PRODUÇÃO DE SEMENTE A PARTIR DE BROTOS E DESEMPENHO DE CULTIVARES DE BATATA EM SISTEMA ORGÂNICO

Abstract

The objective of this work was to study the applicability of the sprout/seed potato technology in an organic production system, using different varieties to test which cultivars best fit for this cropping system. For this purpose, growth, resistance to late blight, spread of viruses and yield it were evaluated. Three experiments were conducted, the first, growing sprouts in greenhouse in Guarapuava - PR, from November 2011 to January 2012, the second, in the field in Candói - PR from May to September 2012 and the third and last, in the field of the IAPAR`s experimental farm in Guarapuava - PR from February to May 2013. In the first two experiments, five potato cultivars (Ana, Catucha, Clara, Cristal and Eliza) were tested and in the third experiment, it was added 4 more cultivars (Agata, Baronesa, Bel and Bintje). The experimental design was a randomized block design with three replications in all three experiments. It was analyzed the incidence of viral diseases at the end of the first two experiments, and in all experiments, it was recorded: length of the main stem, number of stems, number of leaves. These data were taken at 25 and 45 days after planting (DAP) in the first experiment, 45 and 65 DAP in the second experiment and at 45 and 72 DAP in the third experiment. At the end of plant growth, it was recorded the total number of tubers and final tuber yield. In the second experiment it was evaluated the incidence of late blight at 65 DAP and in the third experiment it was also measured the leaf area index, number of tubers initiated and formed, the fresh and dry weight of tubers at 72 DAP and the weekly observations of late blight severity that began at 55 DAP and was done until 76 DAP. In the first experiment there was difference in plant height, yield and average tuber weight, however for leaf number, number and size of tubers, there was no difference among the cultivars, and there was no spread of viruses. Given the fact that the tubers are used for seed production, the total number and weight of tubers are the main factors, in which the cultivars Ana and Clara highlighted in weight and yield, respectively. In the second experiment, there was significant difference in plant height and incidence of late blight among the cultivars, and there was a low spread of viruses, however these factors did not reflect in tuber yield. In the third experiment the cultivar that stood out in total and commercial yield was Catucha. This cultivar showed excellent resistance to late blight the greatest leaf area index, which was considered the main factors to lead this cultivar to reach 13.8 t ha?¹ of total tuber yield. Aiming to meet the actual demand for purchasing seeds for organic farming from the same system, the use of technology bud / seed potato proved to be feasible because after two generations of multiplication, it was observed in cultivar Catucha yield potential above 50% of the national average yield without the use of chemical fertilizer and pesticides.