Biomass Yield Components Research Articles

Genetic diversity for drought tolerance in the native forage grass Trichloris crinita and possible morpho-physiological mechanisms involved.

The use of drought tolerant genotypes is one of the main strategies proposed for coping with the negative effects of global warming in dry lands. Trichloris crinita is a native forage grass occupying extensive arid and semi-arid regions in the American continent, and used for range grazing and revegetation of degraded lands. To identify drought-tolerant genotypes and possible underlying physiological mechanisms, this study investigated drought tolerance in 21 genetically diverse T. crinita genotypes under natural field conditions. The accessions were grown under irrigated (control) and drought conditions for 84 days after initiation of the drought treatment (DAIDT), which coincided with flowering initiation. Various morpho-physiological traits were monitored, including total-, foliage-, and root biomass yield, dry matter partitioning to individual plant organs (roots, leaves, stems, and panicles), total leaf area, chlorophyll content, photochemical efficiency of photosystem II, stomatal conductance, and number of panicles per plant. Broad and significant variation (p<0.001) was found among the accessions for all the traits. Three highly tolerant and three very sensitive accessions were identified as the most contrasting materials, and their responses to drought stress were confirmed over two years of experiments. Under prolonged drought conditions (84 DAIDT), the tolerant accessions were generally more productive than the rest for all the biomass yield components analyzed, and this was associated with a postponed and more attenuated decrease in variables related to the plant photosynthetic activity, such as stomatal conductance, chlorophyll content, and photochemical efficiency. In contrast to previous findings, our data indicate no direct relationship between drought tolerance and the level of aridity in the accessions natural habitats, but rather suggest genetic heterogeneity and ample variation for drought tolerance in T. crinita natural populations derived from a particular location or environment. Also, having low total and forageable biomass yield, or increased biomass allocation to the roots (i.e., lower foliage/root ratio), under optimal water availability, were not associated with greater drought tolerance. The drought-tolerant accessions identified are of value for future genetic research and breeding programs, and as forage for range grazing and revegetation in arid regions.

Breeding Amaranth for Biomass: Evaluating Dry Matter Content and Biomass Potential in Early and Late Maturing Genotypes

Amaranth (Amaranthus spp.) is a promising biomass crop for silage and biogas production. Under long-day conditions, it exhibits prolonged vegetative growth. To evaluate the breeding potential of amaranth for biomass production, we characterized phenotypic variation in biomass yield components, quantitative genetic parameters, and the relationships between traits. We conducted field trials of 10 biomass-type genotypes exhibiting a ‘giant’ growth habit derived from spontaneous hybridization between genetically diverse parents, and used the variety “Bärnkrafft” as check. We observed two contrasting growth patterns: Bärnkrafft is a variety for grain production and was characterized by a short vegetative growth followed by a long seed ripening. In contrast, the biomass genotypes displayed a long vegetative growth followed by a short seed ripening. We observed strong correlations between dry matter content and stem diameter (r =−0.78, p &lt; 0.01) and between plant height and biomass score (r = 0.95, p &lt; 0.001). High values for broad-sense heritability of stem diameter (H2 = 0.88) and plant height (H2 = 0.92) suggest that the dry matter content and yield can be improved by indirect phenotypic selection. We hypothesize that selection for dry matter content and yield implies a trade-off between earliness and photoperiod sensitivity. Hence, dry matter content should be improved first by recurrent selection, which can be then combined with short-day genes to improve dry matter yield. Overall, this work provides an avenue to the breeding of biomass amaranth.

Genetic Variance and Correlation of Forage Yield and Quality Traits in Tropically Adapted Maize

Two F2 populations segregating for biomass yield and forage quality traits were developed from two separate crosses of tropically adapted maize inbred lines. The parental, F1 and F2 generations of both crosses were evaluated to estimate broad sense heritability, genetic advance and correlations for these traits to suggest the best traits as selection criteria towards breeding forage maize with high yield and quality.In Cross 1, biomass yield trait with the highest broad-sense heritability was plant height (70.03%), whereas forage quality trait with the highest heritability estimate was crude protein content (66.60%). Heritability estimates in Cross 2 were high for all biomass yield traits and forage quality traits (&gt;50% for all traits). Indigestible cell wall component represented by acid detergent lignin content was found to be highly heritable in both populations. High genetic advance as percent of mean were found for fresh and dry plant yield as well as for lignin content in both populations. Correlation analysis on all traits showed that all biomass yield components were significantly correlated. All traits related to cell wall content were positively correlated and acid detergent lignin was positively correlated with dry plant yield. Traits with high to moderate heritability and high predicted genetic advance, namely plant height, fresh plant yield and protein content can be used as selection criteria to improve maize biomass yield and nutritive quality for forage utilization. Selecting for higher biomass yield would also result in selecting individuals with higher lignin content as shown by the correlation analysis.

SSR marker analysis of plant height in sweet sorghum [Sorghum bicolor (L.) Moench

Sorghum (Sorghum bicolor (L.) Moench) is one of the most promising bio-energy crops with the ability to produce high biomass with low input. Plant height that has a significant contribution to gain in bio-ethanol production is among the most important biomass yield components. In the present study, sorghum genotypes were screened with four SSR markers which are associated with plant height QTLs. The molecular assays were confirmed with two different environments in two consecutive years. In the first year of the study, molecular analyses were performed with a sorghum collection consisting of 551 accessions as well as plant height measurements were performed under field condition. In the second year, 53 out of 551 accessions were selected and further tests with nine controls were performed in Antalya (a lowland province) and Konya (a highland province) locations along with molecular marker analyses. The results indicated that four SSR markers efficiency were assessed as 38% at lowland and 39% at highland. Markers 40-9187 and 37-1740 were of more powerful to explain plant height QTLs than the other two markers at two environments. This study reported the successful application of the association between markers and plant height in two environments to identify valuable genetic resources for bio-energy production in sweet sorghum.

Functional Analysis of the teosinte branched 1 Gene in the Tetraploid Switchgrass (Panicum virgatum L.) by CRISPR/Cas9-Directed Mutagenesis.

Tillering is an important biomass yield component trait in switchgrass (Panicum virgatum L.). Teosinte branched 1 (tb1)/Branched 1 (BRC1) gene is a known regulator for tillering/branching in several plant species; however, its role on tillering in switchgrass remains unknown. Here, we report physiological and molecular characterization of mutants created by CRISPR/Cas9. We successfully obtained nonchimeric Pvtb1a and Pvtb1b mutants from chimeric T0 mutants using nodal culture. The biallelic Pvtb1a-Pvtb1b mutant plants produced significantly more tillers and higher fresh weight biomass than the wild-type plants. The increased tiller number in the mutant plants resulted primarily from hastened outgrowth of lower axillary buds. Increased tillers were also observed in transgene-free BC1 monoallelic mutants for either Pvtb1a-Pvtb1b or Pvtb1b gene alone, suggesting Pvtb1 genes act in a dosage-dependent manner. Transcriptome analysis showed 831 genes were differentially expressed in the Pvtb1a-Pvtb1b double knockdown mutant. Gene Ontology analysis revealed downregulation of Pvtb1 genes affected multiple biological processes, including transcription, flower development, cell differentiation, and stress/defense responses in edited plants. This study demonstrates that Pvtb1 genes play a pivotal role in tiller production as a negative regulator in switchgrass and provides opportunities for further research aiming to elucidate the molecular pathway regulating tillering in switchgrass.

Biomass yield components for 12 switchgrass cultivars grown in Northern China

Switchgrass (Panicum virgatum L.) has been developed into a major herbaceous bioenergy crop for the production of cellulosic biofuels in North America and many counties in European. As cultivar selection has a major impact on the ultimate biomass productivity, we evaluated the adaptability and yield potential of 12 switchgrass cultivars including both upland and lowland ecotypes from 2010 to 2013 in the Beijing region, Northern China. Plant height was measured after anthesis, but phytomer number and tiller density were investigated at harvest. One single autumn harvest was carried out each year and biomass yields were determined. It was found that the lowland cultivars ‘Alamo’, ‘Kanlow’ and ‘NewYork’ produced the most biomass for their better performances in number of phytomers per tiller and mass per phytomer, though upland cultivars had higher tiller density. ‘Cave-in-rock’ and ‘Trailblazer’ had better biomass production among the upland cultivars and they were also recommended for planting together with lowland ones for their excellent cold tolerance in this region.

Identification of Quantitative Trait Loci Conditioning the Main Biomass Yield Components and Resistance to Melampsora spp. in Salix viminalis × Salix schwerinii Hybrids.

The biomass of Salix viminalis is the most highly valued source of green energy, followed by S. schwerinii, S. dasyclados and other species. Significant variability in productivity and leaf rust resistance are noted both within and among willow species, which creates new opportunities for improving willow yield parameters through selection of desirable recombinants supported with molecular markers. The aim of this study was to identify quantitative trait loci (QTLs) linked with biomass yield-related traits and the resistance/susceptibility of Salix mapping population to leaf rust. The experimental material comprised a mapping population developed based on S. viminalis × S. schwerinii hybrids. Phenotyping was performed on plants grown in a field experiment that had a balanced incomplete block design with 10 replications. Based on a genetic map, 11 QTLs were identified for plant height, 9 for shoot diameter, 3 for number of shoots and 11 for resistance/susceptibility to leaf rust. The QTLs identified in our study explained 3%–16% of variability in the analyzed traits. Our findings make significant contributions to the development of willow breeding programs and research into shrubby willow crops grown for energy.

Accumulation and partitioning of biomass, nutrients, and trace elements in switchgrass for phytoremediation of municipal biosolids

ABSTRACTIn situ phytoremediation of municipal biosolids is a promising alternative to the land spreading and landfilling of biosolids from end-of-life municipal lagoons. Accumulation and partitioning of dry matter, nitrogen (N), phosphorus (P), and trace elements were determined in aboveground biomass (AGB) and belowground biomass (BGB) of switchgrass (Panicum virgatum L.) to determine the harvest stage that maximizes phytoextraction of contaminants from municipal biosolids. Seedlings were transplanted into 15-L plastic pails containing 3.9 kg (dry wt.) biosolids. Biomass yield components and contaminant concentrations were assessed every 14 days for up to 161 days. Logistic model fits to biomass yield data indicated no significant differences in asymptotic yield between AGB and BGB. Switchgrass partitioned significantly more N and P to AGB than to BGB. Maximum uptake occurred 86 days after transplanting (DAT) for N and 102 DAT for P. Harvesting at peak aboveground element accumulation removed 5% of N, 1.6% of P, 0.2% of Zn, 0.05% of Cd, and 0.1% of Cr initially present in the biosolids. These results will contribute toward identification of the harvest stage that will optimize contaminant uptake and enhance in situ phytoremediation of biosolids using switchgrass.

Field-based Robotic Phenotyping for Sorghum Biomass Yield Component Traits Characterization Using Stereo Vision

Abstract: Sorghum is known as a major potential feedstock for biofuel production. Being able to efficiently discover genetic control of many traits over a large number of genotypes, genome-wide association study (GWAS) has become a powerful tool for studying sorghum biomass yield components. However, automated high-throughput field-based plant phenotyping is now the bottleneck for scaling up such experiments. This paper presents an auto-guidance enabled utility tractor which navigates itself between crop rows with a predefined path while collecting stereo images of sorghum samples from both sides of the vehicle. Three levels of stereo camera heads were instrumented to capture images of plants up to 3 meters tall. The stereo images were processed offline to reconstruct 3D point clouds using Semi-Global Block Matching. A semi-automated software interface was developed to measure stem diameter due to the strict sampling strategy and the complexity of high-density crop canopy. An automated hedge-based feature extraction pipeline was proposed to quantify other variations in plant architecture traits such as plant height, leaf area index (LAI) and vegetation volume index (VVI). The stem diameter measured using the semiautomatic method showed high correlation (0.958) to hand measurement.

Dynamics of yield components and stevioside production in Stevia rebaudiana grown under different planting times, plant stands and harvest regime

Stevia rebaudiana (Bertoni) Bertoni is well known because of its accumulation of the sweet-tasting ent-kaurene diterpeneoid glycoside, which tastes about 300 times as sweet as sucrose. Although stevioside is one of the most abundant and best analyzed, more than 30 additional steviol glycosides so far have been identified and described. Stevioside concentration in the leaves is known to vary widely, depending on the growing conditions and agricultural practices. The present study aimed to examine the feasibility of growing Stevia as an open-field crop in Israel. In order to determine the agricultural practices required for optimizing Stevia biomass production and stevioside yield, effects of planting and harvest times upon plant development, biomass yield components, and stevioside content were examined. The optimal planting season, manifested in intensive plant development and maximal plant biomass yield, was at the beginning of spring, i.e., mid-March to early April. A minimal stand of 10 plants/m2 was found more favorable than lower stands of 6, 8, or 10 plants/m2′‘. The optimal harvesting time, with the highest stevioside yield of about 30g/m2 was at the beginning of September, prior to flowering initiation. Moreover, harvesting at this time yielded increased leaf biomass, highly suitable for commercial stevioside extraction. Thus, Stevia rebaudiana offers substantial potential for introduction as a commercial agricultural crop for stevioside production in Israel.

The effects of pigweed redroot (Amaranthus retoflexus) weed competition and its economic thresholds in corn (Zea mays)

The aim of this study was to determine the economic damage threshold of Pigweed redroot for corn regarding its density. An experiment was conducted at the Agriculture Research station of Islamic Azad University branch of Gonabad during 2006. The experiment was carried out as a factorial in a randomized complete block design with three replications. In the experiments, the factors included corn (var. 704) densities of 7.5, 8.5 and 9.5 plants m-2 and pigweed redroot densities of 0, 2, 4, 6 and 8 plants m-2. The increase in Pigweed redroot density, decrease in crop grain and biomass yield components such as ear length, ear diameter, number of grains per row, row number, grain number in ear, grain yield and biological yield of corn, decreased. Also, with an increase in corn density, the number of grain per rows, row number, grain yield and biological yield of corn increased. The economic thresholds density of Pigweed redroot was 0.09 to 0.13 plants m-2 in corn different densities, and increased with corn density increases.

Evaluation of the yield potential and physicochemical properties of the biomass of Salix viminalis × Populus tremula hybrids

This study presents the characteristics of four Salix viminalis×Populus tremula hybrids, produced for the first time in the world grown in a three-year field experiment. Shoot weight per plant and major biomass yield components, including plant height, number of shoots per rootstock and shoot diameter, were determined. The infection severity caused by leaf rust (Melampsora sp.) was also evaluated. The biomass of three-year-old hybrid plants was subjected to chemical analyses and calorimetric tests to determine the energy value of biomass as solid fuel. Among the studied genotypes the highest yield was achieved by one of the studied hybrids. Its biometric parameters did not differ significantly from the standard genotype, and they were superior to the parameters of the maternal form. All Salix×Populus hybrids were more susceptible to rust infections than their maternal form and one hybrid was more resistant to infections caused by fungi of the genus Melampsora. Two hybrids have optimal biomass parameters as regards both calorific value and amount of carbon, hydrogen, sulfur and nitrogen.

Genetic Variability and Trait Relationships in Switchgrass

Greater knowledge of the magnitude of genetic variability for biomass yield and yield components in switchgrass, Panicum virgatum L., and relationships among the biomass yield component traits would facilitate the breeding improvement of the species. Accordingly, we conducted two replicated experiments to assess genetic variation for biomass yield and yield components and quantify relationships among those traits in different switchgrass populations. In Exp. 1, 228 half‐sib families from SU C3 and 261 from NU C3 populations were evaluated at Perkins, OK, while 278 half‐sib families from the SL C0 population were evaluated at Stillwater, OK. Exp. 2 comprised 11 lowland switchgrass populations tested at Chickasha and Perkins, OK, in 1998. Substantial differences (P &lt; 0.01) in biomass yield per plant existed among half‐sib families within the respective SU C3, NU C3, and SL C0 populations. Estimates of genetic variance for biomass yield were significant for each population. However, significant family × year and family × block variance estimates indicated substantial environmental influence in each of the populations. In Exp. 2, significant (P ≤ 0.05) variation existed among the 11 populations over locations for biomass yield per plant, tiller number per plant, tiller length, leaf blade length, and leaf blade width. Phenotypic correlation between biomass yield and tiller number per plant was positive (r = 0.68* at Chickasha and r = 0.60* at Perkins). Path coefficient analyses revealed that number of tillers per plant had the highest positive direct effect on biomass yield at both locations (0.74 at Chickasha and 0.66 at Perkins). Adequate genetic variability was present within the switchgrass populations to allow breeding improvement of biomass yield. Selection for increased number of tillers per plant would be the most effective means of indirectly increasing biomass yield.

Biomass production of sugarcane cultivars and early-generation hybrids

Sugarcane ( Saccharum L. spp. hybrids) is a vegetatively-propagated, perennial crop cultivated primarily for sucrose production. The biomass production of interspecific and intergeneric hybrids is assumed to surpass that of cultivars, but there have been few statistical comparisons. The objectives of this study were to determine effects of plant-cane and ratoon crops on biomass yield components for two sugarcane cultivars and early-generation hybrid derivatives (Experiment 1), and to determine the effect of backcross breeding on biomass yield components (Experiment 2). Two cultivars and 47 hybrid derivatives (F 1-BC 2) were evaluated in replicated, single-row plots near Houma, Louisiana, for four annual harvests (Exp. 1). Thirty random clones from F 1, BC 1, BC 2, BC 3, and elite generations were evaluated in replicated single-rows in the plant-cane crop (Exp. 2). Fresh-weight biomass yield of one hybrid clone, US 74-69, was 307 Mg ha −1 (Exp. 1). Mean fresh-weight biomass yield of hybrids was nearly 50 Mg ha −1 yr −1 greater than that of cultivars ( P ≥ 0.05). Fresh-weight and dry-matter yields decreased linearly across crops (plant-cane through the fourth-ratoon crop) for cultivars, but there was no consistent trend for the early-generation hybrids. Backcrossing (F 1 through BC 3 generations) to elite parents resulted in a marked reduction of many important biomass yield components, including fiber concentration, solids concentration, and stalk number (Exp. 2). No backcross or elite progeny surpassed F 1 progeny in fresh-weight or dry-matter yields ha −1. This study confirmed that early-generation sugarcane hybrids have great potential for high biomass production. Biomass production might be improved in later-generation hybrids by selecting for stalk number and fiber concentration.