RESUMO: Os reguladores de crescimento das plantas são um imenso grupo de substâncias que têm a capacidade de alterar o padrão de crescimento das plantas e podem ser utilizadas para melhorar o crescimento e a produtividade das plantas. Foi realizado um estudo nas pastagens de Xilin Gol, na Mongólia Interior (China), para determinar o crescimento e a produção de biomassa de Stipa krylovii em resposta à aplicação exógena de diferentes reguladores de crescimento em várias concentrações, a saber: ácido naftaleno acético (NAA), 6-benzilaminopurina (6-BA), brassinosteroide (BR), nitrofenolato de sódio (SNP) e forchlorfenuron, e ácido giberélico (GA3). A aplicação de reguladores de crescimento aumentou de forma significativa o crescimento e a produção de biomassa de S. krylovii. Houve melhora na altura do eixo vegetativo pela aplicação de 100 mg L-1 de GA3, ao passo que a altura do eixo reprodutivo foi aumentada nas concentrações de 25 mg L-1 de 6-BA, 100 mg L-1 de SNP + 5 mg L-1 de forchlorfenuron e 50 mg L-1 de SNP + 2,5 mg L-1 de forchlorfenuron, em comparação com a testemunha. Houve aumento da biomassa fresca com a aplicação de 0,02 mg L-1 de BR, 10 mg L-1 de SNP + 0,5 mg L-1 de forchlorfenuron e 50 mg L-1 de SNP + 2,5 mg L-1 de forchlorfenuron. A aplicação de 5 mg L-1 de 6-BA e 50 mg L-1 de SNP + 2,5 mg L-1 de forchlorfenuron mostrou-se mais benéfica no aumento da biomassa seca de S. krylovii, em comparação com a testemunha. Em conclusão, a aplicação exógena de diferentes reguladores de crescimento melhorou o crescimento e produção de biomassa de S. krylovii. Além disso, a aplicação de SNP + forchlorfenuron e 6-BA foi mais eficaz.

ABSTRACT: Plant growth regulators are an immense group of substances that have the ability to alter growth pattern of plants and can be used for improving plant growth and productivity. A study was conducted in the Xilin Gol grassland of Inner Mongolia, China, to ascertain the growth and biomass production of Stipa krylovii in response to exogenous application of different growth regulators at various concentrations viz. naphthalene acetic acid (NAA), 6-benzylaminopurine (6-BA), brassinosteroid (BR), sodium nitrophenolate (SNP) and forchlorfenuron, and gibberellic acid (GA3). Application of growth regulators significantly enhanced the growth and biomass production of S. krylovii. The height of vegetative shoot was enhanced mostly by the application of 100 mg L-1 GA3, while, height of reproductive shoot was increased by 25 mg L-1 6-BA, 100 mg L-1 SNP + 5 mg L-1 forchlorfenuron and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron as compared to control. Fresh biomass was enhanced by the application of 0.02 mg L-1 BR, 10 mg L-1 SNP + 0.5 mg L-1 forchlorfenuron and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron. Application of 5 mg L-1 6-BA and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron proved to be more beneficial in improving dry biomass of S. krylovii, as compared to control. In conclusion, exogenous application of different growth regulators improved growth and biomass production of S. krylovii. Furthermore, application of SNP + forchlorfenuron and 6-BA was more effective.

ABSTRACTThis experiment was conducted to evaluate the combination effect of low dietary non-phytate phosphorus (NPP) concentrations, phytase (PHY) levels, and 25-hydroxycholecalciferol (25-OH-D3) levels on the growth performance and meat quality of broilers. Two levels of NPP, two levels of PHY, and two levels of 25-OH-D3 resulted in a 2�2�2 factorial arrangements, with eight treatments (TRT). The birds on TRT 1-4 were fed diet 1 (NRC NPP was reduced by 0.1) and the birds on TRT 5-8 were fed with diet 2 (NRC NPP was reduced by 0.2). Each diet was mixed with different levels PHY and 25-OH-D3. Performance and meat quality parameters were measured. Results showed that during entire experiment the most advantageous effects were obtained with TRT 3 (NRC NPP reduced by 0.1 + 600 U/kg phytase + 34.5�g/kg 25-OH-D3) and TRT 4 (NRC NPP reduced by 0.1 + 600 U/kg phytase + 69�g/kg 25-OH-D3). The lowest body weight gain (BWG) and feed intake(FI) were observed with TRT 5 (NRC NPP reduced by 0.2 + 300 U/kg phytase + 34.5�g/kg 25-OH-D3). Lowering NRC NPP by 0.1 to 0.2 significantly reduced weight gain (WG) (p< 0.05) and FI (p< 0.05) during the starter phase (ST), while during grower phase (GF) lowering NRC NPP by 0.1 to 0.2 did not affect WG (p>0.05) and produced small decrease in FI. BWG, FI and feed conversion ratio were not influenced (p>0.05) by different PHY or 25-OH-D3 levels. In addition, the meat color, pH, and shear force were not affected by the different NPP, PHY or 25-OH-D3levels.