Fenotipagem de linhagens de arroz de terras altas submetidas à adubação fosfatada gradual

Abstract

In order to guarantee high agricultural productivity, nutrients are required in optimal amounts. On the one hand, the low efficiency of phosphate fertilizers in soils with fertility problems, associated with the responsiveness that comes from the genetic variability of plants, is a widely discussed problem. Fully acidulated sources of phosphorus and ammonium are the most imported phosphate fertilizers used in Brazilian agriculture, on the other hand, slow release sources such as thermophosphates can provide lower losses, greater availability of phosphorus, better agronomic efficiency and improvement of the acidity of the soils, thus ensuring improvements in fertility and, therefore, high grain productivity. The purpose of this study was to evaluate the phenotypic behavior of upland rice lines submitted to slow-release phosphorus fertilization, aiming to achieve new management technologies and responsiveness in relation to fertilization. The experiment was carried out in the 2021/22 season, in the municipality of Lavras, in a randomized block design, with three replications, in a factorial scheme (10 x 4 x 3), comprising ten genotypes, four fertilizer combinations and three dosages. The genotypes came from the Cultivation Value and Use trials of the UFLA upland rice breeding program. The following characteristics were evaluated: plant height, number of days to flowering, disease resistance and grain weight. Genetic variability was observed for plant height, number of days for flowering and grain weight, with plants with better size being obtained when fertilized with magnesium thermophosphate, with emphasis on the CMG 2188 lineage. of grains, the lines were also more responsive to Termax P, as well as to the combination 30%MAP + 70%Termax and 50%MAP + 50%Termax, with emphasis on CMG 2188, CMG 2185 and CMG 1977. Magnesium thermophosphate proved to be advantageous in rice lines as a source of P, especially for highlands that are characterized by a deficiency of this nutrient.