Aboveground Dry Biomass Research Articles

Harvesting Plants in Constructed Wetlands to Increase Biomass Production and Na+ and Cl− Removal from Recycled Greenhouse Nutrient Solution

Recycled greenhouse nutrient solution requires treatment to prevent increased concentrations of both Na+ and Cl− ions from damaging crops or impacting the environment subsequent to its discharge. Constructed wetlands (CW) planted with species capable of hyper-accumulating Na+ and Cl− may be one viable treatment option. To mitigate the unwanted ions from CW, plant material may need to be harvested and removed. Research suggests that multiple harvests throughout the growing season can maximize the CW phytoremediation potential. To determine the ideal frequency of CW plant harvesting, an 18-week, outdoor microcosm experiment was conducted in which three wetland plant species, Juncus torreyi Coville. (Torrey’s rush), Schoenoplectus tabernaemontani (C.C. Gmel.) Palla (softstem bulrush), and Typha latifolia L. (broad leaf cattail), were subjected to the following harvesting treatments: (i) one harvest, (ii) two harvests, and (iii) three harvests. The total amounts of Na+ and Cl− accumulated in the aboveground dry biomass per square meter of plant growth area were calculated. Treatments with the highest Na+ accumulation were as follows: T. latifolia with three harvests, 24.7 g m−2, T. latifolia with two harvests, 16.2 g m−2, J. torreyi with two harvests, 12.7 g m−2. Treatments with the highest Cl− accumulation were as follows: J. torreyi with two harvests, 111.3 g m−2, T. latifolia with three harvests, 94.8 g m−2, T. latifolia with two harvests, 81.4 g m−2. Harvesting, whether two or three times, increased the Na+ and Cl− accumulated by T. latifolia and J. torreyi but did not influence the Na+ and Cl− accumulation or growth of S. tabernaemontani. However, the average Na+ and Cl− removal efficiencies of the all treatments were low, between 1–5 % for Na+ and 7–15 % for Cl−, suggesting that phytodesalinization may not be the best option for Na+ and Cl− treatment.

Estimation of biomass in wheat using random forest regression algorithm and remote sensing data

Wheat biomass can be estimated using appropriate spectral vegetation indices. However, the accuracy of estimation should be further improved for on-farm crop management. Previous studies focused on developing vegetation indices, however limited research exists on modeling algorithms. The emerging Random Forest (RF) machine-learning algorithm is regarded as one of the most precise prediction methods for regression modeling. The objectives of this study were to (1) investigate the applicability of the RF regression algorithm for remotely estimating wheat biomass, (2) test the performance of the RF regression model, and (3) compare the performance of the RF algorithm with support vector regression (SVR) and artificial neural network (ANN) machine-learning algorithms for wheat biomass estimation. Single HJ-CCD images of wheat from test sites in Jiangsu province were obtained during the jointing, booting, and anthesis stages of growth. Fifteen vegetation indices were calculated based on these images. In-situ wheat above-ground dry biomass was measured during the HJ-CCD data acquisition. The results showed that the RF model produced more accurate estimates of wheat biomass than the SVR and ANN models at each stage, and its robustness is as good as SVR but better than ANN. The RF algorithm provides a useful exploratory and predictive tool for estimating wheat biomass on a large scale in Southern China.

Effect of injection depth of digestate liquid fraction on soil carbon dioxide emission and maize biomass production

The aim of this study was to evaluate, in open field conditions, the effect of injection depth of digestate liquid fraction (10 cm, 25 cm and 35 cm) in clay loam soil, on CO2 emission. An un-amended soil was considered as control. The study was performed in 2014 on a farm located in Terrasa Padovana, Veneto region (Italy) distributing digestate before maize sowing. Digestate injection determined a high soil CO2 emission in the first hour after application, followed by a progressive reduction in as early as 24 h, reaching significantly lower values, similar to those measured in the un-amended control, after 48 h. Gas emissions measured 1 h after digestate application decreased as injection depth increased with significantly higher emission values in the 10 cm treatment (median value 23.7 g CO2 m–2 h–1) than in the 35 cm one (median value 2.5 g CO2 m–2 h–1). In the 3 days between digestate distribution and maize sowing, soil CO2 emission was significantly higher in the amended treatments than un-amended one, with median values of 1.53 g CO2 m–2 h–1 and 0.46 g CO2 m–2 h–1 respectively. During maize growing season, no significant soil CO2 emission difference was monitored among treatments, with a median value of 0.33 g CO2 m–2 h–1. Digestate application significantly improved maize aboveground dry biomass with an average yield of 22.0 Mg ha–1 and 16.2 Mg ha–1 in amended and un-amended plots, respectively, due to the different amount of nutrients supplied.

Simulation of crop production in weed-infested fields for data-scarce regions

SUMMARYWeed infestation is a major yield-reducing factor that also decreases crop water productivity. Yet weeds are often neglected in crop productivity simulation studies, because existing empirical equations and mechanistic models are not widely applicable or have a high demand for input data and calibration. For that reason, AquaCrop, a widely applicable crop water productivity model, was expanded with a weed management module which requires only two easily obtainable input variables: (i) relative leaf cover of weeds, and (ii) weed-induced increase of total canopy cover. Using these inputs, AquaCrop directly simulates soil water content, crop canopy development and production as it is observed in weed-infested fields. Despite this simple approach, AquaCrop performed well to simulate soil water content in the root zone (relative root-mean-square error (RRMSE) of 5–13%), canopy cover (RRMSE of 15–22%), dry above-ground crop biomass during the season (RRMSE of 21–39%) and at maturity (RRMSE of 5–6%) and yield (RRMSE of 11–25%) of barley and wheat grown under different weed infestation levels and environments. The current study illustrates that the AquaCrop model can be used to assess the effect of weed infestation on crop growth and production, using a simple approach that is applicable to diverse environmental and agronomic conditions, even in data-scarce regions.

A preliminary investigation of the water use efficiency of sweet sorghum for biofuel in South Africa

Sweet sorghum ( Sorghum bicolor (L.) Moench) has been recognized globally as a potential biofuel crop for ethanol production. Sweet sorghum is a drought-tolerant crop that is widely adapted to different environmental growing conditions. The aim of this study was to determine the water use efficiency (utilisable yield per unit amount of water used) of drip-irrigated sweet sorghum (variety Sugargraze) under two different climatic conditions in South Africa. The sweet sorghum trials were conducted at Ukulinga research farm (University of KwaZulu-Natal, Pietermaritzburg) and Hatfield experimental farm (University of Pretoria, Pretoria), South Africa. Field trials were conducted in two successive seasons, viz., 2010/11 and 2011/12. Seasonal water use was estimated using eddy covariance and surface renewal methods. Fresh and dry aboveground biomass yield, stalk yield and stalk Brix % were measured at final harvest. Theoretical ethanol yield was calculated from fresh stalk yield and Brix %. Water use for the two growing seasons was 415 mm at Ukulinga and 398 mm at Hatfield. The ethanol water use efficiency (WUE) values for the sweet sorghum at Ukulinga were 0.27 and 0.60 L∙m -3 for 2010/11 and 2011/12 growing seasons, respectively. The ethanol WUE estimate of the sweet sorghum at Hatfield was 0.53 L∙m -3 for the 2010/11 season and 0.70 L∙m -3 for the 2011/12 growing season. WUE estimates of the sweet sorghum crop were higher for Hatfield compared to Ukulinga research farm. The results from this study showed that the WUE of sweet sorghum was sensitive to plant density. The WUE values confirm that sweet sorghum has high WUE under different climatic conditions. Keywords: water use efficiency; ethanol yield; biofuel crop; plant density, sweet sorghum, South Africa

Fruit load governs transpiration of olive trees.

We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and late in the season. Tree-scale transpiration, calculated from lysimeter water balance, was found to be a function of fruit load, canopy size and weather conditions. Fruit removal caused an immediate decline in water consumption, measured as whole-plant transpiration normalized to tree size, which persisted until the end of the season. The later the execution of fruit removal, the greater was the response. The amount of water transpired by a fruit-loaded tree was found to be roughly 30% greater than that of an equivalent low- or nonyielding tree. The tree-scale response to fruit was reflected in stem water potential but was not mirrored in leaf-scale physiological measurements of stomatal conductance or photosynthesis. Trees with low or no fruit load had higher vegetative growth rates. However, no significant difference was observed in the overall aboveground dry biomass among groups, when fruit was included. This case, where carbon sources and sinks were both not limiting, suggests that the role of fruit on water consumption involves signaling and alterations in hydraulic properties of vascular tissues and tree organs.

Weed Management, Training, and Irrigation Practices for Organic Production of Trailing Blackberry: III. Accumulation and Removal of Aboveground Biomass, Carbon, and Nutrients

Relatively little is known about aboveground nutrient content of organic blackberry, and there is no published work on total carbon (C) content. Treatment effects on biomass, C, and nutrient content, accumulation, and removal were assessed over 2 years in a mature organic trailing blackberry (Rubus L. subgenus Rubus, Watson) production system that was machine harvested for the processed market. Treatments included two irrigation options (no irrigation after harvest and continuous summer irrigation), three weed management strategies (weed mat, hand-weeded, and nonweeded), and two primocane training times (August and February) in two cultivars (Black Diamond and Marion). Floricanes comprised an average of 45% of the total aboveground plant dry biomass, while primocanes and fruit comprised 30% and 25%, respectively. Depending on the treatment, the total aboveground dry biomass accumulation over the course of the season was 5.0–6.5 t·ha−1 per year, while C stock of the planting was an estimated 0.4–1.1 t·ha−1 in late winter. Carbon accounted for ≈50% of the dry biomass of each aboveground plant part, including primocanes, floricanes, and fruit. Weed management had the largest impact on plant biomass and nutrient content. No weed control reduced aboveground dry biomass, the content of nutrients in the primocanes, floricanes, and fruit, and the annual accumulation of dry biomass and nutrients, whereas use of weed mat resulted in the most dry biomass and nutrient content. Nutrient accumulation was similar between the cultivars, although February-trained ‘Marion’ plants had a greater removal of most nutrients in 2014 than the year prior. The amount of nitrogen (N) removed in the fruit was 22, 18, and 12 kg·ha−1 for weed mat, hand-weeded, and nonweeded plots, respectively, in 2013. In 2014, ‘Marion’ and ‘Black Diamond’ differed in N removed in harvested fruit when grown with weed mat at 18 and 24 kg·ha−1, respectively, whereas there was no cultivar effect when plants were grown in hand-weeded or nonweeded plots. Plots with weed mat tended to have the most nutrients removed through harvested fruit in both years. In 2014, N removal from August-trained ‘Marion’ was 5 kg·ha−1 N less than the other training time and cultivar combinations. Plants that were irrigated throughout the summer accumulated more dry biomass, N, potassium (K), magnesium (Mg), sulfur (S), boron (B), and copper in one or both years than those that received no irrigation after fruit harvest. The irrigation treatment had inconsistent effects on nutrient content of each individual plant part between the two years. Removal of nutrients was often higher than what was applied through fertilization, especially for N, K, and B, which would eventually lead to depletion of those nutrients in the planting.

SUSTAINABLE YIELD INDEX IN SOME MIXTURES

Sustainable yield index (SYI), nitrogen in dry aboveground mass yield and amount of fixed nitrogen of birdsfoot trefoil, sainfoin and subterranean clover pure grown and in mixtures with tall fescue in the next ratios: birdsfoot trefoil + tall fescue (50:50), sainfoin + tall fescue (50:50), subterranean clover + tall fescue (50:50), birdsfoot trefoil + subterranean clover + tall fescue (33:33:33), sainfoin + subterranean clover + tall fescue (33:33:33) were studied. Pot trial was carried out in the Institute of Forage Crops, Pleven, Bulgaria during 2011-2012. SYI in pure grown birdsfoot trefoil (0.767), sainfoin (0.720) and subterranean clover (0.666) was calculated. Sustainable yield index (SYI) in mixtures was found be higher - from 9.6% (sainfoin+tall fescue) to 18.2% (subterranean clover + tall fescue). Birdsfoot trefoil accumulated the highest amount of fixed nitrogen in dry aboveground biomass (8102 mg N/kg DM), followed by subterranean clover (6730 mg N/kg DM) and sainfoin (5598 mg N/kg DM). On averaged from mixtures studied nitrogen in dry aboveground biomass (7540 mg N/kg DM) was found be higher by 10.7% as compared to pure grown crops (6810 mg N/kg DM). Amount of fixed nitrogen obtained from mixtures (95.64 mg/kg DM) was by 15.2% higher as compared to pure grown forage legumes (81.79 mg/kg DM). Parameters as sustainable yield index, nitrogen in dry aboveground biomass, amount of fixed nitrogen were found be higher in mixtures.

大型土壤动物群落对短花针茅草原荒漠化过程的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 大型土壤动物群落对短花针茅草原荒漠化过程的响应 DOI: 10.5846/stxb201311272829 作者: 作者单位: 包头师范学院,包头师范学院生物科学与技术学院,内蒙古农业大学生态环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(41161040);内蒙古自然科学基金项目(2010MS0607) Response of soil macrofauna to desertification in Stipa breviflora desert steppe Author: Affiliation: Department of Resources and Environment,Baotou Teachers’ College,Department of Biological Science and Technology,Baotou Teachers’ College,College of Ecology and Environment,Inner Mongolia Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤动物是草地生态系统的重要组分,对维持草地生态系统结构与功能的稳定性具有重要作用,研究土壤动物群落对草地荒漠化的响应有助于揭示地下与地上生态过程的联系,全面认识荒漠化的本质。选取鄂尔多斯高原西部未荒漠化(Ⅰ)、轻度荒漠化(Ⅱ)、中度荒漠化(Ⅲ)、重度荒漠化(Ⅳ)及极重度荒漠化(Ⅴ)5种短花针茅荒漠草原生境,采用手拣法对大型土壤动物群落进行了野外调查。共获得1门2纲6目25个土壤动物类群,优势类群为蚁科和金龟子总科幼虫,常见类群8个。结果显示,短花针茅荒漠草原大型土壤动物群落具有温带草原土壤动物群落的基本特征。在荒漠化进程中,大型土壤动物群落优势类群(蚁科和金龟子总科幼虫)未发生变化,但群落总个体密度和类群数显著下降(P < 0.01, P < 0.01),群落香浓多样性、丰富度和均匀度降低(P < 0.01, P < 0.01, P < 0.05),群落结构趋于简单。不同荒漠化生境土壤动物群落显示出明显的退化梯度,各土壤动物类群的分布揭示了它们对生境因子的偏好和响应模式的差异。短花针茅草原荒漠化对土壤动物垂直分布的影响具有由个体到类群、由表土层到下层的变化规律,但未改变土壤动物分布的表聚性。荒漠化导致的食物资源减少是蚁科动物个体密度变化的主要原因,轻度荒漠化(Ⅱ)最适宜蚁科动物生存,土壤全氮、有机质和地上生物量对步甲科和象甲科幼虫个体密度影响较大,重度荒漠化(Ⅳ)和极重度荒漠化(Ⅴ)生境将严重影响步甲科和象甲科幼虫的生存,但对金龟子总科和蜘蛛目动物个体密度影响不大。土壤动物与生境因子、生境及荒漠化进程之间的关系综合反应了草地生态系统退化过程。 Abstract:Soil fauna is an important component of grassland ecosystems and plays a key role in maintaining the stability of ecosystem structure and functioning. Studying the response of soil fauna to desertification may reveal the ecological linkage between aboveground and belowground processes, and improve our understanding of the ecological consequences of desertification. A survey of the soil macrofauna community was conducted by hand sorting at No-desertification(Ⅰ), Light-desertification(Ⅱ), Moderate-desertification(Ⅲ), Heavy-desertification(Ⅳ), and Extreme-desertification(Ⅴ) habitats in Stipa breviflora steppe. A total of 25 fauna groups belonging to 6 orders, 2 classes and 1 phylum were found. The dominant groups were Formicidae and Scarabaeidae larvae with 8 common groups. Soil macrofauna communities in the Stipa breviflora steppe were similar to those in other areas in temperate prairies. As desertification progressed, the dominant groups(Formicidae and Scarabaeidae larvae) did not change. However, the structure of soil macrofauna communities became simpler with total individual density and number of soil animal groups(P < 0.01, P < 0.01),biodiversity(P < 0.01),richness(P < 0.01)and evenness indices(P < 0.05) decreasing significantly. Soil fauna communities and soil animal groups in different habitats along a degradation gradient showed different preferences and responses to habitat factors. Desertification in the Stipa breviflora steppe affected the vertical distribution of soil fauna, with first affected individuals and then groups. The first effects were seen in the top layers and later in the deeper layers of the soil, but the highest faunal abundances were found in the top soil layers. The Light-desertification(Ⅱ) habitat was most preferred by the Formicidae, but food shortage resulting from desertification led to a decrease in Formicidae abundance. Soil total nitrogen, organic matter and aboveground dry biomass were the main factors affecting individual densities of Carabidae and Curculionidae larvae, which did not survive in Heavy-desertification(Ⅳ) and extreme-desertification(Ⅴ) habitats. Desertification had little effect on the total individual density of Scarabaeidae and Araneida. The degradation of grassland ecosystems was reflected by the relations among soil fauna, habitat factors, and desertification. 参考文献 相似文献 引证文献

Effect of Pre-emergence Herbicides on Weeds, Nodulation and Yield of Cowpea [&amp;lt;i&amp;gt;Vigna unguiculata&amp;lt;/i&amp;gt; (L.) WALP.] at Haik and Mersa in Wollo, Northern Ethiopia

The experiment was conducted at Mersa and Haik, northern Ethiopia during the 2014 main cropping season to assess the effect of pre-emergence s-metolachlor and pendimethalin on nodulation, and yield of cowpea. There were 12 treatments comprising: s-metolachlor (1.0, 1.5 and 2.0 kg ha-1); pendimethalin (1.0, 1.3 and 1.6 kg ha-1), s-metolachlor at 1.0 kg ha-1 + hand weeding at 5 weeks after crop emergence (WAE), pendimethalin at 1.0 kg ha-1 + hand weeding at 5 WAE, one hand weeding at 2 WAE, two hand weeding at 2 and 5 WAE, weed free and weedy checks. The treatments were arranged in randomized complete block design with three replications. The minimum weed dry weight was registered with the application 2.0 kg ha-1 of s-metolachlor at both locations; however, at 55 DAE and at harvest, weeds accumulated significantly lower dry weight due to s-metolachlor 1.0 kg ha-1 and pendimethalin 1.0 kg ha-1 each pendimethalin superimposed with hand weeding at both locations. The interaction of location with weed management practices was significant on number and dry weight of nodules, number of pods plant-1, grain and aboveground dry biomass yield and yield loss. The maximum grain yield (4277 kg ha-1) was obtained in complete weed free treatment at Mersa which was statistically in parity with complete weed free and two hand weeding treatments at Haik and Mersa, respectively. Due to weed infestation throughout the crop growth, the highest yield loss (70.8%) was recorded at Haik while it was 47.5% at Mersa.

QTL mapping of seedling traits in cucumber using recombinant inbred lines

AbstractSeedling traits are important for development, flower bud differentiation, fruit production and fruit quality of cucumber (Cucumis sativus L.). In this study, 160 recombinant inbred lines (RILs), derived from crossing wild cucumber inbred line PI 183967 (C. sativus var. hardwickii) with ‘931’ northern China cultivated cucumber inbred line 931, were employed to identify quantitative trait loci (QTLs) of cotyledon length (Cl), cotyledon width (Cw), hypocotyl length (Hl), first true leaf length (Fll), first true leaf width (Flw), aboveground fresh biomass (Afb) and aboveground dry biomass (Adb) at seedling stage. A genetic map including 307 SSR markers was developed which spanned 993.3 cM, with an average genetic distance of 3.23 cM between adjacent markers. 36 QTLs associated with the seven traits were detected on chromosomes 1, 2, 3, 5 and 6 in four environments (spring and autumn of 2012 and 2013), explaining 6.1 to 23.6% of the observed phenotypic variations. Among the 36 QTLs, 21 were responsible for more than 10% of observed phenotypic variations. We obtained 2, 2, 1 and 3 QTL loci for the traits of Fll, Flw, Afw and Adw, respectively. In addition, genes in the genetic region spanned by SSR15321‐SSR07711 on chr. 5 may contribute to Flw, Afw and Adw.

Assessment of an Impact of Mechanical Regulation on Selected Morphometric and Productive Parameters of Invasive Species Solidago Canadensis Population in Agricultural Land

Abstract Repeated mowing is considered as one of the effective control methods against species of the genus Solidago. This paper evaluates the impact of the repeated mowing on selected morphometric and productive characteristics of the invasive neophyte Solidago canadensis in the district of Rimavská Sobota in Central Slovakia. Permanent research plots (PRPs) were established within anthropogenic habitat on an abandoned land that was divided into two variants. In the first variant, the mechanical regulation - mowing was applied. The second variant was without the regulation. The mechanical regulation of the populations was carried out in June and August during the growing season 2011. The results showed that the mechanical regulation did not have a clear impact on the population density. The decreasing trend of the number of shoots within the mowed variant was found only in one research plot (PRP3). The other plots showed an increase in the number of individuals by 2.7 and 32.7% between the mowings. Statistically highly significant differences in terms of the mowing impact on the height of the individuals were found in all PRPs. The difference in the weight of dry aboveground biomass between the mowings was 221.87 g, which represents 36.41%. Double the difference (48.8%) was recorded in the dry weight of the underground biomass in the regulated stand compared with the unregulated stand (165.1 and 322.5 g/m2, respectively). Although there was a short-term success achieved by the application of the two mowings during the growing period, the pursued objective was not reached.

The effect of N fertilizer rates on agronomic parameters, yield components and yields of maize grown on Alfisols of North-western Ethiopia

Nitrogen is the most limiting nutrient for crop growth and development; and as in most soils of Ethiopia, the soils of the study area are deficient in nitrogen. Therefore, the objective of this research was to study the effects of mineral N fertilizer rates on agronomic parameters, yield components and yields of maize grown on Alfisols of Northwestern Ethiopia. Analysis of variance indicated no significant variation among treatments (p > 0.05) in plant height, shelling percentage and 1000-grain weight. However, nitrogen fertilizer rates significantly (p < 0.05) affected kernel number per ear and number of ears per plant. All the yield parameters have also shown a significant increase up to the rate of 90 kg N ha−1. Increasing the N rate from 90 to 200 kg N ha−1, however, did not give a significant grain, dry stubble and dry aboveground biomass yields increase. The MRR analysis showed that the treatment with N fertilizer rate of 60 kg N ha−1 gave the highest MRR of 256.7 % followed by the treatment with N fertilizer rate of 90 kg N ha−1. From the results of the study it is possible to conclude that application of nitrogen fertilizer improves yield and yield components of maize. Moreover, judicious nutrient management in maize could ensure high grain yield production and profit. Application of 60 kg N ha−1 gave maximum profit from unit investment which can be recommended for the study area.

Regrowth patterns and rosette attributes contribute to the differential compensatory responses of Arabidopsis thaliana genotypes to apical damage.

A plant's compensatory performance refers to its ability to maintain or increase its reproductive output following damage. The ability of a plant to compensate depends on numerous factors including the type, severity, frequency and timing of damage, the environmental conditions and the plant's genotype. Upon apical damage, a cascade of hormonal and genetic responses often produces dramatic changes in a plant's growth, development, architecture and physiology. All else being equal, this response is largely dependent on a plant's genotype, with different regrowth patterns displayed by different genotypes of a given species. In this study, we compare the architectural and growth patterns of two Arabidopsis thaliana genotypes following apical damage. Specifically, we characterise regrowth patterns of the genotypes Columbia-4 and Landsberg erecta, which typically differ in their compensation to apical meristem removal. We report that Landsberg erecta suffered reductions in the number of stems produced, maximum elongation rate, a delay in reaching this rate, lower average rosette quality throughout the growing period, and ultimately, less aboveground dry biomass and seed production when damaged compared to undamaged control plants. Columbia-4 had no reductions in any of these measures and maintained larger rosette area when clipped relative to when unclipped. Based on the apparent influence of the rosette on these genotypes' compensatory performances, we performed a rosette removal experiment, which confirmed that the rosette contributes to compensatory performance. This study provides a novel characterisation of regrowth patterns following apical damage, with insights into those measures having the largest effect on plant performance.

Comparison Of Energy Sources Grown On Agricultural Land

Abstract The aim of the paper is to compare biomass production of energy plants and selected crops grown on arable land in the south-western Slovakia in 2007–2014, its energy value and the influence of decisive climatic factors on the size of the production. The data on yields of dominant crops grown in the agricultural farm were obtained from the statistical data of the farm. Aboveground biomass of willows and poplars was harvested at the end of the harvest cycle. Aboveground biomass of Miscanthus sinensis was harvested in 2010–2014, always in early spring period of the following year. Winter wheat, spring barley and maize grown for silage during the period 2007–2014 provided the lowest yields in 2010 and the highest in 2011 and 2014. The highest energy value was obtained from maize in 2014 (400.66 GJ ha−1). The short rotation coppice poplars of Italian provenance yielded biomass with energy value of 951.68 GJ ha−1 year−1 at the end of the first three-year harvest cycle in 2012. The analysis of variance confirmed that there are highly significant statistical differences in the poplar biomass yield among the varieties and individual experimental years. The fast growing willows of Swedish provenance provided aboveground biomass energy value of 868.88 GJ ha−1 year−1 at the end of the first four-year harvest cycle in 2011. The biomass production of the perennial grass Miscanthus sinensis, depending on the growing period, can be expressed by a polynomial trend function. The highest biomass production was obtained in the third growing period (2012). At the end of the fifth growing period (2014), the yield amounted to 28.60 t ha−1 of the dry aboveground biomass. The energy value of the aboveground biomass of Miscanthus reached 486.20 GJ ha−1 in 2014. Differences in the biomass yield of the Miscanthus genotypes are statistically highly significant in each of the monitored growing periods. The growth and production process of the selected energy species reflect the specificities of soil and climatic conditions of the individual growing periods, as well as the ability of individual species and varieties to provide biomass production in the given conditions. Regression analysis of the produced aboveground biomass of the crops grown in the Kolíňany cadastre has not confirmed a statistical dependence in selected climatic parameterss.

Crop water productivity and economic evaluation of drip-irrigated soybeans (Glyxine max L. Merr.)

Effective management of water under irrigated agriculture is crucial to ensure food security. One crop that has high irrigation economic potential at local and international scales is soybean. This article presents the outcome of field experiments conducted in the dry seasons of 2013 and 2014 in Nigeria on the effects of deficit irrigation (DI) practices on reproductive stages of soybean. The experimental factor was the timing of irrigation. The five treatments were full irrigation (FI); skipping of irrigation every other week during flowering; pod initiation; seed filling and maturity stages.The crop was planted in a randomized complete block design with three replicates and inline drip irrigation was used to apply water. Leaf area index, dry above-ground biomass and seed yield were measured and the soil water balance approach was used to determine seasonal crop water use. Seasonal crop water use for the treatment in which deficit irrigation was imposed at seed filling stage was 364 mm while for the control treatment with full irrigation, seasonal crop water use was 532 mm. The seed yield reduced by 18.8 and 21.9% when DI was imposed during flowering and pod initiation, respectively. Similarly, the seed yield reduced by 24.4 and 47.9% when DI was imposed during maturity and seed filling. Water productivity (WP) reduced by 6.8 and 12.4% when DI was used during flowering and pod initiation, respectively. However, WP reduced by 20 and 35% during maturity and seed filling. DI during reproductive stages reduced economic water productivity by 6.7–35% while revenue was reduced by 18.5–47.7%. Full irrigation should be practiced to maximize water productivity. Weekly skipping of irrigation during seed filling will substantially reduce the seed yield and water productivity while skipping during flowering may be a viable option when water is scarce and land is not limiting. Economic evaluation will guide policy makers at basin scales for formulating improved and efficient water management plans under all varying weather conditions. DI can be used to optimise water productivity. The results will be beneficial in adopting deficit irrigation in a manner that will improve economic water productivity.

Satellite and in situ derived corn and soybean biomass and leaf area index: Response to controlled tile drainage under varying weather conditions

Controlled tile drainage (CTD) has environmental and crop production benefits, but the effects of CTD on crop growth under varying weather conditions is not well-documented. This study evaluates the responsiveness of field-scale corn and soybean growth from CTD and uncontrolled tile drainage (UCTD) under varying seasonal temperature and rainfall in eastern Ontario, Canada. Leaf area index (LAI) and total above-ground dry biomass were used as crop growth indicators and were estimated from in situ data and satellite imagery between 2005 to 2013. Corn LAI from CTD fields was maintained or significantly higher relative to the LAI from UCTD fields, in 92% of all site-years; corn biomass from CTD fields was also maintained or significantly higher in all site-years of the study in which it was determined. For soybean, LAI from CTD fields was maintained or significantly higher in 67% of the site-years; biomass from CTD fields was maintained in all site years in which it was determined. Higher water tables and soil water contents, and slightly higher groundwater nitrogen concentrations in CTD fields, may explain these responses. Cohen’s d effect size of satellite derived LAI ([Mean CTD LAI−mean UCTD LAI]/pooled standard deviation) for corn was negatively related to total May–August precipitation indicating a stronger CTD effect with a decrease in precipitation. In contrast to the corn results, Cohen’s d of satellite-derived LAI for soybeans was positively related to total May–August (and especially May–July) precipitation, indicating a stronger CTD effect with an increase in precipitation. Results herein could be used to help inform how to optimize the use of growing season CTD for different crops in order to enhance crop growth properties.

Cryptomeria japonica D. Don trees shoot biomass partitioning in a stand located in southeastern Paraná

The purpose of this study was to evaluate the partitioning of individual dry aboveground biomass in Cryptomeria japonica trees, as on its compartments as well as in the vertical profile, and examine whether the Pipe Model Theory, which states a rule between the plant organs, applies to the present case. Data were collected in a plantation established in 1984 in Rio Negro - PR. Twenty representative trees of the population distributed by diameter class were felled and weighed in the field, and their dry biomass were analyzed according to horizontal layers of 5 m wide in the following biomass compartments: sapwood, heartwood, bark, branches and foliage. Biomass is mostly composed by the stem (73.67%). In the wood, 41.66% of the biomass corresponds to sapwood, 26.66% to heartwood and 5.35% to bark. The canopy accounts for 26.33% of the dry biomass, which is represented at 13.75% by branches and 12.58% by foliage. In the first five meters tree biomass is comprised exclusively of wood and bark. From 5 m crown begins to have partici­pation in biomass, becoming the major fraction from 15 m and above in the vertical profile. The partitioning of biomass in heartwood decreases along the vertical profile of the tree, i.e., it is largest at the base and smaller in the lower stratum. This study indicates that the Pipe Model Theory applies to the Cryptomeria japonica forest stand.

Impact of Sowing Date on Yield and Water Use Efficiency of Wheat Analyzed through Spatial Modeling and FORMOSAT-2 Images

Regional analysis of water use efficiency (WUE) is a relevant method for diagnosing the performance of irrigation systems in water-limited environments. In this study, we investigated the potential of FORMOSAT-2 images to provide spatial estimates of WUE over irrigated wheat crops cultivated within the semi-arid Yaqui Valley, in the northwest of Mexico. FORMOSAT-2 provided us with a unique dataset of 36 images at a high resolution (8 m) encompassing the wheat growing season from November 2007 to May 2008. Time series of green leaf area index were derived from these satellite images and used to calibrate a simple crop/water balance model. The method was applied over an 8 × 8 km2 irrigated area on up to 530 wheat fields. It allowed us to accurately reproduce the time courses of Leaf Area Index and dry aboveground biomass, as well as evapotranspiration and soil moisture. In a second step, we analyzed the variations of WUE as the ratio of accumulated dry aboveground biomass to seasonal evapotranspiration. Despite the study area being rather small and homogeneous (soil, climate), we observed a large range in wheat biomass production, from 5 to 15 t·ha−1, which was primarily related to the timing of plant emergence. In contrast, the seasonal evapotranspiration only varied from 350 to 450 mm, with no evident link with sowing practices. A significant gain in crop water productivity was found for the fields sown the earliest (maximal WUE around 3.5 kg·m−3) compared to those sown the latest (minimal WUE around 1.5 kg·m−3). These results demonstrated the value of the FORMOSAT-2 images to provide spatial estimates of crop production and water consumption. The detailed information provided by such high space and time resolution imaging systems is highly valuable to identify agricultural practices that could enlarge crop water productivity.

&lt;b&gt;Interference of weeds on seedlings of four neotropical tree species

Seasonal semideciduous forests in southeastern Brazil have experienced intensive fragmentation, and the interference of weeds may affect the dynamics of restored communities. The purpose of this study was to determine if there were specific densities of the weeds Urochloa decumbens and Ipomoea grandifolia at which the growth of seedlings of four Neotropical tree species – Senegalia polyphylla and Enterolobium contortisiliquum (Fabaceae) and Ceiba speciosa and Luehea divaricata (Malvaceae) – would be negatively affected. A randomized experimental design was conducted in a greenhouse, with five treatments to each tree species (different weed densities per pot per tree species) and four replicates per treatment. After the weeds flowered, the height and stem diameter of seedlings were quantified, including the aboveground dry biomass and the percentages of macro and micronutrients contents in the leaves. The growth of the tree seedlings was affected by the lowest weed density (two weeds per pot) when interacting with U. decumbens or I. grandifolia. In general, significant decreases in the percentage of macro and micronutrients in the leaves were observed, especially at eight weeds/pot. Such results could warrant experimental practices in chemical control in conjunction with alternative methods to control of these two weeds in restored areas.