Carmen Rosa da Silva Curvêlo

Inducers of resistance and silicon on the activity of defense enzymes in the soybean-Phakopsora pachyrhizi interaction

This study aimed to determine the effect of jasmonic acid (JA), Acibenzolar-S-Methyl (ASM) and calcium silicate (a source of soluble silicon, Si), on the potentiation of soybean resistance to Asian soybean rust (ASR). The ASR severity was signifi - cantly reduced on plants sprayed with ASM or supplied with Si in comparison to plants sprayed with JA or deionized water. For chitinases (CHI), significant differences in activity between non-inoculated and inoculated plants sprayed with deionized water or with ASM occurred at 72 hours after inoculation (hai), at 24 and 72 hai when sprayed with JA and at 141 hai when supplied with Si. For β-1,3-glucanases (GLU), significant differences in activity between non-inoculated and inoculated plants sprayed with deionized water occurred at 24, 48 and 141 hai, but not until 72 for plants sprayed with ASM. For phenylalanine ammonia-lyases (PAL), significant differences in activity between non-inoculated and inoculated plants occurred only for plants sprayed with ASM at 72 and 141 hai. In conclusion, the ASR symptoms can be mild on plants sprayed with ASM or supplied with Si and that this amelioration likely involved the defense enzymes.

Estado nutricional de pinheira sob adubação orgânica do solo

From August 2009 to July 2010, an experiment was conducted in a sugar-apple orchard (Annona squamosa L.) in the town of Remigius PB, in order to evaluate the levels of macro and micronutrients and the leaf tissue of the plants in a soil treated with cattle manure and poultry litter. The treatments were distributed into randomized blocks, with plots split with time, three replications and two plants per plot, in a 2 × 5 × 2 factorial arrangement, corresponding to two sources of organic matter of animal origin (cattle manure and poultry litter), five doses of organic material by volume (0.0, 3.5, 5.3, 7.1 and 8.9%), and two periods of plant evaluation, 36 and 48 months after transplanting. The doses of organic material were set based on the organic-matter content of each source. With the exception of magnesium and zinc, the organic-matter sources did not differ statistically from the levels of other nutrients in the leaf dry-matter of the plants. The greatest accumulation of nutrients in the leaf dry-matter of the sugar apple was in the dosage-range of between 6.01 and 8.65% of organic matter.

Mecanismos bioquímicos da defesa do algodoeiro à mancha de ramulária mediados pelo silício

of leaf area, lesion size (LS), foliar Si concentration and the activities of defense enzymes peroxidases (POX), polyphenoloxidases (PPO), chitinases (CHI), s-1,3-glucanases (GLU), and phenylalanine ammonia-lyases (PAL) were evaluated. Data from severity were used to calculate the area under ramularia leaf spot progress curve (AURLSPC). Leaf Si concentration increased by 64% on plants supplied with Si compared to plants not supplied with this element. There were increases of 10 and 14.7% for IP and LP 60 , respectively, on plants supplied with Si. Reductions of 38.6 and 62.4% for NL and 17.2 and 26.6% for LS occurred, respectively, for plants from NuOpal and BRS Buriti cvs supplied with Si. AURLSPC was re- duced by 35% for the +Si treatment compared to the -Si treatment. The concentration of total soluble phenolic compounds on plants of both cv. supplied with Si increased during the progress of ramularia, but the lowest values occurred for the -Si treatment until 18 days after inoculation (dai). The increase on the concentration of lignin derivatives was significant only for plants of cv. BRS Buriti infected by R. areola and supplied with Si. POX activity was higher on plants from the two cultivars supplied with Si compared to plants not supplied with this element. For plants of cv. NuOpal supplied with Si, PPO, CHI, GLU, and PAL activities increased until 18 dai, but the activities of PAL and PPO on plants of cv. BRS Buriti were not potentiated by Si. On plants from cv. BRS Buriti supplied with Si, there was increase on CHI and GLU activities at 21 dai compared to plants not supplied with Si. It can be concluded that cotton resistance to ramularia leaf spot was biochemically enhanced by Si, especially for plants of cv. NuOpal considered susceptible to ramularia leaf spot.

Sweet Corn, Explored as a Companion Plant, Mitigates Sucking Insects in Industrial Tomato Plants, Pre-flowering Stage

Plant diversification mitigates colonization by herbivorous insects in agricultural systems. Tomato and sweet corn generate raw material, for industrial processing, with outstanding production in Goias state, Brazil. Yet, little is known about the potential of sweet corn as a companion plant for sucking insects, and natural enemies, in tomato plants. We collected pests and natural enemies in tomato (pre-flowering stage) plants under three treatments: isolated tomato plants (T1), tomato plants with sweet corn in the border (T2), and tomato plants with polyculture (garlic, lettuce, and squash) in the border (T3). The insects were collected by yellow sticky traps. Dalbulus maidis (29.52%), Frankliniella schultzei (23.90%), F. occidentalis (18.72%) and Myzus persicae (15.20%) corresponded to 87.34% of the total insects collected. Tomato plants cultivated with sweet corn on the border had lower infestation of the thrips, F. schultzei as well as the aphid M. persicae. The number of D. maidis and F. occidentalis adults did not change according to the treatments. Diabrotica speciosa and Astylus variegatus were more collected in tomato plants with adjacent sweet corn. Predators and parasitoids represented only 6.62% of the total abundance. Cycloneda sanguinea and parasitoids were more collected in tomato plants with polyculture (T3). Tomato with sweet corn or polyculture favored the abundance of the predator Sphaerophoria scripta. Considerations around the control of insect pests and the sustenance of natural enemies in tomato plants, with sweet corn acting as a companion plant, in the pre-flowering stage of that Solanaceae, are demonstrated.

Hydrogen Peroxide for Insect and Algae Control in a Lettuce Hydroponic Environment

Insects and algae demonstrate adaptability in hydroponic environments. Algae attract flies, Bradysia spp. (Diptera: Sciaridae) and Scatella stagnalis (Diptera: Ephydridae), called fungus gnats and shore fly, respectively. Flies feed on algae, damaging seedlings radicellae, and may transmit pathogens to lettuce plants. Little information on the management of flies and algae is known. A paradox in the face of the expansion of hydroponics. The objective was to evaluate the potential of hydrogen peroxide (H2O2) as an insecticide and algaecide agent. Entomopathogenic fungi were also evaluated as an alternative control to flies. The experiment was conducted in a commercial hydroponic system under a randomized complete block design with 5 treatments and 4 replicates. The treatments, sprayed on the phenolic foam plates, immediately after lettuce seed deposition, were: H2O2, Beauveria bassiana, Metarhizium anisopliae, Spinosyn and water, as control. The quality of the lettuce seedlings (cv. Brida), the presence of flies and algae evolution in the phenolic foam plates were recorded daily. H2O2 and Spinosyn affected lettuce seed germination, but were able to reduce adult flies on the phenolic foam cells. The highest number of larvae was observed with both fungi, and only water, compared to H2O2. No larvae were found in Spinosyn sprayed phenolic foam cells. However, lettuce seedlings from Spinosyn sprayed plates were those with lower fresh weight. H2O2 severely retained algae infestation in phenolic foam cells over a 15-day observation period. The present work demonstrates the potential that H2O2 can play as an insecticidal and algaecide agent in hydroponic environments.