Effect of nitrogen on the growth and photo‐synthetic activity of salt‐stressed barley

Pot experiments were conducted in the greenhouse to study the effect of nitrogen (N) nutrition on photosynthesis and water relations of barley plants under salinity conditions. Nitrogen decreased the sodium (Na) content and increased the potassium (K) content in shoots. The net photosynthetic rate of leaves increased significantly with added N increasing from 0 to 100 mg N/kg soil. The activity of ribulose 1,5 bisphosphate carboxylase (RuBPC_ase) in leaves of high‐salt plants was lower, and in leaves of the low‐salt plants higher than that in control plants. The photosynthetic rate was reduced by sodium chloride (NaCl) and was significantly correlated with total soluble protein per unit leaf area. At each N level, stomatal conductance in leaves was reduced considerably by salt. Proline content of leaves increased with increasing N level. It was higher in leaves of salt‐treated plants than in those of control plants. The osmotic potential of leaves decreased with increasing N applied, and the turgor pressure of high N plants remained higher under salt treatment condition.     

Assessing a suitable extractant and critical limits of nickel in soil and plant for predicting the response of barley (Hordeum vulgare L.) to nickel grown in Inceptisols

ABSTRACT

Nickel (Ni) is an essential element for plants. Abundant information exists on Ni toxicity in soil–plant system but not much is available on its critical level of deficiency (CLD) in soils and plants. Five chemical extractants were evaluated to find a suitable extractant for Ni in Inceptisol. Twenty-one soils having low to high levels of Ni were used to grow barley (Hordeum vulgare L). The amount of Ni extracted was correlated with Ni concentration and uptake by barley. The diethylene triamine penta acetic acid-calcium chloride (0.005 M DTPA-CaC1₂) was identified as the most promising soil extractant for Ni. The CLD of Ni for 0.005 M DTPA-CaC1₂ in soil was 0.22 mg kg^?1 whereas in barley plant it was 2.14 mg kg^?1. Application of 7.5 mg kg^?1 Ni in soil caused a significant increase in Ni concentration in the shoot of barley in all the soils irrespective of the initial Ni status.     

Soil‐test values after eight years of tillage research on a Norfolk loamy sand

Abstract

Long‐term effects of alternate tillage systems on soil‐test values for Coastal Plain soils were unknown. Therefore, soil pH, organic carbon, and Mehlich I extractable P, K, Ca, and Mg concentrations measured during an eight‐year tillage study on Norfolk loamy sand (fine‐loamy, silicious, thermic, Typic Paleudults) have been summarized. Yields for corn (Zea mays L.), wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.] are also summarized to provide an indication of nutrient removal by the crops. Soil‐test measurements after six years showed no significant differences in Mehlich I extractable nutrient concentrations for the 0‐ to 20‐cm depth between disked (conventional) and nondlsked (conservation) tillage treatments, but for pH, P, Ca, and Mg, the tillage by depth of sampling interaction was significant at P‐0.05. Stratification did not appear to affect crop yield. Soil organic matter concentration in the Ap horizon nearly doubled after eight years of research at this site. This change occurred within both tillage treatments, apparently because high levels of management produced good crop yields, residues were not removed, and even for the disked treatment, surface tillage was not excessive. These results show that long‐term average yields for corn and soybean on Norfolk soil will not be reduced by adopting reduced or conservation tillage practices. They also show that nutrient levels can be maintained at adequate levels for crop production on Coastal Plain soils by using current soil‐test procedures and recommendations for lime and fertilizer application.     

Interactions of oxygen‐nitrogen‐salinity stresses on plant growth and mineral content of sunflower (Helianthus annuus L.) in sand culture

Reports relating the separate and combined influences of soil aeration, nitrogen and saline stresses on the germination, growth and ion accumulation in sunflowers are lacking in the literature. The sunflowers of this report were grown in sand culture in the greenhouse. Separate and combined treatments of two levels of aeration, three levels of nitrogen and three levels of NaCl were applied to plants which were harvested at 40 and 56 days. Seed germination was excellent in all treatments. Plant height and dry weight decreased with each type of stress. Low oxygen (0.20 μg O₂ cm^‐2 min^‐1) and nitrogen (10 ppm) combined with 70 meq/1 NaCl caused the greatest reduction of plant growth. Leaf number was reduced by low nitrogen and excess salt. Low oxygen reduced the accumulation of K, Ca and Mg and increased the Na and N‐NO₃ content of sunflower leaves. Potassium to sodium ratios in plant on sunflower growth could be partially ameliorated with the tissue were decreased by greater EC values of the nutrient solution and low soil ODR. The adverse effects of salt and oxygen stresses addition of nitrogen. Ion accumulation was an earlier indicator of plant stress than plant growth and both parameters provided excellent methods for assessing plant tolerance to soil aeration, nitrogen and saline stresses.     

Effect of seed‐placed fertilizer on the emergence (germination) of soybeans (Glycine max L.) and snapbeans (Phaseolus vulgaris L.)

Abstract

Field trials were established on a loamy fine sand and a silt loam using snapbeans and soybeans as test crops, respectively. Row fertilizer was placed with the seed (seed‐placed). Treatments were arranged in a 3×3×3 factorial experiment, and N, P, and K were applied in all combinations at three rates (0, 3.4, and 6.8 kg/ha). Ammonium nitrate (AN), monoammonium phosphate (MAP), concentrated superphosphate (CSP) and potassium chloride (KCl) were used as sources of N, P and K. Additional treatments compared MAP with diammonium phosphate (DAP) and KCl with potassium nitrate (KNO₃).

The salt index of each treatment was inversely related to emergence, i.e. as the salt index increased, the emergence decreased. Level of N was more important than level of P or K in regards to reduction in emergence. Snapbeans grown on a loamy fine sand were extremely sensitive to damage from seed‐placed fertilizer, even at rates as low as 3.4 kg/ha of N, P or K. Soybeans planted on a silt loam soil were less sensitive than snapbeans planted on a loamy sand. The soybeans were able to tolerate up to 10.2 kg/ha of seed‐placed P plus K or 6.8 kg/ha of seed‐placed N plus P or N plus K without causing a significant delay in emergence.     

Can barley (Hordeum vulgare L. s.l.) adapt to fast climate changes? A controlled selection experiment

The projected future climate will affect the global agricultural production negatively, however, to keep abreast of the expected increase in global population, the agricultural production must increase. Therefore, to safeguard the future crop yield and quality, the adaptive potential of crops to environmental change needs to be explored in order to select the most productive genotypes. Presently, it is unknown whether cereal crops like spring barley can adapt to climate stressors over relatively few generations. To evaluate if strong selection pressures could change the performance of barley to environmental stress, we conducted a selection experiment over five plant generations (G0–G4) in three scenarios, where atmospheric [CO₂] and temperature were increased as single factors and in combination. The treatments represented the expected environmental characteristics in Northern Europe around year 2075 [700 ppm CO₂, 22/17 °C (day/night)] as well as a control mimicking present day conditions (390 ppm CO₂, 19/12 °C). Two different barley accessions, a modern cultivar and an old landrace, were evaluated in terms of yield and biomass production. In all treatments representing future environmental scenarios, the G4-generation of selected plants did not improve its reproductive output compared to the G0-generation, as G4 produced less seeds and had a lower yield than unselected plants. These results indicate that barley might not respond positively to rapid and strong selection by elevated [CO₂] and temperature, contrary to previous results from oilseed rape. The two barley accessions analyzed presented almost the same response pattern in a given treatment, though the modern cultivar had the highest yield in the climate scenarios, while the landrace was superior in yield under present day climate conditions.     

Impact of organic and inorganic nutrition on soil–plant nutrient balance in arecanut (Areca catechu L.) on a laterite soil

The study assessed the impact of continuous application of vermicompost and chemical fertilizers nitrogen, phosphorus and potassium (NPK) on arecanut in India. Key parameters examined were biomass production, nutrient uptake, yield, soil fertility and net benefit. Pooled analysis of 8-year data revealed that nutrient application registered significantly higher yield (2585–3331 kg ha^?1) than no nutrition (1827 kg ha^?1). Yields in organic nutrition were around 85% of the yields obtained in inorganic NPK. The concentrations of leaf N and K were significantly higher with NPK than with vermicompost. Vermicompost significantly increased soil organic carbon and the availability of calcium (Ca), magnesium (Mg), manganese (Mn) and copper (Cu), but reduced exchangeable K in soil. The total uptake of K and Ca together contributed positively to 75% variability in total biomass production. Nutrient removal of iron (Fe), P, K and Cu positively influenced the yield with about 81% variability. Biomass partitioning and nutrient uptake pattern are important for fertilization program of arecanut.     

Effect of nitrogen– boron interaction on plant growth and tissue nutrient concentration of canola (Brassica napus L.)

Pot experiments were conducted in the greenhouse on a calcareous soil to study the effect of nitrogen on the alleviation of boron toxicity in canola (Brassica napus L.). The treatments consisted of factorial combination of six levels of B (0, 2.5, 5, 10, 20, and 40 mg kg^?1 as boric acid), and four levels of nitrogen (N) (0, 75, 150 and 300 mg kg^?1 as urea) in a completely randomized design with three replicates. Boron (B) application significantly reduced the yield, whereas N addition alleviated the growth suppression effects caused by B supplements. Boron concentration increased with addition B. However, boron concentration in shoot declined with increasing N levels. Increasing N and B rates increased N concentration. Soil application of B increased proline concentration. However, the supply of N decreased it. Generally, application of B decreased potassium (K):B and calcium (Ca):B ratios, chlorophyll concentration, while N application increased them. It is concluded that N fertilization can be used effectively in controlling B toxicity in canola grown in B-affected soils.     

Effects of vesicular arbuscular mycorrhizal inoculation on growth and phosphorus nutrition of barley in natural or methyl bromide‐treated soil

The growth and phosphorus (P) nutrition of barley (Hordeum vulgare L.) in a soil, methyl bromide fumigated or untreated and supplied with or without mycorrhizal inoculum, was studied in pots placed under a field environment. Inoculation significantly raised the overall levels of vesicular arbuscular mycorrhizal (VAM) infection. The relative increase was significantly greater in sterile than nonsterile soil. Soil sterilization produced significantly higher dry matter throughout the experiment. Inoculation resulted in a significant growth depression earlier in the season which could not be offset by the following mycorrhizal enhancement in P absorption rates. The primary reasons for this yield depression were most probably the root density and available P status of the soil which might have been over the threshold limit for positive mycorrhizal yield response in barley. In this experiment, the result of inoculation could be regarded beneficial considering 17 and 30% higher P concentrations in grain and straw, respectively, but detrimental with respect to 20% loss in grain plus straw yield.     

Effect of peduncle‐perfused nitrogen,sucrose, and growth regulators on barley and wheat amino acid composition

Abstract

Nitrogen (N) or growth regulator application to small grain cereals near anthesis has been demonstrated to alter grain fill and grain yield, the protein yield and nutritional quality may also be modified by these management factors. The objective of this study was to determine whether delivery of N, growth regulator, or sucrose solutions into greenhouse‐grown barley (Hordeurn vulgare L. cv. Leger) or wheat (Triticum aestivum L. cv. Katepwa), plants through peduncle perfusion altered the amino acid composition of the grain. The following treatments were tested: N (25 and 50 mM), chlormequat (30 μM), ethephon (15 μM), N + chlormequat, N + ethephon, detillering + N, sucrose (250 mM), distilled water check, and non‐perfused check. Perfusion lasted 30 d beginning 5 to 8 d after spike emergence. Addition of N via peduncle perfusion increased protein concentrations and concentrations of all amino acids in both barley and wheat when expressed in terms of grain dry matter. Protein yield and lysine content were also increased. However, the increase in essential amino acids such as lysine, methionine, threonine, isoleucine, arginine, and leucine was relatively small, and the proportions of these amino acids in the grain protein were actually reduced. The sucrose treatment only affected wheat, increasing lysine concentration and decreasing the total protein concentration. Growth regulators used in this study did not alter protein yield or amino acid composition in either crop.     

Effects of Kocide 101® on the bean (Phaseolus vulgaris L.)‐Rhizobium symbiosis

A glasshouse study was undertaken to investigate the effects of the copper fungicide Kocide 101 and its residues in soil on the growth, nodulation and nitrogen fixation of beans (Phaseolus vulgaris L.). The soil used was a sandy clay loam classified as Typic Rhodustalf. The bean variety SUA 90 was used as test crop. The bean rhizobia strains CIAT 899, PV, and a local isolate were used. Kocide 101 applied at the recommended rate (equivalent to 1.7 mg kg^‐1 soil) had no significant negative effects on the growth, nodulation or nitrogen fixation of bean plants. Higher levels of Kocide 101 significantly (P < 0.05) reduced plant growth, nodulation and nitrogen fixation. The bean plants inoculated with the “local isolate”; rhizobia had the highest dry matter weights, nodule numbers and nodule dry weights, and also had more N fixation. They were followed by those inoculated with the PV, strain and, lastly, those inoculated with CIAT 899. The growth and nodulation of bean plants were still curtailed by the Kocide 101 residues four months after the fungicide was first applied to the soil. Therefore, occurrence of high levels of Kocide 101 in soils can have long‐term effects on the performance of the bean‐rhizobia symbiosis.     

Effect of different safflower (Carthamus tinctorius L.)–bean (Phaseolus vulgaris L.) intercropping patterns on growth and yield under weedy and weed-free conditions

Two field experiments were carried out over two consecutive years (2010–2011) in the research field of the College of Agriculture, Shiraz University, Fars Province, southern Iran. The study was a factorial experiment based on a randomized complete block design with three replications: the first factor was the ratio of safflower (Carthamus tinctorius L. Pi cv.) to bean (Phaseolus vulgaris L. Saiad cv.) at five levels (safflower and bean sole cropping, and intercropping of safflower and bean at ratios of 1:3, 2:2 and 3:1); and the second factor was weed management at two levels: weed-free (complete weed control) and weedy (no weed control). The results showed that an intercropping system was the most appropriate method for decreasing the adverse effect of weeds on the performance of both crops. Intercropping was more suitable for weedy than weed-free conditions. According to the land equivalent ratio (LER) value, if the main crop was bean, the best intercropping treatment was one row of safflower and six rows of bean (S₁B₃) under both weedy and weed-free conditions. By contrast, if the main crop was safflower, the best treatment under weedy conditions was S₁B₃, whereas under weed-free conditions the best treatment was two rows of safflower and four rows of bean (S₂B₂). Overall, S₁B₃ can be introduced as the best intercropping method.     

Effect of the swelling ability of a novel hydrolysed acrylonitrile‐sulfonated polystyrene network on growth of tomato and lettuce seedlings

Abstract

The effect of swelling ratio of a novel material as Hydrolysed Sulfonated Styrene Acrylonitrile Copolymer (HSSAN) on the emergence and growth of tomato and lettuce seedlings was investigated. Water insoluble polymers having various swelling ratios were incorporated into soil and quartz sand at a constant concentration of 0.15% w/w and growth curves were obtained for each case study. The data show that HSSAN having high swelling ability produced higher seedlings in a short time. High swelling ratio values reflect the amount of crosslinking agent needed for the preparation of the resin. Low cross‐linking agent concentrations are required for satisfactory results of the conditioner on soil substrate.     

The effect of an NH4 +‐enhanced nitrogen source on the growth and yield of hydroponically grown maize (Zea mays L.)

Increased above‐ground dry matter and grain yields were found for two hydroponically grown maize hybrids (Pioneer‐3925 and Pioneer‐3949) when plants were supplied with an NH₄ ⁺‐enhanced nutrient solution (31 percent of total N) compared with a control (4 percent of total N as NH₄ ⁺). The major difference in yield developed between silking and 2 weeks post‐silking and silking and 4 weeks post‐silking for the P‐3925 and P‐3949 respectively. The reduced nitrogen content of the stover (leaves plus stalk) was consistently higher on the NH₄ ⁺‐enhanced nutrient solution. The decreased production of the control treatment may have resulted from a reduced photsynthetic capacity.     

Soybean response to the application of several elements on a low‐manganese soil

Abstract

Certain soils in the Lower Atlantic Coastal Plain are Mn‐deficient and because of their inherent properties, deficiencies of other elements might be expected. The response of soybean [Glycine max (L.) Merr. cv. ‘Ransom'] to annual soil applications of B, Cu, Fe, Mo, S, and Zn with and without Mn was examined. The study was conducted on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) in 1975, 1976, and 1977. Seed yields, and soil and plant tissue concentrations of certain of the applied elements were determined. Soil pH increased from 6.4 in 1975 to 7.0 in 1977 as a result of lime applications.

Of the seven elements studied, only Mn significantly increased soybean seed yield compared to the check. Leaf concentrations of the respective elements were higher where the element was added than they were in plants grown on the check plots. In 1977, after three years of elemental additions, plant concentrations of Mn, Cu, and Zn were higher, relative to checks, than in 1975. In 1977, with the higher soil pH levels, plants from check plots had lower concentrations of Mn, but unexpectedly equal levels of Cu and higher levels of Zn than in 1975. This unexplained increase in plant Zn was also found in Other experiments in the same field during the same time period. Double acid extracted more soil Mn, Cu, and Zn than did DTPA from similar treatments during all three years. The DTPA‐extractable soil Mn correlated much better with plant Mn than did double acid Mn values, especially over years where a change in soil pH occurred. Correlation coefficients comparing extractable soil versus plant values for Cu and Zn data combined over years were higher for double acid than DTPA, although coefficients for the Cu and Zn data were still generally much lower than for the Mn data.     

Effect of nitrogen and sulphur fertilizers and seed inoculation with rhizobium phaseoli on the nitrogen‐sulphur relationships of bean (phaseolus vulgaris L.)

A greenhouse experiment with beans (Phaseolus vulgaris L.) was performed in order to investigate the effect of nitrogen and sulphur application and seed inoculation on the yield, leaf area, distribution of different nitrogen and sulphur fractions and N/S ratio in shoot, fruit and root.

Inoculation of plants together with nitrogen or sulphur application produces an increase in the concentration of total nitrogen and a decrease in the accumulation of nitrate‐nitrogen and sulphate‐sulphur in shoot, fruit and root. Leaf area increased more with nitrogen than with sulphur application while the highest amounts of fruit dry matter were obtained with sulphur application.

N: S ratios obtained were different according to the part of the plant tested. Sulphur fertilization decreased the N: S ratios in shoot, fruit and root. The data obtained indicate that and adequate N: S ratio can insure maximum production of yield.     

Effect of dicyandiamide on the form and recovery of 15N‐labeled urea in the delayed flood soil system

Abstract

Dicyandiamide (DCD) is a nitrification inhibitor that has been proposed for use in drill‐seeded rice. Immobilization of fertilizer NH₄ ⁺‐N by soil microorganisms under aerobic conditions has been found to be significantly enhanced in the presence of a nitrification inhibitor. The objective of this laboratory study was to determine if DCD significantly delayed nitrification of urea‐derived N, and if this enhanced immobilization of the fertilizer N in the delayed‐flood soil system inherent to dry‐seeded rice culture. Nitrogen‐15‐labeled urea solution, with and without DCD (1: 9 w/w N basis), was applied to a Crowley silt loam (Typic Albaqualf) and the soil was incubated for 10 weeks in the laboratory. The soil was maintained under nonflooded conditions for the first four weeks and then a flood was applied and maintained for the remaining six weeks of incubation. The use of DCD significantly slowed the nitrification of the fertilizer N during the four weeks of nonflooded incubation to cause the (urea + DCD)‐amended soil to have a 2.5 times higher fertilizer‐derived exchangeable NH₄+‐N concentration by the end of the fourth week. However, the higher exchangeable NH₄+‐N concentration had no significant effect on the amount of fertilizer N immobilized during this period. Immobilization of the fertilizer N appeared to level off during the nonflood period about the second week after application. After flooding, immobilization of fertilizer N resumed and was much greater in the (urea + DCD)‐amended soil that had the much higher fertilizer‐derived exchangeable NH₄ ⁺‐N concentration. Immobilization of fertilizer N appeared to obtain a maximum in the urea‐amended soil (18%) about two weeks after flooding and for the (urea + DCD)‐amended soil (28%) about four weeks after flooding.     

Studies on the ecology of actinomycetes in soil— VII. Actinomycetes in a coastal sand belt

Distribution of actinomyeetes in beach and dune sand at two sites was studied. At one site. dunes were eroding while at the other accretion of sand and dune development occurred. Actinomycetes occurred in low numbers in beach sand hul increased sharply when dunes were colonized by Ammophila arenaria (L) Link or Agropyron junceiforme (A & D Löve) A & D Löve. Micromonospora strains predominated in beach sand but Streptomyces was the predominant genus in dunes.Salinity tolerance of isolates was not clearly related to their source but tolerance of dune isolates was generally greater than those from the beach. Tolerance of Streptomyces strains varied but all Micromonospora isolates were intolerant of salinities above that of sea water.Evidence for increased growth of actinomycetes in the root region of A. arenaria and A. junceiforme was obtained but there was little qualitative difference between those in the root region and root-free sand. In laboratory experiments actinomycetes colonized old. dead Ammophila roots more readily than young ones and arose carly in succession on the former. Young, living roots stimulated bacteria and fungi but not actinomyeetcs. It was concluded that most activity of actinomycetes in the Ammophila root region occurred on old root tissue and it was suggested that this might be true of other plants.     

Transfer of rubidium‐86 (potassium) from deeply‐rooted alfalfa (Medicago sativa L.) to associated,shallow‐rooted maize (Zea mays L.) or grain sorghum (Sorghum vulgare pers.).

Circumstantial evidence exists for non‐N‐mineral element transfer in legume‐grass associations. Three experiments were conducted in an effort to directly demonstrate transfer of a non‐N‐mineral element in alfalfa (Medicago sativa L.)‐maize (Zea mays L.) and alfalfa‐grain sorghum (Sorghum vulgare Pers.) associations in two rooting media. Associations were established in double‐tube apparatus so that a single alfalfa plant was rooted in media of top‐ and bottom‐tubes, while an associated grass plant was rooted exclusively in the top‐tube (Intact treatment). Severed treatments (the control) were identical to the Intact treatments except the alfalfa roots in an air gap between the top‐and bottom‐tubes were excised.

⁸⁶Rb was dispensed onto the medium of bottom tubes with movement of the radioisotope determined by analyzing the legume and grass tissues over time. ⁸⁶Rb was detected in: i) soil‐grown maize associated with alfalfa within a 40‐day treatment period; ii) sand‐grown maize associated with alfalfa within 20 days after treatment and iii) sand‐grown sorghum associated with alfalfa within 10 days. Detection of ⁸⁶Rb in grass plants associated with alfalfa demonstrated that transfer of this potassium analog can occur via the root systems of legume‐grass associations.