Introduction and selection through participatory breeding of sweet potato genotypes whit high beta-carotene levels in the state of São Paulo

Abstract

The sweet potatoes is among the seven foods the most important worldwide. This vegetable is considered as capable of ensuring the food security of the population, especially the poorest, by the quality of food and quantity per area produced. The sweet potato root is a rich food both in energy and nutritional aspect. The sweet potato root is a target food in several researches, in several countries, because high content of carotenoids and flavonoids. The biofortification, through of selection of cultivars, aims to raise the nutritional levels and bioactive compounds capable of supplying, in whole or in part, the need of the human organism when inserted in diet. In view of the above, the objective of this project is to introduce and select sweet potato genotypes with high levels of beta-carotene, together with good agronomic characteristics in different locations in the state of São Paulo. The Accelerated Breeding Scheme, developed by the International Potato Center, will be adopted for the conduction of the Sweet Potato Selection/Breeding Program, which features the use of several selection sites and minimizes number of repetition. This new technique allows the development of a sweet potato cultivar in four years and has been routinely used in the development of sweet potato cultivars in Peru and in several African countries, with several cultivars already launched with this technique. An elite population developed by the International Potato Center (CIP) and the Institute of Agricultural Research of Mozambique (IIAM) with high levels of beta-carotene and dry matter wil be used to select sweet potato accesses adapted to the edaphoclimatic conditions of the study regions. This elite population has been obtained by recurrent selection for years ago. The imported/introduced seeds will be mechanically scarified and placed for germination in expanded polystyrene trays of 72 cells filled with commercial substrate. After the complete development of the seedlings, they will be transplanted in 20-liter pots and the plants will be kept in a greenhouse, aiming the supply of propagation material for new planting and evaluation. Four field trials (OT) will be carried out on farmers: Nhunguara quilombo, Iporanga, São Pedro quillombo, in Eldorado, Esmeralda rural settlement, in Pereira Barreto and Estrela da Ilha, in Ilha Solteira. In each site, will be cultivated 250 accesses coming from the CIP and IIAM. It will be selected 20 to 50% of accesses Subsequently, four new trials will be installed, with the best genotypes selected in the first crop cycle. The selection will be based on the agronomic characteristics for the first cycle and agronomic and chemical / nutritional for the second cycle, and through of evaluations of the researchers, technicians and producers as to the appearance attributes of the root and plant (through scale of notes from 1 to 5, where 1 will be less attractive and 5 more attractive). In the evaluation, women will be involved in the production/selection process to select those with the best culinary aspect. The cultivation in both cycles will be in accordance with farmers practices, a premise of participatory genetic breeding. The harvest will be carried out 150 days after the transplanting of the branches. The total dry and starch contents, total and reducing sugars, total phenolic compounds, beta - carotene and zinc content were evaluated. With the average data of each evaluated characteristic and of the assigned grades will be carried out the test of normality and homogeneity of the data. Subsequently will be performed analysis of variance through the F test and clustering of accesses through the Skott Knott methodology, at 5% probability. Then, the effect of the interaction G x A through mixed models will be analyzed, using statistical model 54 of the Selegen-Reml / Blup software. (AU)