Moisture-dependent physical properties of jatropha seed (Jatropha curcas L.)

The study was conducted to investigate some moisture-dependent physical properties of jatropha seed namely, seed dimension, 1000 seed mass, surface area, sphericity, bulk density, true density, angle of repose and static coefficient of friction against different materials. The physical properties of jatropha seed were evaluated as a function of moisture content in the range of 4.75–19.57% d.w. The average length, width, thickness and 1000 seed mass were 18.65 mm, 11.34 mm, 8.91 mm and 741.1 g, respectively at moisture content of 4.75% d.w. The geometric mean diameter and sphericity increased from 12.32 to 12.89 mm and 0.66 to 0.67 as moisture content increased from 4.75 to 19.57% d.w., respectively. In the same moisture range, densities of the rewetted jatropha seed decreased from 492 to 419 kg m⁻³, true density increased from 679 to 767 kg m⁻³, and the corresponding porosity increased from 27.54 to 45.37%. As the moisture content increased from 4.75 to 19.57% d.w., the angle of repose and surface area were found to increase from 28.15° to 39.95° and 476.78 to 521.99 mm², respectively. The static coefficient of friction of jatropha seed increased linearly against the surfaces of three structural materials, namely plywood (44.12%), mild steel sheet (64.15%) and aluminum (68.63%) as the moisture content increased from 4.75 to 19.57% d.w.     

Moisture-dependent physical properties of niger (Guizotia abyssinica Cass.) seed

Moisture-dependent physical properties of niger (Guizotia abyssinica Cass.) seed were studied at 5.60, 12.99, 19.77, 27.08 and 31.65% moisture content (wet basis). The length, width, thickness and geometric mean diameter increased significantly (p < 0.05) from 3.86 to 4.06 mm, 0.96 to 1.02 mm, 0.86 to 0.96 mm and 1.47 to 1.59 mm, respectively with increase in moisture content from 5.60 to 31.65% whereas the increase in sphericity from 38.10 to 39.01% was not significant. Similarly, thousand seed mass, porosity and angle of repose increased (p < 0.05) linearly from 2.50 to 3.69 g, 41.76 to 47.65% and 29.86° to 39.12°, respectively with increase in moisture content under the experimental condition. The bulk density decreased significantly (p < 0.05) from 635.23 to 561.06 kg m^?3 with increase in the moisture content range considered in the study, whereas the true density showed a slight increase from 1090.71 to 1098.42 kg m^?3 with increase in moisture content from 5.60 to 27.08% followed by a drop from 1098.42 to 1071.75 kg m^?3 as moisture content increased from 27.08 to 31.65%. Coefficient of static friction increased (p < 0.05) logarithmically from 0.34 to 0.51, 0.38 to 0.56 and 0.13 to 0.53 on mild steel, plywood and glass surfaces, respectively with increase in moisture content from 5.60 to 31.65%.     

Evapotranspiration,yield, and water-use efficiency responses of Lesquerella fendleri at different growth stages

Lesquerella fendleri (Gray) Wats. is a potential new oilseed crop for the arid southwestern United States. Lesquerella seed oil with similar properties as castor oil is being considered as a domestic replacement for the imported castor oil. Development of new crops with low irrigation needs is of high priority. Because the most critical stage of sensitivity to moisture deficits has not been determined in Lesquerella species, the objectives of this study were: (i) to identify the most critical stage or stages for moisture deficit and, (ii) to determine the effect of moisture deficit on yield, yield components, oil and fatty acid composition. Two-year field studies were conducted at the New Mexico State University, Leyendecker Plant Science Research Center. The experimental design was a randomized complete block. The treatments consisted of (a) T1: Continuous favorable soil moisture [irrigated at 50% soil water depletion (SWD)]. (b) T2: Moisture stress (75% SWD) from establishment to initial flowering with no stress from flowering to final harvest (50% SWD). (c) T3: No stress imposed from establishment to initial flowering (50% SWD) followed by stress to final harvest (75% SWD). (d) T4: Moisture stress (75% SWD) from establishment to final harvest. The amount of water applied ranged from 810 to 729 mm for the first year, and 810 to 625 mm for the second year. Seed weight per plant and number of pods per plant were generally higher when water availability was maintained at or above 50% SWD throughout the growing season. Neither seed number per pod nor seed size was influenced by irrigation treatments. Lesquerella was more sensitive to water availability during flowering and seed development as a greater loss in seed yield occurred when irrigation was delayed to 75% SWD during that stage of development. Seed yield and dry matter production from the 2 year field studies were closely related to the seasonal cumulative evapotranspiration. For each millimeter of evapotranspiration, seed yield increased from 1.8 kg ha⁻¹ mm in 1994–1995 to 1.3 kg ha⁻¹ mm for 1995–1996. The dry matter production increased 13.4 kg ha⁻¹ for each mm increase in seasonal evapotranspiration during 1994–1995. This relationship was a second order polynomial with an R² of 0.86 during 1995–1996. The WUE_gr and WUE_dm were highest under the most favorable water availability conditions for growth and seed development. Delaying irrigation to 75% SWD throughout the crop growth period resulted in the lowest oil content. Lesquerolic acid content was not affected by irrigation during both the growing seasons.     

Effects of clear plastic film mulch on yield of spring wheat

This paper explores the possibility of improving yields of spring wheat (Triticum aestivum) by using plastic film mulching. Field experiments compared three mulching treatments viz. for 20 d (M1), 40 d (M2), and 60 d (M3) after sowing (DAS), with a non-mulch control (CK). Mulching increased temperature and moisture in the upper 5 cm of soil, and shoots emerged 8 d earlier than in CK. Mulching also increased number of tillers, length of the growing period, spikelet and grain numbers per spike, and the duration from flowering to harvest. In the mulched treatments, photosynthesis rate and soluble sugar content were higher in the vegetative period, but soluble sugar content was lower in the grain filling period relative to CK. Grain yield following 20 d mulching was greatest (8207 kg ha⁻¹), and decreased gradually as the mulching period increased (7847 and 6702 kg ha⁻¹ for M2 and M3, respectively). Plastic film removed after 20 d maximizes yield and minimizes soil pollution.     

Moisture-dependent physical properties of Karanja (Pongamia pinnata) kernel

The moisture-dependent physical properties are important to design post harvest equipments of the product. The physical properties of Karanja kernel were evaluated as a function of moisture content in the range of 8.56–22.22% d.b. The average length, width, thickness and 1000 kernel mass were 25.29 mm, 15.58 mm, 7.88 mm and 1036.45 g, respectively, at moisture content of 8.56% d.b. The geometric mean diameter and sphericity increased from 14.55 to 15.97 mm and 0.57 to 0.6 as moisture content increased from 8.56 to 22.22% d.b., respectively. In the same moisture range, the bulk density decreased from 663 to 616 kg/m³, whereas the corresponding true density and porosity increased from 967 to 1081 kg/m³ and 31.44 to 43.02%, respectively. As the moisture content increased from 8.56 to 22.22% d.b., the angle of repose and surface areas were found to increase from 27.69 to 37.33° and 665.74 to 801.63 mm², respectively. The static coefficient of friction of Karanja kernel increased linearly against the surfaces of three structural materials, namely plywood (28.72%), mild steel sheet (29.88%) and aluminium (18.86%) as the moisture content increased from 8.56 to 22.22% d.b.     

Moisture migration in a cereal composite food at high water activity: Effects of initial porosity and fat content

Water sorption isotherms and effective moisture diffusivities were determined at 20 °C for sponge cakes at high water activity as a function of their initial porosity, in the range 86 and 52% (0 g/g dry basis fat content), and of their fat content, ranging between 0 and 0.30 g/g dry basis (67% initial porosity). The equilibrium moisture values were not affected by food structure and decreased with increasing fat content. The effective moisture diffusivity decreased from 7.5 to 0.3×10⁻¹⁰ m²/s with increasing moisture content from 0.30 to 2.20 g/g dry basis. Decreasing initial porosity from 86 to 52% decreased effective moisture diffusivity by more than four orders of magnitude. This behaviour was related to differences of water transfer mechanisms, with the contribution from liquid water diffusion in the solid matrix and from vapour water diffusion in pores. Increasing fat content of 0.30 g/g dry basis in sponge cake, independently of porosity, decreased effective moisture diffusivity by more than five orders of magnitude. A predictive mathematical model was used to simulate moisture intake in two-composite food systems: sponge cakes with varying initial porosities and fat contents and an agar gel as a model of a non-rate limiting water source. Increasing the density of the structure or addition of fat in the cereal-based phase could increase shelf life of composite foods.     

Seed physiological maturity in Cuphea

Cuphea (Cuphea viscosissima Jacq. × C. lanceolata f. silenoides W.T. Aiton, line PSR23) is a new crop being developed in the North Central United States, as an industrial oilseed crop. Cuphea PSR23 seed oil is rich in medium-chain-length fatty acids such as capric acid used to manufacture soaps and detergents. The objective of this research was to determine the time when physiological maturity of cuphea seed is reached and how seed development affects seed moisture, weight, oil content, fatty acid content, germination, and seedling vigor. To evaluate seed development, 2000 cuphea flowers were tagged at anthesis in the field at Prosper, North Dakota in 2004 and 2005. Each flower was tagged when open and the position on the main stem or branch was recorded. Two hundred capsules from the tagged flowers were harvested at 3- to 4-d intervals from 5- to 48-d post anthesis (DPA). Seed weight increased as a function of growing degree days (GDD) and the days from anthesis. Physiological maturity occurred when maximum dry seed weight was attained. Seed weight increases followed the Gompertz function with a R² = 0.90 (2004) and R² = 0.95 (2005). All capsules, regardless of their position on the stem, followed the same growth function for seed weight. The maximum dry seed weight estimated by the Gompertz function was 3.61 for 2004 and 3.58 mg seed⁻¹ for 2005. Physiological maturity estimated with a quadratic function occurred at 38 DPA or 270 GDD in 2004. In 2005, physiological maturity occurred at 26 DPA or 265 GDD. As a visual indicator when the capsules split-open seeds inside that capsule are physiologically mature. Seed moisture decreased from 900 g kg⁻¹ at 37 GDD post anthesis to 450 g kg⁻¹ at 319 GDD post anthesis in 2004; however, in 2005 seed moisture decreased from 850 to 81 g kg⁻¹ at 293 GDD post anthesis. Seed germination increased as seed developed and it was 83% when harvested 234 GDD post anthesis. Oil content increased from 98 g kg⁻¹ at 37 GDD post anthesis to 279 g kg⁻¹ 319 GDD post anthesis. Fatty acid composition varied throughout seed development. Seed development for 111 GDD and greater had more than 66% of capric acid (10:0). Cuphea should be harvested after 265 GDD post anthesis when most capsules on the main stem are split-open, have attained maximum seed weight, germination, seedling vigor, and oil content.     

Soybean–chickpea rotation on Vertic Inceptisols II. Long-term simulation of water balance and crop yields

In rainfed agriculture, climatic variability has profound effects on the performance of management systems in improvements of productivity and use of natural resources. A field study was conducted on a Vertic Inceptisol during 1995–1997 seasons at the ICRISAT Center, Patancheru, India, to study the effect of two landforms, i.e., broadbed-and-furrow (BBF) and flat, and two soil depths (shallow and medium-deep) on crop yield and water balance of a soybean–chickpea rotation. Using two seasons experimental data, a soybean–chickpea sequencing model was evaluated and used to extrapolate the results over 22 years of historical weather records. The simulation results showed that in 70% of years total runoff for BBF was greater than 35 mm (range 35–190 mm) compared to greater than 60 mm (range 60–260 mm) for flat on the shallow soil. In contrast on the medium-deep soil it was greater than 70 mm (range 70–280 mm) for BBF compared to greater than 80 mm (range 80–320 mm) for the flat landform. The decrease in runoff on BBF resulted in a concomitant increase in deep drainage for both soils. In 70% of years, deep drainage was greater than 60 mm (range 60–390 mm) for the shallow soil and ranged from 10 to 280 mm for the medium-deep soil. In 70% of years, the simulated soybean yields were greater than 2200 kg ha⁻¹ (range 2200–3000 kg ha⁻¹) and were not influenced by landform or soil depth. In the low rainfall years, yields were marginally higher for the BBF than for the flat landform, especially on the shallow soil. Simulated chickpea yields were higher for the medium-deep soil than for the shallow soil. In most years, marginally higher chickpea yields were simulated for the BBF than for the flat landform on both soil types. In 70% of years, the chickpea yields were greater than 500 kg ha⁻¹ (range 500–1500 kg ha⁻¹) for the shallow soil, and greater than 800 kg ha⁻¹ (range 800–1960 kg ha⁻¹) for the medium-deep soil. Total productivity of soybean–chickpea rotation was greater than 3000 kg ha⁻¹ (range 3000–4150 kg ha⁻¹) for the shallow soil and greater than 3450 kg ha⁻¹ (range 3450–4700 kg ha⁻¹) for the medium-deep soil in 70% of years. These results showed that in most years BBF, landform increased rainfall infiltration into the soil and had marginal effect on yields of soybean and chickpea. Crop yields on Vertic Inceptisols can be further increased and sustained by adopting appropriate rain water management practices for exploiting surface runoff and deep drainage water as supplemental irrigation to crops in a watershed setting.     

Characterization of hairs and pappi from Cynara cardunculus capitula and their suitability for paper production

The capitula of Cynara cardunculus contain hairs and pappi representing 7% of the total plant biomass. These low density biomass components could be mechanically separated without apparent losses using a whole-plant processing prototype. Hairs and pappi are filamentous structures made up of longitudinally aligned fibre cells, without intercellular voids or pitting, with the following dimensions regarding length, width and wall thickness: 1.35 mm, 19.8, and 4.8 μm for hairs and 1.78 mm, 10.4, and 2.9 μm for pappi. Chemically hairs and pappi have low content of ash (1.9% and 1.1%, respectively), extractives (5.4% and 6.0%) and lignin (10.6% and 17.8%), and high content of holocellulose (77.5% and 72.8%) and α-cellulose (55.2% and 46.8%).Pulps could be produced using a conventional kraft process with high yields and low residual lignin, e.g. 63% at Kappa 7 for hairs and 48% at Kappa 11 for pappi, low coarseness values (0.04 and 0.03 mg m^?1) and adequate pulp properties for paper (40 and 42 N mg^?1 tensile index; 3.6 and 3.4 kPa m² g^?1 burst index in unrefined pulps of hairs and pappi, respectively). The results also indicated that there is scope for improving pulp quality by optimising pulping conditions to this type of new raw materials. The differences between hairs and pappi may also be further exploited namely the lower lignin content of hairs and the higher slenderness and wall thickness of pappi fibres.The utilization of hairs and pappi may strengthen the differentiated use of biomass fractions of the Cynara plant and its potential as a bioenergy crop.     

Effect of SWD irrigation on photosynthesis and grain yield of rice (Oryza sativa L.)

A study was conducted with the objective to determine the influence of (shallow water depth with wetting and drying) SWD on leaf photosynthesis of rice plants under field conditions. Experiments using SWD and traditional irrigations (TRI) were carried out at three transplanting densities, namely D1 (7.5 plants/m²), D2 (13.5 plants/m²) and D3 (19.5 plants/m²) with or without the addition of organic manure (0 and 15 t/ha). A significant increase in leaf net photosynthetic rate by SWD was observed with portable photosynthesis systems in two independent experiments. At both flowering and 20 DAF stages, photosynthetic rate was increased by 14.8% and 33.2% with D2 compared to control. SWD significantly increased specific leaf weight by 17.0% and 11.8% over the control at flowering and 20 DAF stages, respectively. LAI of D2 under SWD was significantly increased by 57.4% at 20 DAF. In addition, SWD with D2 significantly increased the leaf dry weight (DW) at both growing stages. At all the three densities, SWD increased the leaf N content and the increase was 18.9% at D2 density compared with the conventional control. In SWD irrigation, the leaf net photosynthetic rate was positively correlated with the leaf N content (R² = 0.9413), and the stomatal conductance was also positively correlated with leaf N content (R² = 0.7359). SWD enhanced sink size by increasing both panicle number and spikelet number per panicle. The increase in spikelet number per panicle was more pronounced in the 15 t ha⁻¹ manure treatment than in the zero-manure treatment. Grain yield was also significantly increased by SWD, with an average increase of 10% across all treatments. SWD with D2 had the highest grain yield under the both cultivars with or without 15 t ha⁻¹ manure treatment, which was 14.7% or 13.9% increase for Liangyoupeijiu and 11.3% or 11.2% for Zhongyou 6 over the control, respectively.     

Fiber yield and quality of fiber nettle (Urtica dioica L.) cultivated in Italy

To evaluate the production potential of fiber nettle crops in Tuscany (Italy), a German clone of fiber nettle was cultivated during 2006–2007.Although a longer experimentation is essential, the two first years of trials showed that the German clone used also seems to give good results in term of growth and fiber yield in an environment like central Italy, with higher temperatures and generally lower rainfall. Indeed the stalk mean dry matter obtained was about 15.4 Mg ha^?1 with a mean fiber content of about 11% of stalk dry matter, and the resulting fiber yield was 1696 kg ha^?1, comparable to or higher than those reported in the literature.The differences in chemical, physical and mechanical characteristics of fibers extracted from different portions of stalks seemed to indicate an intrinsic heterogeneity of the fibers along the stem. Fiber mean diameter values ranged from 47 to 19 μm and fiber length from 43 to 58 mm moving from stalk bottom to top. Tensile strength of the bottom part of the stalk was much lower than that of the other parts, with mean values of about 24 and 60 cN tex^?1, respectively. More constant mean values along the stalk were found for the elongation parameter (2.3–2.6%). Lignin content decreased moving toward the stalk top from about 4.4% to 3.5%.These physical–mechanical characteristics confirmed the potential of the fibers of nettle cultivated in Tuscany to be used for textile purposes. Indeed they were similar to hemp fibers in diameter, lignin content and elongation, and similar to flax or cotton in tensile strength.     

Comparison on the total phenol contents and the color of fresh and infrared dried olive leaves

The color (L*, a*, b* parameters), the total phenols content and the global chemical composition (moisture, protein, fat, carbohydrates and ash) of four fresh varieties of olive leaves (Chemlali, Chemchali, Zarrazi and Chetoui) were determined. Fresh olive leaves are characterized by a green color (greenness parameter, a*, varying from ?5.01 ± 0.26 to ?9.14 ± 1.21), an intermediate moisture content (0.85 to 1.00 g/g dry matter, i.e. 46 to 50 g/100 g fresh matter) and a variable amount of total phenols according to the olive leaf variety (from ≈2.32 to ≈1.40 g caffeic acid/100 g dry matter).Fresh leaves were submitted to blanching and/or infrared drying at 40, 50, 60 and 70 °C in order to be stabilized by reducing their moisture contents. The impact of IR drying temperature on some quality attributes (color, total phenols and moisture rate removal) was evaluated. Nevertheless, the effect of prior blanching treatment on the quality attributes of dried leaves is less significant and it depends on the olive leaf variety. The infrared drying induces a considerable moisture removal from the fresh leaves (more than 85%) and short drying durations (varying from ≈162 at 40 °C to 15 min at 70 °C). IR drying temperature showed a significant effect of on total phenols content and the color of the leaves whatever the leaf variety. In fact, total phenols content of dried olive leaves increased if compared to fresh ones. For example, total phenols of Chemlali leaves increased from 1.38 ± 0.02 (fresh leaves) to 2.13 ± 0.29 (dried at 40 °C) and to 5.14 ± 0.60 g caffeic acid/100 g dry matter (dried at 70 °C). IR drying allows preserving the greenness color of fresh leaves and enhancing their luminosity. It could be suggested for preserving olives leaves before their use in food or cosmetic applications.     

Genotypic increases in coleoptile length improves stand establishment,vigour and grain yield of deep-sown wheat

Timely sowing is critical for achieving high grain yields in winter cereals. However, inadequate seed-zone moisture for germination commonly delays sowing to reduce biomass and subsequent yield in semi-arid environments. Sowing deep to reach soil moisture is often avoided by growers of Rht-B1b and Rht-D1b semi-dwarf wheat as these wheat show poor emergence when sown deep. Their reduced cell elongation associated with insensitivity to endogenous gibberellins, results in shorter coleoptiles and smaller early leaf area. Alternative dwarfing genes responsive to endogenous gibberellins (e.g. Rht8) are available for use in wheat breeding. These reduce plant height without affecting coleoptile length and offer potential to select longer coleoptile wheat for deep sowing. Nine semidwarf (Rht8, Rht-B1b, and Rht-D1b) and seven tall (rht) wheat genotypes were sown at depths of 50, 80 and 110 mm at three locations in 2 or 3 years. Coleoptile lengths measured in a growth cabinet at four temperatures (11, 15, 19 and 23 °C) were strongly correlated with coleoptile length (r_p = 0.77–0.79^**) and plant number (r_p = 0.49^*–0.79^**) in deep-sown plots in the field. Furthermore, differences in coleoptile length were genetically correlated with greater numbers of emerged seedlings (r_g = 0.97^**), shallower crown depth (−0.58^**), greater seedling leaf area (0.59^**) and seedling biomass (0.44^*). Wheat containing the Rht-B1b or Rht-D1b dwarfing genes produced significantly (P < 0.01) shorter coleoptiles (97 mm) than both Rht8 (118 mm) and tall (117 mm) wheat. In turn, compared with emergence from 50 mm depth, the Rht-B1b and Rht-D1b wheat produced significantly fewer seedlings at 110 mm sowing depth (−62%) than either Rht8 (−41%) or tall (−37%) wheat. Effects of deep sowing early in the season were maintained with reductions in spike number and biomass at both anthesis and maturity. Kernel number was also reduced with deep sowing leading to reductions in grain yield. Over all entries, genotypic increases in plant number were associated with increases in fertile spike (r_g = 0.61^**) and kernel number (0.21^*), total biomass (0.26^*) and grain yield (0.28^*). Reduction in spike number and grain yield with deep sowing was smallest for the Rht8 (−18 and −10%) and rht (−15 and −7%) wheat, and largest for the Rht-B1b/D1b (−39 and −16%) wheat. Plant height and coleoptile length were independent among Rht8 and tall wheat genotypes. This study demonstrates the importance of good seedling emergence in achieving high wheat yields, and the potential use of alternative dwarfing genes such as Rht8 in development of long coleoptile, reduced height wheat suitable for deep sowing.     

Root growth,soil water content and yield of barley under different tillage systems on two soils in semiarid conditions

An experiment was conducted on two soils in a semiarid area in the Spain’s Ebro valley. Soil A was a Fluventic Xerochrept of 120 cm depth and Soil B was a Lithic Xeric Torriorthent of 30 cm depth. Three tillage systems were compared in Soil A: subsoiler tillage, minimum tillage and no-tillage, and two (minimum tillage and no-tillage) in Soil B. The experiment was repeated for 5 years on Soil A and 3 years on Soil B. Root length density, volumetric water content and dry matter were measured at important developmental stages. Yield was determined at harvest. In Soil A, root length density and volumetric water content were significantly greater for no-tillage than for subsoiler or minimum tillage (up to 1.4 cm cm⁻³ and 5%, respectively), mainly in the upper part of the soil profile. At lower depths, differences as great as 0.8 cm cm⁻³ and 6% were also found. Mean yield (4 years) was similar between no-tillage (3608 kg ha⁻¹) and minimum tillage (3508 kg ha⁻¹), and significantly smaller for subsoiler tillage (3371 kg ha⁻¹). In Soil B, no differences were observed between tillage systems for volumetric water content. Significant interactions between tillage and year were found for root length density, dry matter and yield. Mean yield (3 years) was not significantly different for minimum tillage (1806 kg ha⁻¹) and no-tillage (1867 kg ha⁻¹). The results in Soil A showed that surface conditions are of major importance in the water content of the soil and determined the differences among tillage systems. No-tillage favoured greater and deeper water accumulation in the soil profile and greater root growth. This makes this system potentially better for years of low rainfall. In Soil B no tillage system proved to be better because of the low water-holding capacity of this soil (56 mm).     

Modeling the process and costs of fuel ethanol production by the corn dry-grind process

The corn dry-grind process is the most widely used method in the U.S. for generating fuel ethanol by fermentation of grain. Increasing demand for domestically produced fuel and changes in the regulations on fuel oxygenates have led to increased production of ethanol mainly by the dry-grind process. Fuel ethanol plants are being commissioned and constructed at an unprecedented rate based on this demand, though a need for a more efficient and cost-effective plant still exists.A process and cost model for a conventional corn dry-grind processing facility producing 119 million kg/year (40 million gal/year) of ethanol was developed as a research tool for use in evaluating new processing technologies and products from starch-based commodities. The models were developed using SuperPro Designer^® software and they handle the composition of raw materials and products, sizing of unit operations, utility consumptions, estimation of capital and operating costs, and the revenues from products and coproducts. The model is based on data gathered from ethanol producers, technology suppliers, equipment manufacturers, and engineers working in the industry. Intended applications of this model include: evaluating existing and new grain conversion technologies, determining the impact of alternate feedstocks, and sensitivity analysis of key economic factors. In one sensitivity analysis, the cost of producing ethanol increased from US$ 0.235 l⁻¹ to US$ 0.365 l⁻¹ (US$ 0.89 gal⁻¹ to US$ 1.38 gal⁻¹) as the price of corn increased from US$ 0.071 kg⁻¹ to US$ 0.125 kg⁻¹ (US$ 1.80 bu⁻¹ to US$ 3.20 bu⁻¹). Another example gave a reduction from 151 to 140 million l/year as the amount of starch in the feed was lowered from 59.5% to 55% (w/w).This model is available on request from the authors for non-commercial research and educational uses to show the impact on ethanol production costs of changes in the process and coproducts of the ethanol from starch process.     

Increasing the content of leaf and root alkaloids of high alkaloid content mutants of periwinkle through nitrogen fertilization

In industrial plants such as medicinal plants, the content of the economically important metabolite is more important than the yield of the plant part containing the metabolite, as it determines the cost of extraction of the metabolite. Two high alkaloid content mutants of periwinkle (Catharanthus roseus, a medicinal plant yielding anti-cancer and anti-hypertension alkaloids) were developed through induced mutagenesis. Since the availability of nitrogen (N) is expected to play an important role in the biosynthesis and accumulation of alkaloids in plants, the effect of N fertilization on the content of alkaloids of two high alkaloid content mutants of periwinkle was studied, in comparison with their parental variety, Nirmal, to determine the possibility of further increasing their alkaloid contents. The three genotypes were evaluated at three levels of N (0, 100 and 150 kg ha⁻¹) fertilization in a split plot experiment, which was repeated over 2 years. N fertilization significantly increased the content of alkaloids both in leaves and roots of all genotypes. Over genotypes, application of 150 kg ha⁻¹ of N resulted in an increase of 42 and 32% in the content of leaf and root alkaloids, respectively. However, the increase was highest in genotypes with the lowest content of leaf or root alkaloids. The high alkaloid mutants grown at 150 kg ha⁻¹of N fertilization exhibited an increase of 87 and 56% in the content of leaf and root alkaloids, respectively, when compared with their parental variety grown without nitrogen fertilization. N fertilization increased leaf and root yields by 170 and 90%, respectively. The increase in contents of leaf and root alkaloids, due to N application, paralleled the increase in leaf and root yields.     

Nutrient and assimilate partitioning in two tropical maize cultivars in relation to their tolerance to soil acidity

The use of Al-tolerant and P-efficient maize cultivars is an important component of a successful production system on tropical acid soils with limited lime and P inputs. Grain yield and secondary plant traits, including root and aboveground biomass, nutrient content and leaf development, were evaluated from 1996 to 2002 in field experiments on an Oxisol in order to identify maize characteristics useful in genetic improvement. Here we present the results of the 2002 trial and compare them with previous results. The aim of this experiment was to assess the effect of assimilate and nutrient partitioning on the growth and grain yield of two tropical cultivars having different Al tolerance (CMS36, tolerant, Spectral, moderately tolerant). The soil had an Al saturation of 36% in topsoil (pH 4.5) and >45% below 0.3 m depth (pH 4.2). Measurements made from emergence to grain filling included: root, stem and leaf biomass, P and N content, leaf area index (LAI), radiation use efficiency (RUE), soil available N and root profiles at anthesis. The experiments consisted of two P treatments, zero applied or 45 kg P ha⁻¹ (−P and +P). All the treatments received N and K fertilizers. In −P, root biomass and LAI at anthesis were twice as great in CMS36 as in Spectral. In +P the differences between cultivars were negligible. Roots were deeper in CMS36 due to its higher Al tolerance. Total biomass and grain yield were not strongly related to root biomass and LAI. Other factors such as the leaf biomass and the amount of nutrients per unit leaf area were highly correlated with RUE and biomass. In −P, Spectral had the same total biomass but a higher grain yield than CMS36 (2.1 Mg ha⁻¹ versus 1.5 Mg ha⁻¹). This was due to a higher leaf P content (+40%), a greater RUE (+74%), and a lower number of sterile plants. In +P, CMS36 had higher total biomass and grain yield (4.1 Mg ha⁻¹ versus 3.1 Mg ha⁻¹). This was due to its higher leaf P (+25%) and leaf N (+43%) contents, and an increased RUE (+130%) that were associated with higher P and N uptake. Our results indicated that although root tolerance to Al toxicity is necessary for good crop performance on acid soils, assimilate and nutrient partitioning in the aboveground organs play a major role in plant adaptation and may partially compensate for a lower root tolerance.     

Seed oil extraction using a solar powered screw press

An efficient and economical oil expression system that can operate on solar power in rural areas of underdeveloped and developing countries is needed. Recent improvements in both oil extraction and solar energy technologies have indicated the possibilities for fabricating oil extraction equipment. Thus, the objective of our study was to develop a simple oil expression unit capable of producing high quality oil based on solar energy in remote rural areas. A photovoltaic (PV), batch operated, low-pressure oil press, using a 190 W, 12 V dc motor, was designed, fabricated, and tested using coconut and groundnut as the raw material. Samples used in the study were ground to particle size between 500 μm and 2 mm and were pressed at 12 ± 1% moisture content. The press was evaluated based on the oil extraction efficiency (OEE), power consumption, and oil quality. The press had an average OEE of 73% for coconuts and 70% for groundnuts after 12 min of pressing. The oil expression efficiency was characterized by three main stages namely delayed, rapid, and retarded. The power consumption was affected greatly by the pressing time, with power consumption increasing with an increase in the pressing time. The specific energy consumption was found to increase significantly after 8 min of pressing and correlated with the compaction of the cake, which resulted in more power being required to express the entrapped oil. The expressed oil was fresh, free from foots, and of high quality with an average moisture content of 0.015% for coconut oil and 0.019% for groundnut. Analyses showed that the viscosities were 42.1 MPa s (coconut oil) and 59.1 MPa s (groundnut oil), at 25 °C. Overall, the press performed well and was comparable in performance to other types of presses.     

Residual effect of poultry litter applied to cotton in conservation tillage systems on succeeding rye and corn

The burgeoning poultry industry in the southeastern US is presenting a major environmental problem of safe disposal of poultry litter (PL). In a comprehensive study, we explored ways of PL use in conservation tillage-based cotton (Gossypium hirsutum L.) production systems on a Decatur silt loam soil in north Alabama, from 1996 to 1999. The study reported here-in presents the residual effects of PL applied to cotton in mulch-till (MT) and no-till (NT) conservation tillage systems in 1997 and 1998 cropping seasons on N uptake, growth, and yield of rye (Secale cereale, L.) cover crop and rotational corn (Zea mays L.) in 1999. Rye was grown without additional N, whereas corn was grown at three inorganic N levels (0, 100, and 200 kg N ha⁻¹). Poultry litter was applied to cotton in 1997 and 1998 at 0, 100, and 200 kg N ha⁻¹. Residual N from PL applied to cotton in 1997 and 1998 produced up to 2.0 and 17.3 Mg ha⁻¹, respectively, of rye cover crop and corn biomass (includes 7.1 Mg ha⁻¹ of corn grain yield) without additional fertilizer. Therefore, in addition to supplying crop residues which reduce soil erosion, increase soil organic matter, and conserve soil moisture, the rye cover crop was able to scavenge residual N left by the cotton crop, which would otherwise, be at risk of being leached and pollute groundwater resources. Poultry litter applied to cotton also increased corn grain quality as shown by up to 100% increase in grain N content compared to the 0N treatment. Using PL with a slower rate of N release compared to inorganic fertilizer to meet some of the N requirements of corn, will not only reduce N fertilizer costs for corn, but will also reduce the risk of nitrate N leaching into groundwater. The maximum amount of crop residues added to the cotton based cropping system by residual N from PL and inorganic N was 21.3 Mg ha⁻¹. This will lead to an increase in soil organic carbon and soil structure in the long term and a reduction in soil erosion, thereby further improving soil productivity, while at the same time, protecting the environment from nitrate pollution and soil degradation. Our study demonstrates that cotton under conservation tillage system in combination with rye cover crop and rotational corn cropping could use large quantities of PL thereby avoiding serious potential environmental hazards.     

Distribution and characterisation of fructan in wheat milling fractions

Structure and health effects of inulin-type fructans have been extensively studied, while less is known about the properties of the graminan-type fructans in wheat. Arabinoxylan (AX) is another important indigestible component in cereal grains, which may have beneficial health effects. In this study, the fructan content in milling fractions of two wheat cultivars was determined and related to ash, dietary fibre and AX contents. The molecular weight distribution of the fructans was analysed with HPAEC-PAD and MALDI-TOF MS using ¹H NMR and enzymatic hydrolysis for identification of fructans. The fructan content (g/100 g) ranged from 1.5 ± 0.2 in flour to 3.6 ± 0.5 in shorts and 3.7 ± 0.3 in bran. A correlation was found between fructan content and dietary fibre content (r = 0.93, P < 0.001), but with a smaller variation in fructan content between inner and outer parts of the grain. About 50% of the dietary fibre consisted of AX in all fractions. The fructans were found to have a DP of up to 19 with a similar molecular weight distribution in the different fractions.