Variáveis de crescimento e desenvolvimento em acessos de batata-doce (Ipomoea batatas).

Abstract

Sweet potatoes are a valuable source of vitamins and contain moderate levels of iron and zinc. It requires little fertility management, developing under adverse conditions, which can be a lowcost and nutritious solution for developing countries. It can also provide low-cost, high-protein forage for animal feed. The objective of this work was to study the growth of the sweet potato crop, considering the Peasant production system. The study was carried out in a representative area of the Campos Gerais region of Paraná, in the city of Ponta Grossa. The climate of the region is classified as Cfb. Two varieties of sweet potato were used, called BD-8 and BD-26, which belong to the germplasm bank maintained by the Agricultural Mechanization Laboratory of the State University of Ponta Grossa – Lama/UEPG. Eight harvest times were carried out, with an interval ranging from 15-20 days, starting at 54 days after transplanting. Thus, plants were harvested at 56, 81, 100, 115, 135, 154, 175 and 220 days after transplanting (DAT). In each season, four to six plants were harvested from the central lines of the experimental units. With which the dry mass accumulation (DMA), harvest index (HI), leaf area index (LAI), specific leaf area (SLA) and leaf area ratio (LAR) were calculated. A completely randomized design was used, with unbalanced repetitions; the treatments consist of the eight harvest seasons. The variables were submitted to the Shapiro-Wilk tests, in order to verify the normality and homogeneity of the variances, respectively, and subsequent analysis of variance. The variables that showed differences in the analysis of variance were split using polynomial regression to fit the models. The BD-8 variety maintained the highest accumulation of dry mass throughout the growth phase, while the BD-26 variety showed a tendency to present the end of the cycle more quickly. The same tendency for the HI to be higher in the final phase of the cycle was observed for both varieties. The LAI showed similar behaviour in both varieties. In BD-8, SLA followed the same growth profile as LAI, greater at the beginning of the cycle and decreasing later, SLA in BD-26 indicated decreasing trend. For both varieties, as the SLA decreases along the cycle, the LAR also showed the same behaviour.