Crescimento da Cana-de-açúcar cultivada sob diferentes sistemas de plantio e colheita

Abstract

Researches on sugarcane harvesting handling in the landscape of coastal tableland lack information about long term effects. This study is a prolongation of two experiment s carried out in Linhares municipality, Espírito Santo State (Brazil), starting 16 years ago. The experiment is one of the oldest research trials in Brazil about raw and burnt cane harvesting systems. The main hypothesis was that of an increase in cane-plant productivity in the treatments without burning before harvesting. Another important aspect was management of cane planting in the coastal tableland areas, and its direct influence in the production cost as a function of soil tillage system. The study was divided in two chapters. The objective of the first chapter was to evaluate cane-plant growth, through the parameters: height, diameter and tillering; and the yield of cane-plant, in cropping systems with alternation of harvesting forms: cane raw-raw, raw-burnt, burnt-raw, and burnt-burnt. The second chapter had as objective to evaluate effects of soil tillage systems, conventional and minimum tillage, and the interaction with raw and burnt crop systems on cane-plant growth and yield. The RB867515 was the sugarcane (Saccharum sp.) variety used, and the soil was classified as Xanthic Udult. The data were obtained in 2005 and 2006. The evaluated parameters were: height, diameter and number of stems m-1, addition of organic matter and yield of sugarcane. It was adopted a polynomial of 2nd and 3rd degrees regression exponential model to adapt the data to the growth curves, in both experiments. The first experiment was set in a randomized block design with six replicates. The second renewal of the sugar cane plantation was made after seven cultivation cycles, implanted with minimum tillage, and with the following successions of harvesting systems: raw cane for raw (RR), raw cane for burnt (RB), burnt cane for burnt (BB), and burnt cane for raw (BR). The results showed that height and diameter of stems were influenced by the cane harvesting practices. A significant difference was not observed in the number of stems by linear meter, or in the stems productivity as a function of the harvesting systems. In the second chapter, the experimental area was cultivated under conventional tillage for 16 years, without replanting, with harvesting handling of cane-raw and cane-burnt, and in 2005 there occur the first renewal of the sugarcane plantation. The experimental design was of strips with split - splot and six replications of the following treatments: plots with conventional tillage and minimum tillage; and sub plots with raw cane and burnt cane harvesting. The renewal of the sugarcane plantation after 16 years of cultivation, and the height and diameter of stems were affected by the tillage and crop harvesting systems. The number of stems was higher for the conventional tillage and raw cane.There were no differences in the stem productivity for both systems. The straw productivity was affected by the soil tillage system, and cane tips productivity was affected by the harvesting system, thus increasing the plant capacity in supplying photoassimilates to stems at the end of cane cycle.