The Effect of Salinity on Root Architecture in Forage Pea (Pisum sativum ssp. arvense L.)

Background: Plants face different abiotic stresses such as salinity that affect their normal development, growth and survival. Forage pea is an important legume crop for herbage production in ruminants. Its agronomy requires high levels of irrigation and fertilization. This study aimed to evaluate the effect of salinity on seedling root system development in forage pea under semi-hydroponics conditions.Methods: Different treatment of NaCl doses (0, 50, 100, 150, 200, 250 and 300 mM) on root architecture was investigated in two different forage pea cultivars (Livioletta and Ulubatlý) with contrasting root structures under controlled conditions. The experimental design was completely randomized design with three replications and nine plants per replication.Result: Salinity affects root and shoot development differently on these cultivars. Despite the salinity, Livioletta produced more shoot (0.71 g) and root biomass (0.30 g) compared to Ulubatlý (0.52 g and 0.25 g for Root and Shoot biomass, respectively) at 150 mM and all other salinity levels. Livioletta developed a better root system and tolerated salt to a higher dose than Ulubatlý. Understanding root system responses of forage pea cultivars may allow breeding and selecting salinity tolerant cultivars with better rooting potential.

Rice Plant–Soil Microbiome Interactions Driven by Root and Shoot Biomass

Plant–soil microbe interactions are complex and affected by many factors including soil type, edaphic conditions, plant genotype and phenotype, and developmental stage. The rice rhizosphere microbial community composition of nine recombinant inbred lines (RILs) and their parents, Francis and Rondo, segregating for root and shoot biomass, was determined using metagenomic sequencing as a means to examine how biomass phenotype influences the rhizosphere community. Two plant developmental stages were studied, heading and physiological maturity, based on root and shoot biomass growth patterns across the selected genotypes. We used partial least squares (PLS) regression analysis to examine plant trait-driven microbial populations and identify microbial species, functions, and genes corresponding to root and shoot biomass as well as developmental stage patterns. Species identified correlated with increases in either root or shoot biomass were widely present in soil and included species involved in nitrogen cycling (Anaeromyxobacter spp.) and methane production (Methanocella avoryzae), as well as known endophytes (Bradyrhizobium spp.). Additionally, PLS analysis allowed us to explore the relationship of developmental stage with species, microbial functions, and genes. Many of the community functions and genes observed during the heading stage were representative of cell growth (e.g., carbohydrate and nitrogen metabolism), while functions correlated with physiological maturity were indicative of cell decay. These results are consistent with the hypothesis that microbial communities exist whose metabolic and gene functions correspond to plant biomass traits.

Biotreatment of pyrene and Cr(VI) combined water pollution by mixed bacteria

Pyrene and chromium (Cr(VI)) are persistent pollutants and cause serious environmental problems because they are toxic to organisms and difficult to remediate. The toxicity of pyrene and Cr(VI) to three crops (cotton, soybean and maize) was confirmed by the significant decrease in root and shoot biomass during growth in pyrene/Cr(VI) contaminated hydroponic solution. Two bacterial strains capable of simultaneous pyrene biodegradation and Cr(VI) reduction were isolated and identified as Serratia sp. and Arthrobacter sp. A mixture of the isolated strains at a ratio of 1:1 was more efficient for biotreatment of pyrene and Cr(VI) than either strain alone; the mixture effectively carried out bioremediation of contaminated water in a hydroponic system mainly through pyrene biodegradation and Cr(VI) reduction. Application of these isolates shows potential for practical microbial remediation of pyrene and Cr(VI) combined water pollution.

The Response of Red Clover (Trifolium pratense L.) to Separate and Mixed Inoculations with Rhizobium leguminosarum and Azospirillum brasilense in Presence of Polycyclic Aromatic Hydrocarbons

This study aimed to evaluate the impact of co-inoculation Rhizobium sp. and Azospirillum sp. on plant (Trifolium pratense L.) growth in the presence of polycyclic aromatic hydrocarbon (PAH) contamination (anthracene, phenanthrene, and pyrene). Eight strains from the genus Rhizobium leguminosarum bv. trifolii were selected for biotest analysis. Two methods of inoculation were used in the chamber experiment: (1) R. leguminosarum alone and (2) a combined inoculant (R. leguminosarum and Azospirillum brasilense). For comparison, non-contaminated controls were also used. The results demonstrated that co-inoculation of plants with Rhizobium and Azospirillum resulted in more root and shoot biomass than in plants inoculated with R. leguminosarum alone. The results indicated that application of a co-inoculation of bacteria from Rhizobium and Azospirillum species had a positive effect on clover nodulation and growth under the condition of PAH contamination.

Dissection of quantitative trait loci for root characters and day length sensitivity in SynOpDH wheat (Triticum aestivum L.) bi-parental mapping population

The genetics of the root system is still not dissected for wheat and lack of knowledge prohibits the use of marker-assisted selection in breeding. To understand the genetic mechanism of root development, Synthetic W7984 × Opata M85 doubled-haploid (SynOpDH) mapping population was evaluated for root and shoot characteristics in PVC tubes until maturity. Two major quantitative trait loci (QTLs) for total root biomass were detected on homoeologous chromosomes 2A and 2D with logarithm of the odds scores between 6.25–10.9 and 11.8–20.86, and total phenotypic effects between 12.7–17.7 and 26.6–40.04% in 2013 and 2014, respectively. There was a strong correlation between days to anthesis and root and shoot biomass accumulation (0.50–0.81). The QTL for biomass traits on chromosome 2D co-locates with QTL for days to anthesis. The effect of extended vegetative growth, caused by photoperiod sensitivity (Ppd) genes, on biomass accumulation was always hypothesized, this is the first study to genetically support this theory.

Root and Shoot Biomass Growth of Constructed Floating Wetlands Plants in Saline Environments

Constructed Floating Wetlands (CFWs) are increasingly being used globally in freshwater environments such as urban lakes and ponds to remove pollutants from urban stormwater runoff. However, to date there has been limited research into the use and performance of these systems in saline environments. This study compared the root and shoot biomass growth and nutrient uptake of five different plant species, Chrysopogon zizanioides, Baumea juncea, Isolepis nodosa, Phragmites australis and Sarcocornia quinqueflora, in three different saltwater treatments over a 12-week period. The aim of the study was to identify which of the plant species may be most suitable for use in CFWs in saline environments. Plant nutrient uptake testing revealed that Phragmites australis had the greatest percentage increase (1473–2477%) of Nitrogen mass in the shoots in all treatments. Sarcocornia quinqueflora also had impressive Nitrogen mass increase in saltwater showing an increase of 966% (0.208 ± 0.134 g). This suggests that the use of Phragmites australis and Sarcocornia quinqueflora plants in CFWs installed in saline water bodies, with regular harvesting of the shoot mass, may significantly reduce Nitrogen concentrations in the water. Isolepis nodosa had the greatest percentage increase (112% or 0.018 ± 0.020 g) of Phosphorous mass in the shoots in the saltwater treatment. Baumea juncea had the greatest percentage increase (315% or 0.026 ± 0.012 g) of Phosphorous mass in the roots in the saltwater treatment. This suggests that the use of Isolepis nodosa and Baumea juncea plants in CFWs installed in saline water bodies may significantly reduce Phosphorous concentrations in the water if there was a way to harvest both the shoots above and the roots below the CFWs. The study is continuing, and it is anticipated that more information will be available on CFW plants installed in saline environments in the near future.

Green Roof Substrate Composition Affects Phedimus kamtschaticus Growth and Substrate Water Content under Controlled Environmental Conditions

Phedimus kamtschaticus (Fischer) were grown in three experimental crushed brick-based green roof substrates (GRSs) with increasing organic matter (OM) content (10%, 20%, and 40% by volume) and a commercially available blend, Rooflite®, in single-pot replicates in a growth chamber for 6 months. Three unplanted replicates of each substrate were included in the design and received identical irrigation volumes as planted replicates. Three destructive harvests indicated that increased substrate OM increased plant root and shoot biomass; however, plants grown in Rooflite® demonstrated greater succulence in the second and third destructive harvests despite similar substrate OM content. By the end of the growth study, there was no difference in dry weight accumulation between the Rooflite® and 40% OM treatment despite the difference in succulence between the two treatments. Substrate volumetric water content (VWC) ranged from 22.5% to below 5% during three consecutive periods of imposed water stress with no differences in evapotranspiration (ET), indicating plants were accessing substrate water previously assumed to be unavailable. Cumulative water loss (normalized for plant dry weight) indicated a likely shift into crassulacean acid metabolism (CAM) around 60-hour postirrigation. Planted treatments (n = 6) lost more water cumulatively (P < 0.05) compared with the unplanted controls (n = 3), although there were no differences in total water loss between substrate treatments.

Growth and seed production of glyphosate-resistant giant ragweed (Ambrosia trifida L.) in response to water stress

The objectives of this study were to determine the effects of degree and duration of water stress on growth and seed production of glyphosate-resistant (GR) giant ragweed. The degree of water stress included giant ragweed response to 100%, 75%, 50%, 25%, and 12.5% of field capacity. The highest growth index (588 cm3) was achieved at 75% of field capacity with plants typically ≥125 cm tall and ≥57 leaves plant−1. Giant ragweed seed production was ≥55, 35, 20, and 5 seeds plant−1 at ≥75%, 50%, 25%, and 12.5% of field capacity, respectively. The study of duration of water stress included the response of giant ragweed to withholding water for 2, 4, 6, 8, and 10 d following 100% of field capacity. Water stress of 4 d or longer reduced giant ragweed plant height ≥20%, root and shoot biomass ≥66%, number of leaves ≥36%, growth index ≥54%, and seed production by 36% compared with 2 d of water stress. Results from this study indicate that giant ragweed can survive and produce seeds at 12.5% of field capacity or 10 d of water stress.

Effect of nitroxin and humic acid on yield and yield components of faba bean

Quality and quantity improvement of crops using organic matter and low-cost method in the field is very important. Bio-fertilizer nitroxin and humic acid can increase root and shoot biomass through improved intake of nutrition and they can lead to quality and quantity improvement of product. An experiment was carried out as a completely randomized block design with 4 treatments to study the effect of nitroxin and humic acid on faba bean (Vicia faba L.) traits. Trial treatments included control, nitroxin, humic acid and nitroxin + humic acid. Analysis of variance showed that the effect of combination of nitroxin + humic acid was significant (p< 1%) on some traits such as stem height and yield of faba bean. The highest yield (2,315 kg ha-1) was obtained under nitroxin + humic acid treatment.