Pre-Sowing Treatment of Sugarcane Mini-Stalk with Antioxidant Plus Biostimulant: Physiological and Biochemical Approach

The oxidation of reserves and the potential restriction of hormones in the vegetative propagules of sugarcane can impair the adequate initial development of plants in the field, with subsequent restriction to production. The objective of this study was verified the use of tyrosol, as an exogenous antioxidant, associated, or not, with the biostimulant tryptophol on initial sugar cane growth and metabolism. Mini-stalks of sugarcane (Saccharum spp.) cv. RB86-7515, containing only one bud, were treated with: T1—water (control); T2—36.15 µmol tyrosol; T3—72.37 µmol tyrosol; T4—2 µmol tryptophol+36.15 µmol tyrosol; and T5—2 µmol tryptophol+72.37 µmol tyrosol. Then, the mini-stalks were grown under two substrates: under sand in plastic trays and in soil packed in plastic pots. The initial plant growth, °Brix and antioxidant metabolism evaluations of the mini-stalks were performed. Treatments T3 and T5 proved to be efficient in increasing sprouting rate and initial shoot growth; however, the same treatments were harmful to root growth. Furthermore, T4 treatment reduced the catalase activity and improve the total soluble protein content, indicating better modulation in hydrogen peroxide content in sugarcane tissues, concluding that tyrosol and tryptophol have potential for use in the sugarcane crop, by stimulating and protecting mini-stalks under initial development.