Diurnal,shade, and hybrid effects on nitrate content of young corn stalks

Abstract

Significant correlations have been found between the nitrate concentration in young corn (Zea mays L.) stalks and available soi 1 N and relative grain yield when N availability is a yield limiting factor. To successfully use nitrate tissue testing as an indicator of the N status of plants, the effects of factors other than soil or fertilizer N on the nitrate concentration in the tested tissue must be understood. Diurnal effects on stalk nitrate content were studied in a greenhouse experiment, in which stalk samples were collected every two hours for 24 hours, and in a field study, where plants in an N‐fertilizer response experiment were sampled at sunrise and at mid‐day. A significant diurnal cycle was observed for stalk nitrate content in the greenhouse, with a peak at 0800 h and a low at 1400 h, but no diurnal effect was found in the field study, possibly due to plant stress from other environmental factors. In a second greenhouse study, stalk samples from seedlings in direct and 66% shaded natural light were collected for two consecutive days and measured for nitrate content to ascertain the consequences of sampling on overcast days. Significant accumulations of nitrate occurred in stalks of plants sampled after two consecutive days of shading. Stalk samples from three standard hybrid corn trials in central Pennsylvania were measured for nitrate content to determine if hybrid differences existed. Hybrid differences in stalk nitrate were significant in only one of the three sites studied, and the variation in that one may have been due to differences in drought tolerance as well as nitrate metabolism. The results suggest that sampling strategies should be designed to minimize the effects of irradiance level on nitrate accumulation, but that differences in nitrate accumulation among corn varieties may not be a major concern in using nitrate tissue tests to predict N availability.     

Fatty Acid Inheritance in Wide Reciprocal Oilseed Crosses (Brassica rapa and B. napus)

Abstract

Erucic acid content and inheritance were studied in Brassica alboglabra, B. rapa and resynthesized B. napus from these parental species. Although significant variation in erucic acid content was found between the 20 B. alboglabra lines, all of them had to be classified as high erucic types. No major erucic acid gene polymorphism was identified.

In B. rapa the erucic acid content was regulated by one major gene, which showed partial dominance in three of the four crosses analysed. The high erucic gene seemed to function more efficiently in the Yellow Sarson cytoplasm, resulting in maternal differences when reciprocal crosses were compared. In crosses where modern low erucic acid lines were used as female parents the zero erucic acid F₂-individuals occurred more frequently than expected.

Segregation of the erucic acid content in crosses involving resynthesized B. napus showed a good fit to a two locus model. No maternal effects were found, but deviations from mid-parent values in the high erucic acid direction occurred in most of the F₁-hybrids, indicating partial dominance. Crosses between resynthesized oilseed rape and natural oilseed rape resulted in oleic acid transgressive F₅-lines.     

Effects of bacterial inoculants and sources of phosphorus on yield and phosphorus uptake of wheat

Phosphorus (P) mobilizing bacteria play an important role in the availability of soil and fertilizer P for all crops including wheat. Two greenhouse experiments were conducted to evaluate the effects of six P mobilizing bacterial strains and three P sources tricalcium phosphate {[Ca₃(PO₄)₂], calcium hydrogen phosphate [CaHPO₄.2H₂O] and rock phosphate} on yield and P uptake of wheat. All the bacterial inoculants increased grain yield significantly over control in one greenhouse experiment while only three strains produced significantly higher grain yield over control in a second experiment. Difference among P sources were not significant in acquiring grain yield in experiment 1 while Ca₃(PO₄)₂ and CaHPO₄.2H₂O produced significantly higher grain yield over rock phosphate in experiment 2. The differential pattern in results in two experiments might be due to difference in growth conditions. More greenhouse studies as well field experiments are recommended to confirm the beneficial effects of these P mobilizing bacterial strains on wheat.     

Responsiveness of Kansas soil series to sulfur application under greenhouse conditions

Abstract

Soil series of extensive acreage were selected to evaluate their S‐supplying power under greenhouse conditions using alfalfa in one study and corn and grain sorghum as test crops in a second study. The soils were divided into two major groups by textural classification for statistical evaluations. The addition of sulfur significantly increased dry matter yields and sulfur content of the plant material on all soils through the course of these studies. Significant predictors of sulfur uptake include extractable SO₄‐S and organic matter. Organic matter was a significant predictor of the percent yield response above the check yields on soils receiving S applications using corn and grain sorghum as test crops. Based on this equation, yield response would be expected in this greenhouse study with an organic matter content of 2.6% or less.     

Nutrient deficiency diagnosis of corn (Zea Mays L.) plants from yield and composition responses to additions of N and S

Abstract

Corn (Zea mays L.) was grown in the greenhouse in a Laughlin (Ultic Haploxeroll) loam soil, with various amounts of N and S added in order to determine possible interactions of these nutrients with the relationship between plant composition and grain yields. Previous field experience and preliminary experiments had shown that this soil gave yield responses to N and S additions.

Regression equations were used to describe the relationship between composition of various plant parts and grain yields. The best correlation (R² = 0.943) was obtained using the total N concentration in leaf samples taken at the silking stage, but excluding data from plants which, based on their amide N concentrations (greater than 500 ppm), were considered S deficient. Calculations using the first derivative of the cubic polynomial indicated that a concentration of 2.5% N in the lower leaves was necessary in order to obtain maximum grain yields. The concentrations of total N in the upper leaves and the stalks at the silking stage also correlated well with the grain yields. The relationship of NO₃‐N in the stalks at silking to grain yields could be better described mathematically with an exponential function, but the correlation coefficient was low (R² = 0.58). The responses of two genotypes, one containing the opaque ‐ 2 gene, the other its normal counterpart, were similar.

The total N concentration in the leaves collected at the tassel stage did not correlate quite as well with grain yield as those collected later, but using the exponential model NO₃‐N concentrations in the stalks at the earlier stage showed a closer relationship to grain yield than for samples collected at silking. Excluding data for the plants showing S deficiency, a correlation coefficient of 0.90 was obtained. At both tasseling and silking stages, the S deficient plants were characterized by high N:S ratios, with values of 18 to 50 for the stalks, compared to values of less than 10 for the S adequate plants. The marked effect of inadequate S on grain formation was not evident in the amounts of leaves and stalks produced.

Field studies will be necessary to evaluate further the merit of the diagnostic procedure indicated by these experiments.     

Zinc deficiency in winter oilseed rape (Brassica napus L.) is counteracted by N fertilization

Abstract

A two-year experiment was conducted on oilseed rape in 2004–2005 and 2005–2006 in north Iran. Treatments were 0, 50, 100, and 150 kg N ha^?1 as urea (F₀ to F₁₅₀, respectively), 100 kg N ha^?1 as urea +50 kg N ha^?1 as manure (F₁₀₀M₅₀), 50 kg N ha^?1 as urea +100 kg N ha^?1 as manure (F₅₀M₁₀₀), and 150 kg N ha^?1 as manure (M₁₅₀). Results indicated that seed yield in M₁₅₀ was significantly lower than in F₁₅₀ in both years. Seed protein content in the inorganic fertilization system (F₁₅₀) was significantly higher than in the organic (M₁₅₀) and integrated systems (F₁₀₀M₅₀ and F₅₀M₁₀₀). Seed oil content, however, was higher in the organic treatment than in the inorganic treatment. Less N uptake in F₁₀₀M₅₀ compared with F₁₅₀ in the first year and in F₅₀M₁₀₀ compared with F₁₅₀ in the second year did not result in similar differences in grain yield. Owing to the low content of soil-available Zn, the association between Zn and N concentration in shoot in the inorganic treatments was low. In spite of a significant increase in soil-available Zn under the organic and integrated treatments, no significant increase was observed in Zn concentration of shoot in these treatments compared with F₁₅₀. It appears that the excessive availability of P in M₁₅₀, F₅₀M₁₀₀, and F₁₀₀M₅₀ has reduced either Zn uptake or its translocation from root to shoot. Overall, it could be concluded that in order to increase Zn uptake under manure application in a Zn-deficient soil, N availability should increase.     

Nitrous oxide emission,global warming potential,and denitrifier abundances as affected by long-term fertilization on Mollisols of Northeastern China

ABSTRACT

A long-term field experiment was performed to assess the effects of fertilization regimes on greenhouse gas emissions, soil properties, soil denitrifies, and maize (Zea mays) grain yield on Mollisols of Northeastern China. Chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers plus pig manure (MNPK) treatment significantly increased soil N₂O emissions by 29.9–226.4% and global warming potential (GWP) by 29.8–230.7% compared to unfertilized control (CK), chemical N fertilizer only (N), chemical N, P, and K fertilizers (NPK) and chemical N, P, and K fertilizers plus corn straw (SNPK) treatments. However, the MNPK treatment yielded similar greenhouse gas intensity (GHGI) as compared with other treatments, mainly due to higher maize grain yield. There were also higher gene copy numbers of nirK, nirS, and nosZ in topsoil (0–20 cm depth) under MNPK treatment. Automatic linear modeling analysis indicated that main factors influencing soil N₂O emissions were soil organic carbon (SOC), NO₃^? content, and nirK gene abundance. Although the application of chemical fertilizers plus organic manure increases N₂O emissions due to higher N and C availability and nirK gene activity in the soil, this is still a promising fertilizer management due to its notable enhancement of maize grain yield and SOC content.     

Evaluation and utilization of <Emphasis Type="Italic">Aegilops</Emphasis> and wild <Emphasis Type="Italic">Triticum</Emphasis> species for enhancing iron and zinc content in wheat

Grains of 80 accessions of nine species of wild Triticum and Aegilops along with 15 semi-dwarf cultivars of bread and durum wheat grown over 2 years at Indian Institute of Technology, Roorkee, were analyzed for grain iron and zinc content. The bread and durum cultivars had very low content and little variability for both of these micronutrients. The related non-progenitor wild species with S, U and M genomes showed up to 3–4 folds higher iron and zinc content in their grains as compared to bread and durum wheat. For confirmation, two Ae. kotschyi Boiss. accessions were analyzed after ashing and were found to have more than 30% higher grain ash content than the wheat cultivars containing more than 75% higher iron and 60% higher zinc than that of wheat. There were highly significant differences for iron and zinc contents among various cultivars and wild relatives over both the years with very high broad sense heritability. There was a significantly high positive correlation between flag leaf iron and grain iron (r = 0.82) and flag leaf zinc and grain zinc (r = 0.92) content of the selected donors suggesting that the leaf analysis could be used for early selection for high iron and zinc content. ‘Chinese Spring’ (Ph ^I ) was used for inducing homoeologous chromosome pairing between Aegilops and wheat genomes and transferring these useful traits from the wild species to the elite wheat cultivars. A majority of the interspecific hybrids had higher leaf iron and zinc content than their wheat parents and equivalent or higher content than their Aegilops parents suggesting that the parental Aegilops donors possess a more efficient system for uptake and translocation of the micronutrients which could ultimately be utilized for wheat grain biofortification. Partially fertile to sterile BC₁ derivatives with variable chromosomes of Aegilops species had also higher leaf iron and zinc content confirming the possibility of transfer of required variability. Some of the fertile BC₁F₃ and BC₂F₂ derivatives had as high grain ash and grain ash iron and zinc content as that of the donor Aegilops parent. Further work on backcrossing, selfing, selection of fertile derivatives, leaf and grain analyses for iron and zinc for developing biofortified bread and durum wheat cultivars is in progress. Nidhi Rawat, Vijay K. Tiwari, and Neelam Singh have contributed equally to the work.     

Correlation of soil test nitrogen with potato yields

Abstract

Yield response of Idaho Russet Burbank potatoes to nitrogen fertilizer was related to soil test for inorganic N (NO₃ ^‐ and NH₄ ⁺) in a total of 27 field experiments over a 3‐year period using polynomial correlation and regression analysis. Nitrate plus ammonium nitrogen content in the surface foot of soil was found to be useful in predicting yield response of potatoes to applied nitrogen.

Correlations between yield and extractable N were considerably better when the data from each cropping system were analyzed separately than when all locations were analyzed as one group. Additional improvement was obtained by including extractable ammonium nitrogen and nitrogen in the second foot of soil respectively. The best correlation with yield was found using (NO₃ ^‐ + NH₄ ⁺)‐N in the surface foot following grain and the top two feet following non‐grain crops with R² values of 0.875 and 0.821 respectively.     

Diallel Analysis of Wheat Parents and Their F2 Progenies under Medium and Low Level of Available N in Soil

ABSTRACT

Due to high production cost and prevention of environmental pollution, it is important to reduce the amount of nitrogen (N) fertilizer used on wheat (Triticum aestivum L.). The aim of this study was to evaluate N use of 6 × 6 diallel wheat F₂ progenies and parental lines at low (N0, no N fertilizer) and high (N+, 160 kg N ha^{? 1}) N levels. Significant differences were found between N+ and N0 application in grain N content, grain N yield, N use efficiency for grain N yield (NUEgn), and N use efficiency for grain yield (NUEgy). The cultivar ‘84ÇZT04’ showed positive and high general combining ability (GCA) effects for all traits at low N level. Also, it was the best combiner for all traits at both N levels. The cultivar ‘Genç 99’ was the best parent for GCA effects for grain yield and NUEgy. Hybrids ‘Genç 99 × 84ÇZT04’ and ‘84ÇZT04 × Weaver’ showed positive specific combining ability (SCA) effects for all investigated traits at low and high N levels. Variety ‘84ÇZT04 × Apogee’ had the best SCA effects for all traits at low N level. Overall, the data suggest that it is probable to select promising lines suitable for low N conditions by the crossing of high N use efficient parents.     

Ammonia volatilization from ammonium sulphate,ammonium nitrate,and urea surface applied to winter wheat on a calcareous soil

Abstract

Ammonia (NH₃) volatilization losses from surface‐applied ammonium sulphate (AS), ammonium nitrate (AN), and urea to winter wheat and the effects of the NBPT [N‐(n‐butyl) thiophosphoric triamide], PG (Phospho‐gypsum), and PR (byproduct‐Pyrite) were determined in a field experiment. Effects on grain yield and protein content of the grain were also measured. Total NH₃ losses from AS, AN, and urea varied from 13.6–19.5%, 4.4–6.4%, and 3.9–12.0% depending on the compounds and their levels added to nitrogen (N) fertilizers, respectively. The compounds added to AS and AN increased NH₃‐N losses with respect to unamended fertilizers (control). On the other hand, while urea treatments with two tons of PG/ha increased NH₃ losses, the other compounds decreased the losses. The highest reductions of NH₃ loss were observed with NBPT 0.50% and NBPT 0.25% by 63.4% and 52.8%, respectively. Although the effect of nitrogeneous fertilizers on total N losses and protein content of wheat grain was found statistically significant (p<0.01), as the compounds applied with N fertilizers have had no significant effect. Also, a negative and highly significant correlation (r = ‐0.69???) was found between total N loss and protein content of the grain.     

设施土壤盐分的累积、迁移及离子组成变化特征

通过对我国不同地区设施栽培现状的野外调查和取样分析,研究了设施栽培条件下土壤盐分的累积、迁移及离子组成变化特点。结果表明:1)设施栽培条件下,土壤含盐量的变化幅度大,且均明显高于露地土壤,各研究区域内已有40%8～9%的土壤含盐量超过了作物正常生长的临界浓度。2)设施栽培的可持续利用周期较短,连续种植到4年左右的设施土壤,其耕层盐分的累积量可达到作物的生长障碍临界点,之后因设施使用率的下降以及采取的措施而有所降低,但仍高于露地土壤。设施连续使用会导致土壤环境质量的不断恶化。3)设施土壤剖面(0100.cm)盐分含量均高于相邻露地,盐分含量随土层深度增加而降低,其中耕层(020.cm)的盐分含量显著高于其下各层;盐分离子在土壤剖面的运移同时存在着明显的向底层迁移和向表层聚集两种方式,但以表聚为主;此外,盐分离子的大量累积和向底层迁移,特别是NO3-的淋溶已严重影响到部分地区的地下水水质。4)设施栽培后,土壤中的NO3-、SO42-、Cl-、Ca2+、Mg2+、K+、Na+均有不同程度的累积,阴离子以NO3-和SO42-为主,阳离子以Ca2+为主。盐分的大量累积以及某些离子的相对富集在一定程度上引起了作物养分的供需失衡、土壤酸化、棚室内CO2供应不足等生产问题。     

Soil fertility effects with tripartite symbiosis for growth,nodulation and nitrogenase activity of vicia faba L

Fababean (Vicia faba L.) is one of the oldest known important grain legume food crops grown within the temperate and subtropical regions of the world. This species is adapted for both forage and food grain production as a cool season annual crop on a wide range of soil and climatic conditions with effective tripartite symbiosis. Both Rhizobium and endophyte mycorrhiza are essential for high levels of production and symbiotic N₂ fixation. The objective of these greenhouse and field studies was to determine effects of Glomus fasciculatum colonization with soil fertility treatments to a Psammentic Paleustalf (Eufaula series) on growth, nodulation, nitrogenase activity and nodule composition for V. faba, var. Major, fuh Rumi (Nile) inoculated with R. leguminosarum Frank.

Top growth and nodule mass were increased approximately 10 fold and nitrogenase activity about 7 fold with the highly significant effect of mycorrhiza and response to low soluble Ca₃(PO₄)₂ fertilization in greenhouse studies. With both effective mycorrhiza and Rhizobium inoculation in the field experiments, seed yields were correlated with top growth (r = 0.841). Phosphorus and Ca fertilization resulted in highly significant increases in seed yields. Nitrogenase activity was correlated with nodule wt. (r = 0.958) and highly significant increases resulted with P and Ca soil amendment. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. Sodium content decreased significantly with increased K fertilization (r = ‐0.846). Potassium composition increased significantly with P content (r = 0.523). Enhanced N₂‐fixation along with increased high protein forage and food grain production with Fababeans have much potential. However, soil fertility and management techniques for improved production include effective mycor‐rhizal colonization.     

The response of drought-tolerant sugar beet to salinity stress under field and controlled environmental conditions

Abstract

Thirty-four sugar beet drought-tolerant half-sib families were screened in greenhouse experiment under saline (16?dSm^?1) and normal conditions, and a subset of 10 tolerant genotypes were selected for evaluating of yield-related traits, Na⁺, K⁺, and α-amino-N nitrogen contents under saline field condition (12?dSm^?1). Drought-tolerant genotypes showed a different tolerance level under salt stress. Significant correlation was observed between EP2_s and STIEP2 in greenhouse with root yield (RY) in saline field condition. It should be possible that a simple measurement at 16?dSm^?1 in the greenhouse can be used as main part of sugar beet salt-tolerant breeding program. In total, genotypes SBSI-DR I-HSF14-P.23 (# 16) and 436B-HSF9-P.27 (# 26) were recognized as salt- and drought-tolerant genotypes with low Na⁺ and K⁺ contents in root and high white sugar content (WSC) and RY in field. A larger panel of genotypes to validate this kind of association is necessary.     

Effects of urease and nitrification inhibitors on the efficient use of urea for pastoral systems

Abstract

The humic substances contained in an animal organic waste were extracted and the total extract separated into three humic fractions with different molecular weights (low, F₁ <10³; medium, F₂, with molecular weights ranging from 10³ to 10⁴; and high, F₃ >10⁴). The C content was highest in F₂, the same fraction also showing the lowest N content. The molecular weight of the humic fractions influenced the electrical conductivity, the highest molecular weight resulting in the lowest degree of electrical conductivity. Membrane-controlled ultrafiltra-tion (the method used to separate the various fractions from the whole extract) was also suitable for purifying such enzymes as phosphatase and β-glucosidase: the total activity obtained from the three fractions was considerably greater than that determined in the whole extract, Pyrolysis-gas chromatography (Py-GC) applied to the whole extract and humic fractions showed that in the F₃ fraction (highest molecular weight) benzene was the major fragment while furfural was the major fragment of F₁ (lowest molecular weight). For this reason, the humification index benzene/toluene indicates that the fraction with the highest molecular weight was the most humified while the furfural/pyrrole ratio indicates that the fraction with the lowest molecular weight was the most degradable. The whole extract and the fraction F₁ had a negative effect on seed germination when the concentration was equivalent to 100 mg kg^?1 of C, while the germination index was higher than that of the control when only 10 mg kg^?1 were used. The F₂ fraction had a positive effect on germination regardless of the concentration used. When 10 mg kg^?1 of C of the humic substances studied were added to the nutrient solution for growth experiments with maize plants, F₃ led to increases in root weight and F₂ led to increases in shoot weight. An inhibitor effect was observed for fraction F₁.     

Response of photosynthesis and superoxide dismutase to silica applied to creeping bentgrass grown under two fertility levels

Abstract

Responses of photosynthesis, Superoxide dismutase activity, and disease tolerance of creeping bentgrass (Agrostis palustris Huds. A.) to soluble potassium silicate (20.8% SiO₂) treatments was investigated under two fertilization regimes during 1997 and 1998. Potassium silicate was applied twice a month at 603 and 1205 mL 100 m^?2 under high or low fertilization regimes in the field, sampled from which were subjected to low soil moisture in a greenhouse environment. Foliar application of silicate stimulated antioxidant superoxide dismutase (SOD) activity in the bentgarss, especially under the high fertilization regime. Silicate increased photosynthetic capacity (PC) and chlorophyll content when applied at 603 mL 100 m^?2. Dollarspot disease incidence was significantly reduced with silicate treatment regardless of fertilization regime. Silicate did not significantly impact clipping weight. Under low soil moisture (‐0.05 MPa), silicate also enhanced SOD activity, PC, and chlorophyll content as well as root mass of bentgrass. Results suggest silicate may be used to enhance turfgrass drought and disease tolerance of turfgrass.     

河西绿洲区大棚甘蓝产量、品质和养分吸收对不同水肥组合的响应

为探明河西绿洲区塑料大棚甘蓝适宜的水肥管理模式,通过田间小区试验,设定3个施肥量(F_1:N、P_2O_5、K_2O含量为320,160,210kg/hm~2;F_2:N、P_2O_5、K_2O含量为260,120,157.5kg/hm~2,F_3:N、P_2O_5、K_2O含量为200,80,105kg/hm~2)和2个灌水频率(H_1:6d/次,H_2:9d/次),共6个处理,分析甘蓝农艺性状、产量、品质和叶球养分吸收及水肥利用效率对不同施肥量和灌水频率的响应规律。结果表明:H_1处理水平下叶球全氮、磷、钾含量随施肥量增加逐渐升高,H_2处理水平下氮、磷含量随施肥量增加先升高后降低,而钾含量却在随施肥量增加逐渐升高,同一灌水条件下肥料偏生产力随施肥量的减少而升高;同一施肥水平下,叶球中的全氮、磷、钾含量及吸收量高灌水频率大于低灌水频率处理,而肥料偏生产力的变化则相反。水肥耦合作用下,甘蓝叶球纵横径、生物产量和干物质量均H_2F_1处理最高,叶球紧实度、干鲜重比、单球重、经济产量和经济系数均H_2F_2最大,而叶球中心柱长和帮叶比H_2F_3处理最小。灌溉频率和施肥量对甘蓝叶球品质影响显著,且两因素的交互作用达到显著水平,其中硝酸盐含量H_1F_1最高、可溶性糖含量H_2F_1最高、Vc含量H_2F_2处理最大。水肥耦合后全氮和全磷含量及两者吸收量均以H_2F_2最大,全钾及吸收量H_2F_1最高。随着施肥量的增加,水分利用效率也逐渐升高,H_2F_1水分利用效率显著高于其他处理。综合分析表明,水肥耦合对河西绿洲区塑料大棚甘蓝叶球的农艺性状、产量、品质和养分吸收及水分利用率的影响显著,且灌溉频率的影响大于施肥量。H_2F_2处理(灌水频率9d/次,施肥量N、P_2O_5、K_2O为260,120,157.5kg/hm~2)是河西绿洲区塑料大棚甘蓝农艺性状、产量、品质、养分吸收以及水肥利用效率方面最佳的水肥组合模式。     

Late season deficit irrigation for water-saving: selection of rapeseed (Brassica napus) genotypes based on quantitative and qualitative features

ABSTRACT

To select and introduce the best rapeseed genotypes under withholding irrigation, two field experiments were carried out in seasons 2015–2016 and 2016–2017 in Iran. Factorial arrangement of treatments was set up as RCBD with three replications. The experiment factors were two irrigation treatments (normal irrigation during the growing season and withholding irrigation from silique setting stage until the end of the growing season) and 17 genotypes of rapeseed. Grain yield, oil content and fatty acid contents were measured. The results revealed that oleic acid (62.15%) was the highest followed by linoleic (19.28%), linolenic (5.65%), palmitic (5.24%) and stearic acids (2.44%). ODR (oleic desaturation ratio) and LDR (linoleic desaturation ratio) were significantly affected by genotypes and irrigation treatments. The biosynthetic pathway of fatty acids affected by drought stress. This means that linoleic acid increases under withholding irrigation condition, while linolenic acid decreases in such a water deficit stress condition. The highest performance of qualitative and quantitative was detected in HL3721 genotype due to high values of grain yield (3892.45 kg ha^?1), oil content (437.05 g kg^?1), unsaturated fatty acids (87.63%) and low values of saturated fatty acids (7.98%), and it could be used under withholding irrigation in arid and semi-arid climates.     

Response of five tobacco cultivars to sodium phosphate and ammonium polyphosphate

Abstract

Three greenhouse experiments were conducted to compare the response of five tobacco (Nicotiana tabacum L.) cultivars to different levels of NaH₂PO₄ and ammonium polyphosphate (APP) in nutrient media by measuring tissue content of selected nutrient elements (P, Na, K, Ca and Mg). Plants were grown in sand cultures fertilized with nutrient solutions in two experiments and a soil‐sand mix fertilized with solid materials in a third experiment. Plant P and Na content increased as the concentrations of these elements increased in nutrient solution. Plant K content was not generally affected by treatments. Magnesium was reduced in flue‐cured and cigar‐filler tobaccos but was not changed in cigar‐wrapper and Turkish types by increasing amounts of NaH₂PO₄. All of the cultivars responded similarly to NaH₂PO₄ with respect to plant Ca. High levels of P in the nutrient media were consistently related to low levels of Ca in plant tissue.     

Iron requirement for soybean [Glycine max (L.) Merrill] inoculated with selected exotic and native isolates of Bradyrhizobium sp. under irrigated conditions

A field and greenhouse experiments were conducted to determine the requirement of Fe nutrient supplied through foliar and soil application in soybean inoculated with different selected isolates of exotic and native Bradyrhizobium spp. in saline soils. Six soybean genotypes and three Bradyrhizobium spp. were used for the greenhouse experiments, whereas only two soybean genotypes, namely TGx-1336424 and GIZA, were selected for further study under field conditions. Two levels of FeSO₄ (0 and 4 mg Fe kg^?1 soil) directly supplied to the soil and three levels of Fe-ethylenediaminetetraacetic acid (0–2% of Fe) through foliar application were used for greenhouse and field experiments, respectively. The results of the greenhouse experiment indicated a non-significant effect of Fe application on nodulation and shoot biomass in soybean. Fe application did not improve the grain yield and total biomass yield in soybean inoculated with UK isolate and local isolate but showed remarkable improvement with TAL-379. High soil native N might be the cause for insignificant effect of Fe applied at 2% in highly effective inoculated plants. Therefore, it can be concluded that the symbiotic effectiveness of Bradyrhizobium sp. and the native soil N would affect the soybean Fe requirement supplied through foliar application.