Above-ground Dry Matter Production Research Articles

Effects of Planting Density on Root Spatial and Temporal Distribution and Yield of Winter Wheat

The root system is the only vital organ for plants to connect with soil moisture and nutrients and obtain feedback information. This research aimed to explore the response of different spike type winter wheat varieties to plant and row spacing configurations. Multi-spike and large-spike winter wheat varieties were used as materials. By setting different plant row configurations and planting densities, the spatial and temporal distribution of root length density, root diameter, root dry weight density, and the main control factors of root growth and development of winter wheat during the whole growth period were studied. The results showed that the root system was the most widely distributed and the root diameter was the largest in the 0–40 cm soil depth, with an average root system diameter of more than 0.5 mm. The root length density and root diameter peaked at the heading stage, decreased at the maturity stage, and the root dry weight density peaked at the jointing stage. The jointing stage and heading stage are the most vigorous periods of root growth in winter wheat, when the center of gravity of root growth in winter wheat is gradually moving down. Therefore, the rapid growth and elongation time of a root system can be effectively prolonged at the jointing stage and heading stage, and the root growth rate can be improved. Promoting root thickening can effectively meet the needs for water and nutrients, for the formation and filling of aboveground plants and grains, in the later stage, which is conducive to the formation of aboveground dry matter production and final yield. The root distribution was greatest in the 0–60 cm soil depth, accounting for 95.13–97.84% of the total root length. After the heading stage occurs, the upper roots begin to decline in large quantities. Thus, the jointing stage and heading stage require fertilization and other farmland management operations to increase root nutrients for the ground parts and dry matter accumulation to provide sufficient nutrients so that the number of effective panicles, grain weight, and the number of spike grains coordinate to achieve the highest grain yield. Results showed that the highest yield can be achieved with the planting pattern X2M1. A comprehensive analysis showed that the genetic characteristics of winter wheat varieties were different, and there were some differences in the correlation between wheat yield and root system at the different growth stages. The correlation between the root parameters and yield of multi-spike winter wheat during the overwintering-jointing stage was obvious. For large-spike type winter wheat in the jointing stage, the yield correlation is most obvious.

Evaluating Dry Matter Production and Grain Yield of Dual-Purpose Winter Wheat Using Field Experiment and Modelling

The potential of a winter wheat (Triticum aestivum L.) cultivar Wedgetail to provide grazing and grain yield under different sowing times, grazing times, and watering regimes, under current and future climate, was investigated using field experiment and simulation modelling. For the field experiment, there were two watering treatments (unirrigated (D) and irrigated (I)) and four simulated grazing treatments (ungrazed, simulated grazed at growth stage (GS) 25, simulated grazed at growth stage (GS) 32, and grazed at both GS 25 and GS 32). These were designated as D0, D1, D2, and D3, respectively, for the unirrigated treatment and I0, I1, I2, and I3, respectively, for the irrigated treatment. It was found that the soil water depletion was significantly higher (p < 0.05) for the irrigated/ungrazed treatment than that for the simulated grazed treatment. The crop simulated grazed at GS 25 recovered quicker than the crop grazed at GS 32, especially for the unirrigated treatment. As the sowing time is delayed, above-ground dry matter (AGDM) production decreases. For D2 and D3, the amount of simulated grazed AGDM was 3.46 t ha−1 and 3.55 t ha−1, respectively. For I2 and I3, the amount of simulated grazed AGDM was 4.73 t ha−1 and 4.34 t ha−1, respectively. For D1, simulated grazing increased grain yield by 7%, while for D2 and D3, it increased by 18% and 24%, respectively. For I1, simulated grazing reduced grain yield by 16%, while for I2 and I3, it decreased by 42% and 42%, respectively. Simulation using the Agricultural Production Systems sIMulator (APSIM) showed that, for winter wheat sown in the second week of March, the maximum AGDM expected one in two years at the ends of May, June, and July is 4.5 t ha−1, 5.8 t ha−1, and 6.8 t ha−1, respectively. If the crop is sown mid-April, these values are 0.8 t ha−1, 2.2 t ha−1, and 4.3 t ha−1, respectively. Yield did not show response to times of sowing from March to early April. The maximum value reached was about 4.5 t ha−1 when sown in the fourth week of March, after which it started decreasing and reached the lowest value of about 4.1 t ha−1 when sown by the end of May. The total above-ground dry matter (AGDM) obtained by grazing earlier during the feasible grazing period and again towards the end of this period was not significantly different from grazing only once towards the end of this period. The simulation results showed that winter wheat Wedgetail flowering date was less sensitive to sowing time and that yield did not show a significant response to times of sowing, with the maximum occurring for the fourth week of March sowing and the lowest for the fourth week of May sowing.

Development and evaluation of HUME-OSR: A dynamic crop growth model for winter oilseed rape

A new dynamic crop growth model based on empirically derived allometric partitioning rules was developed for winter oilseed rape. The model simulates dry matter production, nitrogen uptake and distribution, leaf, stem and pod area expansion and yield formation under optimal and water- and nitrogen-limited conditions.The model includes hibernation, senescence due to self-shading, freezing and aging, translocation of assimilates and nitrogen, light absorption and reflection by flower layer and oil synthesis. It was parameterized with two data sets from Hohenschulen, northern Germany, and validated with datasets from Germany, France, Great Britain, and the Czech Republic.Model performance in terms of prediction of total aboveground dry matter production gave an RMSE of 180 g m−2 and the linear regression between measured and simulated root/shoot ratios gave an r2 of 0.64. In addition, nitrogen uptake (RMSE 4.26 g m−2) and distribution (r2 simulated/measured leaf N/stem N = 0.44) are quite well represented. In contrast, year-to-year variability of final seed yield was less correctly estimated, probably due to variation in the harvest index, which is not included in the model prediction. Relative differences in seed yield due to sowing date and nitrogen application were well reproduced in most cases. Therefore the model has potential to be used for supporting optimization of management strategies, climate change scenario studies and future breeding progress.

Growth analysis and land equivalent ratio of fenugreek-buckwheat intercrops at different fertilizer types

Summary Intercropping can increase crop growth and yield due to improved resource use efficiency. A two-year field experiment was performed in Shahrekord (Iran) to determine the effect of crop stand composition and fertilizer type on the productions of aboveground dry matter and growth parameters of fenugreek-buckwheat intercrops. Sole crops of fenugreek (F) and buckwheat (B) were compared to the three substitutive intercropping ratios (F:B = 2:1, 1:1 and 1:2). Crop stands were fertilized with chemical fertilizer or broiler litter. Fenugreek could produce in intercrops a similar amount of above-ground dry matter compared to its corresponding share on the sowing ratio. Contrary to that, buckwheat could produce in intercrops more above-ground dry matter than its share on the sowing ratio, especially with a low to medium share of buckwheat. Consequently, the intercrops with F:B (2:1) and F:B (1:1) had an above-ground dry matter yield advantage compared to the pure crop stands of both crops. Broiler litter was more effective in increasing the growth rates and thus the above-ground dry matter production compared to the chemical fertilizer. Thus, growing fenugreek and buckwheat in intercrops fertilized with broiler litter can be beneficial for increasing the biomass production in semiarid environments.

Demographic quantification of carbon and nitrogen dynamics associated with root turnover in white clover.

As well as capturing resources, roots lose resources during their lives. We quantified carbon (C) and nitrogen (N) losses associated with root turnover in white clover (Trifolium repens L.). We grew contrasting cultivars for 18weeks in soil microcosms. Using repeated in situ observations, destructive sampling, and demographic analysis, we measured changes in C and N concentrations in dry matter of 1st- or 2nd-order (terminal) roots to derive C and N fluxes into and out of root cohorts. C and N fluxes from roots during turnover depended on cohort age and order. Ninety per cent of losses occurred from 2nd-order cohorts younger than 18weeks. Losses were greater from roots of the larger, faster growing cultivar Alice than from the smaller lower yielding cultivar S184. C:N ratios of roots and lost material were similar within each order and between cultivars but smaller in 2nd- compared with 1st-order roots. C and N losses during root turnover could be equivalent to at least 6% of aboveground dry matter production in S184 and 12% in Alice at the field scale. C and N losses associated with root turnover will have potentially significant and previously unrecognized impacts on crop productivity, resource dynamics, and long-term soil fertility.

PLANT DENSITY AND NITROGEN FERTILIZATION ON COMMON BEAN NUTRITION AND YIELD

ABSTRACT The objective of this work was to evaluate the effect of plant densities and sidedressed nitrogen (N) rates on nutrition and productive performance of the common bean cultivars IPR 139 and Pérola. For each cultivar, a randomized complete block experimental design was used in a split-plot arrangement, with three replicates. Plots consisted of three plant densities (5, 7, and 9 plants ha-1) and subplots of five N rates (0, 30, 60, 120, and 180 kg ha-1). Aboveground dry matter, leaf macro- and micronutrient concentrations, yield components, grain yield, and protein concentration in grains were evaluated. Lower plant densities (5 and 7 plants m-1) increased aboveground dry matter production and the number of pods per plant and did not reduce grain yield. In the absence of N fertilization, reduction of plant density decreased N concentration in common bean leaves. Nitrogen fertilization linearly increased dry matter and leaf N concentration, mainly at lower plant densities. Regardless of plant density, the N supply linearly increased grain yield of cultivars IPR 139 and Pérola by 17.3 and 52.2%, respectively.

Tillage and fertilizer effect on maize and soybean yields in the Guinea savanna zone of Ghana

BackgroundThe most limiting factors for sustainable maize production in smallholder farming systems of sub-Saharan Africa, especially the savanna agro-ecological zone, are erratic rainfall pattern and low soil fertility.MethodsResearch was conducted with smallholder farmers in 2013 and 2014 in two communities in the Upper West Region of Ghana to evaluate the effects of NPK mineral fertilizer (64–38–38 kg ha−1 N–P2O5–K2O, respectively) on growth and yield of maize at Bompari, and 375 kg ha−1 of YaraLegume™ fertilizer (0–18–13 NPK + 3 CaO + 2 MgO + 4 S) on growth and yield of soybean at Doggoh, under no-tillage (using pre-plant application of glyphosate) and conventional tillage (using hand hoe).ResultsMean grain yields of both maize and soybean were higher in 2014 than 2013. In both years, no-tillage and conventional tillage had similar effect on soybean plant height, pods per plant and aboveground dry matter production. Averaging over fertilizer treatment, grain yield of no-tillage soybean was 51% higher when compared with tilled soybean in 2014 only. Mean grain yield of no-tillage maize was 68% higher than that of tilled maize in 2013 only. Regardless of tillage method, fertilizer application significantly increased maize and soybean grain yields. Application of fertilizer to soybean resulted in 59% (193 kg ha−1) and 54% (474 kg ha−1) increase in grain yields in 2013 and 2014, respectively, over no fertilizer treatment. Mean grain yield of maize was 140 and 252% higher with fertilizer treatment in 2013 and 2014, respectively. No-till system showed cost savings due to reduced labour mainly for weed control.ConclusionThe results of these studies showed that no-tillage with fertilizer, whether for maize or soybean, generally resulted in the highest grain yields. No-tillage also gave the highest economic returns. Farmers can get better returns to the money invested in herbicide for producing maize and soybean under no-till than with their traditional practice even on degraded savanna soils with low levels of plant available nutrients.

Yield and diseases of potato as affected by deep soil tillage and crop succession with grass types

Yield and disease incidence were evaluated in potato ( Solanum tuberosum cv. Atlantic) after six years of cultivation in succession with corn ( Zea mays cv. ‘AG 6080’) under conventional tillage (CT, depth of tillage: 0.20 m) or in succession with three grass types [Guinea grass ( Panicum maximum cv. Tanzânia), Palisade grass ( Brachiaria brizantha cv. Marandu) and corn] under deep tillage (DT, depth of tillage: 0.70 m). Total tuber yield was higher in DT in average 36% the value obtained in CT (17.76 t ha -1 ), with no effect of the grass type. Common scab ( Streptomyces scabies ) incidence was influenced by treatments, the highest (16.9%) and the lowest (9.5%) values being obtained in succession with corn and Guinea grass ( Panicum maximum cv. Tanzania), respectively, both under DT. The lowest incidence of tuber greening at field (2.58%) was also recorded in Guinea DT, significantly lower than obtained in Corn CT (6.33%), possibly due to a more efficient ridging operation. Grass types showed different values of aboveground dry matter production. Guinea grass (26.56 Mg ha -1 ) was the most and Corn under CT and DT (5.72 and 5.56 Mg.ha -1 , respectively, without ears) were the least productive ones. Soil density, macroporosity and resistance to penetration indices were significantly better with DT, the grass type affecting them in a minor degree. The deep tillage system is therefore recommended for potato cultivation regardless the grass type used for crop sucesssion.

Forage potential of six leguminous green manures and effect of grazing on following grain crops

AbstractThere is a need to design intensive cropping systems that can reap multiple benefits from annual forages including animal feed, soil fertility and weed control. Considering pea/oat (Pisum sativumcv. 40–10/Avena sativacv. Legget) as a standard green manure, this study investigated the productivity, weed competitiveness, utilization and nitrogen (N) benefit from grazed and ungrazed green manures to spring wheat (Triticum aestivumcv. Waskada) and fall rye (Secale cerealecv. Hazlet). A set of 3-year experiments was carried out in Carman, Manitoba, Canada in 2009, and was repeated in 2010 and 2011. Green manures were grazed by 2–3 ewes and 2–5 lambs for 24 h (1111–1667 sheep days per ha). Averaged over experiments pea/oat mix, hairy vetch (Vicia villosaL.) and sweetclover (Melilotus officinaliscv. Norgold) above-ground dry matter (DM) production were 5036, 5032 and 4064 kg ha−1, respectively. Lentil (Lens culinariscv. Indianhead), a mixture of seven species and soybean (Glycine maxcv. Prudence) produced the least amount of DM over 3 years; 3589, 3551, 3174 kg ha−1, respectively. Pea/oat and hairy vetch were the most weed-competitive species and, averaged over 3 years, contained less than 15% weed DM. Utilization of green manures by grazing animals varied little among species across years and ranged from 28 to 86% for individual species and years. When combined across experiments grazing increased N availability to the wheat crop. The grazing effect was significant for wheat DM production, N uptake and grain N, but not significant for yield across experiments. Averaged over 3 years, wheat took up 107 kg N ha−1from grazed plots versus 98 kg N ha−1from ungrazed plots. A significant species×management interaction for total (wheat+fall rye) N uptake in 2009 indicated that increasing the proportion of legumes in the green manure increased N benefit from grazing. Fall rye productivity was not affected by grazing. We recommend pea/oat and hairy vetch as two green manure species to enhance the overall system performance to achieve high level of DM production, good weed competition, utilization by sheep and provision of N benefit to the following wheat and fall rye crops.

Soil substrate utilization pattern and relation of functional evenness of plant groups and soil microbial community in five low mountain NATURA 2000

Species rich, semi-natural grassland systems provide several ecosystem functions. The goal was to assess how aboveground composition and evenness affects soil substrate utilization pattern and soil microbial functional evenness. At five German NATURA 2000 grassland sites, the interactions of plant functional groups (graminoids, forbs and legumes) and belowground microbial functional evenness were investigated in relation to soil properties and sampling date. Functional evenness of soil microorganisms was measured with high spatial resolution by community level physiological profiling (CLPP) using multi-SIR (substrate-induced respiration) at three sampling dates during the vegetation period. Evenness indices were used to compare plant functional group diversity and soil microbial functional diversity. All sites differed in the consistently high soil microbial functional evenness, which was strongly predicted by soil pH, but not by plant functional groups or aboveground plant dry matter production. However, soil microbial functional evenness was particularly decreased by an increasing legume proportion and showed seasonal changes, probably driven by shifts in resource availability and soil water content. Our results suggest that changes in soil chemical properties or in a single key plant functional group may have stronger effects on soil microbial functional evenness than changes in plant functional group evenness.

Seed weight in canola as a function of assimilate supply and source-sink ratio during seed filling period

Understanding variation in SW (seed weigh) is of major importance in understanding SY (seed yield) variation. The objective of this study was to determine factors such as SN (seed number) per unit area, SFD (seed filling duration) and SFR (seed filling rate) and temperature, LAI (leaf area index), LAD (leaf area duration), above-ground dry matter, CGR (crop growth rate), leaf dry matter remobilization and efficiency and SSR (source-sink ratio) around SFP (seed filling period), affecting SW in canola (Brassica napus L.). The experiment was conducted at Agricultural Research Station of Gonbad, Iran, during 2005-7. Two cultivars of spring type canola (Hyola401 and RGS003) as subplots were grown at 5 sowing dates (SDs) as main plots, spaced approximately 30 days apart, to obtain a wide range of environmental conditions during SFP. The experiment was arranged in two conditions, i.e. supplemental irrigation (SI) and rainfed (RF). SW was influenced by the growing season rainfall and temperature. The availability of the crop to produce and to remobilize photosynthetic assimilates to developing seeds was a good determinant factor for SW. SW increased with increase in LAI, above-ground dry matter production and remobilization and SSR around SFP, leading to an increased SY, suggested that SW primarily depends on the resource availability. The relationships of SW with SFR and SFD and above-ground dry matter, LAI, leaf dry matter remobilization and efficiency and SSR around SFP, over environmental conditions, sowing dates and cultivars, showed these variables to be generally applicable in canola SW determination.

EVALUATION OF DRY MATTER PRODUCTION OF MISCANTHUS SINENSIS (TATAI) IN THE CONDITIONS OF SOUTH-WESTERN SLOVAKIA

Abstract In this paper, we present the results of research of phytomass production allocated to aboveground organs, leaves and stalks, after the third growing year. The research was conducted in the field experiment conditions of Farm holding in Kolíňany. The results of the aboveground dry matter production are expressed in tonnes of dry weight produced on the area of one hectare (t.ha-1). The total dry weight of the aboveground biomass was 6.89 t.ha-1 at the end of the first growing year 2010. In the growing year 2011, it reached 15.21 t.ha-1 (an increase by 121 %.) The total dry weight of the aboveground phytomass increased by 37% compared to 2011, and it reached 20.82 t.ha-1 in the third growing year (2012). The increase of phytomass is directly proportional to off shoot circle. Average off shoot circle of individuals in the first growing year was 300 mm and the average number of stems produced in a clump was 37.60. In 2011, the average off shoot circle of individuals was 502 mm and there were 43.73 stems created in a clump. In the third growing period of 2013, the extension of the off shoot circle by 113.7% (641 mm) was registered in comparison with 2010 and the amount of 80.19 stems per clump was recorded.

Optical crop sensor for variable-rate nitrogen fertilization in corn: i - plant nutrition and dry matter production

Variable-rate nitrogen fertilization (VRF) based on optical spectrometry sensors of crops is a technological innovation capable of improving the nutrient use efficiency (NUE) and mitigate environmental impacts. However, studies addressing fertilization based on crop sensors are still scarce in Brazilian agriculture. This study aims to evaluate the efficiency of an optical crop sensor to assess the nutritional status of corn and compare VRF with the standard strategy of traditional single-rate N fertilization (TSF) used by farmers. With this purpose, three experiments were conducted at different locations in Southern Brazil, in the growing seasons 2008/09 and 2010/11. The following crop properties were evaluated: above-ground dry matter production, nitrogen (N) content, N uptake, relative chlorophyll content (SPAD) reading, and a vegetation index measured by the optical sensor N-Sensor® ALS. The plants were evaluated in the stages V4, V6, V8, V10, V12 and at corn flowering. The experiments had a completely randomized design at three different sites that were analyzed separately. The vegetation index was directly related to above-ground dry matter production (R² = 0.91; p<0.0001), total N uptake (R² = 0.87; p<0.0001) and SPAD reading (R² = 0.63; p<0.0001) and inversely related to plant N content (R² = 0.53; p<0.0001). The efficiency of VRF for plant nutrition was influenced by the specific climatic conditions of each site. Therefore, the efficiency of the VRF strategy was similar to that of the standard farmer fertilizer strategy at sites 1 and 2. However, at site 3 where the climatic conditions were favorable for corn growth, the use of optical sensors to determine VRF resulted in a 12 % increase in N plant uptake in relation to the standard fertilization, indicating the potential of this technology to improve NUE.

Optical crop sensor for variable-rate nitrogen fertilization in corn: II - indices of fertilizer efficiency and corn yield

Generally, in tropical and subtropical agroecosystems, the efficiency of nitrogen (N) fertilization is low, inducing a temporal variability of crop yield, economic losses, and environmental impacts. Variable-rate N fertilization (VRF), based on optical spectrometry crop sensors, could increase the N use efficiency (NUE). The objective of this study was to evaluate the corn grain yield and N fertilization efficiency under VRF determined by an optical sensor in comparison to the traditional single-application N fertilization (TSF). With this purpose, three experiments with no-tillage corn were carried out in the 2008/09 and 2010/11 growing seasons on a Hapludox in South Brazil, in a completely randomized design, at three different sites that were analyzed separately. The following crop properties were evaluated: aboveground dry matter production and quantity of N uptake at corn flowering, grain yield, and vegetation index determined by an N-Sensor® ALS optical sensor. Across the sites, the corn N fertilizer had a positive effect on corn N uptake, resulting in increased corn dry matter and grain yield. However, N fertilization induced lower increases of corn grain yield at site 2, where there was a severe drought during the growing period. The VRF defined by the optical crop sensor increased the apparent N recovery (NRE) and agronomic efficiency of N (NAE) compared to the traditional fertilizer strategy. In the average of sites 1 and 3, which were not affected by drought, VRF promoted an increase of 28.0 and 41.3 % in NAE and NRE, respectively. Despite these results, no increases in corn grain yield were observed by the use of VRF compared to TSF.

Simulating Guinea Grass Production: Empirical and Mechanistic Approaches

Tropical grasses are economically important for cattle production in Brazil, and accurate simulation models for tropical pastures can benefit forage researchers and farm managers by improving tropical forage production systems. This research calibrated and validated four modeling approaches of contrasting complexity to simulate mass production of Mombaça Guinea grass (Panicum maximum Jacq.). The models included three empirical agro‐climatic models (i.e., using cumulative degree days, photothermal units, and a climatic growth index) and a biophysical simulation model, Agricultural Production Systems Simulator (APSIM)‐Growth. Data sets for calibration and independent validation included frequent records of aboveground dry matter production during the 2005–2006 and 2010–2011 growing seasons from three trials. All models performed well during calibration (R2 = 0.78–0.86; coefficient of variation = 26–32.1%). During model validation, the R2 varied between 0.69 and 0.78, the agreement index was between 0.88 and 0.93, the coefficient of variation between 37.6 and 50.2%, and the mean bias error was between 6 and 470 kg ha−1. Even though all models were in agreement between simulated and observed results, APSIM‐Growth was able to simulate Guinea grass production across broader climatic, soil, and management (e.g., N fertilization) conditions.

Field application of a DNA-based assay to the measurement of roots of perennial grasses

Background and aims DNA-based methods present new opportunities for overcoming the difficulties of accurately identifying and quantifying roots of different plant species in field soils. In order to quantify species-specific root biomass from measurements of DNA, consideration needs to be given to replication and ability to recover roots for calibration purposes in order to account for spatial, temporal and inter- and intra-species variation in DNA content of roots and distribution of roots within the soil profile. Methods This paper develops the field application of a DNA-based technique for direct quantification of roots in soils. The method was applied to a field experiment to investigate differences in root growth of acid-soil resistant and sensitive genotypes of perennial pasture grasses in an acid soil. DNAwas extracted directly from soil and species-specific DNAwas quantified using quantitative real-time PCR prior to estimation of root biomass. Results Root growth of the perennial grasses was quantified using the DNA-based technique, although separate calibration procedures were needed to convert DNA content to root mass for each species, soil layer and sampling date. Compared to acid-soil resistant genotypes, lesser root growth in acid soil layers and reduced above-ground dry matter production was observed for acid-soil sensitive genotypes. Conclusions The DNA-based method allowed genotypic differences in root growth to be assessed directly in soil and was advantageous for rapid processing of a largenumberofsamples.However,highreplication was stillrequiredtoovercomespatialvariabilityandseparate calibrations were required for different species and soil depths across sampling times. The technique demonstrated greater root growth of acid-soil resistant perennial grasses which was beneficial for their establishment and persistence.

Biomass sorghum production and components under different irrigation/tillage systems for the southeastern U.S.

Renewable energy sources are necessary to reduce the U.S. dependence on foreign oil. Sorghum (Sorghum bicolor L.) may be a reasonable alternative as an energy crop in the southern U.S. because it could easily fit into existing production systems, it is drought resistant, and it has large biomass production potential. An experiment was conducted to evaluate several types of sorghum as bioenergy crops in Alabama: grain sorghum – NK300 (GS), forage sorghum – SS 506 (FS), and photoperiod sensitive forage sorghum – 1990 (PS). These sorghum crops were compared to forage corn (Zea mays L.) – Pioneer 31G65 in 2008 and 2009 with and without irrigation, and under conventional (total disked area, 0.15m deep) and conservation tillage (in-row subsoiling, 0.30m deep) in a strip-split-plot design. The parameters evaluated were: plant population (PP), plant height (PH), sorghum/corn aboveground dry matter (ADM), biomass moisture content (ABMC), and biomass quality (holocellulose, lignin, and ash). Sorghum had greater ADM than corn; however, corn had lower ABMC than sorghum. Lodging was observed in PS and FS, probably due to high plant populations (>370,000plantsha−1). Irrigation affected ADM positively in both years, but conservation systems improved ADM production only in 2009. Holocellulose, lignin, and ash variation differed significantly among crops but were lower than 8.3%, 2.0% and 1.9%, respectively, for both years and considered minor. Under conditions of this study, PS was considered the best variety for ADM production as it yielded 26.0 and 30.1Mgha−1 at 18 and 24 weeks after planting (WAP).

Above-ground dry matter production in maize (Zea mays L.) as influenced by sowing dates and poultry manure rates

Above-ground dry matter production in maize (Zea mays L.) as influenced by sowing dates and poultry manure rates

The effect of row spacing and seeding rate on biomass production and plant stand characteristics of non-irrigated photoperiod-sensitive sorghum (Sorghum bicolor (L.) Moench)

To evaluate row spacing and seeding rate effects on yield and plant stand characteristics of high-biomass sorghum, a photoperiod-sensitive cultivar was sown at three different row spacings (76, 38, and 19cm) and seeding rates (218,000, 306,000, and 393,000seedsha−1 for one site-year and 116,000, 204,000, and 291,000seedsha−1 for three site-years) from 2009 to 2010 in Alabama and Arkansas, USA. Measurements included above-ground dry matter production, plant height, stem density, and stem diameter. Narrower row spacing (i.e. 19cm) produced the highest biomass for all site-years. Increasing seeding rate did not affect yield for three of the site-years, and decreased yield for one. The 19cm row spacing produced the highest stem densities. Plant height increased with increasing seeding rates at one site and decreased with higher seeding rates at another site. At one location, stem diameter declined as seeding rates and stem density increased. It was concluded that narrower row spacing (19cm) provides the maximum yield benefit by significantly increasing stem density, and low seeding rates (116,000seedsha−1) are preferable because higher seeding rates do not positively affect yield and may cause morphological changes (i.e. taller plants with thinner stems) conducive to lodging.

Agronomic and physiological performances of different species of Miscanthus, a major energy crop. A review

The European Union recommends the use of lignocellulosic biomass to produce biofuels in order to reduce greenhouse gas emissions. Miscanthus × giganteus, a C4 perennial and rhizomatous plant, has been identified as a good candidate for biomass production because of its high potential yield, of up to 49 t DM.ha−1 for autumn harvest and 26 t DM.ha−1 for winter harvest, under low input levels. Here, we review current knowledge on the biomass production in Europe of M × giganteus and its two parental species, M. sinensis and M. sacchariflorus, under different stress conditions. This review identifies two key areas where M. giganteus crops could be improved: (i) tolerance to frost during winter or early spring is essential, mainly in Northern Europe, in order to ensure overwintering and protect young shoots following early emergence. Susceptibility to winter frost at temperatures below −3.5 °C for rhizomes and −8 °C for young shoots of M. × giganteus can lead to significant plant losses and lower yields, and (ii) a good water supply is necessary to ensure good establishment rates and satisfactory biomass production. Reductions of up to 84% in above-ground dry matter production because of a lack of water for the autumn harvest, and up to 26% for the winter harvest have been observed. M. sinensis, which displays greater genetic variability than M. giganteus, will provide the necessary genetic resources for frost and water stress tolerance. It is also necessary to either identify genotypes among M. sinensis species that are able to produce an above-ground biomass yield close to the biomass production of M. giganteus under limited water supplies and/or low temperatures, or to generate new interspecific hybrids of M. giganteus with greater tolerance. Particular attention should be paid to nitrogen response; although no response to nitrogen supply has been observed in M. giganteus, M. sinensis produces higher levels of biomass with nitrogen inputs.