Effects of nano Fe/SiO2 fertilizers on germination and growth of barley and maize

Iron (Fe) nanoparticles (NPs), with 30–40 nm diameter, were stabilized on sand. The resulting synthesized Fe/SiO₂ NPs, with different Fe contents (0–25 mg kg^?1) were employed as fertilizers in probing the mean germination time (MGT), growth and dry matter of barley and maize and their comparison with common Fe/SiO₂ in a completely randomized design (CRD) experiment. The results showed that our fertilizers had significant effects on MGT, with the lowest of 0.58 day for barley and 0.79 day for maize; at 15 and 5 mg kg^?1 nano Fe/SiO₂, respectively. Application of 15 mg kg^?1 of nano Fe/SiO₂ increased the shoot length: 8.25% and 20.8% for barley and maize, respectively. However, the concentration of 25 mg kg^?1 had a negative impact on shoot length in barley. Increasing the concentrations of both nano and common Fe/SiO₂ particles, increased the root lengths in both plants, however this increase was higher with the application of nano Fe/SiO₂. Likewise, seedling length enlarged with the concentration increase of both Fe/SiO₂ particles and was more pronounced with nano Fe/SiO₂. The application of nano Fe/SiO₂ was more effective compared with the common Fe/SiO₂ in encouraging barley and maize growth. The positive impact was higher in maize than barley.     

Effect of plant growth-promoting bacteria and soil compaction on barley seedling growth, nutrient uptake, soil properties and rhizosphere microflora

Inoculants are of great importance in sustainable and/or organic agriculture. In the present study, plant growth of barley (Hordeum vulgare) has been studied in sterile soil inoculated with four plant growth-promoting bacteria and mineral fertilizers at three different soil bulk densities and in three harvests of plants. Three bacterial species were isolated from the rhizosphere of barley and wheat. These bacteria fixed N₂, dissolved P and significantly increased growth of barley seedlings. Available phosphate in soil was significantly increased by seed inoculation of Bacillus M-13 and Bacillus RC01. Total culturable bacteria, fungi and P-solubilizing bacteria count increased with time. Data suggest that seed inoculation of barley with Bacillus RC01, Bacillus RC02, Bacillus RC03 and Bacillus M-13 increased root weight by 16.7, 12.5, 8.9 and 12.5% as compared to the control (without bacteria inoculation and mineral fertilizers) and shoot weight by 34.7, 34.7, 28.6 and 32.7%, respectively. Bacterial inoculation gave increases of 20.3–25.7% over the control as compared with 18.9 and 35.1% total biomass weight increases by P and NP application. The concentration of N and P in soil was decreased by increasing soil compaction. In contrast to macronutrients, the concentration of Fe, Cu and Mn was lower in plants grown in the loosest soil. Soil compaction induced a limitation in root and shoot growth that was reflected by a decrease in the microbial population and activity. Our results show that bacterial population was stimulated by the decrease in soil bulk density. The results suggest that the N₂-fixing and P-solubilizing bacterial strains tested have a potential on plant growth activity of barley.     

Interrelationships between growth and nutrient uptake in alfalfa and corn

Nutrient requirements o£ plants during their various phases of growth are affected by several internal and external factors. The changes in rate of uptake by root with age are an important factor to meet the increasing plant demand for nutrients. Nutrient culture experiments were carried out under controlled greenhouse conditions with corn (Zea Mays L.) and alfalfa (Medicago sativa L.) to investigate the relationship of stage of growth to changes in plant parameters and nutrient uptake properties. With advancement of age. both plant species increased their ambient growth medium pH towards neutrality. With increasing age in alfalfa there was very little change in observed S:R ratio and root growth rate. On the other hand in corn plants the S:R ratio increased and growth rate for root and shoot decreased with age. Alfalfa contained higher concentrations of N, K, Na, and Ca than corn; while ion concentrations in both crops decreased with plant age. At all stages of growth, alfalfa absorbed less nutrients than corn. The rates of nutrient influx, I_n in both the crops showed various degrees of correlation with age and rate of shoot growth. In corn. I_n for ions reached a maximum at 25 days growth; whereas, in alfalfa, I_n reached maximum at 30 days of growth. The differences in influx rates for different ions in the two species are probably due to the difference in development of shoot and root parameters and shoot demand for the ions.     

不同铵钾比对高铵下拟南芥地上部和根系生长的影响

钾在缓解植物铵毒害的过程中起着重要的作用。本文研究了高铵(30 mmol/L)条件下,不同铵钾比(7.5︰1和150︰1)对拟南芥(Col-0)主根、侧根以及地上部生长的影响。结果表明:30 mmol/L NH4+条件下,高铵钾比(150)处理显著加重了拟南芥铵毒害现象,地上部和根系生长所受的抑制作用更为明显并导致更严重的氧化胁迫。相比低铵钾比水平,在高铵处理下,高铵钾比使得拟南芥主根伸长量降低57.4%,侧根数量减少33.3%,而地上部鲜重减轻69.9%。DAB(3,3￠-二氨基联苯胺,3,3￠-diaminobenzidine)叶片染色结果表明,不加铵处理下,外源不同钾水平(0.2和4.0 mmol/L)对拟南芥叶片的氧化胁迫作用没有显著差异;而高铵处理下,相比低铵钾比处理,高铵钾比显著增加了叶片中过氧化氢的含量,加重了其氧化胁迫。伊文思蓝(Evans blue,EB)染色结果表明,不加铵处理下,外源不同钾水平对拟南芥地上部和根部的膜透性没有显著差异,而高铵处理下,高铵钾比显著增强了拟南芥地上部和根部的膜透性,表明其对细胞的伤害程度加重。可见,高铵抑制拟南芥根系和地上部生长,高铵钾比则会加重这种抑制,其原因除了高浓度钾能减少植物对铵的吸收外,可能与高铵钾比条件加剧了植物的氧化胁迫有关。因此,适宜的铵钾比在植物应对铵毒害的过程中发挥重要作用。     

Phosphorus uptake and growth of barley as affected by soil temperature and mycorrhizal infection

A glasshouse study was conducted to investigate the effects of soil temperatures of 20, 15 and 10°C on growth and phosphorus (P) uptake of barley (Hordeum vulgare L. cv. Galleon) inoculated with Glomus intraradices Schenck & Smith. Vesicular‐arbuscular (VA) mycorrhiza formation was significantly reduced as the soil temperature decreased. Plant growth depression due to temperature stress was more pronounced in mycorrhizal plants than in non‐mycorrhizal plants. The lower the soil temperature, the higher was the root‐shoot ratio. The ratio was also higher in non‐mycorrhizal plants than in mycorrhizal plants. Concentration of P in roots was influenced by mycorrhiza. Significant interaction between mycorrhiza and soil temperature was observed for root dry matter and specific P uptake (P uptake per unit weight of root). Compared to non‐mycorrhizal plants, specific P uptake in mycorrhizal plants was higher.     

不同供磷状况下CO2浓度升高对番茄根系生长及养分吸收的影响

采用培养试验研究了磷缺乏与正常供磷条件下,CO₂浓度由350μL/L升高至800μL/L苗期番茄的生物量、根系特征和不同器官N、P、K养分含量的变化。结果表明,无论缺磷与否,CO₂浓度升高均能显著增加番茄地上部及根系的干物质积累量,提高根冠比。在磷缺乏条件下,CO₂浓度升高对番茄根系生长的促进主要表现为增加根系的体积和表面积;而在磷正常供应条件下主要表现为同时增加根体积和分根数,有利于形成强壮的根系。在两种供磷水平下,CO₂浓度升高对番茄各器官的N、P、K含量产生不同的稀释效应,但N、P、K总积累量却随CO₂浓度升高而显著增加;而且CO₂浓度与供P水平对番茄植株的N、P、K积累量具有极显著的正交互效应。     

Cool Season C3-Grasses (Wheat,Rye, Barley,and Oats) Differ in Shoot: Root Ratio When Applied With Different NPK Sources

Shoot:root (S:R) response in four winter C₃-grasses (cereals) viz. wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.) and oats (Avena sativa L.) was investigated under eight different NPK sources (S₁ = 20-20-20, S₂ = 20-27-5, S₃ = 7-22-8, S₄ = 10-10-10-20S, S₅ = 11-15-11, S₆ = 31-11-11, S₇ = 24-8-16, and S₈ = 19-6-12) in pot experiment at Dryland Agriculture Institute, West Texas A&M University, Canyon, Texas, USA during winter 2009–2010. The experiment was performed in completely randomized design (CRD) with three repeats. The objective of this experiment was to investigate whether the S:R of winter cereals differ or not when applied with different NPK sources. Considerable variations in the shoot: root was noticed in the four grasses at different growth stages, i.e., 30, 60 and 90 days after emergence (DAE) when applied with different NPK fertilizers sources. Wheat had the highest S:R of 3.4 at 30 days after emergence (DAE), barley at 60 DAE (6.5), while oats at 90 DAE (3.9). Among the NPK sources, crops had the highest S:R of 3.6, 6.2 and 3.7 when applied with S₃, S₂, and S₆ at 30, 60 and 90 DAE, respectively. Shoot to root ratio showed positive relationship with increase in shoot weight and negative relationship with increase in root weight. The NPK fertilizer S₆ (31: 11: 11), an acid loving fertilizer had negative effects on the shoot and root development of cool season cereals, but among these cereals under study, barley and oats roots were affected more than wheat and rye. It was concluded from this present study, that the four cool season cereals responded differently in terms of shoot: root to different NPK fertilizers at different growth stages.     

Growth Responses and Nitrogen-15 Absorption of Desert Saltgrass Under Salt Stress

Abstract

Saltgrass [Distichlis spicata (L.) Greene var. stricta (Gray) Beetle], accession WA-12, collected from a salt playa in Wilcox, AZ, was studied in a greenhouse to evaluate its growth responses in terms of shoot and root lengths, shoot dry-matter yield, and nitrogen (N) (regular and ¹⁵N) absorption rates under control and salt (sodium chloride, NaCl) stress conditions. Plants were grown under a control (no salt) and three levels of salt stress (100, 200, and 400 mM NaCl, equivalent to 5850, 11700, and 23400 mg L^{? 1} sodium chloride, respectively), using Hoagland solution in a hydroponics system. Ammonium sulfate [(¹⁵NH₄)₂SO₄], 53% ¹⁵N (atom percent ¹⁵N) was used to enrich the plants. Plant shoots were harvested weekly, oven-dried at 60°C, and the dry weights measured. At each harvest, both shoot and root lengths were also measured. During the last harvest, plant roots were also harvested and oven-dried, and dry weights were determined and recorded. All harvested plant materials were analyzed for total N and ¹⁵N. The results showed that shoot and root lengths decreased under increasing salinity levels. However, both shoot fresh and dry weights significantly increased at 200 mM NaCl salinity relative to the control or to the 400 mM NaCl level. Shoot succulence (fresh weight/dry weight) also increased from the control (no salt) to 200 mM NaCl, then declined. The root dry weights at both 200 mM and 400 mM NaCl salinity levels were significantly higher than under the control. Concentrations of both total-N and ¹⁵N in the shoots were higher in NaCl-treated plants relative to those under the control. Shoot total-N and ¹⁵N contents were highest in 200 mM NaCl-treated plants relative to those under the control and 400 mM salinity.     

Impact of sulfate nutrition on the utilization of atmospheric SO2 as sulfur source for Chinese cabbage

The ability of Chinese cabbage (Brassica pekinensis) to utilize atmospheric sulfur dioxide (SO₂) as sulfur (S) source for growth was investigated in relation to root sulfate (SO ) nutrition. If seedlings of Chinese cabbage were transferred to a sulfate‐deprived nutrient solution directly after germination, plants became rapidly S‐deficient. Plant‐biomass production was decreased and the shoot‐to‐root ratio decreased. Sulfate deprivation resulted in a substantial decrease in total S, sulfate, organic‐S, and water‐soluble nonprotein thiol contents and in an increase in amino‐acid content of both shoot and root. The sulfate‐uptake rate of the root was strongly increased, whereas nitrate‐uptake rate was decreased. Upon resupply of sulfate, the onset of S‐deficiency symptoms was prevented, and growth was restored, whereas sulfate and nitrate‐uptake rates were quite similar to those of the sulfate‐sufficient plants. A 6‐day exposure to 0.12 µL L^–1 SO₂ of sulfate‐sufficient plants did not affect plant‐biomass production, shoot‐to‐root ratio, S and nitrogen (N) compounds of shoot and root, or sulfate and nitrate uptake by the root. Exposure of sulfate‐deprived plants to SO₂ resulted in enhanced total S, organic‐S, and water‐soluble nonprotein thiol contents of the shoot. The contribution of SO₂ as S source for biomass production depended on the duration of the sulfate deprivation. If Chinese cabbage was transferred to a sulfate‐deprived nutrient solution and simultaneously exposed to SO₂, then plants benefited optimally from the foliarly absorbed S. The development of S‐deficiency symptoms was prevented, and shoot‐biomass production was quite similar to that of sulfate‐sufficient plants. However, upon SO₂ exposure root‐biomass production was even higher than that of sulfate‐sufficient plants, whereas sulfate uptake was still enhanced. Evidently, upon SO₂ exposure there was no strict and direct shoot‐to‐root signaling in tuning sulfate uptake by the root and its transport to the shoot to the need for growth, via down‐regulation of sulfate uptake and normalizing shoot–to–root biomass partitioning.     

Inverse Relationship Between Boron Toxicity Tolerance and Boron Contents of Barley Seed and Root

A filter-paper bioassay method was used to investigate the differential response of 23 barley (Hordeum vulgare L.) genotypes to boron (B) toxicity. Two-day-old seedlings with equal radicles were treated with 10 (B10) or 100 (B100) ppm B for 10 d. Root and shoot growth was not affected by B10, but root growth was significantly reduced by B100. The shoot growth at B100 was either unaffected or affected to a smaller extent than the root. A significant inverse correlation was found between B content of seed and seed germination, and between root growth and B contents of root and shoot under B100. The barley genotypes with lower B contents in seeds had a higher germination, longer root length, and accumulated less B in roots and shoots when treated with B100. The B-tolerant genotypes with longer roots had lower B contents in their seed, root, and shoot and vice versa. These results suggest that a great variation exists among barley genotypes in response to high B application. There was no difference between naked (uncovered) and covered varieties in response to B100. The B tolerance could be attributed to the lower B content of seed and lower uptake or accumulation of B in the root and shoot.     

Varied rates of mycorrhizal inoculum on growth and nutrient acquisition by barley grown with drought stress

Effectiveness of arbuscular mycorrhizal fungi (AMF) is crucial for maximum plant growth and acquisition of mineral nutrients under drought. The objective of this research was to determine effects of varied rates of AMF inoculum on plant growth and acquisition of phosphorus (P), zinc (Zn), copper (Cu), and manganese (Mn) by barley (Hordeum vulgare L. cv. SLB‐6) grown with and without drought stress (WS and nonWS). Plants inoculated with four inoculum rates [control (M₀), 120 (M₁), 240 (M₂), and360 (M₃) spores per 100 g dry soil] of Glomus mosseae were grown in a low P silty clay (Typic Xerochrept) soil (pH=8.0) mix in a greenhouse for 45 days. Root AMF colonization increased as inoculum rate increased in plants grown with WS and nonWS. Leaf area and shoot and root dry matter (DM) increased as inoculum rate increased up to M₂ regardless of soil moisture. Shoot concentrations of P, Cu, and Mn were generally higher for mycorrhizal (AMF) than for nonmycorrhizal (nonAMF) plants grown with both WS and nonWS. Shoot contents of P, Zn, Cu, and Mn were higher for AMF than for nonAMF plants grown with nonWS, and shoot contents of P were higher for AMF than for nonAMF plants with WS. For plants grown with WS and nonWS, contents of P, Zn, Cu, and Mn were generally higher for plants inoculated with M₂ compared to other rates of inoculum. The results of this study indicated that plant responses to root colonization with AMF were dependent on AMF rate and soil moisture. Based on enhancements in plant DM and mineral acquisition traits, M₂ inoculum was the most effective rate of inoculation for this AMF isolate.     

EFFECT OF PLANT GROWTH-PROMOTING RHIZOBACTERIA STRAIN ON FREEZING INJURY AND ANTIOXIDANT ENZYME ACTIVITY OF WHEAT AND BARLEY

In 2009 a greenhouse experiment was conducted to determine the effects of boron (B) and plant growth-promoting rhizobacteria (PGPR) on wheat (Triticum aestivum spp. vulgare cv ‘Bezostiya’) and barley (Hordeum vulgare cv ‘Tokak’) on plant growth, freezing injury, and antioxidant enzyme capacity. Results showed that boron (0, 1, 3, 6, 9 kg B ha^?1) and PGPR application (Bacillus megaterium M3, Bacillus subtilis OSU142, Azospirillum brasilense Sp245 and Raoultella terrigena) at which 50% of leaves were injured (LT₅₀) values and ice nucleation activities in both plants were found statistically significant. Boron application with all PGPR strains decreased LT₅₀ values in wheat and barley plants under noncold stress (NCS) and cold stress conditions (CS). There were statistically significant differences between bacterial inoculation and B fertilizer in terms of root and shoot dry weight under NCS and CS conditions. Reactive oxidative oxygen species (ROS) and antioxidant enzyme activities (SOD, POD, CAT) were negatively affected CS conditions and decreased with reduced temperatures of media, but B and PGPR applications alleviated the low-temperature deleterious effects in both plants species tested. The lowest ROS and antioxidant enzyme (SOD, POD, CAT) of wheat and barley were observed with 6 kg B ha^?1 with R. terrigena.     

Mechanisms of aluminum‐induced growth stimulation in tea (Camellia sinensis)

Beneficial effects of aluminum (Al) on plant growth have been reported for plant species adapted to acid soils. However, mechanisms underlying the stimulatory effect of Al have not been fully elucidated. The aim of this study was to determine the possible contribution of photosynthesis, antioxidative defense, and the metabolism of both nitrogen and phenolics to the Al‐induced growth stimulation in tea (Camellia sinensis [L.] Kuntze) plants. In hydroponics, shoot growth achieved its maximum at 50 μM Al suply (24 μM Al³⁺ activity). A more than threefold increase of root biomass was observed for plants supplied with 300 μM Al (125 μM Al³⁺ activity). Total root length was positively related to root Al concentrations (r = 0.98). Chlorophyll a and carotenoid concentrations and net assimilation rates were considerably enhanced by Al supply in the young but not in the old leaves. Activity of nitrate reductase was not influenced by Al. Higher concentrations of soluble nitrogen compounds (nitrate, nitrite, amino acids) and reduction of protein concentrations suggest Al‐induced protein degradation. This occurred concomitantly with enhanced net CO₂‐assimilation rates and carbohydrate concentrations. Aluminum treatments activated antioxidant defense enzymes and increased free proline content. Lowering of malondialdehyde concentrations by Al supply indicates that membrane integrity was not impaired by Al. Leaves and roots of Al‐treated plants had considerably lower phenolic and lignin concentrations in the cell walls, but a higher proportion of soluble phenolics. In conclusion, Al‐induced growth stimulation in tea plants was mediated by higher photosynthesis rate and increased antioxidant defense. Additionally, greater root surface area may improve water and nutrient uptake by the plants.     

Soil‐solution speciation by MINEQL+4.6 model and plant uptake of Cd and Zn by barley (Hordeum vulgare L.) after application of different phosphate fertilizers

A greenhouse experiment was conducted to investigate the immediate effect of application of mono‐ammonium phosphate (MAP), single superphosphate (SSP), and triple superphosphate (TSP) fertilizers containing varying concentrations of Cd on (1) chemical speciation of Cd and Zn in soil solution by chemical‐equilibrium calculations (MINEQL+4.6 model), (2) growth of barley plants, (3) concentrations of Cd, P, and Zn in soil solution and plant tissue, as well as total plant accumulation of Cd, P, and Zn, and (4) monitoring pH and element changes during incubation periods following phosphate application. Results show that, in general, the pH of soil solution increased during the first 40 d of incubation, then declined. Also, at the end of incubation period, pH of soil solution was affected by fertilization source and fertilization rate. The concentration of Cd in soil solution changed with time. Phosphate fertilization (p < 0.05) or fertilizer source (p < 0.05) showed consistent effects. Also, the application of phosphate fertilizers with three rates significantly increased Zn concentrations in soil solution during the first half (0–30 d) of incubation period and then decreased but still more than in the control. In general, application of different sources of phosphate at 100 g kg^–1 did not change the dominant forms of Cd in soil solution during all incubation time intervals. Speciation of Zn in the control after 30 d of incubation had changed, in comparison to 10 d of incubation, and the dominant forms were Zn²⁺, ZnOH⁺, ZnHCO₃, ZnCO₃(aq), and Zn(OH)₂(aq). Adding phosphate fertilizer significantly increased both shoot and root dry weight compared to control, indicating P was a growth‐limiting factor in the control plants. The Zn concentrations in shoot and root were lower in the TSP‐ and SSP‐fertilizers treatment than those in the MAP and fertilizer treatments at all rates of fertilization. Adding phosphate increased the Cd : Zn and P : Zn ratios in the shoot and root tissue, with the effect being greater with increasing fertilization rate. Phosphate fertilization greatly increased the total accumulation of Cd of barley compared with the control plants (p < 0.001), with the effect being greater with increasing fertilization rate. Source and rate of fertilizers, and their interactions had significant effect (p < 0.05) on Cd accumulation in the whole plant.     

Plant and soil responses to mycorrhizal fungi and rhizobacteria in nodulated or nitrate-fertilized peas (Pisum sativum L.)

Rhizosphere organisms affect plant development and soil stability. This study was conducted to determine the effects of a vesicular-arbuscular mycorrhizal (VAM) fungus [Glomus mosseae (Nicol. &>; Gerd.) Gerd. and Trappe] and a rhizobacterium (Bacillus sp.) on nitrate-fertilized or nodulated pea (Pisum sativum L.) plants and on the status of water-stable soil aggregates. The plants were grown in pots in a yellow clay-loam soil, and inoculated with the VAM fungus and the rhizobacterium, with one of the two, or with neither. The Bacillus sp. and G. mosseae did not affect shoot dry mass in nodulated plants. Under N fertilization, the VAM fungus enhanced plant growth, while the rhizobacterium inhibited shoot growth, VAM root colonization, and nodule formation, but enhanced the root:shoot and the seed:shoot ratios. The inhibition of shoot growth and of root colonization appeared to be related. The water stability and pH of the VAM soils were higher than those of the non-VAM soils. The rhizobacterium enhanced the water-stable aggregate status in the non-VAM soils only. Under both N-nutrition regimes, the soils had the greatest proportion of the water-stable aggregates when inoculated with both rhizo-organisms and the lowest when colonized by neither. The two rhizo-organisms affected both plants and soil, and these effects were modified by the source of N input through N₂ fixation or fertilization. Received: 5 April 1995     

Comparison of the effects of nano-iron fertilizer with iron-chelate on growth parameters and some biochemical properties of Catharanthus roseus

Nanofertilizers, which supply nutrients to the plant, are used to replace conventional fertilizers. Iron (Fe) is one of the essential elements for plant growth and plays an important role in the photosynthetic reactions. To study the effects of nano-iron fertilizer on Catharanthus roseus, plants were treated with different concentrations (0, 5 10 20, 30, and 40 mM) of iron oxide nanoparticles (Fe2O3) for 70 days. Fe₂O₃ nanoparticles increased growth parameters, photosynthetic pigments, and total protein contents in the treated plants significantly. The maximum amounts of growth parameters, photosynthetic pigments, and protein contents were obtained with 30 µM Fe₂O₃ and minimum values of these parameters were found with 0 µM Fe₂O₃. The highest value of total alkaloid content was obtained in 0 µM Fe₂O₃ and the lowest value was observed in control plants. Iron oxide nanoparticles increased potassium, phosphorus, and iron absorption but did not show a significant effect on sodium content.     

高低应答CO2水稻品种苗期根系对高C环境的响应

本文利用水培试验和琼脂板培养试验研究了高CO₂条件下产量响应存在显著差异的两个水稻品种：II优084(高响应)和武运粳23(低响应),在幼苗期根系形态对高C的响应差异。水培试验结果表明,在幼苗时期,高应答品种II优084在低氮条件下地上部生物量在高CO₂下增加28.5%,根系干物质量对高CO₂响应显著,增幅为28.5%,而其不定根数目没有显著增加,对干物质量响应贡献较大的为总根长。II优084的总根长在高CO₂下增幅为26.3%,不同根粗的根长均有高响应。低应答品种武运粳23低氮下地上部和根系响应不显著,而在正常氮和高氮下则不同。正常氮条件下,地上部对高CO₂响应不显著,而根系生物量在高CO₂下显著增加76.0%,不定根数目增加25.8%,同时总根长增加45.0%,不同根粗的根长均有高响应,II优084则没有显著响应。在高氮条件下,武运粳23地上部生物量在高CO₂下增加35.5%,根系生物量增加80.3%,不定根数目增加38.5%,根系平均直径增加16.7%,总根长无响应,而II优084生物量在高氮下无显著差异。同时,武运粳23在正常氮和高氮下的根系表面积和体积对高CO₂响应也较II优084显著。琼脂板培养试验的结果与水培结果一致,武运粳23根系形态对高浓度蔗糖的响应普遍高于II优084。试验结果说明品种对高C环境的响应特征不随培养条件的变化而变化。与植株生长后期不同,在幼苗期正常氮条件下低应答品种武运粳23的根系生物量和各形态指标对高C的响应明显高于II优084,说明水稻苗期生长响应参数与后期产量响应参数不一定一致,可能是由于苗期生长高响应的品种在营养生长期旺长,反而不利于后期生殖生长,从而导致后期产量的低响应。     

Ameliorative Effect of Hydro Gel Substrate on Growth,Inorganic Ions,Proline, and Nitrate Contents of Bean under Salinity Stress

The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na₂SO₄), calcium chloride (CaCl₂), calcium sulfate (CaSO₄), potassium chloride (KCl), potassium sulfate (K₂SO₄), magnesium chloride (MgCl₂), magnesium sulfate (MgSO₄)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na₂SO₄, CaCl₂, CaSO_4, MgCl₂, MgSO₄, KCl, and K₂SO₄, and similarly NaCl, Na₂SO₄, CaCl₂, CaSO_4, KCl, K₂SO₄, MgCl₂, and MgSO₄ in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.     

Nitrogen nutritional status of young maize plants (Zea mays) is not limited by NaCl stress

Maize plants (Zea mays L. cv. Pioneer 3906) were grown in hydroponics with four different NaCl treatments (control, 50, 100, 150 mM NaCl). Nitrogen (N) was supplied as 2 mM Ca(NO₃)₂ in the fully concentrated nutrient solution. Plants of half of the pots were treated with additional 1 mM NH₄NO₃ 2 d after start of the NaCl application. After 23 d, the maize plants were harvested and contents and concentrations of nitrate, reduced N as well as chloride were determined in shoots and roots. With increasing NaCl stress net nitrate uptake and net root‐to‐shoot translocation of total N decreased significantly. Under salt stress, decreased nitrate concentrations in shoots probably caused substrate limitation of nitrate reductase. However, the concentrations of reduced N in shoots were not affected by salt stress and no N deficiency was observed. Additional N application to the 100 and 150 mM NaCl treatments did not improve plant growth. A Cl^?/NO antagonism was only weakly pronounced, probably because of the Cl^? exclusion ability of maize. Thus, although net uptake and net translocation of total N were markedly decreased by NaCl application, the smaller maize plants nevertheless took up enough N to meet their demand pointing to other growth‐limiting factors than N nutrition.     

Effect of Glomus etunicatum inoculation on aluminum,phosphorus, calcium,and magnesium uptake of two barley genotypes with different aluminum tolerance

Abstract

This study was conducted to evaluate the effect of vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus etunicatum on growth, absorption, and distribution of calcium (Ca), magnesium (Mg), phosphorus (P), and aluminum (Al) in one Al‐tolerant and one Al‐sensitive barley cultivar. The plants were grown in sand daily irrigated with nutrient solution containing 0 or 600 μM Al at pH 4.8. Significant interaction (P=0.05) among variety, mycorrhiza, and aluminum (VxMxAl) were noted for both shoot and root dry matter (DM); shoot concentration and content of Al, P, Ca, and Mg; root concentration of Al, P, and Mg; and root content of Al, P, Ca, and Mg. With VAM inoculation: i) root colonization degree was about 50% in all treatment, ii) shoot DM yield increased between 30 and 70%, iii) Al concentration and content decrease down to a half both in shoots and roots of sensitive barley, iv) Ca concentration in shoots of sensitive barley showed a high increase at 600 μM Al, and v) P concentration and content in shoots of both varieties increased significantly.