Grasses within the Cynodon genus are widely used perennial forages, and ‘Tifton 85’ (Cynodon spp.) is one of the most popular commercial cultivars. Jiggs and Vaquero are new C. dactylon (L.) Pers. grasses, but there is little information comparing their performance with Tifton 85 under tropical conditions. The objectives were to describe and explain variation in seasonal herbage accumulation (HA) and nutritive value of irrigated Tifton 85, Jiggs, and Vaquero bermudagrasses in response to harvest frequency (14, 28, and 42 d). The trial was performed for 2 yr in Piracicaba, Brazil, on a Kandiudalfic Eutrudox soil. In the warm season, total HA of Jiggs was similar to Tifton 85, and both were more productive than Vaquero. Under the 42‐d frequency, Jiggs had greater annual HA than the other grasses (28.5 vs. 23.7 and 20.1 Mg ha−1, for Tifton 85 and Vaquero, respectively), but when harvested every 28 d, Tifton 85 and Jiggs HA were similar (18.5 Mg ha−1). For the 42‐d harvest interval in the cool season, Jiggs had the greatest HA (10.2 Mg ha−1). Less frequent harvests in both seasons resulted in greater HA. Tifton 85 had a greater proportion of leaves than Jiggs and greater in vitro digestible organic matter (IVDOM) than the other grasses in the warm season. Considering these responses, harvest frequency of Jiggs and Tifton 85 should be ∼28 d in the warm season, while that of Vaquero should be ∼42 d. No single harvest management will be appropriate for all Cynodon grasses.

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Growth analysis of forage crops allows integration of photosynthesis, respiration, and allocation of photosynthate from estimates of physiological and morphological indices. These measurements help explain differences in growth potential between plants across seasons and in response to harvest management. The objective was to describe and explain patterns of growth of ‘Tifton 85’ (Cynodon spp.) and Jiggs [C. dactylon (L.) Pers.] bermudagrasses to three harvest frequencies (14, 28, and 42 d) during 2 yr. Grasses showed different growth patterns during the cool and warm seasons. Crop growth rate (CGR) was similar during the warm season (69 kg ha–1 d–1), but Jiggs had greater relative growth rate (RGR) and lesser stubble mass and residual leaf mass. Jiggs had greater net assimilation rate (NAR) than Tifton 85 during the warm (14.2 vs. 11.4 kg dry matter [DM] m–2 d–1, respectively) and cool seasons (6.9 vs. 2.5 kg DM m–2 d–1, respectively). Tifton 85 partitioned more biomass to leaf than Jiggs (leaf weight ratio [LWR] of 0.35 vs. 0.28 kg kg–1). The 14‐d harvest frequency reduced CGR, RGR, and NAR of both grasses. Small changes in RGR occurred beyond 28 d of regrowth, but leaf area ratio (LAR) and LWR decreased, suggesting that grasses should be harvested ∼ every 28 d during the warm season. Longer regrowth periods during the cool season increased both CGR and RGR. Harvest management affects differently the growth and morphological components of Jiggs and Tifton 85 in this environment.

The essential oils from Mentha viridis L. and Mentha pulegium L. were characterized by gas chromatography coupled to mass spectrometry (GC-MS). These oils were obtained by hydrodistillation and presented linalool (40.70%), carvone (13.52%) and α-terpinene (8.56%) as the principal constituents in the essential oil from Mentha viridis L. Pulegone (50.01%), menthol (31.90%) and menthone (16.56%) were the principal constituents in the essential oil from Mentha pulegium L. These essential oils (in concentrations ranging from 3.91 to 500 μL·mL −1 ) showed satisfactory activities against Escherichia coli, Listeria monocytogenes, Salmonella choleraesuis and Staphylococcus aureus. The antioxidant activities with 2-deoxyribose and phosphomolybdenum and the reducing power (in concentrations ranging from 0.78 to 1000 μL·mL −1 ) were determined. The antioxidant activity was observed for the two oils evaluated by the phosphomolybdenum and 2-deoxyribose methods, whereas the essential oil from M. viridis presented low antioxidant activity in the reducing power assay.

Plants are rich in biologically active compounds. They can be explored for the production of bioherbicides. In this context, the present work aimed to evaluate the allelopathic effect of hydroalcoholic extracts from two Solanaceae species: Solanum muricatum Ait. and Solanum betaceum Cav. For this end, we conducted phytochemical screening and biological assays, determining the effects of the extracts on germination, early development, cell cycle, and DNA fragmentation in plantlets and meristematic cells of the plant model Lactuca sativa L. (lettuce). The percentage of seeds germinated under effect of S. muricatum extract did not differ from the control, but plantlet growth was reduced at the highest concentrations. For S. betaceum extract, dose dependence was observed for both germination and plantlet development, with the highest concentrations inhibiting germination. The growth curves revealed the concentrations of 2.06 and 1.93 g/L for S. muricatum and S. betaceum extracts, respectively, as those reducing 50% of root growth (RG). At these concentrations, both extracts presented mitodepressive effect, besides inducing significant increase in the frequency of condensed nuclei, associated to DNA fragmentation and cytoplasmic shrinkage. The frequency of chromosome alterations was not significant. We further discuss the mechanisms of action related to the chemical composition of the extracts, which presented organic acids, reducing sugars, proteins, amino acids, and tannins, besides catechins and flavonoids, only found in the extract of S. betaceum.