The behavior of 12 interspecific hybrids of Brachiaria brizantha x Brachiaria decumbens x Brachiaria ruziziensis (74-10, 141-10, 392-10, 422-10, 628-10, 798-10, 970-10, 992-10, 1115- 10, 1130-10, 1242-10, 27-11) under excess soil water was compared for 20 days with plants grown in pots, under flooding, or in well-drained soil. The commercial cultivars B. brizantha ‘Xaraés’ and B. decumbens ‘Basilisk’, relatively less susceptible to soil flooding, and the cultivar Marandu of B. brizantha, known to be intolerant to this
stress, as witnesses. The objective was to classify these genotypes in terms of their relative tolerance to soil flooding. Under flooding, the average percentage reduction in leaf elongation rate was greater in genotype 992-10. The decrease in the SPAD index, in response to soil flooding, was greatest in genotypes 992-10 and 628-10 and smallest in genotypes 422-10 and 1115-10. The production of shoot dry mass, in flooded plants, suffered a greater percentage of reduction in genotypes 1242-10, 992-10, 628-10, 392-10 and 74-10, and it was not possible to find distinctions between treatments in production of dry mass in cultivars Xaraés and Basilisk and in genotypes 27-11 and 422-10. Plant vigor reduction in response to flooding was greater in genotypes 1242-10, 1115-10 and 1130-10. Only in the cultivar Xaraés it was not possible to find a difference in vigor between flooded and non-flooded plants. The presence of adventitious roots was relatively low in all genotypes evaluated, being, however, higher in genotype 1130-10 and in cultivars Basilisk and Marandu. The evaluated genotypes differ in terms of relative tolerance to soil flooding: the cultivar Xaraés is the relatively more tolerant genotype. Genotypes 1242-10, 392-10, 628-10 and 74-10 have low tolerance, while genotype 992-10 has very low tolerance to soil flooding. The other genotypes evaluated, including the cultivars Marandu and Basilisk, show regular relative tolerance to soil flooding. These results suggest that, among the 12 hybrids evaluated, there is genetic variation for soil flooding tolerance.

DIAS FILHO, MB; CRUZ, ED; LOPES, MJ dos S.; BARRIOS, SCL; VALLE, CB do. Relative tolerance of twelve interspecific hybrids of Brachiaria spp. to soil flooding. Belém, PA: Embrapa Eastern Amazon, 2020. 36p. (Embrapa Eastern Amazon. Research and Development Bulletin, 141).