Chemical control of water hyacinth by some herbicides and their effect on some aquatic invertebrate

Water Hyacinth (Eichhornia crassipes), regarded as one of worst aquatic weeds in the world, has been an invader in northern Iran, particularly in the Anzali Wetland. Herbicide application as a control method with respect to ecosystem health has been investigated. The effects of three herbicides, glyphosate (Roundup), Glufosinate-ammonium (Basta), and Bispyribac sodium (Nominee) were investigated on water hyacinth and on the survival of five aquatic invertebrates from the Anzali Wetland including Hemiptera, Amphipoda, Odonata, Ostracoda and Daphnia. The treatments consisted of 3 L/ha of glyphosate, 5 L/ha of Glufosinate-ammonium, and 0.3 L/ha of Bispyribac sodium. European Weed Research Council (EWRC) rating scale determining reduction of wet and dry weight of shoot was the basis of assessment to determine the effectiveness of the herbicides in the control of of water hyacinth. All herbicides were effective on water hyacinth while Roundup caused a significant reduction of shoot biomass and scored 98% on the EWRC scale. Bayesian mediation model was used to calculate total and decomposition effect of herbicides on animal groups. Based on the Bayesian mediation model, Basta showed the best performance with lowest probability of a negative effect (PEff<0=0.22). The accuracy of dosages and spraying of herbicides can be considered the most effective in inhibiting water hyacinth and the least destructive to living organisms.

Effect of pyrene-induced changes in root activity on growth of Chinese cabbage (Brassica campestris L.), and the health risks caused by pyrene in Chinese cabbage at different growth stages

Background Polycyclic aromatic hydrocarbons (PAHs) pose a potential risk to ecological safety and human health. They have a range of effects on plant growth and there have been few reports on the health risks associated with ingestion of vegetable crops at different growth stages. Methodology In this study, a pot experiment in which Chinese cabbage (Brassica campestris L.) were grown in a greenhouse for 75 days was used to investigate the dose–effect relationship of pyrene with plant growth and also the exposure risk for adults of ingestion of Chinese cabbage at different growth stages. Results The results showed that low doses of pyrene (5–45 mg kg−1) promoted plant growth (20–220% and 55–97% higher than control treatment for the root biomass and shoot biomass, respectively), but significant inhibition was observed at a high dose (405 mg kg−1) (41–66% and 43–91% lower than control treatment for the root biomass and shoot biomass, respectively). High doses of pyrene reduced soil bacterial abundance and diversity during the growth of Chinese cabbage, and increased malondialdehyde (MDA) levels in the plant. The effects of pyrene on plant biomass were mainly attributed to changes in root activity induced by pyrene, as the relationship between soil pyrene concentration and biomass was similar to that between soil pyrene concentration and root activity. Furthermore, structural equation modeling analysis showed that pyrene altered growth of the vegetable by directly affecting root activity. The incremental lifetime cancer risk for adults is highest for ingestion of Chinese cabbage at the seedling stage, followed in decreasing order by the rosette stages and heading stages. Conclusions The health risk of consumers who have the possibility to ingest the Chinese cabbage planted in pyrene-contaminated soil would be decreased with the increasing growth periods. However, further studies are required to confirm the dose–effect relationship between pyrene concentration and Chinese cabbage growth on a field scale. Graphical Abstract

Photosynthetic traits of Australian wild rice (Oryza australiensis) confer tolerance to extreme daytime temperatures

Key message A wild relative of rice from the Australian savannah was compared with cultivated rice, revealing thermotolerance in growth and photosynthetic processes and a more robust carbon economy in extreme heat. Abstract Above ~ 32 °C, impaired photosynthesis compromises the productivity of rice. We compared leaf tissues from heat-tolerant wild rice (Oryza australiensis) with temperate-adapted O. sativa after sustained exposure to heat, as well as diurnal heat shock. Leaf elongation and shoot biomass in O. australiensis were unimpaired at 45 °C, and soluble sugar concentrations trebled during 10 h of a 45 °C shock treatment. By contrast, 45 °C slowed growth strongly in O. sativa. Chloroplastic CO2 concentrations eliminated CO2 supply to chloroplasts as the basis of differential heat tolerance. This directed our attention to carboxylation and the abundance of the heat-sensitive chaperone Rubisco activase (Rca) in each species. Surprisingly, O. australiensis leaves at 45 °C had 50% less Rca per unit Rubisco, even though CO2 assimilation was faster than at 30 °C. By contrast, Rca per unit Rubisco doubled in O. sativa at 45 °C while CO2 assimilation was slower, reflecting its inferior Rca thermostability. Plants grown at 45 °C were simultaneously exposed to 700 ppm CO2 to enhance the CO2 supply to Rubisco. Growth at 45 °C responded to CO2 enrichment in O. australiensis but not O. sativa, reflecting more robust carboxylation capacity and thermal tolerance in the wild rice relative.

Synergism between feremycorrhizal symbiosis and free-living diazotrophs leads to improved growth and nutrition of wheat under nitrogen deficiency conditions

A controlled-environment study was conducted to explore possible synergistic interactions between the feremycorrhizal (FM) fungus Austroboletus occidentalis and soil free-living N2-fixing bacteria (diazotrophs). Wheat (Triticum aestivum) plants were grown under N deficiency conditions in a field soil without adding microbial inoculum (control: only containing soil indigenous microbes), or inoculated with a consortium containing four free-living diazotroph isolates (diazotrophs treatment), A. occidentalis inoculum (FM treatment), or both diazotrophs and A. occidentalis inoculums (dual treatment). After 7 weeks of growth, significantly greater shoot biomass was observed in plants inoculated with diazotrophs (by 25%), A. occidentalis (by 101%), and combined inoculums (by 106%), compared to the non-inoculated control treatment. All inoculated plants also had higher shoot nutrient contents (including N, P, K, Mg, Zn, Cu, and Mn) than the control treatment. Compared to the control and diazotrophs treatments, significantly greater shoot N content was observed in the FM treatment (i.e., synergism between the FM fungus and soil indigenous diazotrophs). Dually inoculated plants had the highest content of nutrients in shoots (e.g., N, P, K, S, Mg, Zn, Cu, and Mn) and soil total N (13–24% higher than the other treatments), i.e., synergism between the FM fungus and added diazotrophs. Root colonization by soil indigenous arbuscular mycorrhizal fungi declined in all inoculated plants compared to control. Non-metric multidimensional scaling (NMDS) analysis of the bacterial 16S rRNA gene amplicons revealed that the FM fungus modified the soil microbiome. Our in vitro study indicated that A. occidentalis could not grow on substrates containing lignocellulosic materials or sucrose, but grew on media supplemented with hexoses such as glucose and fructose, indicating that the FM fungus has limited saprotrophic capacity similar to ectomycorrhizal fungi. The results revealed synergistic interactions between A. occidentalis and soil free-living diazotrophs, indicating a potential to boost microbial N2 fixation for non-legume crops.

Effects of Different Soils on the Biomass and Photosynthesis of Rumex nepalensis in Subalpine Region of Southwestern China

The performance of Rumex nepalensis, an important medicinal herb, varies significantly among subalpine grasslands, shrublands and forest ecosystems in southwestern China. Plant–soil feedback is receiving increasing interest as an important driver influencing plant growth and population dynamics. However, the feedback effects of soils from different ecosystems on R. nepalensis remain poorly understood. A greenhouse experiment was carried out to identify the effects of different soil sources on the photosynthesis and biomass of R. nepalensis. R. nepalensis was grown in soils collected from the rooting zones of R. nepalensis (a grassland soil, RS treatment), Hippophae rhamnoides (a shrub soil, HS treatment), and Picea asperata (a forest soil, PS treatment). The chlorophyll contents, net photosynthetic rates, and biomasses of R. nepalensis differed significantly among the three soils and followed the order of RS > HS > PS. After soil sterilization, these plant parameters followed the order of RS > PS > HS. The total biomass was 16.5 times higher in sterilized PS than in unsterilized PS, indicating that the existence of soil microbes in P. asperata forest ecosystems could strongly inhibit R. nepalensis growth. The root to shoot biomass ratio of R. nepalensis was the highest in the sterilized PS but the lowest in the unsterilized PS, which showed that soil microbes in PS could change the biomass allocation. Constrained redundancy analysis and path analysis suggested that soil microbes could impact the growth of R. nepalensis via the activities of soil extracellular enzymes (e.g., β-1,4-N-acetylglucosaminidase (NAG)) in live soils. The soil total soluble nitrogen concentration might be the main soil factor regulating R. nepalensis performance in sterilized soils. Our findings underline the importance of the soil microbes and nitrogen to R. nepalensis performance in natural ecosystems and will help to better predict plant population dynamics.

Phenotypic response to soil compaction varies among genotypes and correlates with plant size in sorghum

Aims Soil compaction is a major yield-reducing factor worldwide and imposes physico-chemical constraints to plant growth and development. Facing limitations, roots can adapt and compensate for loss of functioning through their plasticity. Being primarily a belowground challenge, tolerance to soil compaction needs to be associated with root phenotype and plasticity. It is therefore of importance to distinguish between size-related apparent and size-independent adaptive plasticity. We determined the above- and belowground plasticity of sorghum genotypes varying in overall plant size. Methods We quantified plasticity as the degree response (adaptive and apparent plasticity) to soil compaction and conducted two experiments with sorghum and two soil density levels (1.4 and 1.8 Mg m−3). First, we quantified the shoot biomass plasticity of 28 sorghum genotypes. Second, we studied the root plasticity of six genotypes varying in shoot size and tolerance to soil compaction. Results Plasticity was correlated with plant biomass with larger genotypes responding earlier and more intensely. Soil compaction affected roots more than shoots and plasticity was expressed foremost in nodal root number and fine root length. Impeded plants produced 35 and 47% less root mass and length, respectively. Conclusions Plasticity to soil compaction varies among genotypes, but less-sensitive lines are in general smaller-sized genotypes. The association between tolerance and plant biomass may pose challenges to crop production; however, vigorous genotypes with unresponsive shoots to soil compaction do exist. Maintaining shoot growth relatively stable while the root modifies its structure can be an important adaptation mechanism to soil compaction.

Evaluating the Growth-promoting Effects of Microbial Biostimulants on Greenhouse Floriculture Crops

Microbial biostimulants can promote ornamental plant growth during production and improve crop performance under abiotic stresses. Even though biostimulants have shown potential in many agricultural applications, the effectiveness and specificity of many products are not well understood. The objective of this study was to analyze the growth-promoting effects of microbial biostimulants during the greenhouse production of floriculture crops. We evaluated 13 biostimulant products in greenhouse-grown zinnia (Zinnia elegans ‘Magellan Ivory’) and petunia (Petunia ×hybrida ‘Carpet White’) at low fertility (one-third of the optimal fertilizer concentration). Biostimulant products 1 and 2 containing multiple species of beneficial bacteria and fungi, and product 10 containing Bacillus subtilis QST 713, were found to increase various aspects of plant growth, including the growth index, leaf chlorophyll content (SPAD index), and shoot biomass. Both flower biomass and numbers were greater in petunia treated with product 1, and leaf size increased in zinnia treated with products 1, 2, and 10. Plants treated with these effective biostimulants at low fertility had similar or better growth and quality than untreated plants grown under optimal fertility. The concentration of various nutrient elements in leaves was higher in zinnia plants treated with biostimulant products 1, 2, or 10 compared with the negative control. Some putative mechanisms for biostimulant effectiveness, the possible reasons for biostimulant ineffectiveness, and the potential for using biostimulants as a sustainable cultural strategy are discussed. This study provides useful information about microbial biostimulant effectiveness, which is important for the development and utilization of biostimulants in the greenhouse production of floriculture plants.

Shade stress on maize seedlings biomass production and photosynthetic traits

ABSTRACT: The responses of two maize (Zea mays L.) cultivars, ‘LY336’ (shade tolerant) and ‘LC803’ (shade sensitive), to shade stress in a pot experiment conducted in the 2015 and 2016 growing seasons were investigated. The impact of 50% shade stress treatment on shoot biomass, photosynthetic parameters, chlorophyll fluorescence, and malondialdehyde (MDA) content was evaluated. The shoot biomass of the two maize hybrids was decreased significantly by shade stress treatment, for shade stress 7 d, the LC803 and LY336 were reduced by 56.7% and 44.4% compared with natural light. Chlorophyll fluorescence parameters of LY336 were not significantly affected by shade stress, whereas those of LC803 were significantly affected, the Fo increased under shade stress; however Fm, FV/FM and ΦPSII were decreased under shade stress. Among photosynthetic parameters measured, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate were significantly decreased compared with natural light, LY336 and LC803 reduction by 28.0%, 22.2%, 57.7% and 35.5%, 18.9%, 62.4%; however, intercellular CO2 concentration (Ci) was significantly increased, for the two cultivars. Under shade stress for different durations (1, 3, 5, 7 d), Pn, Gs, Ci, and MDA content differed significantly between the two cultivars. Results indicated that different maize genotypes showed different responses to shading. Shade-tolerant genotypes are only weakly affected by shade stress.

Potensi Produksi dan Mutu Benih serta Produksi Biomassa Sorghum bicolor Varietas Samurai 2 pada Umur Panen Berbeda sebagai Bahan Pakan

Sorghum bicolor var. Samurai 2 can be used as raw material in silage production for ruminant feed. The problem encountered is the difficulty of obtaining certified seeds for commercial sorghum production. So that is necessary to do this research to investigate potential sorghum seed production and its quality of Sorghum bicolor var. Samurai 2. The study was conducted at University Research Station-Jonggol Animal Education and Research Unit, Bogor Agricultural University. The experimental design used was a randomized block design with 4 treatments and 5 replicates. Five individual plants were taken to measure the variables at each treatment set. The treatments consisted of different harvesting times, namely P95 (harvested 95 days after planting), P100, P105 and P110. The variables observed were dry weight of shelled seeds, seed weight per panicle, weight of panicle stalk, panicle weight, seed production per ha, seed moisture content, seed viability test, and shoot biomass production per ha. The results showed that seed production per ha, panicle dry matter weight, fresh seed moisture content, panicle stalk dry weight was not significantly different. Dry weight of shelled seeds, dry weight of seeds per panicle, panicle dry weight, seed viability, weight of biomass per ha were significantly different (p<0.05). The potential for the production of shelled seeds, dry matter of seeds per panicle was the best in the P105 and P110, the viability of the seeds in the P105 and shoot biomass production per ha in the P105. The potential for shelled seed production (4038 kg ha-1), seed dry weight per panicle (54.87 g panicle-1), seed viability (92.8%) and the best biomass production (55.88 tons ha-1) were in treatment P105. Key words: seed production, shoot biomass, Sorghum bicolor, viability

Interactive Effects of Biochar, Nitrogen, and Phosphorous on the Symbiotic Performance, Growth, and Nutrient Uptake of Soybean (Glycine max L.)

Numerous studies reported the positive effect of soil amendment with biochar on plant development. However, little is known about biochar and its interrelation with nitrogen (N) and phosphorous (P) additions and their impact on plant growth. We carried out greenhouse experiments to understand the interactive effects of nitrogen and phosphorus supply, as well as biochar amendment, on the symbiotic performance of soybean (Glycine max L.) with Bradyrhizobium japonicum, and plant growth and nutrient uptake. The biochar was produced from maize by heating at 600 °C for 30 min and used for pot experiments at an application rate of 2%. Plants were fertilized with two different concentrations of P (KH2PO4) and N (NH4NO3). Biochar application significantly increased the dry weight of soybean root and shoot biomass, by 34% and 42%, under low nitrogen and low phosphorus supply, respectively. Bradyrhizobium japonicum inoculation enhanced the dry weight of shoot biomass significantly, by 41% and 67%, in soil without biochar and with biochar addition, respectively. The nodule number was 19% higher in plants grown under low N combined with low or high P, than in high N combinations, while biochar application increased nodule number in roots. Moreover, biochar application increased N uptake of plants in all soil treatments with N or P supply, compared with B. japonicum-inoculated and uninoculated plants. A statistical difference in P uptake of plants between biochar and nutrient levels was observed with low N and high P supply in the soil. Our results show that the interactions between nitrogen, phosphorus, and biochar affect soybean growth by improving the symbiotic performance of B. japonicum and the growth and nutrition of soybean. We observed strong positive correlations between plant shoot biomass, root biomass, and N and P uptake. These data indicated that the combined use of biochar and low N, P application can be an effective approach in improving soybean growth with minimum nutrient input.