Como o manejo do nitrogênio da planta-mãe interfere na biologia de sementes de feijão carioca superprecoce?

Abstract

In literature on seed technology, mothe plant fertilization is a common issue, but papers ate based on established recommendations for grain production, especially in conventional agronomy systems. Taking this into account, I hypothezed that nitrogen management in the mother plant nutrition modifies seed biology by altering aspects of chemical composition seeds and, therefore, the germination and early development of plants. The BRS FC104 cultivar from common bean served as a biological model because it was superprecise and theoretically critical in the response to nitrogen fertilization management. My objective was to evaluate the biology of BRS FC104 super-common bean seeds, produced by mother plants in mutualism with nitrogen-fixing bacteria (Rhizobium leucaenae) and / or fertilized with nitrogen doses, applied in the physiological stages of higher demand nutrient for the crop under the no-tillage system. For that, mother plants were submitted to nitrogen variations (50, 100 and 150 kg ha -1 ), nitrogen application times based on physiological stages (V 0, V 2 , and V4 ) and inoculation with or without nitrogen fixing bacteria (FBN) (Rhizobium leucaenae). Dose application was performed only once, indenpendely of the N dose. Two additional treatments were performed, one with and one without FBN, both with 0 kg ha -1 of N fertilizer. Therefore, the experiments followed the 3 x 3 x 2 + 2 factorial ANOVA scheme, in a completely randomized design, with four replications. With the seeds harvested, the following analyzes were carried out: physicochemical composition, germination physiology (germination measures, survival analysis, risk rate, accumulated germination and relative frequency of germination), growth performance of young plants stricto sensu and seed resilience to stress. In general, the germination pattern of common bean (Phaseolus vulgaris L.), cultivar BRS FC104, is a species-specific conservative characterer. The stress mother plant increases the variability of the offspring. Early fertilization increases the uniformity of individual-seedlings and the tolerance of individual seeds to stress, but reduces lipid levels in seeds. Late N fertilization has an impact on the development of lower seedling individuals. Isolated N fertilizer results in a higher probability of not germinating at the lower dose and lower probability at the higher dose; and, when associated with BNF, increases the probability that the seeds do not germinate initially. The 50 kg ha -1 dose promotes germination with more uniform and predictable germination kinetics. Increasing the dose leads to a reduction in sulfur content and, therefore, reduces seed tolerance to stress. FBN does not substantially affect the deposition of seed reserves, however, it increases the probability of germination over time; and, when associated with 100 kg ha -1 of N applied early, improves the establishment of seedlings. Increases in carbohydrate contents, copper and potassium are indicated as inducers to stress tolerance in bean seeds.