Aplicação de maturador e fertilizante foliar em cana-de-açúcar

O uso de maturadores visa o acúmulo de sacarose em cana-de-açúcar, antecipando sua maturação e flexibilizando a logística de colheita. Objetivou-se com este trabalho avaliar o crescimento, a produtividade, a qualidade tecnológica e o ganho de açúcares da cana-de-açúcar de ciclo médio-tardio sob aplicação aérea de maturador e fertilizante foliar associado ao uso de adjuvante. As aplicações foram realizadas 12 meses após o primeiro corte de uma variedade de ciclo médio-tardio. Os tratamentos consistiram de um maturador da classe dos inibidores da enzima acetolactato sintase (sulfometuron methyl) e de um biocatalizador formado por um fertilizante foliar (Atriun®), e de suas misturas com adjuvante (Startec). Foram avaliados o ATR (açúcares totais recuperáveis), a altura de plantas, o teor de fibra, a produtividade de açúcar por hectare (TAH), o teor de sacarose (POL) e o índice SPAD (Soil Plant Analyzer Develop). O uso do fertilizante foliar sem adjuvante proporciona maiores altura de plantas, ATR e POL, teor de fibra e ganho de TAH na cana ao final de safra e o maturador Sulfometuron methyl aumenta a altura de plantas com redução do teor de fibra, porém quando associado ao adjuvante diminui ATR e POL, com índice de ganho constante de TAH. A aplicação dos produtos sem adjuvante proporciona melhores resultados quanto à qualidade tecnológica e índice de ganho de TAH da cana-de-açúcar de ciclo médio-tardio para final de safra.

Engineering Herbicide-Tolerance Rice Expressing an Acetohydroxyacid Synthase with a Single Amino Acid Deletion

The acetohydroxyacid synthase (AHAS) is an essential enzyme involved in branched amino acids. Several herbicides wither weeds via inhibiting AHAS activity, and the AHAS mutants show tolerance to these herbicides. However, most AHAS mutations are residue substitutions but not residue deletion. Here, residue deletion was used to engineering the AHAS gene and herbicide-tolerant rice. Molecular docking analysis predicted that the W548 of the AHAS was a residue deletion to generate herbicide tolerance. The AHAS-ΔW548 protein was generated in vitro to remove the W548 residue. Interestingly, the deletion led to the tetramer dissociation of the AHAS, while this dissociation did not reduce the activity of the AHAS. Moreover, the W548 deletion contributed to multi-family herbicides tolerance. Specially, it conferred more tolerance to sulfometuron-methyl and bispyribac-sodium than the W548L substitution. Further analysis revealed that AHAS-ΔW548 had the best performance on the sulfometuron-methyl tolerance compared to the wild-type control. Over-expression of the AHAS-ΔW548 gene into rice led to the tolerance of multiple herbicides in the transgenic line. The T-DNA insertion and the herbicide treatment did not affect the agronomic traits and yields, while more branched-chain amino acids were detected in transgenic rice seeds. Residue deletion of W548 in the AHAS could be a useful strategy for engineering herbicide tolerant rice. The increase of branched-chain amino acids might improve the umami tastes of the rice.

Weed control efficacy and tolerance of Canaan fir to preemergence herbicides

PRE herbicides are the backbone of a successful weed management program in Christmas tree production. In a 2-yr field study, weed control efficacy and tolerance of newly transplanted Canaan fir to different PRE treatments were evaluated. Herbicide treatments consisted of two rates of each of atrazine plus mesotrione plus S-metolachlor at 561 + 150 + 1,504 and 1,122 + 300 + 3,008 g ai ha−1, flumioxazin at 214 and 429 g ai ha−1, hexazinone plus sulfometuron methyl at 289 + 27 and 480 + 46 g ai ha−1, indaziflam at 20 and 41 g ai ha−1, simazine plus oryzalin at 3,366 + 1,683 and 3,366 + 3,366 g ai ha−1, and a nontreated control. Averaged over 2 yr, all PRE treatments controlled giant foxtail, large crabgrass, and redroot pigweed at least 80% throughout the summer. Only the high rates of atrazine plus mesotrione plus S-metolachlor maintained >80% season-long control of yellow foxtail. Horseweed was controlled >85% with flumioxazin at both rates and at high rates of atrazine plus mesotrione plus S-metolachlor, hexazinone plus sulfometuron methyl, and indaziflam. The season-long PRE control of both red sorrel and wild carrot was maintained ≥80% with atrazine plus mesotrione plus S-metolachlor and hexazinone plus sulfometuron methyl regardless of application rate. By 16 wk after treatment, within-row densities of weeds evaluated in this study were reduced >75% in plots treated with atrazine plus mesotrione plus S-metolachlor at both application rates or hexazinone plus sulfometuron methyl at 480 + 46 g ai ha−1. Within-row weed densities in the nontreated control plots were 50, 32, 36, 25, 27, 31, and 19 plants m−2 for large crabgrass, giant foxtail, horseweed, redroot pigweed, red sorrel, wild carrot, and yellow foxtail, respectively. No discernible injury was observed in Canaan fir with any PRE treatment in both study years.