Global climate changes have increased temperatures,radiation indexes,and consequently,irregularities in rainfall in mainly tropical countries,considerably hindering plant establishment in recovering degraded areas.The...Global climate changes have increased temperatures,radiation indexes,and consequently,irregularities in rainfall in mainly tropical countries,considerably hindering plant establishment in recovering degraded areas.The objective of this study was to evaluate the growth and physiological characteristics of one species of each successional group:pioneer,secondary,and climax when subjected to different light intensities and hydrogel as a soil conditioner during rainy and dry periods.The experiment was conducted in the ecotone between Brazil’s two largest biomes,the Cerrado and the Amazon in the State of Maranh?o.The parameters consisted of three species:Guazuma ulmifolia Lam.(pioneer),Astronium fraxinifolium Schott(secondary),and Cariniana rubra Gardner ex Miers(climax).There were two light intensities:70%and 100%,and two planting conditions:with and without soil conditioner(hydrogel).Gas exchanges were higher during the rainy season;the pioneer and secondary species had greater heights and photosynthetic rates in the dry period;the climax species had the lowest gas exchange and lowest recovery as rainfall resumed.The pioneer and secondary species showed higher physiological plasticity,denoting better adaption to environments with high irradiance.Hydrogel improved the photosynthetic performance of these species in the dry season and in areas with 100%sunlight.展开更多
Considering the expansion of forest plantations over the Brazilian territory and the imminent increase in air temperatures due to global warming,the search for technologies that ensure high levels of productivity and ...Considering the expansion of forest plantations over the Brazilian territory and the imminent increase in air temperatures due to global warming,the search for technologies that ensure high levels of productivity and high quality plants in clonal nurseries is essential.Applying kaolin-based particle films(KBPF)has been used as a physical barrier to reduce the negative effects of excessive solar radiation and adverse temperatures.The effects of KBPF on production and physiological quality of eucalyptus mini-cuttings were evaluated during two different seasons.A randomized block design was used,consisting of five treatments and four replications.Five concentrations(0,3%,5%,7%,and 10%)were tested here and six weekly replicates of each concentration was applied.The different kaolin concentrations and seasonal variations resulted in a quadratic response of the leaf SPAD reading during both daily evaluation periods.KBPF applications resulted in a quadratic response of photochemical efficiency in the morning period,and an increasing specific leaf weight linear response,and during the dry season,the different kaolin concentrations resulted in a bud length quadratic response.The results indicated that the kaolin application maintained the production and yield index statistically equal between weekly KBPF applications,improving photochemical efficiency,leaf thickness,SPAD reading,and bud length.The use of KBPF could reduce the intervals between collections of mini-cuttings and increase nursery yields in environments that present high temperatures.展开更多
文摘Global climate changes have increased temperatures,radiation indexes,and consequently,irregularities in rainfall in mainly tropical countries,considerably hindering plant establishment in recovering degraded areas.The objective of this study was to evaluate the growth and physiological characteristics of one species of each successional group:pioneer,secondary,and climax when subjected to different light intensities and hydrogel as a soil conditioner during rainy and dry periods.The experiment was conducted in the ecotone between Brazil’s two largest biomes,the Cerrado and the Amazon in the State of Maranh?o.The parameters consisted of three species:Guazuma ulmifolia Lam.(pioneer),Astronium fraxinifolium Schott(secondary),and Cariniana rubra Gardner ex Miers(climax).There were two light intensities:70%and 100%,and two planting conditions:with and without soil conditioner(hydrogel).Gas exchanges were higher during the rainy season;the pioneer and secondary species had greater heights and photosynthetic rates in the dry period;the climax species had the lowest gas exchange and lowest recovery as rainfall resumed.The pioneer and secondary species showed higher physiological plasticity,denoting better adaption to environments with high irradiance.Hydrogel improved the photosynthetic performance of these species in the dry season and in areas with 100%sunlight.
基金financially supported by CAPES(Coordenacao de Aperfeicoamento de Pessoal de Nível Superior)to CNPq(Conselho Nacional de Desenvolvimento Científico e Tecnológico)+2 种基金to FAPEMA(Fundacao de AmparoàPesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhao)FAPERJ(Fundacao Carlos Chagas Filho de AmparoàPesquisa do Estado do Rio de Janeiro)CNPq(fellowships awarded 312959/2019,Campostrini E.)。
文摘Considering the expansion of forest plantations over the Brazilian territory and the imminent increase in air temperatures due to global warming,the search for technologies that ensure high levels of productivity and high quality plants in clonal nurseries is essential.Applying kaolin-based particle films(KBPF)has been used as a physical barrier to reduce the negative effects of excessive solar radiation and adverse temperatures.The effects of KBPF on production and physiological quality of eucalyptus mini-cuttings were evaluated during two different seasons.A randomized block design was used,consisting of five treatments and four replications.Five concentrations(0,3%,5%,7%,and 10%)were tested here and six weekly replicates of each concentration was applied.The different kaolin concentrations and seasonal variations resulted in a quadratic response of the leaf SPAD reading during both daily evaluation periods.KBPF applications resulted in a quadratic response of photochemical efficiency in the morning period,and an increasing specific leaf weight linear response,and during the dry season,the different kaolin concentrations resulted in a bud length quadratic response.The results indicated that the kaolin application maintained the production and yield index statistically equal between weekly KBPF applications,improving photochemical efficiency,leaf thickness,SPAD reading,and bud length.The use of KBPF could reduce the intervals between collections of mini-cuttings and increase nursery yields in environments that present high temperatures.
