Relative Total Yield Research Articles

Neutral interactions between native Alternanthera sessilis and exotic Alternanthera philoxeroides along a light gradient under tropical climatic conditions

AbstractRiparian ecosystems are under a serious threat of invasion due to the clearance of riparian vegetation, which allows for increased light levels at ground level. This study presents the interactions between native Alternanthera sessilis (L.) R. Br. ex DC and invasive Alternanthera philoxeroides (Mart.) Griseb. during the colonization stage along a light gradient under tropical climate conditions. We conducted a 6 week growth experiment with monocultures of A. philoxeroides and A.sessilis and mixed communities of two species under four light levels (100%, 46%, 26% and 14% of full sunlight). Exposure to full sunlight (nearly 1800 μmol m−2 s−1) resulted in a significantly high biomass accrual in both species. However, biomass accrual did not correlate with the light intensity. At higher shade levels, reduction of lateral spread and shoot/root ratio was observed. Community composition had no influence on biomass accrual or morphological variations. Plasticity index values were approximately same in both species. Total relative yield was approximately two in all shade conditions, indicating that the two species interact neutrally along the light gradient. Therefore, the results of the study indicate that increased light levels will accelerate the proliferation of both species in riparian zones. Nevertheless, increased or decreased shade is unlikely to alter neutral interactions between A. philoxeroides and A. sessilis.

Combination of Lolium perenne L. and Festuca arundinacea Schreb. improve yields under low phosphorus availability

AbstractPhosphorus (P) is one of the main nutrients for all plants, including grasses. However, sources of P fertilizer are not renewable, are not evenly distributed and overfertilization can lead to serious environmental degradation. Smart combinations of grasses may be able to more efficiently take up P from soils through complementarity. In a two-year field mesocosm experiment, we compared the performance of Lolium perenne L. and Festuca arundinacea Schreb. in monocultures and in combination, as well as a mixture of both species with a tetraploid variety of Lolium perenne L and Phleum pratense L. Plants were grown in an unfertilized low P soil and in P fertilized soil for two growing seasons. We measured biomass production, root traits, nutrient uptake, microbial biomass and enzymatic activities. In the unfertilized plots the combination of Lolium perenne and Festuca arundinacea generated the highest cumulative yields (25,951 ± 4059 kg ha−1), relative total yield (> 1) and P nutrition index (0.79). We related this to the complementarity found in root traits and lower intraspecific competition of Festuca arundinacea and Lolium perenne diploid. Festuca arundinacea produced higher root biomass than Lolium perenne diploid at deeper soil layers (98 vs. 44 g m−2; p < 0.05). On the other hand, Lolium perenne diploid had significantly finer roots than Festuca arundinacea both at topsoil and bottom layers (0.19 vs. 0.22 mm and 0.19 vs. 0.23 mm at top and bottom layers respectively). The 4 species combination did not result in higher yields. Our results show that, in low P soils, combinations of grass species with contrasting root traits could lead to significantly higher yields than monocultures.

Intercropping on Mars: A promising system to optimise fresh food production in future martian colonies.

Future colonists on Mars will need to produce fresh food locally to acquire key nutrients lost in food dehydration, the primary technique for sending food to space. In this study we aimed to test the viability and prospect of applying an intercropping system as a method for soil-based food production in Martian colonies. This novel approach to Martian agriculture adds valuable insight into how we can optimise resource use and enhance colony self-sustainability, since Martian colonies will operate under very limited space, energy, and Earth supplies. A likely early Martian agricultural setting was simulated using small pots, a controlled greenhouse environment, and species compliant with space mission requirements. Pea (Pisum sativum), carrot (Daucus carota) and tomato (Solanum lycopersicum) were grown in three soil types ("MMS-1" Mars regolith simulant, potting soil and sand), planted either mixed (intercropping) or separate (monocropping). Rhizobia bacteria (Rhizobium leguminosarum) were added as the pea symbiont for Nitrogen-fixing. Plant performance was measured as above-ground biomass (g), yield (g), harvest index (%), and Nitrogen/Phosphorus/Potassium content in yield (g/kg). The overall intercropping system performance was calculated as total relative yield (RYT). Intercropping had clear effects on plant performance in Mars regolith, being beneficial for tomato but mostly detrimental for pea and carrot, ultimately giving an overall yield disadvantage compared to monocropping (RYT = 0.93). This effect likely resulted from the observed absence of Rhizobia nodulation in Mars regolith, negating Nitrogen-fixation and preventing intercropped plants from leveraging their complementarity. Adverse regolith conditions-high pH, elevated compactness and nutrient deficiencies-presumably restricted Rhizobia survival/nodulation. In sand, where more favourable soil conditions promoted effective nodulation, intercropping significantly outperformed monocropping (RYT = 1.32). Given this, we suggest that with simple regolith improvements, enhancing conditions for nodulation, intercropping shows promise as a method for optimising food production in Martian colonies. Specific regolith ameliorations are proposed for future research.

Catalytic upgrading of bio-oil from halophyte seeds into transportation fuels

Because of socioeconomic considerations, wide-scale production of biofuel necessitates the utilization of nonedible biomass feedstock that does not compete for land and fresh water resources. In this regard, Salicornia bigelovii (SB) is the most investigated halophyte species. The high oil content in SB seeds has sparked mounting research that aims to utilize SB as an industrial crop in the production of bio-oil, particularly in coastal areas where these plants thrive. However, the oil extracted from the pyrolysis of raw SB seeds is largely dominated by oxygenated fatty acids, most notably 9,12-octadecadienoic acid and 9,17-octadecadienal, typical to that of other crops. The pyrolysate bio-oil of the raw SB seeds exhibited a relative yield of oxygenated compounds that decreased from 57.05 % at 200 °C to 9.81 % at 500 °C, and the relative yield of nitrogenated compounds increased from 4.86 % at 200 °C to 21.97 % at 500 °C. To improve the quality of the produced bio-oil, herein we investigated the catalytic hydrodeoxygenation (HDO) of the fragments that were produced from the thermal degradation of SB seeds. A 5 %Ni–CeO2 catalyst was prepared and characterized by a wide array of methods X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, scanning electron microscope, Brunauer-Emmett-Teller analysis, and thermogravimetric analyzer. The catalytic run was executed between 200 and 500 °C in a flow reactor. The deployed catalytic methodology displayed a profound HDO capacity. At 400 °C, for instance, the gas chromatography mass spectroscopy (GC–MS) detected loads of paraffin and aromatic compounds exists at appreciable values of 48.0 % and 28.5 %, respectively. With a total relative yield of 43.2 % (at 400 °C), C8–C15 species (i.e., jet fuel fractions) were the most abundant species in the upgraded SB bio-oil. The release of H2, CO, CO2, and CH4 was analyzed qualitatively and quantitatively using gas chromatography thermal conductivity detector and Fourier infrared spectroscopic analysis. When the Ni–CeO2 catalyst was utilized, a complete deoxygenated bio-oil was obtained from SB seeds using the surface-assisted HDO reaction. On the basis of the elemental analysis, the biochar's hydrogen and oxygen contents were found to decrease significantly. Density functional theory computations showed mechanisms for reactions that underpinned the experimentally observed hydrodeoxygenation process. Outcomes presented herein shall be instrumental toward the effective utilization of halophyte in the production of commercial transportation fuels.

Land Optimization With Sweet Corn (Zea mays saccharata, Sturt) and Eggplant (Solanum melongena L.) Overlapping Systems in Nagari Gadut, Tilatang Kamang District

Research conducted experiment using a completely randomized design with 6 treatments that is the time of planting eggplant as secondary crops to the cultivation of sweet corn (M) consisting of: M1 = planting at same time; M2 = time of planting eggplant 1 week after planting sweet corn; M3 = time of planting eggplant 2 weeks after planting sweet corn; M4 = time of planting eggplant 3 weeks after planting sweet corn; M5 = single planting sweet corn planting time = M1. M6 = single eggplant planting time = M1. The results planting showed that eggplant can be planted together with sweet corn planting time, up to three weeks after planting sweet corn. Results of sweet corn is not influenced by the timing of planting different eggplant. The M3 and M4 treatments resulted in relatively more profitable production based on the total relative yield (RYT) and land equivalent ratio (LER).

EFECTO DE UN BIOESTIMULANTE EN EL RENDIMIENTO DE FORRAJE DE TRITICALE (x Triticosecale) EN SIEMBRA ESCALONADA ASOCIADA CON HABA (Vicia faba)

<p><strong>Background.</strong> The associations of poaceae and fabaceae forage species are important to provide cattle with a balanced diet between proteins and carbohydrates; also to contribute to the sustainable management of soils. <strong>Objective</strong>. The objective of the research was to determine the effect of the natural biostimulant on the triticale forage components during staggered sowing associated with faba bean. <strong>Methodology</strong>. The research was carried out under a randomized complete block experimental design with three repetitions. The genetic material was a line of semi-late triticale and a local variety of faba bean. Applications of a biostimulant were made in two phenological of the triticale stages forage during the staggered sowing (0, 20 and 40 days after sowing the bean). The variables evaluated were percentage increase of foliar N in triticale, biomass in triticale and broad bean, green forage yield of triticale and faba bean, presence of <em>Rhizobium</em> nodules in faba bean and interspecific competition indices of the associated system. <strong>Implications</strong>. The establishment of a triticale-faba bean association requires certain planting arrangements, varieties and nutrition to avoid the effects of competition, which cause the dominance or displacement of any of the species. <strong>Conclusions</strong>. The application of biostimulant in triticale in the tillering stage 20 days after sowing the bean, the highest yield of triticale forage was found, allowing the increase in the concentration of foliar nitrogen (1.8%) and rhizobial nodules per plant (175.83) of broad bean; higher biomass (6.49 t ha<sup>-1</sup>) in triticale and higher amount of total forage (39.02 t ha<sup>-1</sup>). The competition indices indicate that the bean cultivation in association favors the total relative yield without showing aggressive behavior between crops (A = 0); triticale and faba bean share their competitive capacity (CR>1) according to staggered plantings with and without biostimulant in a certain phenological state of triticale.</p>

Effects of Pigeon Pea (<i>Cajanus cajan</i>) Intercropping on Sorghum Crop Production and Soil Fertility Level in Case of Harari Regional State (Erer Research on Station)

The study was conducted during 2019 main cropping season at Erer research station Babile district PA. Globally pigeon pea (<i>Cajanus cajan</i> (L.) Millsp.) is the fifth most important pulse crop mainly grown in the developing countries by resource-poor farmers in drought prone areas and on degraded soils. It is a multipurpose leguminous crop that can provide food, forage, fuel wood and fodder for the small-scale farmer in subsistence agriculture. Pigeon pea is a deep-rooted and drought tolerant grain legume that adds substantial amount of organic matter to the soil and has the ability to fix up to 235 kg N/ha). Harari regional state, farmers didn’t accept drought tolerant sorghum variety, because of small harvests of total biomass. Thus why, pigeon pea sorghum intercropping can solve the problem of low availability of forage and low soil fertility in this low land area. The treatments of the experiments were, Sole sorghum (malkam) variety, Sorghum + Accession 16520, Sorghum + Accession 16527, sorghum +Accession 16528, pigeon pea Accession 16520, Pigeon pea Accession 16527 and Accession 16528 respectively. The design of the experiment was, RCBD with three replication. The result showed significant difference statistically, in terms of plant height, panicle length, and panicle diameter at 5% (table 1). The highest plant height was obtained from the treatment with sorghum intercropped with pigeon pea accession 16527 (tsegas variety). The result that obtained was statistically not significant in terms of grain yield (p < 0.01) among treatments (both sole and intercropped one). In (Table 1) was indicated that intercropping of pigeon pea Accessions had no negative significant effect on grain yields of sorghum. The maximum grain yields were obtained from T3 (sorghumX16527 pigeon pea accession); (2894) kg ha^-1), followed by T2 (16527 pigeon pea accession) (2856) kg ha^-1 respectively. The minimum grain yield obtained from sole sorghum (2339 kg ha^-1). The most probable reason for this variation could be due to leguminous nature of pigeon pea accessions that add nitrogen nutrients to the soil and affect sorghum positively. When observed graphically, there is mean yield difference. Both land equivalent ratio and relative total yield was calculated and the obtained result is about 1.22. So this intercropped experiment is advantageous. Partial budget analysis was conducted and the experiment is economically viable.

Estimating the impact of ground ozone concentrations on crop yields across China from 2014 to 2018: A multi-model comparison

Ground level ozone exerts a strong impact on crop yields, yet how to properly quantify ozone induced yield losses in China remains challenging. To this end, we employed a series of O3-crop models to estimate ozone induced yield losses in China from 2014 to 2018. The outputs from all models suggested that the total Relative Yield Losses (RYL) of wheat in China from 2014 to 2018 was 18.4%–49.3% and the total RYL of rice was 6.2%–52.9%. Consequently, the total Crop Production Losses (CPL) of wheat and rice could reach 63.9–130.4 and 28.3–35.4 million tons, and the corresponding Total Economic Losses (TEL) could reach 20.5–44.7 and 11.0–15.3 billion dollars, stressing the great importance and urgency of national ozone management. Meanwhile, the estimation outputs highlighted the large variations between different regional O3-crop models when applying to large scales.Instead of applying one unified O3-crop models to all regions across China, we also explored the strategy of employing specific O3-crop models in corresponding (and neighboring) regions to estimate ozone induced yield loss in China. The comparison of two strategies suggested that the mean value from multiple models may still present an inconsistent over/underestimation trend for different crops. Therefore, it is a preferable strategy to employ corresponding O3-crop models in different regions for estimating the national crop losses caused by ozone pollution. However, the severe lack of regional O3-crop models in most regions across China makes a robust estimation of national yield losses highly challenging. Given the large variations between O3-crop interactions across regions, a systematic framework with massive regional O3-crop models should be properly designed and implemented.

Phosphorus in Spring Barley and Italian Rye-Grass Biomass as an Effect of Inter-Species Interactions under Water Deficit

With global warming, the problem of soil water deficit is growing in Central Europe, including Poland, and the use of catch crops is recommended to mitigate climate changes. This study aimed to determine the influence of water deficit on phosphorus (P) content and accumulation in the above-ground biomass of spring barley and Italian rye-grass growing separately and in the mixture, and on the inter-species interactions between these crops. The study was based on a pot experiment established in accordance with the additive design. The experimental factors were as follows: A. water supply of the plants: an optimal dose and a dose reduced by 50% in relation to the optimal dose, and B. the sowing type: barley sown as a single species, rye-grass sown as a single species, and barley with rye-grass catch crop. Based on the P accumulation in plant biomass, the relative yield of barley and rye-grass, the total relative yield, and the competitive equilibrium index were determined. Water deficit had no effect on the P content in the plants, but it reduced the P accumulation in barley stems, leaves and spikes, as well as in rye-grass stems and leaves, from the emergence to the end of plants’ growing period, both when the plants were sown as a single species and as a mixture. Barley was a stronger competitor than rye-grass. Inter-species competition occurred at the stem elongation and heading of barley. The intensification of inter-species competition for P under water deficit conditions should be taken into account when recommending the undersowing of barley with rye-grass for sustainable agriculture.

ONION PLANT GROWTH AND YIELD AS AFFECTED BY NITROGEN, POTASSIUM AND SULPHUR COMBINATIONS UNDER EL-ARISH REGION CONDITIONS

A field experiment was carried out at The Experimental Farm of Fac. Environ. Agric. Sci., Arish University, North Sinai, Egypt, during the winter seasons of 2014-2015 and 2015-2016 to study the effect of different combinations among nitrogen, potassium and sulphur levels on growth, yield, and pungency of onion (Allium cepa L.) cv. White Sweet Spanish compared to control (recommended doses of N, K and S). The results indicated that application of 150% N+ 75% K2O+ 200% S of recommended dose was the best treatment wherein increased fresh weight of leaves, bulbs and total fresh weight as well as the dry weight of the same previous parameters and photosynthetic pigments in the 1st season. Concerning yield and its components, application of 150% N+ 75% K2O+200% S was the best treatment for increasing the total yield and its components compared to the recommendation treatment and the other treatments. The previous treatment recorded increases of total relative yield by 131.42% and 115.77% in 1stand 2nd seasons, respectively compared to control treatment (recommended dose); increment in marketable yield by 130.95% and 112.08% in 1st and 2nd seasons, respectively; increase in relative yield of both 1st and 2nd grades which increased by 131.04% , 115.22% for the 1st grade in both seasons, respectively, and by 127.89 and 111.77% for the sum of 1st + 2nd grades in the 1st and 2nd seasons, respectively, while application of 150% N+ 75%K2O + 100% S recorded the lowest value of bulb pungency.

Productivity, relative yield and plant growth of forage corn intercroppedwith soybean under different crop combination ratio

An experiment was carried out to evaluate influence of different crop combination ratios of corn and soybean in terms of forage yield in corn-soybean intercropping. The experiment compared both corn and soybean as monocultures and in different intercropping ratios from 25:75, 50:50 and 75:25 of corn to soybean. The crop combination ratio had significant effects on physiological traits and dry matter yield of forage. The ratio of 75:25 and 50:50 recorded DM yields similar to those of monocropped corn (14.77 t/ha). Relative yield total (RYT) values of intercropping were higher than that of monocrop corn and soybean. Mixtures with 50:50 combination ratio had higher mean total relative yield values (1.15) in comparison with the other ratios. Land equivalent ratio (LER) increased with corn-soybean intercropping and the highest total LER value was recorded with 50:50 ratio (1.13). The crop ratio of 50:50 gave the best combination based on DM yield, relative yield, LER of the combined forage.

The Effect of Variable Seed Rate Proportions on Agronomic Attributes, Dry Matter Production, Biological Potential and Economic Viability of Some Grass-Legume Mixed Pastures

An experiment was conducted to assess the agronomic attributes, dry matter (DM) yield, biological potential and economic viability of grass-legume mixtures at Haramaya University in Ethiopia during 2004 and 2005. Chloris gayana, Panicum coloratum, Melilotus alba and Medicago sativa were planted as pure stand and in mixtures using 50:50, 33: 67, 67: 33, 25: 75 and 75: 25 seed rate proportion to give 24 treatments in a randomised complete block design with 3 replications. There were significant (P < 0.05) differences in the number of seedlings per m2 (SLM), row cover, number of tillers per m2, days to 50% flowering (DF 50%) of the grass components among the grass/legume combinations due to seed rate proportions. Moreover, SLM, the number of branches per m2, the height of the plant at harvest, DF 50% of the legume components were significantly (P < 0.05) affected among the mixtures due to seed rate proportions. There was a significant (P < 0.05) difference in the DM yield of pure stand grasses and legumes, and their mixtures due to seed rate proportion. Significant (P < 0.05) effects were also observed on the relative yield (RY), the relative total yield (RTY), the relative crowding coefficient (RCC) and the aggressivity index of both the grass and legume components and their mixtures due to different seed rate proportions throughout the study. The two years\' mean RTY of all grass-legume mixtures were greater than one (range: 1.23-2.11) and Chloris mixed with Melilotus and Medicago with 67: 33 seed rate proportion had higher RTY than other mixtures. Both the grass and legume components in the mixture produced mean RCCs values in excess of unity and almost equal values in both components, indicating that all yielded better in the mixture than expected in pure stands at different seed rates. Chloris gayana mixed with Melilotus alba at 50:50 and 33:67 seed rate proportion gave higher DM yield, average net return/ha and average net return/ha/yr compared to pure stand grasses and legumes and their different mixtures during the study. Therefore, to alleviate the feed scarcity in the area; these grass-legume mixtures could be introduced to smallholder farms. In addition, further studies on animal performances should be conducted using feeding trials and under grazing conditions. Keywords: Agronomic Attributes; Biological Potential; Dry Matter Yield; Economic Viability; Grass/Legume Mixture; Seed Rate Proportion East African Journal of Sciences Vol. 2 (2) 2008: pp. 95-104

Kajian Defoliasi Sorgum Pada Tumpangsari Dengan Kacang Hijau

Study on Defoliation of Sorghum under Cropping Pattern by Mungbean . The aim of the research was to find out the effect of defoliation of sorghum under cropping pattern toward the yield of sorghum, Mungbean and total relative result of the best sorghum and Mungbean in intercropping system has been carried out in Kebun Percobaan Fakultas Pertanian Universitas Gadjah Mada in Banguntapan, Bantul Regency from February up to June 2006. The research method used was split plot design with 2 factors and 3 repetitions. The main factor was defoliation of sorghum comprising of 2 levels: sorghum defoliation (D 1 ) and without sorghum defoliation (D 2 ). The sub factor of sub was cropping pattern, comprising of 5 levels: monoculture of Mungbean (H 100 ). 75% sorghum: 25% Mungbean (S 75 H 25 ), 50% sorghum: 50% Mungbean (S 50 H 50 ), 25% sorghum: 75% Mungbean (S 25 H 75 ) and monoculture sorghum (S 100 ). The results of the study showed that 1) the defoliation sorghum did not affect the yield of mungbean and sorghum, 2) cropping pattern of mungbean monoculture resulted bean/plant amount, seed/plant weight and seed weight/ha of mungbean as higher compared to other cropping pattern, 3) cropping pattern of 25% sorghum: 75% mungbean resulted seed weight/malai sorghum was higher compared to other planting patterns and the highest seed weight/ hectare was resulted in sorghum monoculture planting pattern, 4) the highest total relative yield was 1,303 given planting pattern at 50% sorghum: 50% mungbean and 5) the form of the relation between sorghum and mungbean in intercropping pattern and sorghum defoliation was complementary, while intercropping and without sorghum defoliation was supplementary. Keywords: defoliation, intercropping, result of mungbean and sorghum, total relative yield

Forage yield and quality of common vetch mixtures with oat and triticale in two seeding ratios

Mixtures of annual forage legumes with winter cereals for forage production are used extensively in the Mediterranean region. Common vetch ( Vicia sativa L.), oat ( Avena sativa L.), and triticale (× Triticosecale Wittmack) monocultures as well as mixtures of common vetch with each of the above cereals, in two seeding ratios (55:45 and 65:35), were used to investigate forage yield and quality as well as the effect of intercropping on growth rate of the three species used in the mixtures. Oat and triticale monocultures as well as both common vetch–oat mixtures provided greater forage yield than mixtures of common vetch with triticale and monoculture common vetch. Total relative yield exceeded unity in common vetch–oat (65:35) indicating that at this seeding rate there was an advantage of intercropping in using the environmental resources. Growth rate of common vetch, oat, and triticale in mixtures was lower than that in monocultures. Crude protein content was highest in monoculture common vetch followed by common vetch–oat (65:35). However, quality characteristics such as lignin content, neutral detergent fiber, total digestible nutrients and to a much smaller degree the acid detergent fiber, digestible dry matter, dry matter intake and relative feed value were affected by intercropping. Highest forage quality was achieved when common vetch was grown as a monoculture or when at a high proportion in mixtures, especially with oat. The results showed that mixture of common vetch with oat at the 65:35 seeding ratio achieved a higher forage yield and protein content than the other mixtures studied.

Dissociative electron attachment in uracil: Total anion yield

The total relative yield of anions produced by electron impact on uracil has been measured at energies below ionization. Peaks associated with vibrational Feshbach, shape and core-excited resonances are observed, although the relative sizes differ from those measured using mass analysis. Observation of positive ionization in uracil permits normalization to the ionization cross section. Feil et al. [J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 3013] have used the semi-classical Deutsch–Märk ionization cross section for this purpose. Using the D–M cross section for normalization, we find that the cross section for production of (U–H) − is substantially smaller than their mass selected result.

Dairy pasture responses to soil physical properties

Relationships between relative seasonal pasture yields (total, spring, or summer/autumn) and soil physical properties were investigated. Dairy farm data were collected from trials over 7 years. There were few significant response relationships between total relative yield and each soil physical property at each soil depth, from 0 to 20 cm. Macroporosity (air-filled porosity; pores &gt;30 μm), percentage of pores &gt;300 μm, and total porosity at both 0–5 and 5–10 cm soil depths all had highly significant positive relationships with spring relative yield, with the best fit being for macroporosity. Summer/autumn relative yield had significant but negative relationships with macroporosity and the percentage of pores &gt;300 μm at both 0–5 and 5–10 cm soil depths, and saturated hydraulic conductivity at 0–5 cm. Summation of yield data into seasonal totals gave more meaningful relationships with macroporosity, compared with summation over several individual yield harvests within a season. Macroporosity at 0–5 and 5–10 cm was the most useful indicator for predicting spring and summer/autumn pasture yields, but none of the physical measurements was a reliable indicator of total yield.

Thin target 7Li(p, p'g)7Li inelastic gamma-ray yield measurements

Thin target angular distributions of inelastic gamma-ray yields resulting from 7Li(p, p'g)7Li interaction have been measured for incident proton energies between 1.0 and 1.8 MeV. McMaster 3 MV KN Van de Graaff accelerator facility primarily dedicated to in-vivo neutron activation measurements has been used to perform experiments using a thin lithium metal target and 7.62 cm × 7.62 cm, 12.7 cm × 12.7 cm NaI(Tl) scintillation detectors and HPGe detectors. The uncertainty in the relative yield determination is based on the statistics of the data, uncertainty in the 478 keV peak area determination due to other interfering reactions, and the uncertainty in the recording of the proton charge. The results for the angular distribution provide an evidence for anisotropic nature of the radiation as compared to the presumed isotropic nature. The total relative yield was determined from the angular distributions and then compared with the published total cross sections for the reaction. Thick target yields calculated from thin target yields were also found to be in good agreement with other studies.

Formation of Strecker aldehydes and pyrazines in a fried potato model system.

Sugars and amino acids were removed from potato slices by soaking in water and ethanol. They were then infused with various combinations of sugars (glucose and/or fructose) and amino acids (asparagine, glutamine, leucine, isoleucine, phenylalanine, and/or methionine) and fried. Volatile compounds were trapped onto Tenax prior to gas chromatography-mass spectrometry. Relative amounts of compounds (relative to the internal standard) and relative yields (per mole of amino acid infused into the slices) were determined. Amounts of 10 pyrazines, 4 Strecker aldehydes, and 4 other compounds were monitored. Relative amounts and relative yields of compounds varied according to the composition of the system. For the single amino acid-glucose systems, leucine gave the highest relative amount and relative yield of its Strecker aldehyde. Asparagine and phenylalanine gave the highest total relative amount and total relative yield, respectively, of pyrazines. In the system containing all of the amino acids and glucose, the relative amount of 3-methylbutanal was higher, whereas the amounts of the other monitored Strecker aldehydes were lower. Most of the relative amounts of individual pyrazines were lower compared to the glucose-asparagine system, whereas the total relative yield of pyrazines was lower, compared to all of the single amino acid-glucose mixtures. Addition of fructose to the mixed amino acid-glucose model system generated Strecker aldehydes and pyrazines in ratios that were more similar to those of untreated potato chips than to those from the same system but without fructose. Both the sugars and the amino acids present in potato are crucial to the development of flavor compounds in fried potato slices.

EFFECT OF COOKING METHOD ON THE AROMA CONSTITUENTS OF SWEET POTATOES [IPOMOEA BATATAS (L.) LAM.

ABSTRACTTo better understand the factors controlling the flavor of horticultural products, the effect of method of cooking on the volatile flavor of sweet potatoes was assessed. Volatile extracts from sweet potatoes cooked by baking, boiling, and microwaving were studied by GC, GC‐MS and GC olfactory assessment. GC‐olfactory analysis identified 37 compounds that were odor‐active, 36 of which were identified. Compared with conventional baking, boiling and microwaving yielded only 54.26% and 6.43% of the relative total yield of aroma‐active compounds, respectively. From aroma extract dilution analysis, four compounds contributed to the aroma from each cooking method. In addition, cooking method specific aroma contributing compounds accounted for the unique aroma of each of the cooked products. Thus the flavor of cooked sweet potatoes is dependent upon the method of cooking both on a sensory and chemical level.

Collision induced intersystem crossing in methylene on reactive surfaces: application of a new technique to CH2(a 1A1) + H2

The ratio, β, of the rate of collision induced intersystem crossing (CIISC) to the total rate of removal, has been determined for CH2(a1A1) + H2. 1CH2 was generated from ketene by laser flash photolysis at 308 nm. 3CH2, formed directly by photolysis or by CIISC with either He or H2, was probed by LIF on conversion to OH by reaction with NO. The total relative yields of 3CH2 were determined from an analysis of the time dependence of pairs of OH time profiles, obtained in the presence and absence of H2, at a total pressure of 10 Torr, with a helium buffer gas and at 295 K. The hydrogen pressure was varied over the range 0–1.2 Torr. Corrections were made to the profiles for differential quenching of the OH LIF signals. A value of β = 0.10−0.04+0.10 was obtained from a global analysis of the data and from analysis of pairs of profiles.