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Drought is one of the most important abiotic stresses responsible for reduced crop yields. Drought stress induces morphological and physiological changes in plants and severely impacts plant metabolism due to cellular oxidative stress, even in C4 crops, such as sugarcane. Seaweed extract-based biostimulants can mitigate negative plant responses caused by drought stress. However, the effects of foliar application of such biostimulants on sugarcane exposed to drought stress, particularly on plant metabolism, stalk and sugar yields, juice purity, and sugarcane technological quality, have received little attention. Accordingly, this study aimed to evaluate the effects of foliar application of a seaweed extract-based biostimulant on late-harvest sugarcane during the driest period of the year. Three experiments were implemented in commercial sugarcane fields in Brazil in the 2018 (site 1), 2019 (site 2), and 2020 (site 3) harvest seasons. The treatments consisted of the application and no application of seaweed extract (SWE) as a foliar biostimulant in June (sites 2 and 3) or July (site 1). The treatments were applied to the fourth ratoon of sugarcane variety RB855536 at site 1 and the fifth and third ratoons of sugarcane variety SP803290 at sites 2 and 3, respectively. SWE was applied at a dose of 500 ml a.i. ha−1 in a water volume of 100 L ha−1. SWE mitigated the negative effects of drought stress and increased stalk yield per hectare by up to 3.08 Mg ha−1. In addition, SWE increased stalk sucrose accumulation, resulting in an increase in sugar yield of 3.4 kg Mg−1 per hectare and higher industrial quality of the raw material. In SWE-treated plants, Trolox-equivalent antioxidant capacity and antioxidant enzyme activity increased, while malondialdehyde (MDA) levels decreased. Leaf analysis showed that SWE application efficiently improved metabolic activity, as evidenced by a decrease in carbohydrate reserve levels in leaves and an increase in total sugars. By positively stabilizing the plant's cellular redox balance, SWE increased biomass production, resulting in an increase in energy generation. Thus, foliar SWE application can alleviate drought stress while enhancing sugarcane development, stalk yield, sugar production, and plant physiological and enzymatic processes. [ABSTRACT FROM AUTHOR]

The objective of this research was to evaluate the activity of acid and neutral invertases in controling the storage of sucrose in sugarcane variety SP80-3280 due to plant regulators application in the middle of the cropping season in Igaraçu do Tietê (SP), Brazil. The experiment was carried out in ratoon cane (crop 2004 and 2005) in a randomized block design with five replications. The treatments consisted of four plant regulators application of the class of growth retainers (Ethephon, Ethyl.trinexapac, Potassium nitrate and Potassium nitrate + Boron) and a control (natural ripening), whose commercial products (c.p.) were Ethrel, Moddus, Krista Kana and Krista Kana Plus, with dosage of 2L c.p. ha-1, 0.8L c.p. ha-1, 3kg c.p. ha-1 and 3c.p. kg ha-1, respectively, without adjuvants application. The growth regulators provide alterations of different and significant intensity in soluble acid invertase and neutral invertase levels enzymes. The agricultural efficiency of maturators was affected significatively by the weather and time of application. The treatments with maturators, were affected most in 2004, when wheater conditions were unfavourable to natural ripening, were favour the ripening sugarcane process implicating in improvement technological quality of stems. [ABSTRACT FROM AUTHOR]

The ripening sugarcane is the most important aspect in production sistem for sugar and alcohol industry. The objective of this research was to evaluate technological quality, productivity and agricultural contribution margin of sugarcane variety RB855453 in function of plant regulators application at the beginning of the cropping season, in Igaraçu do Tietê (SP), Brazil was studied. The experiment was carried out in a randomized block design with five replications. The treatments consisted of four plant regulators application of the class of growth retainers (Ethephon, Ethyl.trinexapac, Potassium nitrate and Potassium nitrate + Boron, in dosage commercial products of 2L ha-1, 0.8L ha-1, 3kg ha-1, e 3kg ha-1, respective) and a control (natural ripening). The maturators, general manner, provided the improvement technological quality of stems with positive reflex in productivity of sugar and agricultural contribution margin. The maturators Potassium nitrate + Boron, Ethephon and Ethyl-trinexapac, under weather conditions unfavourable to natural ripening process of sugarcane, allowed to anticipate the crop in five, eight, and twenty-five days, respectively, in relation a control treatment. In the subsequent crop season, under optimus weather conditions the ripening process of sugarcane, had no difference when compared to the control treatment. [ABSTRACT FROM AUTHOR]