Selection of full-sib families of Panicum maximum Jacq under low light conditions

Abstract

RESUMOThe silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values (GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance. Seleção de progênies de irmãos completos de Panicum maximum Jacq sob condições de redução de luminosidadeA implantação de sistemas silvipastoris é uma alternativa tecnológica à criação extensiva de gado e, para que haja sucesso, é necessário identificar genótipos de gramíneas forrageiras adaptados à redução de luminosidade. O objetivo deste estudo foi selecionar progênies de P. maximum, tolerantes à redução de luminosidade, para uso em programas de melhoramento, e estudar o controle genético e o desempenho de alguns caracteres associados à tolerância. Foram avaliadas seis progênies de irmãos completos, a sol pleno, a 50% e a 70% de redução da luminosidade, em vasos e sob cortes. Os valores genotípicos (VG) das progênies, em relação à altura das plantas (ALT) e à área foliar específica (AFE), aumentaram com a redução da luminosidade. Para os caracteres acúmulo de massa seca total (MS) e massa verde de lâminas foliares (MSVLF), esses VG foram maiores, com 50%, e interme-200 Douglas Mochi Victor et al.

Productivity of Benggala grass (Panicum maximum) at different ages of oil palm

“…The number of tillers at the control location was higher than the number of tillers in oil palms aged less and more than 5 years (table 4). A decrease in the number of tillers in selected shaded Benggala grass cultivars was also reported by [13] and [14]. Shade changes the intensity and quality of radiation in plants, and affects the potential number of tillers [15].…”

Fatores de desenvolvimento para plantas forrageiras e suas respostas sob condições de estresse

“…Photosynthetically active radiation influences the increment of the specific leaf area (Victor et al, 2015) interfering in the leaf area index (LAI) (Gastral and Lemaire, 2015;Gomes et al, 2019), as well as in the tiller population (Queiroz et al, 2018), in which this population can be reduced, but compensated by the increase in the specific leaf area. This compensation effect is considered a mode of plant adaptation to low light conditions.…”

Morphology of Panicum genotypes submitted to periods of cessation of irrigation

“…is the most productive tropical forage propagated from seed, and is used worldwide due to its high productivity, forage quality and adaptability to different soil and climatic conditions (Jank et al, 2010). Brazil has a large germplasm bank, which has allowed for improvement of this species (Victor et al, 2015). Panicum maximum is a C 4 forage plant with high yield potential.…”