Modelling nitrogen fixation of pea ( Pisum sativum L.)

Abstract

Nitrogen fixation was simulated for a leafless variety (Delta) of pea (Pisum sativum L.) in central Sweden. It is assumed that N₂ fixation is basically proportional to root biomass, but limited by high root N or low substrate carbon concentrations. Input data on root carbon and nitrogen were estimated from observations of above-ground biomass and nitrogen. The simulated N₂ fixation was compared with estimated values from observations using the ¹⁵N labelling technique. Test data were taken from pea monocultures and pea-oat mixtures with varying pea biomass levels during 1999. Simulated within-season accumulated N₂ fixation correlated to the estimated N₂ fixation with a correlation coefficient (R ²) of 0.74. For seasonal simulations, the predictability was higher (R ²=0.93). Two alternative non-dynamic models, estimating seasonal N₂ fixation as proportional to above-ground biomass and above-ground N, respectively, gave lower predictability (R ²=0.83 and 0.80, respectively). The models were also applied to a second year (1998) and two other sites by comparison with accumulated N₂ fixation estimated by the Difference method. A halved specific N₂ fixation rate (expressed per unit of root biomass) in 1999, compared with 1998, corresponded to essentially dryer and warmer soil conditions during 1999. It was indicated that the variations in soil moisture were more important than soil temperature. It was concluded that the abiotic responses might be of great importance for modelling N₂ fixation rate under different soil conditions.     

Nitrate alters the flavonoid profile and nodulation in pea (Pisum sativum L.)

A rhizosphere application of NO _inf3 ^sup- and/or naringenin affected the Pisum sativum — Rhizobium leguminosarum biovar viciae symbiosis. NO _inf3 ^sup- (5 mM) lowered while naringenin raised the nodulation status (nodule numbers and weight) and nodule efficiency (C₂H₂ reduction activity). However, the inhibitory effect of NO _inf3 ^sup- was to some extent alleviated when applied in combination with naringenin. The plant biomass was increased by the application of NO _inf3 ^sup- and naringenin, either alone or in combination, while a higher root: shoot ratio was observed only in the naringenin-treated plants. Root flavonoids are known to regulate the expression of nod genes; their high-performance liquid chromatography profile was influenced in different ways by NO _inf3 ^sup- and naringenin.     

Yield structure components of autumn- and spring-sown pea (Pisum sativum L.)

ABSTRACT

Climate change brings increasing attention to winter sowing of traditionally spring sown crops. Crop stand height, soil coverage, grain yield and yield components of six winter pea varieties and one spring pea variety were compared in eastern Austrian growing conditions in 2014 and 2015. Crop stands of winter pea were taller up to the end of May before they declined and crop stands of spring pea were taller from early June on. Winter pea covered the soil at least partly over winter and showed faster soil coverage in spring. At the end of May, just some weeks before harvest, spring pea attained equal soil coverage. Grain yield of winter pea was almost double that of spring pea due to higher pod density whereas spring pea produced more grains pod^?1 than four out of six winter pea varieties and a higher thousand grain weight than all winter pea varieties. Consequently, grain density was higher for winter pea while the single pod yield was higher for spring pea. Growing winter peas in Central Europe might be a good strategy for increasing grain legume productivity and thereby European feed protein production.     

Carbon costs of nitrate reduction in broad bean (Vicia faba L.) and pea (Pisum sativum L.) plants

The present study aimed at the assessment of carbon (C) costs for nitrate reduction by measuring the additional CO₂ amounts released from roots of nitrate‐fed plants in comparison with urea‐fed plants. Only roots were suitable for these determinations, because nitrate reduction in illuminated shoots is fed nearly exclusively by reducing equivalents coming directly from photosynthetic processes. Therefore, in a first experiment, the sites of nitrate reduction were determined in nodule‐free broad bean (Vicia faba L.) and pea (Pisum sativum L.) plants grown in pots filled with quartz sand and supplied with KNO₃. The extent of nitrate reduction in the various plant organs was determined by measuring in vitro nitrate reductase activity and in situ ¹⁵NO reduction. Only between 9% and 16% of nitrate were reduced in roots of German pea cultivars, whilst 52% to 65% were reduced in broad bean roots. Therefore, C costs of the process could be determined only in broad bean, using an additional pot experiment. The C costs amounted to about 4.76 mol C (mol N)^–1 or 4 mg C (mg N)^–1, similar to those measured earlier for N₂ fixation. The high proportion of nitrate reduction in shoots of pea plants implies that only very little C is required for this nitrate fraction. This can explain the better root growth of nitrate‐nourished pea plants in comparison with N₂‐fixing organisms, which need C compounds for N₂ reduction in roots. Moreover, a different availability of photosynthates in roots of plant genotypes could explain physiologically the occurrence of “shoot and root reducers” in nature.     

Influence of maturation on the alteration of allergenicity of green pea (Pisum sativum L.)

The IgE-binding capacity of different maturation levels of green pea seeds (Pisum sativum L.) of the variety Maxigolt is examined to determine the influence of maturation on the alteration of allergenicity. Different protein extraction methods to get total protein extracts and the protein fractions glutelin, globulin, and albumin from different maturation levels of green pea seeds are applied to SDS-PAGE/silver staining as well as SDS-PAGE/immunoblotting and EAST inhibition experiments using sera of 15 green pea allergic individuals. The SDS-PAGE/silver-staining experiments show the continuous change of protein pattern during maturation. SDS-PAGE/immunoblot and EAST inhibition demonstrate that all levels of green pea seeds show relevant IgE-binding capacity, as do immature seeds. Total IgE-binding capacity rises with the progress of maturation. Although the main allergenic activity is dependent upon the albumin fraction, the glutelin and globulin fractions are also important. The implication of these results is an obvious allergenic potency of all maturation levels, even immature seeds, whereas an increase of allergenicity during maturation could be notched up. The highest allergenic potency is caused by the albumin fraction, but globulin and glutelin fractions also contribute to the allergenicity of green pea.     

Identification and Characterization of Slow Rusting Components in Pea (Pisum sativum L.)

Three hundred and forty five accessions of pea of diverse origin, height, leaf types and disease reaction were screened for rust disease severity and area under disease progress curve (AUDPC). The frequency of slow rusting types in the tall, dwarf, early and late groups appeared comparable. Of the 345 accessions, forty-four genotypes were evaluated for disease intensity, which was converted into AUDPC, number of pustules/leaf and pustule size. Wide range of variation was found for these traits. The slow rusting attribute of 16 genotypes was further confirmed by testing these under unprotected (inoculated) and protected (fungicidal spray) conditions for two successive years for disease intensity by assessing the AUDPC, seed yield/plot, and 100-seed weight. The fast rusting genotypes exhibited lower AUDPC, accompanied with increased seed yield and seed weight when grown under the protected condition, as compared to those raised under the unprotected condition. The genotypes Pant P 11, FC 1, HUDP 16, JPBB 3 and HUP 14 appeared as slow rusting genotypes.     

Ancestry and characterization of U.S. contemporary proprietary garden pea (Pisum sativum L. convar. medullare Alef.) germplasm

A major objective of this work is to elucidate the ancestry and genetic background of contemporary U.S. garden pea (Pisum sativum L. convar. medullare Alef.) cultivars used as cultivated vegetables. This is facilitated through pedigree analysis of 147 cultivars registered during the era from 1990 through 2010 by collecting data from U.S. Plant Variety Protection, U.S. utility patent, and journal publication. Proprietary breeding programs developed 141 cultivars and public programs six, with over half (82 of 147 cultivars) originating from the two (Seminis Vegetable Seeds, Inc. and Syngenta Seeds, Inc.) largest proprietary breeding programs. During this era, the semi-leafless (afila) trait was bred into cultivars to decrease lodging, and 43 % of the cultivars were afila. Registered cultivars were 86 % of determinate growth habit. Bi-parental breeding crosses were used in the development of 78 % of these cultivars. The lineages of the cultivars ‘Bolero’, ‘Spring’, ‘Genie’, and ‘Rally’ made large contributions to the genetic composition of this germplasm, ‘Bolero’ contributed 6.5 % (29 progeny), ‘Spring’ 6.4 % (29), ‘Genie’ 4.0 % (18), and ‘Rally’ 3.6 % (23) of the genes. The garden pea ancestor cultivar ‘Perfection’ fostered the most descendants (75) among the 147 cultivars of this era.     

Change in particle size of pectin reacted with pectinesterase isozymes from pea (Pisum sativum L.) sprout

Four pectinesterase (PE) isozymes were isolated by CM-Sepharose CL-6B chromatography from etiolated pea (Pisum sativum L.) sprouts and then reacted with citrus pectin (degree of esterification = 68%, 30-100 kDa) to observe the change in pectin particle size using a laser particle size analyzer. After incubation of a pectin-PE mixture (pH 6.5) at 30 degrees C for 4 h, PE 1 was observed to catalyze the transacylation reaction most remarkably, increasing the particle size from approximately 50-70 to approximately 250-350 nm, followed by PE 3, PE 2, and PE 4.     

HPLC determination of chlorophyll and carotenoid pigments in processed green pea cultivars (Pisum sativum L.)

Chlorophyll and carotenoid pigments from six cultivars of processed green peas (Avola, Tristar, Rampart, Turon, Bella, and Greenshaft) were extracted with 100% acetone and analyzed by reversed-phase HPLC. A total of 17 pigments were identified in the pea cultivars including 8 xanthophylls ((all-E)-neoxanthin, (9'Z)-neoxanthin, (all-E)-violaxanthin, neochrome, (all-E)-lutein epoxide, (all-E)-lutein, neolutein B, neolutein A), 4 chlorophyll b related compounds (chlorophyll b derivative, chlorophyll b, chlorophyll b', and pheophytin b), 4 chlorophyll a related compounds (chlorophyll a derivative, chlorophyll a, chlorophyll a', and pheophytin a), and (all-E)-beta-carotene. The efficiency of different extraction procedures using 100% acetone showed that initial extraction followed by three reextractions without holding time between gave a higher extraction yield than no reextraction and 30 or 60 min holding time. All six cultivars contained the same pigments, but the concentration of each pigment varied significantly. On average of the two years, the chlorophyll a concentration varied from 4800 to 7300 microg/100 g fresh weight, the chlorophyll b concentration from 2100 to 2800 microg/100 g fresh weight, the (all-E)-lutein concentration from 1200 to 1900 microg/100 g fresh weight, and the (all-E)-beta-carotene concentration from 300 to 490 microg/100 g fresh weight in the processed pea cultivars. These differences in pigment concentration between the investigated cultivars are discussed in relation to maturity, product color and nutritional quality.     

Effects of grinding and thermal treatments on hydrolysis susceptibility of pea proteins (Pisum sativum L.)

The effects of three particle sizes with two types of grindings and two thermal treatments on pea protein extraction (PE) and susceptibility to in vitro enzymatic hydrolysis (pepsin plus trypsin) were studied. Degrees of hydrolysis (DH) were calculated. Remaining peptides were detected by SDS-PAGE and identified by immunoblotting and MS/MS spectrometry. The increase in particle size decreased PE and DH due to a restricted access of solvents and enzymes to proteins. The thermal treatment induced a decrease in PE but did not modify DH. Heating improved legumin (alphaM) and convicilin pepsin hydrolyses but reduced the pea albumin 2 (PA2) hydrolysis. After pepsin and trypsin hydrolysis, only peptides from vicilin and lectin were identified by LC-MS/MS analyses, whatever the treatment.     

Yield potential of garden pea (Pisum sativum L.) varieties,and soil properties under organic and integrated nutrient management systems

The identification of suitable crop varieties that respond best to organic management is the key to achieving better crop yields. A field experiment was conducted during the winter season of 2005–2006 and 2006–2007 at Almora (Indian Himalayas) to evaluate the performance of five varieties of garden pea (Pisum sativum L.) and changes in the soil properties under organic and integrated nutrient management (INM) systems. The yield reduction under organic management was 14.4% in 2005–2006 and 10.1% in 2006–2007 compared with INM. Among the garden pea varieties ‘Vivek Matar 9’, ‘Vivek Matar 8’ and ‘Azad pea 1’ produced similar but significantly higher pod yield compared to other varieties. The soil pH, organic carbon, and microbial activities in terms of dehydrogenase and phosphatase (acid and alkaline) were higher in the plots under organic management compared to INM. The latter, however, had higher activity of urease, and N, P, and K contents in soil. We conclude that at least 15–20% price premium for organic garden pea may be required to offset the higher cost of cultivation and low yields under organic production system. Among the garden pea varieties, ‘Azad pea 1’, ‘Vivek Matar 8’ and ‘Vivek Matar 9’ were found suitable for organic cultivation.     

N-utilization by maize (Zea mays L.) as influenced by crop rotation and field pea (Pisum sativum L.) residue management

Abstract. A five year field experiment was conducted to assess the influence of crop rotation and field pea residue incorporation into the soil on maize yield. The data indicated a 30% increase in maize yield grown in rotation with field pea compared to when it was grown after wheat and a further increase of 35% when field pea residues were incorporated into the soil. The effect of field pea and residue incorporation was greater in the presence of fertilizer nitrogen indicating the enhanced capacity of the crop to utilize N from the residue. Legume residue management in sub-tropical regions of the world, having coarse textured soils low in organic matter, could help to increase the yield of cereals besides saving some of the expensive fertilizer input.     

Nutritional evaluation of pea (Pisum sativum L.) protein diets after mild hydrothermal treatment and with and without added phytase

The effect of mild hydrothermal treatment and the addition of phytase under optimal conditions (pH 5.5, 37 degrees C) on the nutritive utilization of the protein of pea (Pisum sativum L.) flour was studied in growing rats by examining the chemical and biological balance. Mild hydrothermal treatment produced reductions of 83, 78, and 72%, respectively, in the levels of alpha-galactosides, phytic acid, and trypsin inhibitors and also produced a significant increase in the digestive utilization of protein. The additional fall in the levels of phytic acid caused by the addition of phytase did not lead to a subsequent improvement in the digestive utilization of protein. The mild hydrothermal treatment of pea flour produced a significant increase in the metabolic utilization of protein and carbohydrates, which was reflected in the protein efficiency ratio and food transformation growth indices. These effects were not observed in the phytase-supplemented pea diet.     

Influence of soil humic substances and herbicides on the growth of pea (Pisum sativum L.) in nutrient solution 1

No morphological and length modifications of the root and shoot systems are apparent in pea (Pisum sativum L.) plants of three varieties grown in the presence of 100 mg/L humic acid or fulvic acid or 20 mg/L linuron [3‐(3,4‐dichlorophenyl)‐l‐methoxy‐l‐methylurea] or ametryne [2‐ethylamino‐4‐iso‐propylamino‐6‐methylthio‐1,3,5‐triazine]. A combination of humic substance and herbicide at these concentrations produces in all pea varieties a differentiated and marked reduction in root length and large morphological alterations of roots. Statistical analysis of data show that differentiated and highly significant or significant effects are produced on the shoot and root dry weight by either the humic substance or herbicide alone, and by any combination of two or three factors considered (variety, humic substance, herbicide).     

Bioavailability and Rhizotoxicity of Cd to Pea (Pisum sativum L.)

Risk assessment of cadmium (Cd) contamination in soils requires identifying the bioavailable portion of the total Cd, a portion that is determined by environmental conditions such as pH and calcium (Ca) level in soils and by the physiological processes going on in the plant roots. Growth tests in solutions were conducted to develop a terrestrial biotic ligand model to describe uptake and rhizotoxicity of Cd to pea (Pisum sativum L. cv. Lincoln). Inhibition concentration associated with a 50% reduction in root elongation (IC₅₀) values were found to vary with external Ca²⁺ and H⁺ activities. Root-bound Ca was found to reach a plateau of about 63 µmol g^?1 (dry weight) although Ca treatment increased from 0.04 to 2 mmol L^?1. When experimental treatments (e.g., pH 6, Ca 0.2 to 2 mM) resulted in sufficient Ca supply, dose–response curves relating root elongation to root-bound Cd could be modeled with Weibull equations; IC₅₀ values were expressed in terms of root-bound Cd concentration. When the treatments (e.g., pH 4 or 5, Ca 0.04 mM) suggested a low Ca supply, root elongation was more sensitive to Ca content and root-bound Ca concentration became the dominant predictor variable. Cd accumulation was modeled by treating the pea roots as an assemblage of biotic ligands with known site densities (Q _Lj ) and proton binding constants (K _HLj ). The logK _Ca and logK _Cd values were established using measured root-bound ion concentrations and solution chemistry. The logK _Ca values were negatively correlated to root Ca contents. The logK _Cd values were positively correlated to logK _Ca values. Explanations for the changing of constants are discussed.     

Effect of soil treatment with cereal straw and method of crop establishment on field pea (Pisum sativum L.) N2 fixation

The effects of soil incorporation with cereal straw (nil, 2.5, 5 and 10 t straw ha^?1) and direct drilling on the proportion and amount of pea N derived from biological N fixation were investigated in three field experiments. Fixed N was determined by¹⁵N dilution using barley as a reference plant. The three sites were on acidic, red clay-loams in the cropping zone of southeastern Australia. Seasonal plant available soil N, as determined by the N accumulated in barley, was 31, 56 and 158 kg N ha^?1, for the three sites. Incorporated straw reduced soil nitrate at sowing by 10–50 kg N ha^?1 (0–30 cm), and 5 or 10 t straw ha^?1 reduced barley uptake of N by 10–38 kg N ha^?1. However, reducing plant available soil N was generally ineffective for increasing the N fixed by pea. Fixed N increased only at the site with the least plant-available N, and only one-third of the increase could be attributed to lower soil N uptake by pea. There was no evidence that direct drilling pea increased fixed N by decreasing crop uptake of soil N. It is proposed that a lower requirement for soil N by pea as compared to barley, and availability of mineral N beneath the soil layer treated with straw, minimise the effectiveness of straw incorporation for increasing the N fixed by pea.     

Response of Rhizobium leguminosarum isolates to different forms of inorganic nitrogen during nodule development in pea (Pisum sativum L.)

Combined nitrogen inhibits nodule development and nitrogen fixation in Rhizobium -legume symbioses. Isolates of R. leguminosarum which had been shown to vary in symbiotic effectiveness in the presence of NN₄NO₃ were used as inoculum for peas grown with NH₄NO₃ KNO₃ or NH₄Cl and harvested between 14 and 24 days after planting. Plants grown in 2mm NH₄NO₃ showed inhibition of nodule development and function 17 days after seeding but there were no significant differences (SDs) between isolates of high and low effectiveness. In the presence of 5 mM NH₄NO₃ nodule development and C₂H₂ reduction were severely inhibited from 14 days onwards. Plants inoculated with isolates of high effectiveness had more tap-root nodules, higher C₂H₂ reduction rates and higher leghemoglobin content than those inoculated with isolates of low effectiveness. In plants grown with 5 mm KNO₃ or 5 mm NN₄Cl, NO₃⁻ had the major inhibitory effect on nodulation and nodule development, but NH₄⁺ began to show inhibitory effects on nodule development after 17 days. There were no SDs between isolates of low and high effectiveness at these concentrations of NO₃⁻ and NH₄⁺. Differences in symbiotic response of R. leguminosarum to combined nitrogen are small and appear during nodule development rather than at nodule initiation.     

Nutritional assessment in vitro and in vivo of raw and extruded peas (Pisum sativum L.)

The effects of extrusion cooking on the nutritional properties of Pisum sativum L. have been evaluated in vitro and in vivo. The treatment greatly elevated protein and starch digestibility in vitro. Also, the amounts of intact starch diminished while total free sugars increased. In addition, the levels of antinutritional factors, such as protease inhibitors and lectins, were greatly decreased. Concentrations of methionine and cystine were low in raw peas and were further reduced by extrusion treatment. The nutritional performance of rats fed extruded pea diets for 15 days was no better than that of rats given raw pea diet. This was due to the overriding effects of amino acid deficiencies in the diets. Weight gains by rats fed extruded pea diets supplemented with amino acids were, however, much higher than those achieved by rats fed supplemented raw pea diets. Food transformation index and protein efficiency ratio values were also greatly improved. Extrusion treatment did therefore significantly improve the nutritional quality of peas.