Efecto de la aplicación del herbicida metsulfuron metil en mezcla con glifosato, en el establecimiento de plantaciones de Eucalyptus globulus Labill

- Bravo, T. Forestal Mininco S.A., Los Angeles, Chile. - Muñoz, F. ;Sánchez-Olate, M. Facultad de Ciencias Forestales, Universidad de Concepción. Casilla 60-C, Concepción, Chile.La rentabilidad de las plantaciones de Eucalyptus globulus está en relación, entre otros factores, con la adecuada implementación de un programa de control de malezas. Según las condiciones en la cual se desarrolla la plantación, la aplicación de herbicidas antes de la plantación es una adecuada alternativa de control de las malezas. Para ello, se ha utilizado ampliamente mezcla de herbicida persistente en el suelo (Simazina) en combinación con un herbicida sistémico de amplio espectro (Glifosato). Debido al cuestionamiento ambiental del herbicida Simazina, se estudió su reemplazo por el herbicida Metsulfuron-metil. El ensayo se estableció en el año 2005 en un predio ubicado en la comuna de Mulchen, de propiedad de la empresa Forestal y Agrícola Monte Aguila S.A., de acuerdo a un diseño factorial de dos factores. Un factor es el herbicida Metsulfuron-metil en tres niveles (dosis de 50, 75 y 100 g/ha) y el otro, tiempo de carencia de plantación en dos niveles (15 y 30 días de aplicación antes de la plantación). La aplicación de Metsulfuron-metil se realizó en mezcla con Glifosato. Las variables respuesta fueron diámetro a la altura del cuello, altura y sobrevivencia de las plantas. A los 8 meses de aplicados los tratamientos hubo diferencias significativas en el crecimiento de las plantas de Eucalyptus globulus, no así, en su sobrevivencia

Rhizogenic induction in adult Juglans regia l. cv. serr tissue induced by indole butyric acid and Agrobacterium rhizogenes .

The in vitro introduction of adult walnut ( Juglans regia L.) tissue represents an opportunity to clone elite genotypes whose selection occurs in advanced ontogenic states. With the purpose of developing a protocol to allow mass propagation of valuable genotypes from adult material, a comparison was made between two root induction systems of walnut microshoots of the fourth subculture of adult walnut tissue of an in vitro introduction program previously reinvigorated through traditional grafting. Rhizogenic induction by indole-3-butyric acid (IBA) and Agrobacterium rhizogenes was used. The rhizogenic process was analyzed in two phases for both auxinic (T1: 3 mg L -1 IBA; T2: 5 mg L -1 IBA) and A. rhizogenes inductions (T3: A-477; T4: A-478). The first phase of root induction was during 3 days in the dark while the second phase, root manifestation, was 27 days. Rooting percentage was evaluated and the induced root systems characterized (number, length, diameter, and root insertion zone) in all the procedures. The best rooting results were obtained in T2, although the response obtained with A. rhizogenes didn′t differ from the T1 response. This appears to be an increasingly interesting methodology for adventitious rhizogenesis in this species

Photosynthetic and leaf anatomical characteristics of Castanea sativa: a comparison between in vitro and nursery plants

The anatomic and functional leaf characteristics related to photosynthetic performance of Castanea sativa growing in vitro and in nursery were compared. The irradiance saturated photosynthesis in in vitro grown plantlets was significantly lower compared to nursery plants (65 vs. 722 mu mol m(-2) s(-1)). The maximum photosynthetic rate (P-Nmax) was 4.0 and 10.0 mu mol(CO2) m(-2) s(-1) in in vitro microshoots and nursery plant leaves, respectively. Carboxylation efficiency (C-E) and electron transport rate (ETR) were three-folds higher in nursery plants than in microshoots. The non-photochemical quenching (NPQ) was saturated at 80 mu mol m(-2) s(-1) in microshoots suggesting limited photoprotection by thermal dissipation. The microshoots had wide open, spherical stomata and higher stomatal density than nursery plants and they had almost no epicuticular wax. Consequently, the microshoots had high stomatal conductance and high transpiration rate. These anatomic and functional leaf characteristics are likely major causes of the low survival rates of plantlets after ex vitro transfer

Seasonal changes in photosynthesis, phenolic content, antioxidant activity, and anatomy of apical and basal leaves of Aristotelia chilensis

Aristotelia chilensis (Mol.) Stuntz is an evergreen species endemic to Chile. It grows in open areas or under tree canopy, and its leaves emerge in early spring and summer. The objective of this study was to determine changes in photosynthetic parameters, total phenol content (TPC), antioxidant activity, and anatomy of apical and basal leaves of A. chilensis during the year. Photosynthesis performance was determined by measuring electron transport rate (ETR), the quantum efficiency of photosystem II (Fv/Fm), photochemical quenching (qP), and non-photochemical quenching (NPQ) with a fluorimeter. Leaf extracts were analysed to determine TPC and antioxidant activity. The maximum ETR and qP were recorded in spring and summer when the photosynthetically active radiation (PAR) at midday was higher (1901 and 1968 µmol m-2 s-1, respectively) than in other parts of a year. The Fv/Fm had typical physiological values in both types of leaves (about 0.8 in all the seasons). Also the NPQ was not influenced by the kind of leaves and season of the year. In concordance, the basal spring leaves had the highest TPC values. In contrast, the highest values of antioxidant activity were recorded in basal winter leaves followed by basal spring leaves. The results suggested that an increase in PAR (spring) positively affected the antioxidant activity and TPC, which correlated with higher ETR and qP values. The apical leaves showed morphological adaptations during the year and areas of intercellular spaces and palisade parenchyma were larger than in the basal leaves.This research was supported by the VRID project 218.142.037-1.0 "Evaluation of phenolic and alkaloids compounds production from vegetative organs of Aristotelia chilensis: an effective alternative for sustainable use”; Universidad de Concepción, Chile. The authors are grateful for the support provided by Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil. Beca ANID Doctorado Nacional 2019/21191038 is greatly acknowledge

Global characteristics and outcomes of SARS-CoV-2 infection in children and adolescents with cancer (GRCCC): a cohort study

Background: Previous studies have shown that children and adolescents with COVID-19 generally have mild disease. Children and adolescents with cancer, however, can have severe disease when infected with respiratory viruses. In this study, we aimed to understand the clinical course and outcomes of SARS-CoV-2 infection in children and adolescents with cancer. Methods: We did a cohort study with data from 131 institutions in 45 countries. We created the Global Registry of COVID-19 in Childhood Cancer to capture de-identified data pertaining to laboratory-confirmed SARS-CoV-2 infections in children and adolescents (<19 years) with cancer or having received a haematopoietic stem-cell transplantation. There were no centre-specific exclusion criteria. The registry was disseminated through professional networks through email and conferences and health-care providers were invited to submit all qualifying cases. Data for demographics, oncological diagnosis, clinical course, and cancer therapy details were collected. Primary outcomes were disease severity and modification to cancer-directed therapy. The registry remains open to data collection. Findings: Of 1520 submitted episodes, 1500 patients were included in the study between April 15, 2020, and Feb 1, 2021. 1319 patients had complete 30-day follow-up. 259 (19·9%) of 1301 patients had a severe or critical infection, and 50 (3·8%) of 1319 died with the cause attributed to COVID-19 infection. Modifications to cancer-directed therapy occurred in 609 (55·8%) of 1092 patients receiving active oncological treatment. Multivariable analysis revealed several factors associated with severe or critical illness, including World Bank low-income or lower-middle-income (odds ratio [OR] 5·8 [95% CI 3·8–8·8]; p<0·0001) and upper-middle-income (1·6 [1·2–2·2]; p=0·0024) country status; age 15–18 years (1·6 [1·1–2·2]; p=0·013); absolute lymphocyte count of 300 or less cells per mm3 (2·5 [1·8–3·4]; p<0·0001), absolute neutrophil count of 500 or less cells per mm3 (1·8 [1·3–2·4]; p=0·0001), and intensive treatment (1·8 [1·3–2·3]; p=0·0005). Factors associated with treatment modification included upper-middle-income country status (OR 0·5 [95% CI 0·3–0·7]; p=0·0004), primary diagnosis of other haematological malignancies (0·5 [0·3–0·8]; p=0·0088), the presence of one of more COVID-19 symptoms at the time of presentation (1·8 [1·3–2·4]; p=0·0002), and the presence of one or more comorbidities (1·6 [1·1–2·3]; p=0·020). Interpretation: In this global cohort of children and adolescents with cancer and COVID-19, severe and critical illness occurred in one fifth of patients and deaths occurred in a higher proportion than is reported in the literature in the general paediatric population. Additionally, we found that variables associated with treatment modification were not the same as those associated with greater disease severity. These data could inform clinical practice guidelines and raise awareness globally that children and adolescents with cancer are at high-risk of developing severe COVID-19 illness. Funding: American Lebanese Syrian Associated Charities and the National Cancer Institute