The present study aimed to characterise and establish the phenological stages of arrowroot (Maranta arundinacea L.) by employing the extended BBCH (Biologische Bundesanstalt Bundessortenamt und Chemische Industrie) scale system and reporting a detailed biometric evaluation. An experiment with individual plants grown in separate pots was set up in a greenhouse for the identification and characterisation of phenological stages (the phenotypic characterisation and tuberisation process was accompanied by histological analyses every 2 months) and for biometric evaluation (plant height, root volume, dry biomass, leaf area and accumulated starch). We identified 36 secondary stages within eight principal stages of arrowroot growth which comprise: (0) sprouting; (1) leaf development-main stem; (2) formation of lateral stems; (3) elongation-main stem; (4) rhizome formation and tuberisation; (5) inflorescence emergence; (6) flowering, and (9) senescence. Results were categorised and recorded by way of photographs and technical drawings. The total growth cycle in this experiment was 230 days, concluding at the point of harvest. It was possible to observe the phenological events that characterised the changes at each stage (colouration, flag leaf emission, inflorescence and the rhizome tuberisation process).The BBCH system was efficient in identifying arrowroot phenological data. It constitutes a tool for agricultural calendar delineation and contributes to the standardisation of research on the species. K E Y W O R D S growth stages, Marantaceae, plant development, rhizomes harvest time, starch

Sugarcane mills produce sugar and ethanol and have always used bagasse as fuel to generate energy for self-consumption. Recently some mills have been also producing surplus electricity to sell in the market a third product from sugarcane. Although any boiler can be efficient, the sale of electricity has stimulated the improvement of the burning process. However, the investment in high-pressure boilers, much more expensive than any common boiler, is essential for the exportation of electricity. Among the 22 sugarcane mills from Mato Grosso do Sul, Brazil, only 12 power plants sell electricity to the grid. The power generation efficiency depends on the pyrolysis in boilers, which results in ashes that match the unburned mineral fraction of the fuel as oxide. Both the bagasse and the straw are composed predominantly of lignin, hemicellulose and cellulose with calorific power near to the wood at the same moisture content. However the bagasse leaves the mill with about 50% of moisture while the straw reaches the industry with about 15% of humidity. This paper characterize the ashes samples from burned bagasse from seven sugarcane mills at Mato Grosso do Sul Brazilian state, to compare the methodology available for use to measure the efficiency of the pyrolysis system. Among these sugarcane mills only two are highlighted by their higher burning efficiency, both of them selling electricity, while the others showed unburned portions characterizing an inefficient system. For these industries the ash content in the ashes showed values compatible with the Superior Calorific Value as an efficiency index for the combustion degree in boilers.

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The main problem in anaerobic digestion of low-protein residues is the instability caused acidity. The use of limestone at the same time as a neutralizing agent and support material is innovative because stones wear allows the slow release of the calcium carbonate thereby eliminating dispersers. Free calcium content in the system was measured in two plug flow reactors filled with vinasse at initial pH of 4.50. The proportion of 1.8 tonnes of limestone per m³ of vinasse was evaluated at the Hydraulic Retention Times (HRT) of 24, 48, 72, 96 and 120 hours, allowing stabilisation at 96 hours. The ratio of Volatile Acids/Total Alkalinity (VA/TA) ranged from 0.2 to 0.4 and the pH reached 7.0, at the HRT of 120 hours. Increasing the HRT also increased the volatile total solids (VTS) and fixed total solids (TFS) in a similar profile to the measured free calcium content, but calcium remained at the appropriate level of 100 to 250mg l-1. The proportion of limestone/vinasse was adequate to ensure stabilisation, but it is not recommended to reduce the HRT below 96 hours due to the risk of compromising the stability of the anaerobic system.