in leaf K⁺ concentration, this was mainly achieved by less Na⁺ ions reaching the younger leaves. The antioxidative system represents a component of the complex olive salt‐tolerance mechanism, and it seems that the role of SOD in protection from oxidative stress depends on sodium accumulation in leaves.     

Effects of salt stress on plant growth characteristics and mineral content in diverse rice genotypes

ABSTRACT

When rice is grown under moderate salinity (6?dS m^?1), yields are reduced by up to 50%. The development of salt-tolerant varieties is a key strategy for increasing yields. We conducted an experiment using a hydroponic system with ion components similar to seawater to determine useful parameters for assessing salt tolerance. Two-week-old seedlings were grown for 7 days on Yoshida hydroponic solution. The treatment group then additionally received an artificial seawater solution (electrical conductivity, 12 dS m^?1). After a 2-week period of salt stress, standard evaluation scores (SES) of visual salt injuries were assessed. The K, Na, Mg, and Ca contents were then determined in the roots, sheaths, and leaves of each plant. Following the SES results, we divided the 37 genotypes into four groups: salt-tolerant groups (STGs), moderately salt-tolerant groups, salt-sensitive groups (HSSGs), and highly salt-sensitive groups (HSSGs). In the control, STGs had the highest sheath K content (30.1 mg g^?1 dried weight [DW]), whereas HSSGs had the lowest (21.4 mg g^?1 DW). Sheath K was also highly and negatively correlated with SES. This suggests that sheath K may be useful for identifying salt-tolerant varieties under non-saline conditions. Plant growth was significantly affected under salt stress, but STGs had the smallest decrease in sheath DW. SES was significantly correlated with sheath and leaf Na, sheath K and Mg, and sheath and leaf Na/K and Na/Mg ratios. The results suggested that sheath K, Na/K, and Na/Mg may be useful indicators for genetic analyses of salt-tolerant varieties under salt-stress conditions. The salt-tolerant cultivars, KCR20, KCR124, and KCR136, are possible candidates for such studies because they had high sheath K content (31.19, 31.21, 29.44 mg g^?1 DW, respectively) under non-saline conditions and low SES (3.3, 3.6, 3.9, respectively), and low sheath Na/K (0.64, 0.52, 0.92, respectively) and Na/Mg ratios (2.96, 2.27, 3.03, respectively) under salt-stress conditions.     

Effect of salinity and nitrogen on growth,sodium, potassium accumulation,and osmotic adjustment of halophyte Suaeda aegyptiaca (Hasselq.) Zoh

Suaeda aegyptiaca is an important native annual halophyte in salt-affected soils around coastal areas of the Persian Gulf. In order to study the effects of different levels of saturation paste soil salinity (10, 20, 40, 60, and 80 dS m^?1) and nitrogen supply (25, 50, and 75 mg kg^?1 N as urea) on growth and physiological characteristic of S. aegyptiaca, a greenhouse factorial experiment in completely randomized design was conducted with three replications. Salinity treatments were established after early growth of plants and nitrogen was applied in two steps. Results showed that increasing salinity up to 20 dS m^?1 led to increase in dry weight (DW) of plants and this decreased by increasing salinity. Also, DW of plants was significantly increased by application of 75 mg kg^?1 nitrogen. Increasing salinity significantly decreased plant height, chlorophyll index, and total nitrogen content; while proline content and total soluble solids (TSS) were significantly increased. The electrolyte leakage (EL) and sodium concentration were increased under salinity stress. However, further increase in salinity decreased these two parameters. By increasing the nitrogen levels, relative water content (RWC), chlorophyll index, proline, and total nitrogen contents were increased, whereas EL was decreased.     

硅对干旱胁迫下小麦幼苗生长及光合参数的影响

采用溶液培养试验,以两个抗旱性不同的小麦品种:低抗的扬麦9号(Yangmai.9)和高抗的豫麦18(Yumai.18)为材料,用PEG6000(聚乙二醇6000,渗透势约为-0.589MPa)模拟干旱胁迫条件,研究了硅对干旱胁迫下小麦幼苗生长、光合作用及可溶性糖含量的影响。结果表明,干旱胁迫条件下,小麦幼苗的生长和光合作用显著受到抑制,加硅处理能有效地提高干旱胁迫条件下小麦幼苗的生长状况及光合作用,且1.0.mmol/L.Si处理的效果优于0.1mmol/L.Si处理。与不加硅处理相比,干旱胁迫条件下加硅处理后,小麦幼苗的鲜干重、叶片可溶性蛋白含量、净光合速率(Pn)、蒸腾速率(Tr)、水分利用率(WUE)和气孔限制值(Ls)均显著升高,叶绿素含量也有一定程度的升高;而气孔导度(Gs)和细胞间隙CO2浓度(Ci)显著下降,可溶性糖积累量也降低。因此,硅可显著提高小麦对干旱胁迫的抗性。     

Effect of salinity on growth,photosynthesis and mineral composition in leguminous plant Alhagi pseudoalhagi (Bieb.)

Leguminous plant Alhagi pseudoalhagi was subjected to 0 (control), 50, 100, and 200 mM NaCI treatments during a 30 d period to examine the mechanism of tolerance to salinity. Plant dry weight, net CO₂ assimilation rate, leaf stomatal conductance, intercellular CO₂ concentration, and solute concentration in leaves, stems, and roots were determined. Total plant weight in the 50 mM treatment was 170% of that of the control after 10 d of treatment. Total plant weight was lower in the 100 and 200 mM treatments than in the control. The leaf CO₂ assimilation rate was approximately 150% of that of the control in the 50 mM treatment, but was not affected significantly by 100 mM of NaCI, while it was reduced to about 60% of that the control in the 200 mM treatment. Similarly stomatal conductance was consistent with the CO₂ assimilation rate regardless of the treatments. Intercellular CO₂ concentration was lower in the NaCI-treated plants than in the control. Changes in CO₂ assimilation rate due to salinity stress could be mainly associated with stomatal conductance and the carboxylation activity. Although the leaf Na⁺ concentration increased to 900 mmol kg^-1 dry weight in the 200 mM treatment compared to 20 mmol kg^-1 in the control, the plants did not die and continued to grow at such a high leaf Na⁺ concentration. Uptake and transportation rates of Na+, Ca²⁺, Mg²⁺, and K⁺, and the accumulation of N were promoted by 50 mM NaCI. Na⁺ uptake rate continued to increase in response to external NaCI concentration. However, the uptake and transportation rates of Ca²⁺, Mg²⁺, and K⁺ behaved differently under 100 and 200 mM salt stress. The results suggest that A. pseudoalhagi is markedly tolerant to salinity due mainly to its photosynthetic activity rather than to other physiological characteristics.     

Growth and chlorophyll,mineral, and total amino acid composition of tomato and wheat plants in relation to nitrogen and iron nutrition II. Chlorophyll content and total amino acid composition

Studies of the amino acids distribution in plants subjected to nutrient regimes are limited. The present study investigated the effect of NO₃‐N and FeSO₄‐Fe regimes on chlorophyll and total amino acids composition of tomato and wheat plants. Also the distribution of 17 amino acids between the different plant parts was studied. Increasing the NO₃‐N level up to 200 mg kg^‐1 greatly increased the total amino acids content of tomato plants. The total amino acids content of wheat plants continued to increase with addition of NO₃‐N up to 400 mg kg^‐1. The response of chlorophyll content to NO₃‐N supply was highly dependent on Fe level both in tomato and wheat plants. The interaction between NO₃‐N and FeSO₄‐Fe had a great effect on the total amino acids content and distribution. Iron increased the translocation of proline from roots to leaves. The overall amino acids contents of leaves was higher than that of stems or roots.     

Differences in antioxidant enzyme activities and oxidative markers in ten wheat (Triticum durum Desf.) genotypes in response to drought,heat and paraquat stress

Changes in enzymatic antioxidants and oxidative injury were evaluated in leaves of 10 wheat genotypes under drought, heat and paraquat (PQ) stress. The seedlings of wheat were germinated in plastic pots and grown in a greenhouse under semi-controlled conditions. Each treatment was performed at the 4th–5th leaf stage. Antioxidant enzyme activities catalase (CAT), guaiacol peroxidase (GPOX), lipid peroxidation (LPO), hydrogen peroxide (H₂O₂) production, chlorophyll content and cell membrane leakage were determined. Results indicated that the three treatments decreased membrane stability, chlorophyll content and increased the LPO, H₂O₂ content and activities of CAT and GPOX. The ANOVA analysis revealed significant differences between genotypes in response to the various treatments imposed. Wheat genotypes Bidi 17, Beliouni and Djennah khetifa showed the lowest LPO and H₂O₂ content and the highest total chlorophyll content, relative electrolyte leakage (REL), CAT and GPOX activities, while Colosseo, Waha, Vitron and Benisuif showed the lowest antioxidant defends, lowest REL and the highest H₂O₂ and MDA contents. Oued zenati, Beltagy and Bousselam showed intermediate response in terms of oxidative stress and antioxidant activity.