Higher Plant Biomass Research Articles

Exogenous application of gibberellic acid and silicon to promote salinity tolerance in pea (Pisum sativum L.) through Na+ exclusion

Salinity is a worldwide problem limiting the plant growth and risking food security. This study was conducted to examine exogenous application of silicon (Si), gibberellic acid (GA3) upon the ion transport, growth, yield, and antioxidant enzymes activities of pea plant in saline conditions. Two pea varieties Meteor-FSD and Samrina Zard were pre-treated with GA3 (10-4 M) for 12 h. Plants were allowed to grow with or without silicon in washed silica sand. Ten days old seedlings were shifted in pots with 10 kg soil. Twenty-five days old plants were exposed to 0 and 5 dS m−1 sodium stress. Results showed that exogenous application of GA3 + Si was the best treatment for increasing plant biomass and yield in the presence and absence of NaCl. Furthermore, application of Si or GA3 enhanced chlorophyll content in the leaves, thereby increasing the net assimilation rate of pea varieties under NaCl stress by increasing the antioxidant enzyme activity. Treatment of Si alone or in combination with GA3 significantly reduced Na+ movement in both pea varieties. Results showed that Si has more prominent role than GA3 alone to build-up high plant biomass, yield, soluble protein content and reduction of Na+ transport. Samrina Zard variety showed higher yield, shoot and root dry weight as compared to Meteor-FSD variety in presence and absence of salt. It was concluded that Si can be used as a nutrient for pea under saline or non-saline conditions. Moreover, application of GA3 has a potential role for increasing salinity tolerance, mostly in sensitive pea varieties.

Growth and Pb Uptake of Brassica campestris Enhanced by Two Ecological Earthworm Species in Relation to Soil Physicochemical Properties

A comprehensive understanding of the influence of earthworms on the growth and Pb accumulation of leafy vegetables is significant for soil management and human health. This study was aimed to evaluate the different influences of two ecological earthworm species on the growth and Pb accumulation of Brassica campestris in a Pb-contaminated soil and their relationship with soil physico-chemical properties. In a 30-day microcosm experiment, the anecic and native earthworm species Amynthas aspergillum and the epigeic species Eisenia fetida were inoculated in soil artificially contaminated with Pb at different levels (i.e., 0, 100, 500, and 1,000 mg kg−1), and B. campestris was grown. With a survival rate of 81%–100%, A. aspergillum was more tolerant to Pb contamination than E. fetida with 46%–84%. At the same time, earthworm inoculation significantly increased soil Pb bioavailability (p < 0.05). At the 500 and 1,000 mg kg−1 Pb levels, the treatments with earthworm inoculation showed higher plant biomass, leaf area, and chlorophyll concentration than the treatments without earthworm. The principal component analysis (PCA) showed that earthworm inoculation exerted a stronger effect on soil properties than Pb contamination, but the latter had a stronger effect on plant growth and Pb accumulation. Compared with A. aspergillum, E. fetida had a greater effect on soil cation exchange capacity, available Pb, and plant growth and Pb accumulation. In contrast, A. aspergillum had a greater effect on soil C and N contents than E. fetida. The co-inertia analysis revealed that plant Pb accumulation was positively correlated with soil available Pb and CEC. The leaf chlorophyll concentration was closely related to soil Eh, pH, and Dissolved organic carbon. The findings of this study showed that in the Pb-contaminated soils, earthworm inoculation exerted a strong effect on soil physicochemical properties and the growth and Pb accumulation of the leafy vegetable B. campestris. Both the epigeic earthworm species E. fetida and the anecic species A. aspergillum were associated with higher Pb accumulation or concentration in B. campestris, which may bring a possible risk to food security.

Weed cutting in a large river reduces ecosystem metabolic rates in the case of River Gudenå (Denmark)

Problems related to extensive macrophyte growth are widespread both in modified and man-made canals and streams, and in streams with natural morphology and rich vegetation. The weed cutting is a common management practice in order to reduce flood risk and enhance water conveyance. Although the short- and long-term impacts on the stream physical habitats and biota have been extensively studied, only little information exists on the effects of weed cutting on ecosystem metabolism, especially for larger rivers. This study aims to quantify effects of weed cutting on metabolic rates in a large lowland river in Denmark. We measured Gross Primary Production (GPP), Ecosystem Respiration (ER) and physical parameters (water depth, discharge, water velocity and reaeration rate) one week prior and 2–6 weeks after weed cutting in 2014 and 2020. Physical river conditions changed significantly after the removal of approximately 60% of macrophytic volume, and a significant reduction in water depth and increased water velocity was recorded. We found an immediate 38% and 61% reduction in GPP and 28% and 35% reduction in ER after weed cutting in 2014 and 2020 respectively. We also found that the metabolic rates did not recover to pre-weed cutting levels within 2–6 weeks after weed cutting. The higher decline in GPP compared to that in ER indicates that the heterotrophic contribution to ER was higher compared to the autotrophic contribution. Our results display that even in a large macrophyte-rich river, where only one-third of the channel is managed by weed cutting, GPP and ER can be reduced significantly. The cascade effects of metabolic rates alterations on ecosystem structure and functioning need to be considered in the future management plans, where higher plant biomass and increased flow is anticipated due to the ongoing climate change and thus, the demand for weed cutting might be intensified.

Soil Mineral Status, Plant Ionome and Agro-Morphological Traits of Schkuhria Pinnata (L.), An Antimalarial Herb: Implications for Cultivation

Background: Schkuhria pinnata L., is an antimalarial plant that is highly threatened by the destructive harvesting methods and its collection largely relies on wild sources, that are also exposed to over-exploitation and habitat destruction. Aim of the study: The study aimed at figuring out where S. pinnata grows best and what its growth requirements are; in order to promote the informed cultivation practices and soil selection as a viable alternative to wild harvesting. The agronomical soil nutrient status of S. pinnata, and how it relates to the agro-morphological traits and plant ionome, clues on fertiliser formulations for soils where S. pinnata does not shrive were reported. Methods: A randomised complete block design was employed in agronomical experimental plots in different agro-ecological zones that host Bushenyi, Ntungamo and Kasese districts. Standard procedures for soil and plant analysis were used to analyse soil physicochemical and plant ionome parameters while agro-morphological traits were physically evaluated. Results: Results demonstrated that soil physicochemical characteristics differed significantly across the study sites (p ≤.05). S. pinnata significantly performed better in slightly acidic to neutral soils (pH between 5.87-7.25) in Kasese than in other sites. S. pinnata harvested from Kasese had the largest total leaf area (mean = 31.43 ± 2.41cm2) and the highest plant biomass (mean = 7.65 ± 0.64 g). Conclusion: The study concluded that S. pinnata grew best in slightly acidic to neutral, sandy loam, non-saline soils of Kasese in Western Medium-High Farmland

Effects of Variety, Spacing and Nitrogen Application on Chickpea (Cicer arietinum) Growth and Yield in Embu County, Kenya

Chickpea is a pulse crop that is rich in proteins and helps in fulfilling the requirement of protein for vegetarian people thus yield maximization needed. This study aimed to determine the effects of spacing, nitrogen rates, and their interactive effects on the growth and productivity of the selected chickpea varieties. Field experiments were conducted at Mwea, Kenya between 2017 and 2018 involving four varieties (Saina K, Mwanza 2, Chaina I and Chaina III) at a spacing of 50x10cm, 50x20cm, and 50x30cm, and starter nitrogen-fertilizer application rates 0kg, 30kg, 60kg, and 90kg ha-1. A split-split plot design arranged in a 4x3x4 layout was used in the current study. Data related to plant height, biomass, grain yield, and harvest index were collected and subjected to statistical analysis by GLM in SAS 9.4 computer software. Variations occurred in measured traits like the height of crops (34.81-38.00cm), biomass yield (3.31 - 8.08t ha-1), seed yield (0.14 to 1.9t ha-1), and percent harvest index (5 - 45%) was reported. Mwanza 2 expressed the highest plant height, biomass, and grain yield. The highest plant biomass was obtained under 50x10cm spacing, while the highest grain yield weight was reported under 50x30cm spacing x 60kg N ha-1. From the results of the study, it can be concluded that the highest enhanced growth and productivity of chickpea were realized at interactions of Mwanza 2x50x10cmx90kg ha-1 nitrogen rate in the study area.

Resource recovery and freshwater ecosystem restoration — Prospecting for phytoremediation potential in wild macrophyte stands

The primary aim of this study was to understand the factors, e.g., harvest frequency and plant community type, that can facilitate optimising phytoextraction in wild macrophyte communities as part of a strategy for water-quality improvement and resource recovery. This was achieved by surveying wild macrophyte communities and quantifying standing stocks of key nutrient pollutants such as N and P, and a range of other recoverable macro and micro-nutrients (Ca, K, Mg, Cu, Fe, Mn, Mo, Zn, Na and Cr). By scaling-up the pollutant export potential over a decade, it was determined which harvest strategy and plant community types provide the greatest levels of nutrient export. Grime’s CSR plant strategy framework was used to categorise each surveyed community, where large-statured, higher biomass producing competitor and stress tolerator-type communities were compared with ruderal-type communities that have rapid growth and high nutrient acquisition but smaller standing biomass and statures. High biomass plant communities containing competitor or stress tolerator species, produce greater standing stocks of macronutrients (such as N and P) for harvesting, while yields of micronutrient-type pollutants are more likely to be influenced by specific physiological traits that determine leaf tissue concentration. Utilising a high frequency harvest regime over a multi-year time scale suggested that small fast-growing ruderals could yield 4–6 times the concentration of macronutrients and micronutrients for export compared to competitor or stress tolerator-dominated communities e.g., P yields from ruderals were 25 g/m2 versus 5 g/m2 from competitor/stress tolerator-dominated communities. These results emphasise the need to consider both the plant community and the harvesting regime when using phytoextraction as a management tool. We anticipate that these results will help guide environmental managers in their approach in developing circular economy schemes that improve water quality through nutrient export.

Phytoremediation of toxic heavy metals by Brassica plants: A biochemical and physiological approach

Contamination of soils and water bodies by toxic heavy metals (HMs) such as cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As), lead (Pb), and zinc (Zn), is a major environmental concern. Phytoremediation by botanical genus Brassica emerges as an important technique, in which plants are used to decontaminate these areas. Brassica spp. are reported as potential phytoremediators and hyperaccumulators our aim was to elucidate the physiological and biochemical potential use of different species belonging to the genus Brassica to bioremediate and tolerate the harmful effects of these environmental contaminants on their metabolism. Since these species display efficient phytoremediation processes, such as phytovolatilization, phytostabilization, and phytoextraction. These species also have physiological processes that aid the absorption, translocation, and accumulation of toxic HMs into low-activity cell organelles, in addition to an efficient enzymatic and non-enzymatic defense mechanism that attenuates the oxidative damage induced by the overproduction of reactive oxygen species (ROS). In addition to enzymatic and non-enzymatic mechanisms, our review also is an effort to gather the scattered information on other phytoremediation assistive techniques, such as the use of chelating and acidifying agents, selection of tolerant cultivars, and genetic engineering. Although techniques for the management and disposal of biomass obtained after the phytoremediation process are reported, this issue still lacks studies that present a consensus regarding which techniques are safer, more efficient, and economically viable. Phytoremediation of toxic HMs by Brassica species is, a promising technique, however, the need for further studies aimed at agronomic techniques that assist in high plant biomass production, tolerance and, structuring the hyperaccumulation network of these contaminants, so that their applicability and feasibility can be used for larger areas (cropping areas).

Post-termination Effects of Cover Crop Monocultures and Mixtures on Soil Inorganic Nitrogen and Microbial Communities on Two Organic Farms in Illinois

Cover crops can continue to affect agricultural systems even after they have been terminated by influencing nitrogen dynamics and by altering soil microbial communities. These post-termination effects can influence soil fertility, weed pressure, and the dynamics of potential plant pathogens in the narrow window of time between cover crop termination and cash crop emergence. We evaluated the post-termination effects of 12 different spring-sown cover crop mixtures and monocultures on soil nitrogen and microbial communities on two different organic farms in Central Illinois (on Lawson silt loam soil) and Northern Illinois (on Virgil silt loam soil). In comparison to control plots with no cover crops, all cover crop treatments significantly reduced soil nitrate levels but increased the potentially mineralizable nitrogen pool following termination. Nitrate levels of cover crop plots approached those of controls after 2 and 4 weeks, respectively, but potentially mineralizable nitrogen levels in cover plots remained elevated for at least 4 weeks following termination. Monocultures of Brassica cover crops showed the greatest decrease in soil nitrate, while Brassicas and unplanted control plots containing high biomass of weeds showed the greatest increase in potentially mineralizable nitrogen in comparison to plant-free control plots. In contrast to their effect on soil nitrogen, cover crops had very limited impact on the composition of soil microbial communities. Overall microbial community composition varied across sites and years, and only soil fungi significantly responded to cover cropping treatments. Nevertheless, we found that some highly correlated groups of soil microbes showed significant responses to soil nitrate and to high plant biomass. Key members of these correlated groups included ammonia-oxidizing organisms and saprotrophic fungi. Our results suggest that cover crops may reduce the potential for springtime nitrogen leaching losses by retaining nitrogen in the soil organic pool, and they may also have impacts on the soil microbial community that are particularly relevant for nitrogen cycling and decomposition of plant residues.

How and why grasshopper community maturation rates are slowing on a North American tall grass prairie.

Invertebrate growth rates have been changing in the Anthropocene. We examine rates of seasonal maturation in a grasshopper community that has been declining annually greater than 2% a year over 34 years. As this grassland has experienced a 1°C increase in temperature, higher plant biomass and lower nutrient densities, the community is maturing more slowly. Community maturation had a nutritional component: declining in years/watersheds with lower plant nitrogen. The effects of fire frequency were consistent with effects of plant nitrogen. Principal components analysis also suggests associated changes in species composition-declines in the densities of grass feeders were associated with declines in community maturation rates. We conclude that slowed maturation rates-a trend counteracted by frequent burning-likely contribute to long-term decline of this dominant herbivore.

Small-scale agricultural grassland management can affect soil fungal community structure as much as continental scale geographic patterns.

ABSTRACTA European transect was established, ranging from Sweden to the Azores, to determine the relative influence of geographic factors and agricultural small-scale management on the grassland soil microbiome. Within each of five countries (factor ‘Country’), which maximized a range of geographic factors, two differing growth condition regions (factor ‘GCR’) were selected: a favorable region with conditions allowing for high plant biomass production and a contrasting less favorable region with a markedly lower potential. Within each region, grasslands of contrasting management intensities (factor ‘MI’) were defined: intensive and extensive, from which soil samples were collected. Across the transect, ‘MI’ was a strong differentiator of fungal community structure, having a comparable effect to continental scale geographic factors (‘Country’). ‘MI’ was also a highly significant driver of bacterial community structure, but ‘Country’ was clearly the stronger driver. For both, ‘GCR’ was the weakest driver. Also at the regional level, strong effects of MI occurred on various measures of the soil microbiome (i.e. OTU richness, management-associated indicator OTUs), though the effects were largely regional-specific. Our results illustrate the decisive influence of grassland MI on soil microbial community structure, over both regional and continental scales, and, thus, highlight the importance of preserving rare extensive grasslands.

Influence of period of weed interference and age of pepper (Capsicum annuum L. cv. Cayenne pepper) seedlings on pepper fruit quality and marketability

The field trials were conducted in the early and late wet seasons of 2012 at the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria. The objective of the study was to evaluate influence of period of weed interference on fruit quality and marketability of pepper fruit under different seedling ages. Split-plot arrangement in a randomized complete block design with three replicates was adopted in the trials. The main plot treatments were ages of pepper seedlings at transplant, four and six weeks after sowing (WAS). Sub-plot treatments consisted of 10 periods of weed interference. Data collected on weed cover score, cumulative dry weed weight, dry plant biomass, number of leaves, fruit girth, fruit length, marketable fruit count and yield as well as non-marketable fruit count and yield were subjected to analysis of variance and treatment means were separated using least significant difference at p ≤ 0.05. The results showed that six week old pepper seedling had higher plant biomass, number of leaves and marketable fruit yield than the four week old. Also, pepper growth parameters, pepper fruit quality and marketability increased with weed free period and decreased with weed infestation period. Uncontrolled weed infestation for whole season caused 98.4% and 91.8% reduction in pepper marketability in the early wet and late wet season, respectively.

Bioprospecting aerobic rice (Oryza sativa) and mycorrhizal interaction for nutrient uptake and plant growth

With the growing concern of water scarcity in agriculture, aerobic rice (Oryza sativa L.) is a promising mode of cultivation for reducing water use, although the reduced optimal plant growth and yield are major constraints. Arbuscular mycorrhiza (AM) are known to readily colonize rice roots under aerobic conditions, however, the response of upland and lowland rice genotypes has not been investigated. This study was carried out during 2018-19 at ICAR-IARI, New Delhi, using a mycorrhizal consortium and percent colonization was observed to be higher by 58% in upland rice genotypes. AM- upland plants also showed 20% higher plant biomass. AM colonization significantly enhanced rice growth under aerobic conditions, with the upland rice genotypes. Pyari and Satyabhama showed higher response upon AM inoculation. AM colonization increased the total chlorophyll by 54% and the upland rice genotypes showed 51% enhanced nitrogenase activity in their root zones, with highest recorded for Satyabhama. The AM plants showed enhanced activities of nitrate reductase (NR) and glutamine synthetase (GS), and interestingly, the rice genotypes with higher NR and GS (Pyari, Satyabhama) also exhibited more (20%) biomass production and plant N content (36%). Significant varietal differences were recorded in terms of accumulation of antioxidant compounds such as ascorbate, glutathione and proline in AM inoculated plants, which helped to alleviate negative effects of water stress in rice plants under aerobic cultivation.

Forestation delivers significantly more effective results in soil C and N sequestrations than natural succession on badly degraded areas: Evidence from the Central Loess Plateau case

Vegetation restoration is an important factor affecting soil carbon (C) and nitrogen (N) sequestration. However, the effects of the type of vegetation restoration on soil C and N sequestration varies owing to different environmental conditions. Therefore, additional studies should explore the effects of vegetation restoration type on soil C and N sequestration, especially between natural restoration and artificial afforestation. This study explored the differences in improving soil C and N sequestration between artificial forests (AF) and natural grasslands (NG) that had been converted from sloping cropland over 20 years since the implementation of GGP (Grain for Green Program) on the Central Loess Plateau, China. The results showed that NG and AF significantly increased the 0–20 cm soil organic carbon (SOC) content but had a minimal impact on the 20–100 cm SOC content after 20 years of vegetation restoration. In addition, the two vegetation restoration types significantly increased the 0–60 cm soil total nitrogen (STN) content, but they both had no significant effects on the 60–100 cm soil layer. Moreover, the C and N sequestration capacities of AF were higher than those of NG due to the AF had higher plant biomass and lower plant biomass C:N ratios compared to NG. The AF and NG both significantly increased the soil aggregate structure and stability following cropland conversions. Apart from soil aggregates playing a crucial role in affecting soil C and N sequestration, plant biomass and its C:N ratios also had the most substantial effects. The results suggested that soil aggregate stability and the quantity and quality of input organic matter have strongly influenced soil C and N sequestration post-restoration; moreover, N fixing species is more conducive to soil C and N sequestration and the artificial forests had higher C and N sequestration capacities than natural grasslands in the Loess Plateau, with a mean annual precipitation of 505 mm.

Large Mammalian Herbivores and the Paradox of Soil Carbon in Grazing Ecosystems: Role of Microbial Decomposers and Their Enzymes

Grazing is the dominant land use across the world, and large mammalian herbivores exert strong influence over biogeochemical cycles. Grazing ecosystems feature C-rich soils, even though herbivores consume a major fraction of plant production to reduce detrital input to soil. Yet, counter-intuitively, moderate grazing can promote net soil-C storage in many ecosystems compared to grazer-exclusion. We address this enigmatic influence of grazers on soil-C and test their indirect effect on proximate drivers of decomposition: microbial extracellular enzyme activity. We used a replicated long-term grazer-exclusion experiment to measure responses in above- and belowground plant biomass, soil-C stock, microbial biomass, labile/recalcitrant C pools and three enzymes relevant to the C-cycle: peroxidase—which initiates decomposition of recalcitrant matter, alongside beta-glucosidase and cellobiohydrolase—which act further downstream on more labile fractions. Consistent with other ecosystems, upto 12 years of herbivore exclusion did not increase soil-C in the fenced plots despite higher plant biomass and higher potential detrital C-inputs. Grazer-exclusion did not alter microbial biomass; peroxidase increased threefold and beta-glucosidase was doubled; cellobiohydrolase was unaffected. Grazer-exclusion also led to twofold increase in recalcitrant-C and in microbial respiration, but it did not influence labile-C. Structural equation models supported the hypothesis that grazing favours soil-C via its indirect effect on peroxidase, but they did not support that the effects can run in the opposite direction where soil-C affects enzymes. Grazer-mediated shifts in how microbes deploy enzymes emerge as a plausible mechanism that affects soil-C. These linkages may be important to maintain soil-C sequestration in drylands which support large mammalian herbivores.

Sesamum indicum Oleosin L improves oil packaging in Nicotiana benthamiana leaves.

Plant oil production has been increasing continuously in the past decade. There has been significant investment in the production of high biomass plants with elevated oil content. We recently showed that the expression of Arabidopsis thaliana WRI1 and DGAT1 genes increase oil content by up to 15% in leaf dry weight tissue. However, triacylglycerols in leaf tissue are subject to degradation during senescence. In order to better package the oil, we expressed a series of lipid droplet proteins isolated from bacterial and plant sources in Nicotiana benthamiana leaf tissue. We observed further increases in leaf oil content of up to 2.3‐fold when we co‐expressed Sesamum indicum Oleosin L with AtWRI1 and AtDGAT1. Biochemical assays and lipid droplet visualization with confocal microscopy confirmed the increase in oil content and revealed a significant change in the size and abundance of lipid droplets.

Browsing behaviour of impala, Aepyceros melampus in two contrasting savannas

Impala are medium-sized antelopes, widely distributed throughout East and Southern Africa. They consume grasses in the wet season, switching to browsing in the dry season. African savannas are classified into arid-eutrophic and moist-dystrophic. The arid-eutrophic savannas have fertile soils which support plant biomass of high nutritive value, utilised by small and medium-sized herbivores. The moist-dystrophic savannas have nutrient-poor soils and high plant biomass of relatively low nutritive values, utilised by large-bodied herbivores. Impala occur in both savannas, though more abundant in the arid-eutrophic savannas. I studied browsing behaviour of impala in Mikumi National Park, a moist-dystrophic savanna, and Serengeti National Park, an arid-eutrophic savanna. A car was driven in all access roads in the Parks during the wet and the dry season. The car was stopped for recording whenever impala were sighted browsing within 50 m from the road. I recorded tree species browsed, browsing height, number of bites, and habitat type. The study showed differences between the seasons and the savannas. The animals took more bites during the dry season compared to the wet. Biting rate was higher during the dry season and when spineless trees were utilised. Small and large leaves reduced biting rate while medium size leaves promoted biting rate. The impala frequently browsed at head level in both savannas, however variations between the savannas were observed during the wet season. The differences in forage quality and quantity between the savannas and the seasons, and in herbivore community between the savannas are likely to attribute the results.

Unlocking the potential plant growth‐promoting properties of chickpea (Cicer arietinum L.) seed endophytes bio‐inoculants for improving soil health and crop production

AbstractSustainable agronomic practices are tried all over the world to promote safe and eco‐friendly crop production. Therefore, in the present study, the effect of seed endophytic bacteria and its consortium on soil biochemical property and yield of chickpea (Cicer arietinum L.) under field and pot conditions are investigated. Both the experimental results proved a significant increase in total soil organic carbon (OC), electric conductivity (EC), organic matter (OM), and soil nutrients like available N, P, and K content and important soil enzymes like dehydrogenase (DHA), beta glucosidase, alkaline phosphate, urease, and microbial population in soil was observed under the Enterobacter hormaechei BHUJPCS‐15 (T1), Enterobacter cloacae BHUJPCS‐21 (T2), and combined T3 (consortium of T1 and T2) treatments. Similarly, a significant increase in the grain yield (27–45% and 57–73%) in microbial treatment was found in pot and field experiments, respectively, than in control. In addition, whereas the higher plant biomass (14–38% and 42–78%) was recorded in treated plant over the control plant. Similarly, the plant photosynthetic pigments (Chl a, b, total Chl) were increased in microbial treated plant than the control untreated chickpea plant. Consortium of endophytes were recorded effective result for enhancing plant growth attributes, productivity, and soil health. The consortium can be further used as biofertilizers for sustainable chickpea production. Our present study highlights the significance of sustainable agronomic practices for improving the soil quality and agricultural yield while reducing adverse impacts of chemicals by the use of seed endophytic microbes and its consortium.

Comparison of soft spring wheat breeding lines and F1 hybrid according to economically valuable traits

Creation of doubled haploid lines in wheat is a promising direction of research in Russia. However, the criteria for identifying good cross combinations, for which it is advisable to carry out androgenesis in vitro, have not been defined. One of these criteria could be the rate of heterosis in F1 or F2. The aim of this work was to establish the possibility of achieving the yield level of the F1 hybrid by the lines of later generations. The studies were carried out at the experimental fields of the FSBSI “Federal Altai Scientific Center for Agrobiotechnology” in 2017-2019. Varieties ‘Golubkovskaya’, ‘Omskaya 28’, ‘Saratovskaya 70’, F1 ‘Omskaya 28’ × ‘Saratovskaya 70’, F1 ‘Golubkovskaya’ × ‘Saratovskaya 70’, four breeding lines from cross ‘Golubkovskaya’ × ‘Saratovskaya 70’ and seven breeding lines from cross ‘Omskaya 28’ × ‘Saratovskaya 70’ were material for this research. Germination, survival rate, plant height, number of spikes per m2, plant biomass, number of spikelets per spike and grain per spike, 1000-seed weight, grain weight per spike and plant, harvest index, yield, duration of the “germination – ear formation” period, lodging resistance and leaf and stem rust resistance were examined. In three cases out of six, high-parent heterosis in the studied F1 hybrids was observed (yield increase – 3–19 %). Five cases of significant yield improvement in breeding lines compared to F1 hybrids were detected in 2017–2019 (additional yield 2–44 %). Lines exceeding hybrid F1 in the context of yield were taller (+5–30 cm), with more extended period “germination – ear formation” (+7–8 days), higher plant biomass (+1.24–5.16 g), a larger number of spikelets per spike (0.5–2.8 units) and larger number of kernels (+3.5–8.0 units). Pure lines of soft spring wheat can be compared in yield to F1 hybrid, from which they were obtained. This fact was possible due to the selection of lines for desired traits determined by recessive genes.

Using plants to remediate or manage metal-polluted soils: an overview on the current state of phytotechnologies

Soil contamination by metals threatens both the environment and human health and hence requires remedial actions. The conventional approach of removing polluted soils and replacing them with clean soils (excavation) is very costly for low-value sites and not feasible on a large scale. In this scenario, phytoremediation emerged as a promising cost-effective and environmentally-friendly technology to render metals less bioavailable (phytostabilization) or clean up metal-polluted soils (phytoextraction). Phytostabilization has demonstrable successes in mining sites and brownfields. On the other hand, phytoextraction still has few examples of successful applications. Either by using hyperaccumulating plants or high biomass plants induced to accumulate metals through chelator addition to the soil, major phytoextraction bottlenecks remain, mainly the extended time frame to remediation and lack of revenue from the land during the process. Due to these drawbacks, phytomanagement has been proposed to provide economic, environmental, and social benefits until the contaminated site returns to productive usage. Here, we review the evolution, promises, and limitations of these phytotechnologies. Despite the lack of commercial phytoextraction operations, there have been significant advances in understanding phytotechnologies' main constraints. Further investigation on new plant species, especially in the tropics, and soil amendments can potentially provide the basis to transform phytoextraction into an operational metal clean-up technology in the future. However, at the current state of the art, phytotechnology is moving the focus from remediation technologies to pollution attenuation and palliative cares.

Agricultural Practices Modulate the Beneficial Activity of Bacterial-Feeding Nematodes for Plant Growth and Nutrition: Evidence from an Original Intact Soil Core Technique

Free-living nematodes have beneficial effects on plant growth and nutrition. Exploring how agricultural practices modulate these beneficial effects is still challenging. A study was conducted in Ferralsols from Madagascar from one unmanaged grassland and 16 upland rainfed rice fields, representative of different agricultural practices: rotation, agroforestry and monoculture. Intact soil cores in plastic cylinders were sampled in the field to assess the effects of agricultural practices on changes in plant growth and nutrition induced by the presence of bacterial-feeding nematodes. The soil cores were fumigated to kill the nematodes and moistened with a filtered fresh soil suspension containing only microbial cells. A rice seed was introduced in the core, which was then incubated under natural climatic conditions for 40 days with or without inoculation of the bacterial-feeding nematode Acrobeloides sp. The inoculation of the nematodes induced lower, similar or higher plant biomass and nutrient content in comparison to the control according to the agricultural practices. Positive effects of Acrobeloides sp. on plant functions were frequent in soil cores sampled from fields with high plant diversity, especially from agroforestry systems. The intact soil core technique appears to be a robust means of mimicking field conditions and constitutes a promising tool to assess effects on soil processes of the ecological intensification of agricultural practices.