Leaf area estimation of cassava from linear dimensions

ABSTRACT The objective of this study was to determine predictor models of leaf area of ​​cassava from linear leaf measurements. The experiment was carried out in greenhouse in the municipality of Botucatu, São Paulo state, Brazil. The stem cuttings with 5-7 nodes of the cultivar IAC 576-70 were planted in boxes filled with about 320 liters of soil, keeping soil moisture at field capacity, monitored by puncturing tensiometers. At 80 days after planting, 140 leaves were randomly collected from the top, middle third and base of cassava plants. We evaluated the length and width of the central lobe of leaves, number of lobes and leaf area. The measurements of leaf areas were correlated with the length and width of the central lobe and the number of lobes of the leaves, and adjusted to polynomial and multiple regression models. The linear function that used the length of the central lobe LA = -69.91114 + 15.06462L and linear multiple functions LA = -69.9188 + 15.5102L + 0.0197726K - 0.0768998J or LA = -69.9346 + 15.0106L + 0.188931K - 0.0264323H are suitable models to estimate leaf area of ​​cassava cultivar IAC 576-70.

Sugars levels of four sugarcane genotypes in different stem portions during the maturation phase

ABSTRACT Maturation is a characteristic of sugarcane plant (Saccharum spp.) and even when grown under the same soil and climate conditions the varieties differ on the maturation curve. Thus, studies that allow establishing maturation curves of different sugarcane genotypes in the local soil and climate may indicate the proper harvesting period to ensure better quality of the raw material. This study aimed to analyze the levels of soluble sugars during the maturation phase and assess the technological and productivity indexes of four irrigated sugarcane genotypes in the region of Rio Largo, Alagoas. The experiment was conducted in randomized blocks in a 4 x 2 x 5 factorial: four genotypes (RB92579, RB98710, RB99395 and RB961003), two stem portions (internodes 1-4 and internodes 5-8) and five seasons (82, 49, 25, 13 and 3 days before harvesting), each treatment with three replications. Internodes 1-4 showed the highest levels of reducing sugars, while the largest accumulation of sucrose and total soluble solids occurred in internodes 5-8. RB99395 genotype showed more stability in the sugar levels during sugarcane maturation, which can indicate early maturation and high agricultural yield.