Root Characteristics of Sugarcane Varieties Planted by Pre Sprouted Seedlings in Brazilian Conservation Agriculture Systems

In Brazil sugarcane is cultivated in more than 10 million hectares for production of sugar, energy and bioethanol. Long-term trial about soil tillage it was used to evaluate the root characteristics of different sugarcane varieties, IACSP955000 (hybrids of Saccharum officinarum L.) and Energy Cane (hybrids of Saccharum spontaneum L.). It was adopted a randomized complete block design in a split-plot scheme, with four replications. The main plots were consisted by three soil managements; conventional tillage, reduced tillage (use of Rip Strip^® before planting) and no-tillage, and the secondary plot were the sugarcane varieties, both were planted (May 2015) by pre sprouted seedlings in an eutrophic Clayed Rhodic Hapludox (Oxisol) located at Experimental Station of APTA/IAC, Ribeirao Preto city, Brazil. Root system was evaluated by probe method. In each plot 30 soil samples were collected in different positions apart the sugarcane row (15, 45 and 75 cm in both sides), in two dates (September 2015 and February 2016) and 5 layers (from the top to 100 cm depth). After washing, sieving and cleaning all the samples collected, the images of roots were analysed by Safira^®software in order to determine the length, diameter, area and volume. After that, samples were dried to know the dry biomass. Results showed that for all root characteristics evaluated the conservation tillage were better than conventional tillage. In terms of root distribution, regarding the soil layer of 100 cm, the no-tillage and reduced tillage provide 540 and 290 kg ha^-1 more dry biomass than the conventional tillage (see Figure bellow). The highest soil strength was observed in the conventional tillage (> 5,0 MPa) at depth of 0,14 m, followed by no-tillage (2,92 MPa at 0,15 m) and reduced tillage (2,28 MPa at 0,30 m). On the other hand, no significant differences were observed between sugarcane varieties.