Analysis of growth, yield and control of Cophes notaticeps and Polyphagotarsonemus latus in Jatropha curcas plants under different doses of silicon

The present study aims to evaluate the effects of Si on growth, yield and resistance of Jatropha curcas plants to Cophes notaticeps and Polyphagotarsonemus latus. The study was carried out in two consecutive years with J. curcas plants with 3 years old in 3x2 m spacing. The assays were set up with randomized complete block design with five concentrations (0, 10, 20, 40 and 80 mM L-1) and five replications. It was set up another experiment in a greenhouse following completely randomized factorial design 5x2 with five silicon concentrations (0, 10, 20, 40 and 80 mM L-1) and two water supply: daily irrigation with water volumes according to 50% and 100% of evapotranspiration, six replications and one plant per plot. The present study allows clarifying that J. curcas plants are non-accumulating plants, for accumulating less than 1% of silicon in the leaves. The low accumulation of silicon in the leaves did not significantly inferred in growth of J. curcas, however, the reduction of specific leaf area possibly occurred by the formation of a thin silica layer and reduced the yield by the decrease sunlight absorption. The silicon did not mitigated the damages by Cophes notaticeps and Polyphagotarsonemus latus by the low ability of the plant to accumulate silicon, however, is possible to affirm that the injuries severity by Cophes notaticeps is proportional to stem diameter

Genomic history of coastal societies from eastern South America

Sambaqui (shellmound) societies are among the most intriguing archaeological phenomena in pre-colonial South America, extending from approximately 8,000 to 1,000 years before present (yr bp) across 3,000 km on the Atlantic coast. However, little is known about their connection to early Holocene hunter-gatherers, how this may have contributed to different historical pathways and the processes through which late Holocene ceramists came to rule the coast shortly before European contact. To contribute to our understanding of the population history of indigenous societies on the eastern coast of South America, we produced genome-wide data from 34 ancient individuals as early as 10,000 yr bp from four different regions in Brazil. Early Holocene hunter-gatherers were found to lack shared genetic drift among themselves and with later populations from eastern South America, suggesting that they derived from a common radiation and did not contribute substantially to later coastal groups. Our analyses show genetic heterogeneity among contemporaneous Sambaqui groups from the southeastern and southern Brazilian coast, contrary to the similarity expressed in the archaeological record. The complex history of intercultural contact between inland horticulturists and coastal populations becomes genetically evident during the final horizon of Sambaqui societies, from around 2,200 yr bp, corroborating evidence of cultural change