Sugarcane giant borer (Telchin licus licus) is a serious sugarcane pest in Americas whose endophytic lifestyle hampers effective chemical and biological controls. Therefore, development of alternative control methods is extremely important. Envisaging development of transgenic plants resistant to this pest, we investigated the effect of the Bacillus thuringiensis Cry protein Cry1Ia12synth (truncated protein lacking C-terminus with plant codon usage) and variants against T. l. licus. cry1Ia12synth gene was used to generate mutated variants, which were screened for toxicity toward T. l. licus. For that purpose, an innovative technique combining cry gene shuffling with phage-display was used to build a combinatorial library comprising 1.97x10(5) Cry1Ia12synth variants. Screening of this library for variants binding to T. l. licus Brush Border Midgut Vesicles led to the identification of hundreds of clones, out of which 30 were randomly chosen for toxicity testing. Bioassays revealed four variants exhibiting activity against T. l. licus as compared to the non-toxic Cry1Ia12synth. Eight single substitutions sites were found in these active variants. Based on theoretical molecular modelling, the probable implications of these mutations are discussed. Therefore, we have four genes encoding Cry1Ia12synth variants active against T. l. licus promising for future development of resistant transgenic sugarcane lines.

ResumoA cana-de-açúcar é uma forragem que apresenta limitações nutricionais, devido aos baixos teores de proteína, de fósforo e de enxofre, entretanto, a adubação fosfatada pode melhorar sua qualidade nutricional, pois influencia na absorção e no metabolismo do nitrogênio e do fósforo. No presente estudo, avaliaram-se, no ciclo de cana-planta, o acúmulo de matéria seca, de fósforo e de proteína bruta e a produção de sacarose de duas variedades de cana-de-açúcar em função da adubação fosfatada. O estudo foi um fatorial 2 x 6, constituído de duas variedades de cana, RB867515 e RB92579, e seis doses de fósforo: zero, 30, 60, 90, 120 e 150 kg ha -1 de P, com os tratamentos distribuídos em blocos ao acaso, com cinco repetições. Utilizou-se também adubação nitrogenada e potássica em doses equivalentes a 100 e 200 kg ha -1 de N e K, respectivamente. A adubação fosfatada influenciou no acúmulo de matéria seca e de sacarose, havendo efeito quadrático. Houve efeito linear, mas discreto, das doses de P sobre a concentração desse elemento na matéria seca, o que não foi observado para a concentração de proteína bruta. Por outro lado, os acúmulos de proteína e de fósforo foram significativamente influenciados pela adubação. Palavras-chave: Alimentação animal, nutrição mineral, produtividade, qualidade da forragem AbstractThe sugarcane is a fodder that presents nutritional limitations, due to low levels of protein, phosphorus and sulfur; however, the phosphorous fertilization can improve its nutritional quality, because it influences in the absorption and the metabolism of nitrogen and phosphorus. In this study, the accumulation of dry substance from phosphorus and raw protein and the production of sucrose from two sugarcane varieties in function of the phosphorous fertilization in the sugarcane -plant cycle were evaluated. The study was a 2 x 6 factorial, consisted of two sugarcane varieties, RB867515 and RB92579, and six doses of phosphorus: zero, 30, 60, 90, 120 and 150 kg ha -1 of P, with treatments distributed in blocks at random, with five repetitions. Nitrogen and potassium fertilization in doses equivalent to 100 and 200 kg ha of N and K were also used respectively. The phosphorous fertilization influenced in the accumulation

Resumo -O objetivo deste trabalho foi avaliar o efeito de diferentes quantidades de palhada sobre o sistema radicular e a produtividade da cana-de-açúcar (Saccharum officinarum), de primeira e segunda soqueiras, em Latossolo Vermelho eutroférrico. Seis tratamentos foram avaliados: 0, 5 (25%), 10 (50%), 15 (75%) e 20 Mg ha -1 (100%) de palhada e cana-queimada, na primeira e segunda soqueiras. Utilizou-se a cana-de-açúcar 'SP80-1816'. Avaliou-se a massa de raízes a 0,45 e 0,75 m de distância da linha de plantio, até 0,60 m de profundidade. Na primeira soqueira, os tratamentos com 50, 75 e 100% de palhada proporcionaram maior massa radicular até 0,20 m de profundidade, em comparação aos tratamentos cana-queimada, 0 e 5 Mg ha -1 (25%) de palhada. Os tratamentos com 50 e 75% de palhada proporcionaram produtividades 43% maiores do que a da cana-queimada (110 Mg ha -1 ). O tratamento com 10 Mg ha -1 (50%) foi suficiente para proporcionar aumento da massa radicular e da produtividade da cana-de-açúcar. O sistema radicular e a produtividade da cana-de-açúcar são favorecidos pela mudança do sistema de colheita de cana-queimada para o de cana sob palhada.Termos para indexação: Saccharum officinarum, biomassa, cana crua, colheita mecanizada, enraizamento, manejo da palhada, produção agrícola. Root system and productivity of sugarcane ratoon associated to different quantities of strawAbstract -The objective of this work was to evaluate the effect of different amounts of straw on the root system and productivity of sugarcane (Saccharum officinarum), of first and second ratoons, in an Oxisol. Six treatments were evaluated: 0, 5 (25%), 10 (50%), 15 (75%), and 20 Mg ha -1 (100%) straw and burned sugarcane of the first and second ratoons. 'SP80-1816' sugarcane was used. Root mass at 0.45 and 0.75 m away from the row, and up to 0.60 m deep was evaluated. In the first ratoon, treatments with 50, 75 and 100% straw provided greater root mass up to 0.20-m depth, in comparison to treatments of burned sugarcane, and 0 and 5 Mg ha -1 (25%) straw. The treatments with 50 and 75% straw had 43% higher yields than burned sugarcane (110 Mg ha -1 ). The treatment with 10 Mg ha -1 straw (50%) was sufficient to provide increased root mass and productivity of sugarcane. The root system and the productivity of sugarcane are favored by the change of burned-sugarcane harvesting system to sugarcane under straw.

Sugarcane straw mulch left in the field after its mechanical harvest has become very valuable raw material for second generation ethanol and bioelectricity production. However, little information is available on how much straw mulch is needed to be left in the field so that agricultural productivity is not affected and high sustainability is provided for the bioenergy production system. The objective of this work was to evaluate the productivity and industrial quality of sugarcane after five years of cultivation when different amount of straw mulch is removed from the field. The experiment was installed in clay texture Eutroferric Red Latosol (Oxisol). Six treatments were evaluated: 0%, 25% (5 t ha −1), 50% (10 t ha −1), 75% (15 t ha −1), 100% (20 t ha −1) of straw mulch and burnt cane harvesting (where 100% of the straw mulch was burned). Evaluated parameters included sugarcane productivity (tons/hectare) and its industrial quality (Pol, soluble solids (°Brix), apparent purity and total sugars (TS)). Productivity was calculated at the end of the cycle whereas industrial quality parameters were evaluated during three phases i.e. 180, 240 and 350 days after cutting (DAC). Straw mulch of 50 and 75% were statistically at par with each other but resulted in higher sugarcane production with 47% more productivity as compared to 0 and 25% of straw mulch as well as burned cane harvesting. Straw mulch didn't affect the industrial quality; however, higher sugar production was supported by higher agricultural productivity, under low moisture condition. It is possible to remove 50% of straw mulch from the field for the production of second generation ethanol or bioelectricity, without any damage to the crop.

Due to mechanical harvesting large amount of straw is left in the field which implicates modification throughout the agriculture environment. This straw is beneficial for both soil and plant. However, there is no information about the sufficient quantity which can be used to achieve such effects and also whether it can be used in other sectors like electricity and ethanol production. Therefore, a research was designed with the objective to evaluate the effect of different amounts of straw on the development and productivity of sugarcane during the first and second ratoons. Treatments used in the experiment included: burned cane, 0%, 25%, 50%, 75% and 100% (20 t ha −1) of sugarcane straw left on the soil surface. The tested variables included leaf area index (LAI), number, diameter, length and production of stems. Plants were evaluated at 60, 120, 180, 240 and 370 days after harvest (DAH) for the first ratoon and at 60, 120, 180, 240 and 270 DAH for the second ratoon. Replacing burned cane harvest system for soil management with straw promotes the development and productivity of sugarcane ratoons. Field managements with burned cane, total removal of the straw, or keeping 25% of straw result in low number of tillers, leaf area index, stem diameter and productivity of sugarcane ratoons, under water stress conditions. Whereas keeping 50% of straw mulch is enough to improve the growth and yield of sugarcane with drought occurrences, while the remaining 50% can be used for second generation of ethanol production or electricity without damaging the crop yield.