Multivariate analysis of the temporal variability of sugarcane ripening in south-eastern Brazil

Abstract

Sugarcane ripening is a process controlled by cultivar characteristics and the interaction of genotypes with local climate. The objective of this study was to characterise the temporal variation of sugarcane ripening by assessing the multivariate structure contained in sugarcane quality data, and by correlating the results with local climatic conditions. Eight sugarcane cultivars were evaluated from March to October in Piracicaba, São Paulo State, Brazil. Characteristics related to the quality of raw sugarcane juice were submitted to statistical analysis by ANOVA, hierarchical and non-hierarchical (k-means) clustering methods, and principal components, in order to classify the cultivars into groups for each month of sampling. The ANOVA showed a clear difference (P < 0.001) among harvesting months for all sugarcane quality variables, which was reinforced by the cluster analysis for the whole dataset that selected groups according to the month of harvest. By analysing the quality variables by months, patterns of similarity among sugarcane cultivars were identified, which allowed three ripening groups to be established: early, middle and late. As the harvesting season progressed, the variations within each group, as well as among groups, were explained mainly by local soil-water availability conditions. The early ripening cultivars showed polarisable sugar (Pol) values >13% in early May, whereas these values were reached by the middle cultivars in July, and the late ones in August–September. However, the differences among groups tended to decrease through the harvest season, as expressed by the Euclidean distance, which decreased from 5.62 in March to 1.82 in September, when the water deficit reached the maximum accumulated value, totalling >130 mm. The non-hierarchical analyses (k-means) and principal components methods agreed, resulting in the identification of the same three main cultivar groups. The approach proposed for cultivar classification in this study is more complete than the usual analysis of Pol variation over time, since it allowed all of the variability contained in the sugarcane quality dataset to be analysed in an integrated way, providing a better understanding of the differences observed in the ripening of different cultivars.

Yield and technological performance of sugarcane cultivars grown under Af climate conditions

“…Another factor that stimulates the accumulation of sucrose in sugarcane is the stress caused by water deficit, which reduces the soil humidity and, consequently, decreases the water content in the plant tissues (dehydration forces the conversion of the reducing sugars in sucrose). Cardozo, Sentelhas, Panosso and Ferraudo (2014) verified that the water content in the sugarcane stalk is inversely proportional to the sucrose content, and good water availability slows down the maturation process. Oliveira et al (2012) reported that a high humidity in the soil affects the sucrose accumulation of the plant, which is positively correlated with moisture and reducing sugars and negatively associated with sucrose.…”

Multivariate analysis to identify groups of biodiesels in the operation of an agricultural engine

“…In Table 2 it can be seen that the variables power on the drawbar showed the highest significant F value, followed by volumetric hourly consumption, weight and travel speed, indicating that these variables are the main criteria for assigning objects (biodiesels) to the groups (Cardozo et al, 2014).…”

Maturity Classification of Sugarcane (Saccharum officinarum L) Genotypes Grown Under Different Production Environments of Ethiopia

“…Moreover, genotypes that mature beyond 18 months crop age (those genotypes that loosely correlated with all crop ages) can be classified as poorly performed or and late maturing genotypes. Cardozo et al [24] reported similar classifications by analyzing the quality variables by months in which patterns of similarity among sugarcane cultivars were identified, which allowed three ripening groups to be established and classified as early, middle and late. (Figure 2c).…”