Fungivory: a new and complex ecological function of Doru luteipes (Scudder) (Dermaptera: Forficulidae)

We report the discovery that the earwig predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) feed on Puccinia polysora Underw uredospore, the causal agent of Southern Rust of Corn (SRC), which is a primary disease affecting the maize crop in Brazil. We performed experiments in laboratory and greenhouse to test the effect of D. luteipes (1st/2nd and 3rd/4th instars, and adults) fungivory on the P. polysora uredospore concentration. All trials showed a significant reduction of the initial concentration of uredospore. There was a reduction in uredospore concentration with increase in number of D. luteipes feeding on them. We also tested the uredospore consumption by quantifying its percentage in the feces of D. luteipes. Nymphs of the 2nd, 4th instar and adults fed 88%, 85%, and 83.8% of the uredospore, respectively. For nymphs of the 3rd instar, the percentage of uredospore consumption (75.6%) was statistically significant compared with the other groups. In greenhouse experiment, at twenty-eight days after plant inoculation with 9.9 x 104 uredospores, the percentage of uredospore consumption was 81.7%. Our results confirmed the fungivory of D. luteipes on P. polysora uredospore. This is the first report of D. luteipes fungivory, which may play an important role in the biological control of P. polysora in corn.

Effect of nano-particle compounds and P. indica on bio-degradation of petroleum compounds in the soil contaminated with Cd under cultivation of triticale plant

Background and Purpose: Phytoremediation efficiency of heavy metals is an important factor in environmental studies. This study was conducted to investigate the effect of multi-walled carbon nanotubes (MWCNTs), zeolite, and P.indica on bio-degradation of mazut in a soil treated with Cd and mazut. Materials and Methods: Treatments consisted of applying zeolite (0, 1 and 2% (W/W)), MWCNTs (0, 1 and 2 % (W/W)) in the presence and absence of P.Indica in the Cd (0 , 5 and 10 mg/kg soil) polluted soil that was simultaneously polluted with mazut (0 and 6 % (W/W)). After 70 days, plants were harvested, and plant and soil Cd were measured using AAS. In addition, the degradation percentage of mazut in soil was determined. Results: Addition of 2 % (W/W) MWCNTs and zeolite to the soil polluted with 6 % (W/W) mazut significantly increased the bio-degradation percentage of mazut in the soil by 11.3%. For soil and plant Cd concentration, it was decreased by 10.6 and 12.8%, respectively. In addition, plant inoculation with P.indica significantly increased the bio-degradation of mazut in the Cd polluted soil (10 mg Cd/kg soil) by 14.3%. Increasing soil pollution to mazut from 0 to 6 % (W/W) significantly increased the soil microbial respiration by 14.4%. Conclusion: Based on the results, addition of MWCNs and zeolite in the soil and plant inoculation with P.indica significantly increased the mazut bio-degradation in the soil. However, the amount and type of pollutant had a significant effect on phytoremediation efficiency.

Screening US peanut mini-core accessions for resistance to Sclerotinia blight caused by Sclerotinia sclerotiorum

Sclerotinia blight is a destructive disease of peanut caused by Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotinia minor Jagger. Crop management practices are routinely used to control Sclerotinia blight, however, development of resistant cultivars together with crop management practices may provide a lasting solution to control the disease in peanut fields. In this study, 95 accessions of United States’ peanut mini-core collection were evaluated using detached leaflet and whole plant inoculation methods under greenhouse conditions. The area of detached leaflet infected was scored using a scale from 0 (no disease) to 4 (76%–100% leaflet area infected). Whole plants were evaluated based on disease severity index (DSI) from 0% (no disease) to 100% (entire plants infected). In the detached leaflet inoculation method, accessions PI-268586, PI-268696, PI-356004, PI-372305, and PI-429420 had the lowest average disease score of 2.7. In the whole plant inoculation method, accessions PI-200441, PI-259658, PI-319770, PI-323268, and PI-337293 had the lowest DSI from 86% to 90%. The two inoculation methods resulted in different set of accessions with the lowest disease level. These results may reflect differences in disease pressure between the two screening methods.

Application of mycorrhizal fungus Tuber melanosporum to stimulate the growth and development of soybean and spring barley

Aim. To evaluate the effect of soybean and spring barley seeds treatment with haploid cells of fungus Tuber melanosporum IMB F- 100106 on the growth and development of soybean and spring barley. Methods. The study was conducted in field conditions on the experimental field of the Department of Agroecology and Biosafety IAP NANU. The level of development of the fungus was evaluated visually and by counting ectomycorrhizal threads. Morphometric and biochemical methods were used to characterize the structure of the crop. Results. The treatment of soybean and spring barley seeds with T. melanosporum promotes productive growth and increases the yield of crops. Conclusions. Plant inoculation with T. melanosporum promotes productive growth and increases the yield of soybean and barley, promotes the possibility of creating new technologies of organic and regenerative agriculture and allows preserving of the genetic stability of this fungus. Keywords: mycorrhiza, Tuber melanosporum, crop yields, genetic stability.

MORPHOLOGICAL, PRODUCTIVE, AND CHEMICAL TRAITS OF XARAÉS GRASS: NITROGEN TOPDRESSING VERSUS INOCULATION WITH DIAZOTROPHIC BACTERIA

Nitrogen topdressing is essential for forage production, but the high cost of fertilizers stimulates the search for new technologies, such as the use of diazotrophic bacteria, which can fix the atmospheric nitrogen. To evaluate the potential of this technology in providing the amount of nitrogen requested by xaraés grass as topdressing, plants were fertilized at planting with an N rate of 100 kg ha-1, inoculated with strains of diazotrophic bacteria and Azospirillum brasilense, and compared with plants that received 100 kg ha-1 of N at planting and as topdressing during two periods of shoot growth (58 days in the first period and 26 days in the second period) in 20-dm3 pots. The data were subjected to analysis of variance and means compared by the Scott-Knott test at 5% significance. The leaf area of xaraés grass inoculated with strain UN42 was similar to that of plants that received nitrogen topdressing. However, grass biomass production was higher when nitrogen topdressing was applied. Plant inoculation with Azospirillum brasilense and strains UN16, UN17, UN21, UN33, UN49, and UN78 increased crude protein contents of xaraés grass when compared to nitrogen fertilization at planting without inoculation. However, grass inoculation with diazotrophic bacteria does not replace nitrogen topdressing completely.

Effect of Bacillus subtilis on phosphorus uptake by cucumber as affected by iron oxides and the solubility of the phosphorus source

In this work, we examined the effects of Bacillus subtilis strain QST713 by assessing plant P uptake from variably P compound .The experiment performed involved three factors: (i) P source [KH2PO4 at 100 mg kg–1, and phosphate rock (PR) at 100 or 200 mg kg–1]; (ii) plant inoculation with QST713 (inoculated and non-inoculated); and (iii) Fe oxide (ferrihydrite) in the growth medium (0 or 300 mg kg–1 concentration of citrate–ascorbate-extractable Fe). Ferrihydrite decreased dry matter yield in plants by more than 50 %. Inoculation with QST713 increased plant growth, and total accumulation of P and P uptake in plants. Overall, QST713 increased P uptake by 40 %, the effect being independent of the presence of ferrihydrite and P source. The increased P uptake observed can be ascribed to increased solubilization of P and to increased root growth. Therefore, QST713 improves P nutrition in plants grown on media with a high P adsorption capacity irrespective of the solubility of the P compound.